Creating a Materials Library for Mechanical Engineering Students
by
Patricia Das and Roget Mo
Submitted to the
Department of Mechanical Engineering
in Partial Fulfillment of the Requirements for the Degree of Bachelor of Science in Mechanical Engineering
at the
Massachusetts Institute of Technology
June 2017
2017 Patricia Das and Roget Mo. All rights reserved.
Signature of Authors: Certified by: Accepted by: OF TEGHNOLOGY
JUL 2
5
201
LIBRARIES
ARCHIVES
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Department of Mechanical EngineeringMay 23, 2017
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I D yrtment of Mechanical Engineering
inauMae red17
Signature redacted
David Wallace Professor of Mechanical Engineering
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ThesisSupervisorRohit Karnik Associate Professor of Mechanical Engineering Undergraduate Officer
The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in
Creating a Materials Library for Mechanical Engineering Students
by
Patricia Das and Roget Mo
Submitted to the Department of Mechanical Engineering on May 23, 2017 in Partial Fulfillment of the
Requirements for the Degree of
Bachelor of Science in Mechanical Engineering
ABSTRACT
A material can enhance or distract from the end-user experience and is an important decision for
designers. As such, material libraries exist to provide designers with a hands-on resource to understanding materials beyond just data sheets. When we took 2.009, a mechanical engineering capstone class, we found it difficult to decide which materials to use. Thus, in this work, we sought to create a materials library under an engineering context for student product designers to use.
To understand how material libraries function and which materials would best suit the collection, we benchmarked three physical and one virtual material library. We also sought input from those involved in product design classes, such as past students, Professor Wallace who teaches 2.009, and Pappalardo shop staff who support the students in their creations. We also looked at past receipts to supplement our knowledge as well as looked at distributors and what they offered to expand our selection. Our six main categories of materials were: woods, metals, composites, polymers, fabrics, and Smooth-On products.
The material libraries key criteria were to be well organized, portable, and useful. We went through several design sketches before deciding on utilizing a modular wire rack so we could place dividers and shelves as necessary. A coding system was also implemented that included
main categories and subcategories with associated colors to help with the user experience of quickly locating, using, and returning. Each material comes attached with information and a more complete overview is located in an information packet.
While this first version the materials library was met with excitement, it is by no means
complete. As such, there are also a number of ways to improve the experience and the collection.
Thesis Supervisor: David Wallace
Acknowledgments
First and foremost, we would like to thank Professor Wallace for providing us with this opportunity to work on a materials library, as well as for his guidance and patience with our unexpected drop-ins to ask him a plethora of random questions.
We would like to thank Chevalley Duhart for fielding all our reimbursement requests and for helping us place an order for dividers for the wire rack. Thank you to Rachel Reed as well for being amazing and helping us order materials as well as being patient and answering our questions and Victor Hung for taking a few minutes out of his schedule and helping us learn how to use the vinyl cutter.
Additionally, we would like to thank the Pappalardo Staff. Thanks to Danny Braunstein for putting up with us (again!) for another semester and allowing us to work in Pappalardo, Jimmy Dudley for taking the time out of his busy schedule to help us cut our larger materials, Steve Haberek finding us the biggest mallet possible and offering us pizza, and Tasker Smith for sharing his expertise and excitement about material libraries. Without their help, this thesis would not have been possible.
We would also like to thank the staff at the Boston Architectural College, Harvard's Material Collection, and Materials Connexion for answering our questions and hosting us.
A special shout-out to Sabrine Ahmed Iqbal '17 and Daphne Lin '19 for their support in
prepping the materials library and help in giving feedback.
Patricia would like to thank her parents for allowing her to realize her own potential.
Roget would like to thank her family for their support throughout writing this thesis and also life in general.
Table of Contents Abstract 2 Acknowledgements 3 Table of Contents 4 List of Figures 6 1. Introduction 7 1.1 Motivation 7 1.2 2.009 Experience 8 1.3 Scope 10 2. Benchmarking 11
2.1 Case 1: The Materials Library at Boston Architectural College 11
2.1.1 Features 11
2.1.2 Analysis 11
2.2 Case 2: The Materials Collection at Harvard University GSD 13
2.2.1 Features 13
2.2.2 Analysis 15
2.3 Case 3: Materials Connexion 17
2.3.1 Features 17
2.3.2 Analysis 20
2.4 Case 4: Virtual SolidWorks Materials Library 20
2.4.1 Features 20
2.4.2 Analysis 21
3. Materials 22
3.1 Selection Criteria 22
3.1.1 Input from Others 22
3.1.2 2.009 Receipts from 2013 22
3.1.3 2.009 Product Gallery 23
3.2 Final Materials 23
3.2.1 Woods 24
3.2.3 Composites 27 3.2.4 Fabrics 28 3.2.5 Polymers 29 3.2.6 Smooth-On 30 4. Library Design 31 4.1 Requirements 31 4.2 Design Iterations 32 4.3 Final Design 35
4.3.1 Wire Rack Shelving 35
4.3.2 Coding System 38
4.3.3 Design of Rack Labels 39
4.3.4 Design of Material Labels 40
4.3.5 Design of Information Packet 41
5. User Testing 44 6. Conclusions 45 6.1 Summary 45 6.2 Future Work 45 7. Bibliography 47 8. Appendices 48 Appendix A: Distributors 48
List of Figures
Figure 1: Initial sketch of vertical treadmill game. 9
Figure 2: One wall of the BAC materials library. 12
Figure 3: The viewing station for materials at the BAC material's library. 13 Figure 4: One of the shelves at Harvard's materials library. 15
Figure 5: A typical entry in Harvard's material library. 16
Figure 6: A typical information sheet included in an entry at Harvard's material library. 16
Figure 7: Materials laid out on a table. 18
Figure 8: Material Connexion's display 19
Figure 9: A display of a natural material. 19
Figure 10: SolidWorks materials rendering. 21
Figure 11: A typical wood sample. 25
Figure 12: A typical metal sample. 26
Figure 13: One of our composite samples. 27
Figure 14: A typical fabric sample. 28
Figure 15: A typical polymer sample. 29
Figure 16: A typical Smooth-On sample set. 30
Figure 17: Pegboard with materials. 33
Figure 18: Display or wall with materials mounted. 33
Figure 19: Rolling display. 34
Figure 20: A bookshelf idea. 35
Figure 21: Smooth-On samples stored in containers. 36
Figure 22: Our final materials library. 37
Figure 23: A key describing the coding system. 38
Figure 24: An example code. 38
Figure 25: The coding system used for box placement on the shelves. 40 Figure 26: An example label for one of the material samples. 41 Figure 27: A two-page spread of the introduction to the woods category. 42
1. Introduction
Material libraries exist to provide designers with a hands-on resource to understanding materials and their properties beyond just data sheets and online resources. A material can enhance or distract from the end-user experience and is an important decision for designers in creating form for the product as well as facilitating how the user interacts with the product.
