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Ultra large deflection of thin PZT/aluminium cantilever beam

Ultra large deflection of thin PZT/aluminium cantilever beam

applications. Multiple spin-coating at 6000 rpm leads to a PZT thickness of around t p ¼ 3 μm. Each layer has been crystallized at 650 ○ C for 2 min in an open air furnace, resulting in a perovskite phase without preferred orientation. In order to apply the electric field to obtain the piezoelectric effect, aluminium top electrode of 1 cm  4 cm area (  200 nm thick) has been evaporated through a shadow mask, the aluminium foil being directly used as bottom electrode. The piezoelectric film has been poled using a Sawyer-Tower circuit with a 4.7 μF serial capacitor under a 200 kV/cm sinusoidal electric field at 50 Hz. The resulting P –E measurement leads to a 13 μC/cm 2 value for the remnant polarization and a 76 kV/cm value for the coercive field. The remnant polarization could be improved by increasing the applied electric field, but it would increase the risk of di- electric breakdown because of the large size of the sample and the top electrode. Moreover, the aluminium substrate is not oriented and does not promote the crystallization of the PZT film. The ferroelectric properties are also mitigated by the oxidation of the metal during the heat treatment, which forms an interfacial dielectric oxide layer at the aluminium/ PZT interface leading to a high coercive field value. For bending-mode actuation measurements, the aluminium/PZT sample has been clamped on one side resulting on an unimorph cantilever beam of 3.4 cm long, 1.1 cm wide and 20.5- μm thick. A laser vibrometer (Polytech OFV 2200) has been used to measure the tip deflection at the free end of the beam.
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Stress-relieving techniques for cantilever beam tests in an ice cover

Stress-relieving techniques for cantilever beam tests in an ice cover

Cantilever beam tests carried out on a freshwater ice cover showed that introducing stress relief holes at the root of the beam increased flexural strength, as determi[r]

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Measuring the surface bonding energy: A comparison between the classical double-cantilever beam experiment and its nanoscale analog

Measuring the surface bonding energy: A comparison between the classical double-cantilever beam experiment and its nanoscale analog

FIG. 1. Schematics of (a) the classic double-cantilever beam experiment and (b) its nanoscale equivalent. In the case of the classic DCB, a thin razor blade is inserted between the two bonded wafers. The razor blade imposes an opening δ and propagates a debonding crack at length L. In the case of the nano-DCB experiment, the thin membrane obtained after wafer bonding and removal of one of the wafers is probed using instrumented nano-indentation. The area of the membrane that is immediately under or near the indenter is plastically displaced. This displacement creates a torque that, far from the indented region, debonds the membrane from the underlying substrate. The elastically debonded part of the membrane is again held at a height δ and the debonding crack propagates for length L.
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Analysis of Rollover Shape and Energy Storage and Return in Cantilever Beam-Type Prosthetic Feet

Analysis of Rollover Shape and Energy Storage and Return in Cantilever Beam-Type Prosthetic Feet

In this work we present an analysis of cantilever beam- type prosthetic feet. The motivation behind this work is ultimately to design a low cost, high performance, mass- manufacturable prosthetic foot for the developing world. The need for a prosthetic foot designed with the developing world context in mind is huge; in India alone there are nearly 600,000 lower limb amputees [1]. Amputees in these settings introduce a unique set of culturally specific requirements, such as being able to squat, sit cross-legged, and walk barefoot through mud, in water and over uneven terrain. These together with a low price point preclude the use of any feet available in the western market.
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The flexural behaviour of ice from in situ cantilever beam tests

The flexural behaviour of ice from in situ cantilever beam tests

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at The flexural behaviour of ice from in situ cantilever beam tests Frederking, R. M. W.; Hausler, F.-U. https://publications-cnrc.canada.ca/fra/droits

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Reduced-order modeling for a cantilever beam subjected to harmonic forcing

Reduced-order modeling for a cantilever beam subjected to harmonic forcing

HARMONIC BASE-EXCITATION The aim of this section is to develop a complete model for the cantilever beam subjected to a harmonic base- excitation. Reduced-order models (ROMs) are considered by using the precedently-defined NNMs. These ROMs are computed in order to compare model predictions with a se- ries of measurements realized by Pai and Lee [8], as well as to give insight into some open questions raised by their study.

