• Aucun résultat trouvé

Lifeboat Release Mechanism Tests

N/A
N/A
Protected

Academic year: 2021

Partager "Lifeboat Release Mechanism Tests"

Copied!
106
0
0

Texte intégral

(1)

Publisher’s version / Version de l'éditeur:

Technical Report, 2009-01-01

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.

https://nrc-publications.canada.ca/eng/copyright

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la

première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez

pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the

first page of the publication for their contact information.

NRC Publications Archive

Archives des publications du CNRC

For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien

DOI ci-dessous.

https://doi.org/10.4224/18227294

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Lifeboat Release Mechanism Tests

Simões Ré, A.; Oxford, L.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site

LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

NRC Publications Record / Notice d'Archives des publications de CNRC:

https://nrc-publications.canada.ca/eng/view/object/?id=86c28b75-0af4-4728-85f1-5ff831781af3

https://publications-cnrc.canada.ca/fra/voir/objet/?id=86c28b75-0af4-4728-85f1-5ff831781af3

(2)

National Research

Council Canada

Institute for

Ocean Technology

Conseil national

de recherches Canada

Institut des

technologies oc ´eaniques

TR-2009-23

Technical Report

Lifeboat Release Mechanism Tests.

Simões Ré, A.; Oxford, L.

(3)

DOCUMENTATION PAGE

REPORT NUMBER

TR-2009-23

NRC REPORT NUMBER

DATE

November 2009

REPORT SECURITY CLASSIFICATION

Unclassified

DISTRIBUTION

Unlimited

TITLE

Lifeboat Release Mechanism Tests

AUTHOR(S)

António J. Simões Ré, Leslie Oxford

CORPORATE AUTHOR(S)/PERFORMING AGENCY(S)

National Research Council – Institute for Ocean Technology

PUBLICATION

SPONSORING AGENCY(S)

Petroleum Research Atlantic-Canada, Transport Canada –Marine Safety

IOT PROJECT NUMBER

42_2373_26

NRC FILE NUMBER

KEY WORDS

On-load, off-load, release mechanism, hooks, static,

dynamic, inline, offline, cyclic

PAGES

vi,44,

App.

A-C

FIGS.

55

TABLES

24

SUMMARY

The capabilities of three on-load and one off-load release mechanisms were investigated for

normal, extreme and failure type release operations at the Institute for Ocean Technology.

The failure of release mechanisms during maintenance and exercise drills is a

well-documented occurrence. However, until very recently the possible causes of the failures

have only been postulated but never tested in a systematic way. The current study aims for

a better understanding of the operational performance of lifeboat release mechanisms with

respect to normal, extreme and failure operational situations..

Thus far all the results from in-line to offline, and from dynamic to static indicate that Hook

C, the next generation design, appears to have a higher degree of stability than the other

two sample hooks.

ADDRESS

National Research Council

Institute for Ocean Technology

Arctic Avenue, P. O. Box 12093

St. John's, NL A1B 3T5

(4)

National Research Council Conseil national de recherches

Canada Canada

Institute for Ocean

Institut des technologies

Technology

océaniques

LIFEBOAT RELEASE MECHANISM TESTS

TR-2009-23

António J. Simões Ré and Leslie Oxford

(5)

EXECUTIVE SUMMARY

The capabilities of three on-load and one off-load release mechanisms were

investigated for normal, extreme and failure type release operations at the Institute for

Ocean Technology.

The failure of release mechanisms during maintenance and exercise drills is a

well-documented occurrence. However, until very recently the possible causes of the failures

have only been postulated but never tested in a systematic way. The current study aims

for a better understanding of the operational performance of lifeboat release

mechanisms with respect to normal, extreme and failure operational situations.

Three twin fall davit on-load release mechanisms and one off-load release mechanism

were tested in the experimental study. All the release mechanism design types are fully

certified by the regulatory bodies. Of the three on-load release mechanisms, two were

of older existing design types while the third was of a newer (next generation) design.

Of the four release mechanisms tested, two of the mechanisms were new and never

used outside of this study. Also, one of the never used new mechanisms was of an

older design while the other was the next generation design. The never used

mechanisms had a loading capacity of 6 tonnes, while the third on-load release

mechanism had been in operation for some time and had a capacity of 3 tonnes. The

off-load mechanism had also been in use and had a capacity of 12 tonnes.