Currently, it is difficult to find materials libraries that service the general public. A small selection of design, art, and architectural colleges also have a materials library to support their interior design, industrial design, and architecture students. In addition, design firms will also have their own internal proprietary libraries to help facilitate communication with their clients and to understand what their clients are looking for.
MIT currently does not have a materials library, and even more so in an engineering context. MIT students would most likely encounter a materials library by using CAD software, however, they are provided under the context of running simulations and so do not provide the user with any information with respect aesthetics of the materials. Thus, there is not room for an engineering student to consider the design implications of using a certain material picked using an engineering analysis.
1.1 Motivation
In the mechanical engineering capstone class, 2.009: Product Engineering Processes, students work to design and build high quality, functional alpha prototypes of new products. During this product design process, exploring different materials can often aid in creativity and/or detailed execution. Material libraries offer a connection between the creative design process and the science and engineering behind materials. We are two students who were both on the same team in 2.009 and aim to create such a library for mechanical engineering students.
Through the benchmarking of existing materials libraries in the fields of design and technology and the gathering of data from 2.009 and the students who have participated in it, a first version of the materials library was designed and implemented.
1.2 2.009 Experience
Every fall semester, in 2.009, 8 groups of students are given a budget of $7000 and less than 4 months to go from ideation to full alpha prototype product [1]. With such a tight timeline and a need to deliver, obtaining the necessary information and making critical decisions can be challenging, especially when deciding what materials to use for the students' final product.
During our experience in 2.009, we struggled when benchmarking other products, trying to find similar materials to use, and locating distributors to purchase said materials. Our product was a vertical treadmill that serves as an interactive rock-climbing game for kids [2]. Initially, when we came up with this idea, it was relatively late in the ideation stage, so we had to immediately jump to creating a miniature wall as a proof of concept (Figure 1). We had to go through the mockup stage in less than a week and struggled to figure out how we were going to build a miniature prototype. We thought that pieces of wood were needed to support the rock-hold panels for a proof-of-concept mockup. We were worried that we would have to disassemble and reassemble the wood a few times, which would waste time since the rock-hold panels were what we were interested in testing.
variable climb holdings
adjustable incline set routes/difficulty
level
alterable climb routes
Figure 1: Initial sketch of vertical treadmill game. Sourced from Red Team's mockup
presentation.
In a moment of desperation, we were struck with inspiration of using aluminum 80-20s instead of wood for our structure for ease of building the prototype, allowing us to have the panels slide (since 80-20s have T-slots for sliding) [3]. But, the only reason we could come up with such a simple solution to our material needs was because we had previous exposure to using
80-20s, whereas the rest the members had not used it before.
And, even when we created the actual product, we found it difficult to make the jump from aluminum 80-20s to perforated steel tubing, and then finally steel tubing. We also made the mistake of buying galvanized steel when we needed to weld our steel tubes together, so we had to spend time sanding off the galvanized coating. This wasted time that could have been spent on other parts of the product, simply because we did not realize there was a difference between galvanized and ungalvanized steel.
This short narrative of our experience illustrates the need for a materials library in a design context. Most of our materials for our product were procured based on previous exposure
to materials, consulting our mentors on how to proceed, or trying to understand what materials similar products used. The other part is that throughout our mechanical engineering career, we are given the tools to problem solve and understand materials, however, we have had less exposure and opportunities to explore the amount of materials that there are and to interact and understand them from an aesthetic and design standpoint.
1.3 Scope
Because this work involved creating a materials library from scratch, the scope of the project was defined as a first version that has common and some interesting materials. The material sample should also have accompanying information. All the information should also be centralized in a database. The final deliverable is a physical materials library with materials that can be used for products in an engineering context. In particular, the library will help supplement the design experience for engineering students in 2.009.
2. Benchmarking
To gain an understanding of how material libraries functioned, we visited three material libraries and looked at a virtual material library.
2.1 Case 1: The Materials Library at Boston Architectural College
2.1.1 Features
The Materials Library at the Boston Architectural College (BAC) is a self-service library that is accessible to students and faculty. The library features thousands of samples, including ceramic tile, fabric, glass, and metal. In addition, the library houses a range of material samples that are geared more specifically towards the architectural and interior architectural field such as a wide variety of flooring options, a large selection of window treatments, and furniture
hardware.
One key point that was noted when speaking with Denise Rush, the Director of Undergraduate Interior Architecture at BAC with regards to their materials library is that their system originally was organized differently because they had a full-time staff member to maintain the system. However, due to the full-time staff member leaving, the library is now monitored by student workers and the library itself had to be catalogued and restructured since only the full-time staff member knew what was in the library and there was no online database that the student workers could consult.
2.1.2 Analysis
The library utilized various design styles (Figure 2). One wall consisted of bookshelves with a variety of sample sets from companies and manufacturers in binder format, ring format, and box sets. These collections allowed users to browse the different materials and subsequently encouraged users to contact the manufacturers if they wished to acquire the material. For the
library, the upkeep of such a design is optimal for maintainability, as these samples did not require replenishment.
The library also included various shelves that had boxes of miscellaneous samples that users were able to check-out for a period of time, as well as other samples that users were welcome to keep. It was not immediately obvious which samples needed to be returned and which samples were dispensable. The checkout process relied on the honor system in which students sign-out materials and are trusted to return them. As there was a large range of samples, with constant new additions, there was no maintained online database.
Figure 2: One wall of the BAC materials library. The design appears very assorted with a mix of binders, box sets, and miscellaneous samples.