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Design and evaluation of a cantilever beam-type prosthetic foot for Indian persons with amputations

Design and evaluation of a cantilever beam-type prosthetic foot for Indian persons with amputations

In order to determine how users would respond to a prosthetic foot that exhibited a physiological roll-over shape and energy storage and return by means of a mechanical[r]

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Cantilever beam tests in an ice cover: influence of plate effects at the root

Cantilever beam tests in an ice cover: influence of plate effects at the root

The analyses of in situ, cantilever, ice beam test results, using a simple beam theory or Hetenyi closed- form solution for a beam on elastic foundation, can lead to su[r]

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Cantilever Sensors: Nanomechanical Tools for Diagnostics

Cantilever Sensors: Nanomechanical Tools for Diagnostics

Abstract Cantilever sensors have attracted considerable attention over the last decade because of their potential as a highly sensitive sensor platform for high throughput and multiplexed detection of proteins and nucleic acids. A micromachined cantilever platform integrates nanoscale science and microfabrication technology for the label-free detec- tion of biological molecules, allowing miniaturization. Molecular adsorption, when restricted to a single side of a deformable cantilever beam, results in measurable bend- ing of the cantilever. This nanoscale deflection is caused by a variation in the cantilever surface stress due to biomolecular interactions and can be measured by optical or elec- trical means, thereby reporting on the presence of biomolecules. Biological specificity in detection is typically achieved by immobilizing selective receptors or probe molecules on one side of the cantilever using surface functionalization processes. When target molecules are injected into the fluid bathing the cantilever, the cantilever bends as a function of the number of molecules bound to the probe molecules on its surface. Mass- produced, miniature silicon and silicon nitride microcantilever arrays offer a clear path to the development of miniature sensors with unprecedented sensitivity for biodetection applications, such as toxin detection, DNA hybridization, and selective detection of pathogens through immunological techniques. This article discusses applications of cantilever sensors in cancer diagnosis.
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Free vibrations of linear viscoelastic polymer cantilever beams

Free vibrations of linear viscoelastic polymer cantilever beams

Manuscript received 17th April 2020, revised 12th June 2020, accepted 15th June 2020. 1. Introduction In shoe sole applications, polymers are preferred for various reasons such as comfort, lightness, resistance to wear, cushioning effect, and so on. Good shock absorption is often desired, but in some sport applications, like running, elastic energy recovery is also crucial to providing good bouncing. For this reason, sport brands together with polymer companies are looking for materials offering a perfect compromise. To compare materials, the free vibration of a slender cantilever beam was introduced by Arkema as a characterization test. To obtain a quantitative analysis of this test, the vibration of a linear viscoelastic cantilever beam was calculated using the Euler–Bernoulli beam theory. The theory was first validated on actual experimental data and
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Boundary condition effects on vibrating cantilever beams

Boundary condition effects on vibrating cantilever beams

By starting with the most basic of compliant mechanisms, the cantilever beam, and utilizing Buckingham Pi theory the dynamic behavior of the vibrating beams could be[r]

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Positron beam extraction from an electron-beam-driven plasma wakefield accelerator

Positron beam extraction from an electron-beam-driven plasma wakefield accelerator

The range of z over which the inverse error function of sion is finite in Eq. (3) tells the maximum distance the drive beam can propagate. This theoretical limit is plotted in Fig. 4 by taking the reduction of the mean energy and the emittance growth predicted by Highland into account. The beam parameters in the Sec. II A are used except that the initial normalized emittance ϵ N0 is varied for both drive and trailing beams, and thus the beam radii σr are changed according to the matched beam radius for the plasma density n 0 ¼ 4.5 × 10 16 cm −3 . In the same figure, the ionization distances simulated for different target thickness Δz ¼ 0.5, 1 and 2 mm are shown. The results are shown
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Reconfigurable transmitarrays for beam-steering and beam -forming at millimeter-waves

Reconfigurable transmitarrays for beam-steering and beam -forming at millimeter-waves

Reconfigurable antennas are needed in many applications requiring beam scanning and/or beam shaping, such as radar systems, satellite communications, and mm-wave 5G for mobile backhaul links or mobile access points. Previously, reconfigurable antennas were designed using mechanically-rotating systems. This beam reconfiguration technique is still employed because it is cheap, weather resistant and easy to implement. However, this technique can cause instabilities due to mechanical vibrations, a higher latency, and is bulky in the case of a large-aperture transmitarray. Since the 1980s, thanks to the miniaturization and progress of electronics components, electronically-reconfigurable antennas have been implemented by including these components in the transmit/receive modules. In the open literature, beam- steering transmitarray antennas from C-band to mm-wave frequencies are designed using electronically-reconfigurable unit-cells which integrate switchable or tunable devices such as PIN diodes, microelectromechanical systems (MEMS), micro-fluidic systems or varactors to control locally the transmission phase of the considered TA. Despite these numerous researches, efforts are still ongoing to improve the phase resolution, the cost, the weight and reliability of active unit-cells for electronically-reconfigurable transmitarrays. Several linearly- or circularly- polarized electronically-reconfigurable unit-cells and transmitarray antennas with 1-bit of phase quantization have been already demonstrated in our frequency band of interest (27-32 GHz). However, to our best knowledge, a single example of 2-bit electronically-reconfigurable transmitarray at Ka band has been previously presented in the open literature [49] and it demonstrated a rather limited experimental efficiency due the high insertion loss and/or lack of reliability of MEMS devices.
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Beam tuning and stabilization using beam phase measurement at GANIL