The experiments were conducted in the material testing facility of the Institute for Ocean

Technology of the National Research Council of Canada and encompassed the

following tests:

Inline/offline on-load tests

Inline/offline static tests

Offline cyclic loading

Offline damage release cable

Inline off-load tests

Results for the above mentioned tests will be presented in this report. Thus far all the

results from in-line to offline, and from dynamic to static indicate that hook C, the next

generation design, appears to have a higher degree of stability than the other two

sample hooks. The off-load release mechanism was limited to inline tests and followed

a different testing procedure as the on-load mechanisms. The off-load release

mechanism worked as intended in the limited test conditions.

(6)

TABLE OF CONTENTS

EXECUTIVE SUMMARY...

II

L

IST OF

F

IGURES

...

IV

L

IST OF

T

ABLES

...

VI

1.0 INTRODUCTION ... 1

1.1

Definitions ... 1

2.0 RELEASE SYSTEM ... 2

2.1

Release

Mechanisms... 3

3.0 TEST

SET-UP ... 4

3.1

Test

Procedures ... 7

4.0 TEST

MATRIX... 8

4.1

On-Load

Inline

Test Series ... 8

4.1.1

Normal

on-load release tests ... 8

4.1.2

Static load tests... 9

4.2

On-Load

Offline Test Series ... 9

4.2.1

On-load

release tests ... 10

4.2.2

Static

release tests... 10

4.2.3

Damaged

cable tests ... 12

4.2.4

Wave

loading tests... 13

4.3 Off-Load

Test Series... 14

5.0 RESULTS ... 15

5.1

On-Load Inline Test Series Results ... 15

5.1.1 Normal on-load release tests results... 15

5.1.2 Static load tests results ... 16

5.2

On-Load Offline Test Series Results ... 17

5.2.1 On-load

release

tests results ... 17

5.2.2 Static

release

tests results ... 22

5.2.3 Damaged cable tests results ... 24

5.2.4 Wave loading tests results ... 34

5.3

Off-Load Test Series Results... 42

6.0 CONCLUSIONS ... 43

(7)

LIST OF FIGURES

Figure 2-1: On-Load Release System ... 2

Figure 2-2: Hook A ... 3

Figure 2-3: Hook B ... 3

Figure 2-4: Hook C ... 3

Figure 2-5: Hook D ... 3

Figure 3-1: Hook A Set up for Inline Tests ... 4

Figure 3-2: Hook B Set Up for Inline Tests... 4

Figure 3-3:

Hook C Set Up for Inline Tests... 5

Figure 3-4: Hook A Set Up for Forward Pull Offline Tests ... 5

Figure 3-5: Hook B Set Up for Forward Pull Offline Tests ... 6

Figure 3-6: Hook C Set Up for Forward Pull Offline Tests... 6

Figure 3-7: Hook D set up for Loading ... 6

Figure 4-1: Torque Wrench and 10:1 Torque Multiplier... 14

Figure 5-1: Hook A - Inline On-load Release Test - 1500 kg Load... 15

Figure 5-2: Hook B: Inline On-load Release Test - 3000 kg Load ... 16

Figure 5-3: Hook C: Inline On-load Release Test - 3000 kg Load... 16

Figure 5-4: Hook A - Offline On-load Release Test Aft Pull - 1500 kg Load... 18

Figure 5-5: Hook B - Offline On-load Release Test Aft Pull - 3000 kg Load... 18

Figure 5-6:

Hook C - Offline On-load Release Test Aft Pull - 3000 kg Load... 19

Figure 5-7: Hook A - Offline On-load Release Test Forward Pull - 1500 kg Load ... 19

Figure 5-8: Hook B - Offline On-load Release Test Forward Pull - 3000 kg Load ... 20

Figure 5-9: Hook C - Offline On-load Release Test Forward Pull - 3000 kg Load... 20

Figure 5-10: Hook A - Offline On-load Release Test Side Pull - 1500 kg Load ... 21

Figure 5-11: Hook B - Offline On-load Release Test Side Pull - 3000 kg Load ... 21

Figure 5-12: Hook B - Offline On-load Release Test Side Pull - 3000 kg Load ... 22

Figure 5-13: Aft Pulls at 2/3 of Total Load ... 23

Figure 5-14: Forward Pulls at 2/3 of Total Load ... 23

Figure 5-15: Side Pulls at 2/3 of Total Load ... 24

Figure 5-16: Hook A Change in Cam Angle Aft Pull ... 26

(8)

LIST OF FIGURES (CONT’D)

Figure 5-19: Hook A Change in Cam Angle Forward Pull ... 29

Figure 5-20: Hook C Change in Cam Angle Forward Pull ... 30

Figure 5-21: Hook A Change in Cam Angle Side Pull ... 31

Figure 5-22: Hook B Change in Cam Angle Side Pull ... 32

Figure 5-23: Hook C Change in Cam Angle Side Pull ... 33

Figure 5-24: Hook A Aft Pull... 34

Figure 5-25:

Hook A Forward Pull ... 35

Figure 5-26: Hook A Side Pull ... 35

Figure 5-27: Hook B Aft Pull... 35

Figure 5-28:

Hook B Forward Pull ... 36

Figure 5-29: Hook B Side Pull ... 36

Figure 5-30: Hook C Aft Pull... 37

Figure 5-31: Hook C Forward Pull ... 37

Figure 5-32: Hook C Side Pull ... 37

Figure 5-33:

Hook A Aft Pull ... 38

Figure 5-34: Hook A Forward Pull ... 38

Figure 5-35:

Hook A Side Pull ... 39

Figure 5-36: Hook B Aft Pull... 39

Figure 5-37: Hook B Forward Pull ... 39

Figure 5-38: Hook B Side Pull ... 40

Figure 5-39: Hook C Aft Pull... 40

Figure 5-40: Hook C Forward Pull ... 41

Figure 5-41: Hook C Aft Pull... 41

(9)

LIST OF TABLES

Table 4-1: On-load Inline Tests ... 8

Table 4-2: Static Tests for Hook A ... 9

Table 4-3: Static Tests for Hook B ... 9

Table 4-4: Static Tests for Hook C ... 9

Table 4-5: On-load Offline Tests ... 10

Table 4-6: Static Offline Tests for Hook A ... 10

Table 4-7: Static Offline Tests for Hook B ... 11

Table 4-8: Static Offline Tests for Hook B ... 11

Table 4-9: Damaged Cable Tests for Hook A... 12

Table 4-10: Damaged Cable Tests for Hook B... 12

Table 4-11: Damaged Cable Tests for Hook C ... 13

Table 4-12: Wave Loading Tests for Hook A... 13

Table 4-13: Wave Loading Tests for Hooks B and C ... 13

Table 4-14 Applied Loads for Hook D ... 14

Table 5-1: Static Tests Results at 50% of Total Load ... 17

Table 5-2: Change in Cam Angle for Hook A Aft Pull ... 25

Table 5-3: Change in Cam Angle for Hook B Aft Pull ... 26

Table 5-4: Change in Cam Angle for Hook C Aft Pull... 27

Table 5-5: Change in Cam Angle for Hook A Forward Pull ... 28

Table 5-6: Change in Cam Angle for Hook C Forward Pull ... 29

Table 5-7: Change in Cam Angle for Hook A Side Pull ... 30

Table 5-8: Change in Cam Angle for Hook B Side Pull ... 31

Table 5-9: Change in Cam Angle for Hook C Side Pull ... 33

Table 5-10: Summary of Wave Loading Hook Stability ... 41

Appendices

Appendix A: Test Set-up Drawings

Appendix B: Calibrated Sensors

Appendix C: Test Log

(10)

1.0 INTRODUCTION

The release mechanisms of davit-launched lifeboats have been the cause of many

accidents during regular maintenance and drills. Transport Canada, the shipping

industry and the oil industry have placed a high priority on the acceptance process of

lifeboat release mechanisms and the possible causes for failure.

In 2006 Transport Canada, Petroleum Research Atlantic-Canada, Transportation Safety

Board and the Institute for Ocean Technology of the National Research Council of

Canada entered into a collaborative agreement aiming at establishing the operational

performance of lifeboat release mechanisms.

The project involved a systematic study of three on-load release mechanisms and one

off-load release mechanism. The on-load release mechanisms were tested for normal

release operations, static loading at various cam angles and abnormal operations

(failures or extreme) such as malfunctioning release cables, or cyclic wave loading. The

study also aimed at gaining a better understanding of the effects of offline loads versus

online. The off-load release mechanism was tested for determining the torque

necessary to release the mechanism when the load is on. These tests were limited to

the inline operation condition.

In the inline portion of the study a total of 229 tests were performed with 56 for normal

release operations and 173 for the investigation of static loading at various cam angles.

In the offline study a total of 968 tests were performed with 106 looking into the effect of

off-axis loading in the fore and aft axis as well as the side axis for normal operations

and 862 evaluating the effect of off-axis loading combined with wave loading, release

cable failure and static loading at various cam angles. A total of 26 tests were done on

the off-load hook, investigating the torque that would be required to release the hooks,

given that the cables are still loaded.

1.1 D

EFINITIONS

On-load Release not a normal operating procedure and occurs when the coxswain

releases the lifeboat from the hooks while the lifeboat is still

suspended above the water (i.e. weight of lifeboat on the fall wires

and hooks). This is a regulatory requirement.