A unique design feature of this library was a viewing station for the materials as shown in Figure 3. This consists of a white box with interchangeable light bulbs of different colors. This allows users to experiment with different materials and see how the lighting affects their color.
Figure 3: The viewing station for materials at the BAC material's library. Users can
examine how different materials change appearance under different lighting conditions.
2.2 Case 2: The Materials Collection at Harvard University GSD
2.2.1 Features
The Materials Collection at the Harvard University Graduate School of Design is a collection of over 600 materials. With both a physical collection and an online database, it encourages users to rethink conventional material applications and promote design
experimentation [4]. The materials are organized into five categories and subcategories as follows:
A. Biocomposites: Biologically derived composites of polymers and fibers that contain mostly organic and sometimes inorganic compounds sourced from living organisms and/or
formed by biochemical processes Al. Plant.
A2. Animal A3. Fungi
B. Polymers: Petroleum-derived, human-made, non-renewable materials comprised of long, repeating, molecular chains whose central atom is almost always carbon
B 1. Thermoplastic B2. Thermoset B3. Elastomer
C. Metals: Pure metallic elements, compounds, and alloys characterized by metallic bonds
whose atoms readily lose electrons to form positive ions (cations)
C1. Ferrous C2. Non-Ferrous
D. Minerals: Inorganic, crystalline solids, and chemical compounds possessing a
characteristic crystalline structure and chemical composition, sometimes with restricted variations
D1. Geogenic D2. Anthropogenic
E. Ceramics: Nonmetallic, inorganic solids formed by the ionic bonding of mineral material
through human based processes of mixing and/or heating
El. Clay-Based E2. Cementitious E3. Glass
There were clear posted instructions throughout the library for the users:
1. Look up materials in database
2. Remove box from shelf
3. Use work tables to examine materials
2.2.2 Analysis
The library design consisted of a very organized system of shelves. Each material had its own entry, which was placed in its own upright file, size permitting, as shown in Figure 4.
Within each file, for the same material, there was usually a number of samples with variations in size, color, and sometimes texture. Each file also contained an information packet with key facts about the material, including manufacturer information, specifications from data sheets, as well as examples of how the material can be used in different design applications (Figures 5 and 6). For materials that were too bulky, they were placed directly on the shelf, but had visible labels. The materials in the physical collection are ordered based on a coding system, making things easier to find from the accompanying online database.
I
I
Figure 4: One of the shelves at Harvard's materials library. Each material is in its own
Figure 5: A typical entry in Harvard's material library. It was moved from the shelf to
the table for examining.
*umemm
27
Figure 6: A typical information sheet included in an entry at Harvard's material library.
It includes keys facts such as flame shield, fire classification, temperature stability, and colors available.
2.3 Case 3: Material Connexion
2.3.1 Features
Located in New York, Material Connexion is one of 17 full-service materials libraries in the world and the only one in the United States. Members pay a fee to gain access to their database and can visit the library to experience the materials firsthand. Every month, the employees of Material Connexion evaluate 50 to 60 material samples that are sent to them, and they pick the most compelling to display. The materials located at Material Connexion are broken down into eight categories, and the provided description is as follows:
1. Carbon-based: materials whose main constituent is carbon in the form of diamond, graphite, buckyballs, nanotubes, or carbon fiber
2. Cement-based: composites of Portland or other cement with additives such as sand, glass, metal fibers, or other aggregates
3. Ceramic: a molecular combination of a metal such as aluminum or zinc and a nonmetal such as oxygen or carbon to create hard, durable, heat-resistant, and electrically insulating materials
4. Glass: amorphous or crystalline structures of ceramics based upon silicon and oxygen (SiO2) that are transparent or translucent
5. Metal: a single metallic element or combination of metallic and other elements (alloy) that produces ductile, durable, electrically and heat-conductive materials that tend to reflect light,
6. Natural: a material that has been grown or mined from the earth
7. Polymer: long-chain molecules, mostly carbon based which are synthetic, moldable, colorable, and lightweight
8. Process: a manufacturing method to combine, deposit, form, foam, or otherwise manipulate a material.
Users can come into the library and take the materials off the display shelves to the back table to arrange and compare (Figure 7). There are also computers provided so that users may access the online database. Each material is mounted to its own display board and color-coded with its category. The material is mounted using either adhesives, zip ties, screws, or brackets (Figure 8). Each material is also labeled in the format of ##-###. The first number before the dash represents the manufacturer, the second number represents the material number. This number needs to be inputted into the online database in order to obtain the material information as well as the manufacturer. There is a brief description of the material as well as icons if certain characteristics apply (i.e. light, environmentally friendly, food safe, etc.) On the display is also a QR code and barcode that users can scan to look up detailed information immediately using their phones (Figure 9). Additionally, the material sample's display does not have the name of the material on it, so users re forced to look at and interact with the material.
Figure 7: Materials laid out on a table. A user had been comparing different materials he was interested in.
Figure 8: Material Connexion's display. Materials were hung on these "walls" and could
be removed and brought to the back table to look at.
Figure 9: A display of a natural material. The material is displayed, along with a brief
description, a QR code, a labeling code, and an icon indicating that it is recyclable.
Because Material Connexion serves a wide audience and because the materials are there to show their innovative purposes, the material sample displays do not seem to lend themselves to being checked out and instead is more of sampling the potential that the material may hold. In fact, if one wanted to spend some more time with the material, one would have to request to rent
it.
2.3.2 Analysis
The strengths of this library compared to Boston Architectural College's materials library is the variety of information that is available, the online database, the full-time staff, and the amount of materials. The weaknesses, however, is that there is only one material example, because the intent is to showcase the interesting materials to a variety of audiences, whereas for
BAC, there was a variety of woods to help architectural students decide on the exact flooring
they want. Material Connexion also has a full-time staff to maintain, update, and service the library and its guests. With BAC, due to changes in staff, BAC has less manpower to maintain and look after the library, so they have turned to student involvement. Material Connexion does not supply samples for customers to take, however, BAC does allow their students to browse through the extra samples bins.