Beam tuning and stabilization using beam phase measurement at GANIL

Procedure for users is the following : - phasemeters operating in relative measurement mode - loop tuning with the help of a zero detector to get a null correction (SC » 0) and loop s[r]

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Direct measurement of spatial modes of a micro-cantilever from thermal noise

Direct measurement of spatial modes of a micro-cantilever from thermal noise

in these fits. In table 1 the Q n values of the first four modes are compared with the hydrodynamic predictions of the Sader model [ 19 ] that account for viscous effect in the fluid. These predictions were computed with tabulated values of silicon and gold for Young’s modulus and density, and the physical dimensions of the cantilever (length, width and thickness) were tuned within the manufacturer tolerance to match the experimental observations. Note that the elastic modulus of gold and silicon are of the same order of magnitude, whereas the density of gold is about eight times that of silicon, therefore even a thin coating layer of 70 nm produces a mass increment of about 60% that cannot be neglected in the evaluation of total mass.
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Electron beam water calorimetry measurements to obtain beam quality conversion factors

Electron beam water calorimetry measurements to obtain beam quality conversion factors

/ La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur. For the publisher’[r]

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Precise damping and stiffness extraction in acoustic driven cantilever in liquid

Precise damping and stiffness extraction in acoustic driven cantilever in liquid

paper, 10 the coefficient b was omitted because the driving force was calculated using a point-mass-oscillator model. In a real experiment, part of the cantilever excitation comes from the base vibration, and the other part comes from the acoustic wave that propagates from the piezo-actuator through the fluid. 14 The total excitation is the sum of these two parts of excitation. Accurate determination of the contribution of the acoustic wave propagation is complicated because it may depend on the shape and the fixation of the cantilever on the holder. We show below that it is much easier to measure the whole driving force for a given cantilever in liquid.
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Cantilever-based microsystem for contact and non-contact deposition of picoliter biological samples

Cantilever-based microsystem for contact and non-contact deposition of picoliter biological samples

This shape is highly dependent on the amplitude of the force with which the cantilevers touch the surface. Indeed, for a spring constant of about 0.1 N/m, and a greater force contact, the cantilevers tend to bend (or even slip when the force is too high) thus enlarging the wetting surface between the cantilever end and the surface and, therefore, the amount of deposited liquid. In our case, this force was not precisely controlled. This could be achieved by using piezoresistive cantilevers to accurately monitor the contact force.

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Monte Carlo Beam Search

Monte Carlo Beam Search

Monte-Carlo Tree Search algorithms close to UCT parallelize quite well until 16 cores [6], [7], [10], [12], while Nested Monte-Carlo Search parallelizes quite well until at least 64 cores [8]. The parallelization of Monte-Carlo Beam Search is even more simple than the paralleliza- tion of Nested Monte-Carlo Search. It consists in having a master process that performs the search at the highest level, and some remote processes that perform the search at the lower levels. The master process computes all the po- sitions following the positions in the beam and sends them to the remote processes. The remote processes apply the lower level Monte-Carlo Beam Search to the positions they receive and send back the result to the master process. Once the master process has sent all the following positions, it receives all the searched positions and only keeps the best ones for the beam. The master and the remote processes are given in algorithms 3 and 4.
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Decoupled cantilever arms for highly versatile and sensitive temperature and heat flux measurements

Decoupled cantilever arms for highly versatile and sensitive temperature and heat flux measurements

Fabrication was based on 300 μ m thick double side polished (DSP) 4” silicon (Si) substrates, on which 400 nm of low-stress silicon rich silicon nitride (SiN x ) was grown by low pressure chemical vapor deposition (LPCVD). A 100 nm gold (Au) layer with a 10 nm titanium (Ti) adhesion layer was structured by sputtering, photolithography and wet etching. Sputtering was chosen rather than evaporation due to lower metal deposition temperatures which induce less intrinsic stress and subsequently less initial bending in the bimorph layer. The metal to insulator thickness ratio was chosen to maximize the thermal bending response behavior. 13 A second mask alignment was carried out to pattern the bi-arm cantilever structures by photolithography and reactive ion etching (RIE). Backside alignment is necessary for the final cantilever release where the bulk of the sacrificial Si substrate was etched by deep reactive ion etching (DRIE) before a final cantilever release in potassium hydroxide (KOH). After rinsing in isopropyl alcohol (IPA) and gentle nitrogen (N 2 ) drying, a fishnet design allowed the cantilevers with a 1.5 ×4 mm support chip to be broken out of the substrate wafer.
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