Off-load Release normal operating procedure for lifeboat launching and occurs when

the lifeboat is fully water borne and its entire weight is off the fall

wires and hooks.

Pre-mature

the release mechanism opens without a deliberate action from the

coxswain to release the hook

Release

Dynamic

on-load functional tests

Static

The load on the cam will be tested at various cam angles. The

intention here is to investigate how an incorrectly reset cam affects

the load on the whole release system.

(11)

Cyclic

to simulate wind and wave action on the boat various cyclic loads will

be applied to the hook system

Damaged Cable to simulate a damaged or broken release cable the hook will be

loaded with the release cable detached from the cam.

2.0 RELEASE SYSTEM

The on-load twin fall release mechanisms tested consist of two hooks located opposite

each other on the forward and aft sections of the lifeboat. A release control unit is

attached to the hooks via telescopic cables, and is located inside the lifeboat near the

steering console for use by the coxswain once the lifeboat is waterborne. The release

control unit has a hydrostatic interlock, preventing the hook from releasing until it is

waterborne, but this interlock can be overridden if necessary. The arrangement can be

seen below in Figure 2.1.

The off-load release mechanism tested consists of one hook located at the mid-ship

location of the lifeboat. A release control unit is attached to the hook via a cable and is

located inside the lifeboat next to the coxswain position for activation after the lifeboat is

waterborne.

(12)

2.1 Release Mechanisms

Each release mechanism has a unique size and shape. Shown below are dimensioned

drawings of each hook. Hooks A and B are shown in Figures 2-2 and 2-3 respectively.

These hooks along with hook C in Figure 2-4 are on-load release mechanisms. Figure

2-5 shows the only off-load release hook, hook D.

(13)

3.0 TEST SET-UP

The release mechanisms were tested in the Material Testing Apparatus (MTA) at the

Institute for Ocean Technology. The apparatus is a standardized hydraulic testing

machine that allows for a uniaxial force to be applied to the test sample or in this case to

the release mechanisms. The apparatus was used normally for the inline tests, however

a special apparatus was designed to permit the use of the same testing machine for the

offline testing. The technical drawings for this apparatus are located in Appendix A. The

MTA applies a load to the hook in a controlled, repetitive and safe manner. Figures 3-1

to 3-6 illustrate the different release mechanisms set-up in the MTA for both inline and

offline tests, while Figure 3-7 shows the set-up for the off-load hook tests.

Figure 3-2: Hook B Set Up for Inline

Tests

Figure 3-1: Hook A Set up for Inline

Tests

(14)
(15)

Figure 3-5: Hook B Set Up for Forward Pull

Offline Tests

Figure 3-6: Hook C Set Up for Forward Pull

Offline Tests

(16)

In addition to the MTA and the offline testing frame the following equipment was also

used during the experiments:

Inline – bullring and shackle, electric actuator (activate hook opening), two load cells

(MTA and release cable), two linear displacement transducers (MTA and hook)

and an angular displacement transducer (cam angle)

Offline – bullring and shackle, electric actuator (activate hook opening), three load cells

(MTA, release cable, deck and pin), one linear displacement transducer (MTA),

and an angular displacement transducer (cam angle)

To apply a load the bullring and shackle were used to connect the MTA to the release

mechanism’s hook. The electric actuator enabled the rotation of the cam in a controlled

and repetitive manner. An inline load cell was connected between the actuator and the

hook cam lever. The angular displacement transducer recorded the cam angles. In the

offline condition two additional load cells were used to measure the compressive load at

the hook-canopy interface and at the hook –lifeboat attachment pin.

For the inline off-load experiments, the load was applied through the bullring and

shackle connecting the MTA to the release mechanism. A manual torque wrench was

used to rotate and force the cam open.

3.1 Test Procedures

The three on-load release mechanisms were tested according to the following

procedure:

With no load connect the bullring to the hook

Rotate the cam to the specified angle with the electric actuator

Start the data acquisition

Let the system settle for 20-30 seconds and then apply the required load to the

hook using the MTA.

For Dynamic tests – rotate the cam until the hook releases

For Static tests – rotate the cam to the desired position, slowly bring the load on

and record loads, angles, etc, for 30 seconds.

Stop data acquisition

Unload the applied load from the hook.

After each test the data is checked for integrity by plotting each individual channel time

series and performing basic stats on the data.

The single off-load release mechanism is a different type of hook and therefore had to

be tested using an alternate procedure which is as follows:

With no load connect the bullring to the hook

Close the release mechanism

(17)

Let the system settle for 20-30 seconds and then apply the required load to the

hook using the MTA.