2.4 Case 4: Virtual SolidiWorks Materials Library
2.4.1 Features
Material libraries under an engineering context aren't readily accessible, if at all, to engineering students, except in.the case of using CAD programs such as SolidWorks. As such, SolidWorks' materials library was benchmarked. SolidWorks offers engineers the ability to apply a material to a CAD and to simulate engineering tests. The library also has relevant parameters such as Young's modulus and tensile strength. There are a variety of metals and
polymers, and students can even add to the materials library if they want to CAD a part in a specific material.
2.4.2 Analysis
The downside of material libraries that are accessible on a computer is that they are not physical. For example, in SolidWorks, although a material can be applied to a CAD part, it is not discernable by eye. Aluminum looks the same as steel - both are gray bars. Even when applying plastic, the material still looks gray unless a texture is applied, and even then, the texture
ultimately depends on how well it is rendered. Thus, the visual properties of the CAD model and material can be misleading (Figure 10).
Figure 10: SolidWorks materials rendering. Different textures can be rendered to indicate different materials. Sourced from GrabCad.
BAC and SolidWorks's have different approaches to their materials library. SolidWorks assumes the user already knows which material they would like to use, whereas BAC assumes the user does not and encourages the user to go through the information. The two materials
3. Materials
3.1 Selection Criteria
To gain a sense of which materials would be most useful in an engineering library, input from various people were sought after, receipts of 2.009 purchases of a previous year were looked at, and the 2.009 gallery was browsed.
3.1.1 Input from Others
A survey was sent out to some past 2.009 students asking them about their material usage and what they found to be the most important factors in making their materials selections.
Although we did not receive many responses, combined with our own experiences, a few common user needs did emerge, such as ease of access and similarity to finished products.
This input helped guide us through the process of filtering the past 2.009 receipts to understand what materials were being purchased.
3.1.2 2.009 Receipts from 2013
To get a sense of what materials 2.009 teams had explored in the past, we looked at receipts from 2013 to understand which materials teams were purchasing. We wanted to look at raw materials, such as metals, woods, polymers, fabrics, coatings, and anything else that was
interesting or could be used for building. We ignored electronics and benchmarking materials. We recorded the name of the material, the product ID number, the cost, the amount, the vendor, and the team.
In particular, we were interested in looking at the types of materials purchased and the vendor. We were interested in the vendor because we wanted to see what else they had to offer
and where to purchase materials for our library. In particular, the three most used stores were Reynolds Advanced Materials, McMaster-Carr, and Home Depot. Reynolds Advanced Materials
mainly sold mold-making and casting materials, including plastics, resins, and foams. McMaster-Carr was a jack of all trades and sold anything including metals, composites, polymers, fabrics, and even some woods. Home Depot mainly sold wood which most teams acquired this through the 2.009 store.
3.1.3 2.009 Product Gallery
Since there wasn't access to other years 2.009 receipts, we decided to also browse the
2.009 Product Gallery to see if any materials were highlighted as key components and to
understand how certain products might be made. For the most part, materials were not highlighted in the product brochures. The ones that were mentioned were mentioned because they were used in an innovative way or known for their novelty.
3.2 Final Materials
Initially, a list was made of the materials based on what was commonly used in 2.009 receipts, product galleries, and discussion with others. We then organized this list into categories consisting of metals, woods, fabrics, composites, and coatings. However, because we wanted to expand the available options and exposure to materials, we also looked at what the distributors had to offer and based our list off of their catalogue. We tried to keep to one distributor per category so that we could obtain everything we needed in one-stop, but also tried to find a distributor that had a variety of materials. We began by looking at McMaster-Carr for metals, Home Depot for woods, and Reynolds Advanced Materials for polymers.
However, once we looked at the cost of the materials we wanted, we were concerned that it might be too much, especially considering we had not even budgeted for the actual
buying raw materials, so that meant we would have to cut everything to size and there would be excess materials leftover, which would be a waste.
We had a breakthrough when we decided to visit Pappalardo to discuss what they would recommend as a display for the materials library since the shop staff understand the lab the best and have observed the students at work. Steve Banzaert suggested that we look for sample sets of materials and to see if they can be obtained for free [5]. The goal was to create a materials library rather than to fabricate individual material sample sets. Thus, the cost of the original budget for the materials library would be reduced and there would not be excess materials.
3.2.1 Woods
From the receipts, it was observed that most teams obtained Home Depot wood through the 2.009 store and used what was available at the time. Thus, the goal for woods was to offer a broader selection so that students can begin to consider the aesthetics and difference between wood properties. To do so, woods were divided into the subcategories of hardwoods and softwoods.
Initially, a list was drafted up with respect to which woods are good for beginners to use while still giving options for staining and different finishes [6]. However, the selection quickly expanded once we found a distributor, Boulter Plywood Corporation [7], that had a large sample set of woods. We obtained two sample sets, one of different woods, and one of woods with different thicknesses that could be laser cut. The laser cut sample set is important because it showcases the versatility of woods that woods have.
Most of the woods are 8 inches by 8 inches as this was the size of the sample set we obtained, and we cut the larger samples we obtained to match this size (Figure 11). The woods we obtained from the laser cutting samples are 6 inches by 6 inches.
Figure 11: A typical wood sample. This specific sample is an 8" by 8" piece of OSB.
3.2.2 Metals
Aluminum and steel were the only two types of metals we decided to include. Most 2.009 students used McMaster-Carr for their metals, so when looking at their metal offerings, we initially included titanium, bronze, and copper. However, these materials are extremely expensive and are for very specific uses. For example, although titanium is strong and lightweight and is great against resisting corrosion in marine environments, for 2.009, it is unlikely that students will order this expensive material especially considering budgetary constraints. In addition, titanium is mostly used in aircraft, spacecraft, and missiles, and it is unlikely that in the scope of 2.009, students will start building such products. Finally, these metals are difficult to machine, so we d6cided to exclude them.
Still, there were some types of aluminum and steel that were not applicable to 2.009. For example, aluminum 2024 and 7075 are generally used for aircraft purposes or where strength is extremely critical. Stainless steel 316 has better corrosion resistance compared to stainless steel
304, but stainless steel 316 is more expensive and given the time scale of 2.009, it is not expected that the final alpha prototype not have a product life cycle long to see corrosion.
Thus, for metals, a few select examples of aluminum and steel were chosen. For steel, galvanized was chosen to showcase the coating regarding corrosion and to educate that ungalvanized helps with weldability. Stainless steel was chosen because it is used in food handling and processing, as well as for chemicals and welding. Then, hot rolled and cold rolled steel were chosen to help with understanding how different treatments affect the tolerances of steel.
On the other hand, aluminum is a very versatile metal. Rods, sheets, and bars are
relatively common, so the focus was placed on interesting form factors that aluminum can come in. For example, honeycomb is interesting in that it is lightweight yet still strong. 80-20s were also chosen to help with ease of prototyping while also allowing strength. Most of the metal samples were 6 inches by 6 inches (Figure 12). This is an ideal size for examining without being too heavy to handle.
Figure 12: A typical metal sample. This specific sample is a 6" by 6" piece of 3003
3.2.3 Composites
We wanted to include some unique composite materials in our library. The two we decided on are carbon fiber and fiberglass. These two fiber-reinforced plastics are extremely strong and lightweight. The two are similar in many ways, but their differences could be of interest to users. For example, carbon fiber is slightly stronger than fiberglass and can replace metal in certain applications. On the other hand, fiberglass has a lower tensile strength, but a much lower tensile modulus allows it to bend and strain more without breaking [8]. We also wanted to have these two materials in their own category, rather than with the rest of the polymers, due to the safety hazards that they pose. When the material is cut, the fibers they create pose an inhalation risk.
Because the materials cannot be cut using traditional methods, we left each sample at its manufactured sized of 12 inches by 12 inches. We also taped the edges of the material to minimize damage when sliding the sample in and out of its slot (Figure 13).
Figure 13: One of our composite samples. This is a 12" by 12" piece of Fiberglass. The sides are taped to prevent damage.
3.2.4 Fabrics
In our final selection of fabrics, we wanted to include a range of fabrics with varied applications, including flame resistant, water repellent, and porous. As our library is geared toward engineering students, we avoided some of the more typical upholstery fabrics and textiles that we observed at the materials libraries in BAC. We turned to McMaster-Carr for their wide range of fabrics. Many of their fabrics come in different varieties, so we selected one with a specific feature such as heat resistance, but also noted the other varieties available. This way, students can get a general understanding for a fabric, but also learn about other options that are available and might better suit their needs. We also did this to avoid wasting the fabrics because they came in very large rolls and we only needed a small square.
The fabrics were cut to a size of 6 inches by 6 inches and then mounted on some of the balsa and cedar wood that we had leftover. They were mounted with a large binder clip (Figure 14), allowing them to be easily removed and better observed.
Figure 14: A typical fabric sample. This specific sample is a 6" by 6" piece of HDPE Mesh Fabric. It is held to the wooden mounting board using a binder clip.
3.2.5 Polymers
We included a range of polymers that were popular in previous years of 2.009 as well as other common elastomers and thermoplastics. For some of the elastomers, we wanted the users to be able to observe the difference between durometers of the same polymer. To accomplish this, we included natural gum foam rubber in the three varieties that McMaster-Carr offers: ultra soft, extra soft, and medium. We also ordered neoprene rubber of five different hardness levels: 30A, 40A, 50A, 60A, and 70A.
The polymers were either purchased or cut to a size of 6 inches by 6 inches for ease of examination.
3.2.6 Smooth-On Materials
We had originally consulted Reynolds Advanced Materials for polymers, and after visiting, we discovered the large and comprehensive range of rubbers, plastics, and foams that Reynolds Advanced Materials had to offer were made by Smooth-On, Inc. The multitudes of samples were each labeled with information from Reynolds detailing the properties and uses of each material. Smooth-On also organized the information into a user-friendly online database
[9]. For these reasons, we decided to include Smooth-On products in their own category. This allowed us to adopt the sub-categorization techniques used by Smooth-On as well as easily access the information we wanted to include in our library. Our library now includes a range of casting epoxies, silicone and urethane foams and rubbers, and urethane plastics that can prove useful in a variety of prototyping applications (Figure 16).
Figure 16: A typical Smooth-On sample set. This sample is a set from the Smooth-Cast®
Collection, a group of urethane plastics.
4. Library Design
4.1 Requirements
With the selection of materials chosen with the goal of stimulating creativity when making design decisions by providing students with a range of material options, the library itself was be designed in such a way that this array of materials is presented in a useful manner. To make the library easier to use, one design requirement is that it should utilize a well-organized
system for categorization. This could be similar to the coding system that Harvard's Materials Library utilizes in which the categories and subcategories of the materials are coded and the entries are clearly labeled in that order. Another possibility is a color-coded system, which provides users with a visual cue to finding materials and replacing them, especially as they become more familiar with the system.
Another design requirement to make the system easy to use would be to allow multiple users to use the library at the same time. This can be achieved in a number of ways. One option is to have each material be its own entry that can be removed and examined separately. For this, the type of containers used to house each material must be taken into consideration. If a larger
container is utilized that contains multiple material entries, it means that all those materials would no longer be readily available for multiple users to browse at once, limiting the usefulness of the library. A system in which each material entry stands alone allows for maximum usage.
Along with the actual material samples, an important design decision is centered upon what information about the materials is presented and how it is presented. Considering the material libraries that were benchmarked, Harvard's library with each material having its own information booklet was something to be emulated. This is especially important in an
useful values, such as Young's modulus, yield strength, and other relevant engineering values were provided so that it may help a student decide which material they would like to use. In addition, information and examples about how this material has been used in a design context could aid in creativity. An online database could be another option for organizing useful information and having it readily accessible even when the physical library is not.
In designing a first order implementation of this materials library, it should be maintainable in order to extend the library's useful life, to prevent defects, and to, overall, maximize efficiency. On one hand, the design needs to encourage students to use the materials library freely and easily. We want them to be able to hold and examine the materials liberally. At the same time, there is the risk that users might borrow the material and forget to return it. This causes maintenance problems for library upkeep in terms of replenishing missing samples. An ideal library design should suggest the materials are not for keeping.
Along the lines of maintainability, it is important to consider the environment in which the library is to be housed in. Some of the selected materials, especially, the polymers can become easily damaged with dust or excess light exposure. As the Pappalardo Laboratory is a dusty environment, many of the materials need to be stored in such a way to preserve their condition for a long period of time. In addition, the library is to be housed in a small area of the lab. The design must be able to fit and be transported in and out of this allotted space.
Furthermore, as this is a first order implementation of the library, room for growth and additional material entries would a useful design feature.
4.2 Design Iterations
The design of the physical materials library went through several iterations. Initially, we imagined a large wall or rack where material samples could be hung, much like a peg board or a
shopping store where retail goods are hung and organized (Figures 17 & 18). However, we quickly realized that this would not be possible that this wall would take up valuable space in labs. In addition, hanging the heavier materials, such as steel, poses a risk of injury.
e
a-eer
Figure 17: Pegboard with materials. The materials would have a hole in which bead
chain would be thread. The info card would also accompany the material.
Figure 18: Display or wall with materials mounted. The name of the material would be
Then, we decided that there might be a need to make our own portable display board that was large enough and customized to our needs (Figure 19). However, this would require a
significant amount of time and would not be flexible in allowing the materials library to expand. We wanted to display the materials with the square side facing the user. This would not be a good use of space considering the amount of materials that we would have.
Figure 19: Rolling display. The materials would sit in troughs much like document
holders and the outside of the trough would have information.
To simplify things, we wanted to try and use CD separators or magazine holders. However, finding quality magazine and file holders at reasonable price was difficult to do. In addition, since our material samples were of assorted sizes with some reaches 12 inches by 12 inches, they were too large to fit inside CD holders. However, we did want to continue this line
of thinking and pursue modularity and ease of rearranging because it would be an efficient use of space. We started to brainstorm in the direction of a rolling bookshelf (Figure 20).
Figure 20: A bookshelf idea. The materials would show the thicknesses and would be either labeled or mounted onto a board if it was more flexible.
4.3 Final Design
4.3.1 Wire Rack Shelving System'
For our final design, we decided'to obtain a mobile wire shelving system from ULINE [10]. The racks come with shelves of adjustable height. This provides design freedom, allowing us to adjust the height to our sample sizes which ranged anywhere from 1 inch to 12 inches tall.
/CO
l~'ick%
ULINE also offers shelving dividers that can be used on the racks. This allows us to save space
as the materials are arranged much like books. To prevent the materials from falling through the gaps in the shelf, we lined the shelves with leftover wood and cardboard samples. This is temporary (but environmentally friendly) solution. Initially, we had purchased shelf liners from
ULINE, but unfortunately, they are too brittle to be cut down to size.
We decided on an open display that incorporates boxes to contain some of the polymers that are more sensitive light. We choose containers that were semi-clear to allow users to peer in, but also protect the polymers light and dust, since Pappalardo can also get dusty during building time. In addition, since the Smooth-On samples obtained from Reynolds Advanced Materials are mostly circular disks with holes, we decided to string together sample collections (Figure 21).
BOX
-12
S-UP-06
S-UP-07
Figure 21: Smooth-On samples stored in containers. Each set of samples is indicated by
their labels and strung together.
Our library is designed with a total of five shelves (Figure 22). We arranged the shelves with woods on the top two shelves. This is because they are lightweight and do not pose a large threat if they happen to fall on the user. Metals and composites were placed on the third shelf from the top. This is at a lower height, allowing the user to handle the heavier and more
dangerous materials with care. The fabrics fit in nicely on this shelf as well, as we had the perfect amount of slots to complete the shelf. Finally, the polymers and Smooth-On materials are toward the bottom. The boxes are relatively easier to grab on the lower levels, especially since we have one box stacked on top of another.
MateraLs Library To Use The System
Ma- ra s Lbrr
RtM~ R, Aa-a
Figure 22: Our final materials library. The shelving labels are color-coded and the sign describes how to use the library and explains the coding system.
4.3.2 Coding System
We developed a coding system for our materials consisting of three parts. The first part of the code is a letter indicating the main material category. The second part is a letter indicating the subcategory, if any. Finally, the last part of the code is a number, which was assigned to each material when placed in alphabetical order within its subcategory, or if none, category.
The System
S
mooth-On Casting Epoxies Foams Silicone Rubbers Urethane Plastics Urethane Rubbers Ijolymers Elastomers Thermoplasticsoods
Hardwoods Softwoods Engineered MiscellaneousI
etals
Aluminums Steels ompositesFUabrics
Figure 23: color.A key describing the coding system. Each main category is represented by a
EXA MPLE
S-CE-03
main category I I THIRD MATERIAL
SMOOTh-ON sub-category CASTING EPOXIES
Figure 24: An example code. "S" is used to indicate the main category of Smooth-On materials. "CE" is used to indicate the sub-category Casting Epoxies, "03" is used to indicate that his material was third within it subcategory when placed in alphabetical order.
4.3.3 Design of Rack Labels
For the library's labels on the shelf, we decided not to write the full name of the material, but instead use the coded system. This way, students are encouraged to browse through the materials and to take them out and explore them. At the same time, if something is missing, it is
also obvious to see the spot in which the material is missing from. We tried to keep the system simple by associating certain colors with their symbolic meaning. For example, woods are natural products so they are green. Another example is that users should be cautious with the composites, so they are orange like a traffic cone. We also wanted to keep in the theme of the end users being 2.009 students, thus, the specific colors chosen were pulled from the colors used on the 2.009 website. The labels were formatted on PhotoShop and plotted onto semi-matte paper, which was then attached to foam core and taped to the shelves.
In dealing with the Smooth-On boxes, we realized it might be unclear which box goes where, as they are stacked on top of each other. To avoid cluttering the rack labels with an abundance of codes in one spot, we developed a system where the rack has a label depicting two box numbers arranged vertically. Each box has a corresponding number so users know where to return it on the shelf (Figure 26).
BOX02
Figure 25: The coding system used for box placement on the shelves.
We also labeled the shelving library with the following directions on how to use the system:
" Take out material to examine. Each material has a label with info. " Read info packet for more details.
e Return material to their original material.
These directions imply that the materials can be removed to examine and that there is more information available. In addition, we wanted to emphasize that these materials need to be returned.
4.3.4 Design of Material Labels
To provide information to the users, we designed color-coded labels to go on each material sample that would have the name of the material, the code, and some important
parameters for engineering analysis (Figure 26). For the Smooth-On materials, the box itself is labeled with a box number as well as with the material code so the user knows which materials each box contains. The labels were printed onto 31/3 inch by 4 inch label paper.
Balsa is generally the lightest and softest of
commercial woods and is famous worldwide. It
has excellent sound, heat, and vibration insulating
properties, and is incredibly buoyant. It is used in
rafts, surfboards, and musical instruments.
AVERAGE DRIED WEIGHT
150 kg/M
3JANKA HARDNESS
300
N
MODULUS OF RUPTURE
19.6 MPa
ELASTIC MODULUS
3.71 GPa
CRUSHING STRENGTH
11.6 MPa
ROT RESISTANCE
perishable
DISTRIBUTOR: BOULTER PLYWOOD
Figure 26: An example label for one of the material samples. It is color-coded and includes the name of the material, a brief description, key information such as elastic
modulus and distributor.
4.3.5 Design of Information Packet
As the information that can be fit onto each material is limited, we decided to include an information packet, which contains more details. In addition to information about each material that was included on the individual labels, the information packet includes an introduction to each material category and subcategory, an explanation of relevant parameters, along with
images of each material (Figures 27 & 28). Students can also browse the packet without physically browsing through the materials.
oods
Wood is the cellular tissue of the tree inside the cambium and is composed of 40-50% cellulose, 20-30% hemiceluiose, and 20-30% lignin. Lignin makes
timber strong in compression and tension. Wood and wood products are
often graded based on the quaity of the feedstock.
H -Hardwoods: Hardwoods refer to woods derived from deciduous/ broad leaf trees (angiosperms). They are mostly harder in density than softwoods.
S - Softwooda: Softwoods refer to woods derived from coniferous/
evergreen trees (gymnosperms). They are mostly softer and easier to work than hardwoods.
E -Engineered: Engineered wood, also called composite wood, man-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles. fibers, or veneers or boards of wood, together with adhesives,
or other methods of fixation to form composite materials.
M -MIscellaneous: This category consists items related to woods but isn't expansive enough to have its own sub-category.
Figure 27: A two-page spread of the introduction to the woods category. On the left is information the category and sub-categories. On the right is an explanation of the key parameters in the woods section.
White Ash is one of the most commonly used hardwoods in N. America,
especially in shovels and hammers where toughness and impact resistance is important. It is often used in turned objects, and can be shaped with hand or machine tools.
I 675 kg/m3 5,870 N 103.5 MPa 12.00 GPa 51.1 MPa Perishable Boulter Plywood
Balsa is generally the lightest and softest of commercial woods and is famous worldwide. It has excellent sound, heat, and vibration insulating
properties, and is incredibly buoyant. It is used in rafts, surfboards, and
musical instruments. 4
~,,
p
AVERAGE DRIED WEIGHT
JANKA HARDNESS MODULUS OF RUPTURE ELASTIC MODULUS CRUSHING STRENGTH ROT RESISTANCE DISTRIBUTOR 150 kg/m3 300 N 19.6 MPa 3.71 GPa 11.6 MPa Perishable Boulter Plywood
Figure 28: A page with entries from the wood category. the labels, there is also an image of the material.
In addition to the information on AVERAGE DRIED WEIGHT
JANKA HARDNESS MODULUS OF RUPTURE ELASTIC MODULUS CRUSHING STRENGTH ROT RESISTANCE DISTRIBUTOR
5. User Testing
Although we were not able to do comprehensive user testing, we did have users interact with the library. In one instance, a third-year mechanical engineering student was observing the fabrics in the library. The fabrics were all originally attached onto their wooden mounting boards using Velcro, making them easy to remove from the board so that users can further examine them. The user was observing F-03, the HDPE mesh fabric. Upon trying to remove it from the board, the entire Velcro piece peeled off from the fabric. This was not the intention. After this user test, we revised our design so that the materials are attached to the mounting boards using a binder clip instead.
In another instance, we had a user try to locate materials. This was before we had set up the display board explaining the code. The setup was straightforward enough that she could figure out that "W" meant "woods" and it made sense to her that "H" was for "hardwoods" and
"S" was for "softwoods." When she figured out that "E" meant "engineered woods," she became
excited and exclaimed, "Oh, that makes perfect sense!" When we gave her another test of putting materials back, she could quickly locate the slot by first looking at the colors and then reading the rack labels for the specific material slot. This same user found that browsing through the materials was an exciting process of discovering interesting materials.
Although we could not conduct more rigorous user testing and we only had a small sample set, our initial interactions allowed us to make some changes and also showed that the materials library has promise for its ease of use. We would like to test this materials library on more users, however, this would probably be best done in the beginning of product design classes such as 2.009 when students are beginning to make design decisions.
6. Conclusions
6.1 Summary
Material libraries provide a resource to bridge the gap between the creative design process and the science and engineering of materials. We aimed to design and implement a first version of such a library for mechanical engineering students in the course 2.009, the mechanical engineering capstone class. From gathering the input of students and others involved in the course, and looking at historical information from the course's previous years, we selected a range of materials that would both be useful in the mechanical engineering context and, at the same time, offer a uniqueness to encourage the creative design process. Through the
benchmarking of existing materials libraries and the iterative design process, we developed and designed a materials library to house our material collection. The color-coded label system makes for an organized library. The featured information both on each material sample and in the information packet provide users with a useful starting point in their material explorations. Featuring a modular and portable shelving system, the library has the opportunity to change and grow over time.
6.2 Future Work
Although the materials library has been made, there is still quite a bit of work to do in order to refine it. The biggest drawback of this material library is that it has not undergone rigorous user testing. Since it is a materials library for 2.009, it must wait until the upcoming fall semester to be put to use. A long-term study should be conducted to understand which materials go missing and how often, and to identify the root causes. Furthermore, surveying students about the use of the materials library and their materials experience will be helpful to understand what
materials are most used and which are not. It could also be interesting to see how the materials library impacts 2.009 students' material selection behavior compared to previous years.
Finally, the materials library has room for growth. The original plan was to have small 1 square-inch cubes of different materials for students to easily one against the other, such as how aluminum might feel different from steel with respect to weight. The difficult part was obtaining materials of this size. Thus, it is recommended that material scraps and cubes are slowly
collected. Additionally, the products used to build the materials library are easily obtainable from ULINE. Therefore, it will not be too difficult to add more materials to the collection.
Overall, because this is a first version of a materials library, there is quite a lot to still optimize. The two biggest issues are user testing and expanding the selection. Despite this, our
Bibliography
[1] "2.009 Product Engineering Processes" [Online]. Available:
http://web.mit.edu/2.009/www/index.html. [Accessed: 22-May-2017].
[2] "2.009 Gallery -RTM (Fall 2016)" [Online]. Available: http://designed.mit.edu/gallery/list-2016.html. [Accessed: 22-May-2017].
[3] "McMaster-Carr -T-Slotted Framing" [Online]. Available:
https://www.mcmaster.com/#47065t101. [Accessed: 22-May-2017].
[4] "Materials Collection -Harvard Graduate School of Design" [Online]. Available:
http://www.gsd.harvard.edu/frances-loeb-library/materials-collection/. [Accessed: 22-May-2017].
[5] "MECHE PEOPLE: Stephen Banzaert I MIT Department of Mechanical Engineering" [Online]. Available: http://meche.mit.edu/people/staff/sgtist@mit.edu. [Accessed: 22-May-2017].
[6] "Woodworking For Dummies Cheat Sheet" [Online]. Available:
http://www.dummies.com/crafts/woodworking-for-dummies-cheat-sheet/. [Accessed: 22-May-2017].
[7] "BoulterPlywood.com...." [Online]. Available: http://boulterplywood.com/. [Accessed: 22-May-2017].
[8] "Carbon Fiber vs. Fiberglass -Infogram, Charts & Infographics" [Online]. Available: https://infogr.am/carbon-fiber-vs-fiberglass. [Accessed: 22-May-2017].
[9] "Smooth-On, Inc. I Mold Making & Casting Materials I Rubbers, Plastics, Foams & More!" [Online]. Available: https://www.smooth-on.com/. [Accessed: 22-May-2017].
[10] "ULINE - Shipping Boxes, Shipping Supplies, Packaging Materials, Packing Supplies" [Online]. Available: https://www.uline.com/. [Accessed: 22-May-2017].
[11] "The Wood Database" [Online]. Available: http://www.wood-database.com/. [Accessed: 22-May-2017].
[12] "Definitions of Technical Terms" [Online]. Available: https://www.smooth-on.com/support/faq/107/. [Accessed: 22-May-2017].
Appendix A: Distributors
Products Woods
Address 425 Riverside Ave
Medford, MA 02155
Website http://boulterplywood.com/
Phone 888-958-6237
E-mail Christopher Boulter (chris@boulterplywood.com)
Products Woods
Address 75 Mystic Ave
Somerville, MA 02143
Website http://www.homedepot.com/
Phone 617-623-0001
-Products Metals, Polymers, Fabrics
Address 200 New Canton Way Robbinsville, NJ 08691-2343 Website https://www.mcmaster.com/ Phone 609-689-3000 609-259-8900 E-mail nj.sales@mcmaster.com Products Metals
Address 16A 6th Road
Woburn, MA, 01801
Website https://www.metalsupermarkets.com/
Phone 781-933-0176
-Appendix B: The Information Packet
W - Woods: Wood is the cellular tissue of the tree inside the cambium and is composed of 40-50% cellulose, 20-30% hemicellulose, and 20-30% lignin. Lignin makes timber strong in compression and tension. Wood and wood products are often graded based on the quality of the feedstock.
H - Hardwoods: Hardwoods refer to woods derived from deciduous/broad leaf trees (angiosperms). They are mostly harder in density than softwoods.
S - Softwoods: Softwoods refer to woods derived from coniferous/evergreen trees (gymnosperms). They are mostly softer and easier to work than
hardwoods.
E - Engineered: Engineered wood, also called composite wood, man-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibers, or veneers or boards of wood, together with adhesives, or other methods of fixation to form composite materials.
M - Miscellaneous: This category consists items related to woods but isn't expansive enough to have its own sub-category. For example, peel and sticks as well as treatments of woods are included.
The relevant parameters are as follows [11]:
Average Dried Weight: This is a measure of a wood's weight in relation to a preset volume.
Janka Hardness: This number is incredibly useful in directly determining how well a wood will withstand dents, dings, and wear-as well as indirectly predicting the difficulty in nailing, screwing, sanding, or sawing a given wood species. Modulus of Rupture: Frequently abbreviated as MOR, (sometimes referred to as bending strength), this is a measure of a specimen's strength before rupture. It can be used to determine a wood species' overall strength. unlike the modulus of elasticity, which measures the wood's deflection, but not its ultimate strength. That is to say, some species of wood will bow under stress, but not easily break. Elastic Modulus: This measures a wood's stiffness, and is a good overall
indicator of its strength.
Crushing Strength: Sometimes known as Compression Strength parallel to the grain, this is a measurement of the wood's maximum crushing strength when weight is applied to the ends of the wood (compression is parallel to the grain).
Rot Resistance: This refers to a wood's ability to resist elemental and natural forces of decay.
W--0 As - ht
Other Names
-Description White Ash is one of the most commonly used hardwoods in
N. America, especially in shovels and hammers where toughness and impact resistance is important. It is often
used in turned objects, and can be shaped with hand or machine tools.
Average Dried Weight 675 kg/m3
Janka Hardness 5,870 N
Modulus of Rupture 103.5 MPa
Elastic Modulus 12.00 GPa
Crushing Strength 51.1 MPa
Rot Resistance Perishable
Distributor Boulter Plywood
Other Names
-Description Balsa is generally the lightest and softest of commercial
woods and is famous worldwide. It has excellent sound, heat, and vibration insulating properties, and is incredibly buoyant. It is used in rafts, surfboards, and musical instruments.
Average Dried Weight 150 kg/m3
Janka Hardness 300 N
Modulus of Rupture 19.6 MPa
Elastic Modulus 3.71 GPa
Crushing Strength 11.6 MPa
Rot Resistance Perishable