With the torque wrench attempt to rotate the cam

Stop data acquisition

Read the torque wrench value and record.

After each test the data is checked for integrity by plotting each individual channel time

series and performing basic stats on the data.

4.0 TEST MATRIX

The experiments for the three on-load hooks were divided into inline and offline pulls

and also into two categories, normal on-load release operations and static load at

various cam angles. The offline tests covered the same tests as the inline condition but

also looked into extreme and operational conditions such as cyclic loading and cable

malfunction or a combination of both.

The normal on-load tests measured the functional design load characteristics of the

individual release mechanisms while the static tests gave insight into the cam and

release cable loading for improperly reset cam angles. The failure and extreme

operational experiments investigated scenarios such as severed release cable and

cyclic loading due to wind and waves.

The testing for the off-load hook was inline, in order to investigate whether or not the

hook could be manually opened while loaded.

4.1 On-Load Inline Test Series

The inline test series involved loading the three on-load hooks along their vertical axes,

and were divided into normal on-load release tests and static load tests. The set-up for

this was previously seen in figures 6 through 8. The hooks were placed in the MTA

allowing for normal operation of the apparatus, that is, the loads were applied straight

up along the vertical axis of the hook for on-load and static conditions.

4.1.1 Normal on-load release tests

These experiments were performed to confirm that the hook was operating as required

by regulation, to establish the cam angle at which the hook releases under load and to

measure the force required to rotate the cam enough to open and release the hook.

Table 1 shows the on-load release test matrix developed for the three hooks. The table

consists of the range of loads applied for which the hook is certified and the range of

cam angles possible. In this case, the cam was rotated until the hook opened.

Table 4-1: On-load Inline Tests

Applied Load (kg)

Hook A

Hook B

Hook C

Cam Angle

(degrees)

0 0 0

0 → open

(18)

(Table 4-1 continued)

1000 2000 2000 0 → open

1500 3000 3000 0 → open

2000 4000 4000 0 → open

2500 5000 5000 0 → open

3000 6000 6000 0 → open

4.1.2 Static load tests

In this series of experiments, tests were performed for each of the loadings specified

previously in Table 4-1 at a pre-assigned cam angle. Once the release point was

established, additional tests were performed around it in order to properly bracket the

release. The increments for these experiments were on the order of half to one degree.

This establishes the actual static release point for the hook at different levels of loading.

Tables 4-2 to 4-4 show the static test matrix employed for hooks A, B and C

respectively.

Table 4-2: Static Tests for Hook A

Applied Load (kg)

Cam Angles (degrees)

500

0, 10, 20, 30, 40, 45, 47, 48, 48.5, 49

1000

0, 10, 20, 30, 40, 45, 48, 48.5

1500

0, 10, 20, 30, 40, 45, 48, 48.5

2000

0, 10, 20, 30, 40, 45, 48, 48.5

2500

10, 20, 30, 40, 45, 48

3000

10, 20, 30, 40, 45, 48

Table 4-3: Static Tests for Hook B

Applied Load (kg)

Cam Angles (degrees)

1000

0, 10, 20, 30, 40, 50, 60, 65, 70

2000

0, 10, 20, 30, 40, 50, 60

3000

0, 10, 20, 30, 40, 50, 60

4000

0, 10, 20, 30, 40, 50, 60

5000

0, 10, 20, 30, 40, 50, 60

6000

0, 1, 10, 20, 30, 40, 50, 60, 65

Table 4-4: Static Tests for Hook C

Applied Load (kg)

Cam Angles (Degrees)

1000

0, 10, 20, 30, 40, 50, 60, 69, 70, 71, 72, 73, 74, 75, 80

2000

10, 20, 30, 40, 50, 60

3000

10, 20, 30, 40, 50, 60, 66, 67, 68, 69, 70

4000

10, 20, 30, 40, 50, 60

5000

10, 20, 30, 40, 50, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70

6000

10, 20, 30, 40, 50, 60, 61, 63, 64, 65

4.2 On-Load Offline Test Series

(19)

the cam angle was either adjusted until the hook opened, or the cam angle was

previously determined. For these tests however, the hooks were loaded from aft,

forward and side directions at nominal angles of 50, 50 and 20 degrees respectively.

This set-up was previously seen in Figures 3-1 to 3-6.

The additional tests simulated damaged cable and wave loading scenarios. The wave

loading scenario examines the forces experienced by the release mechanisms in the

event of wind and/or wave loading on the lifeboat during its descent to the water

surface. The damaged cable scenario explores the hook function in the event of a

severed or damaged release cable.

4.2.1 On-load release tests

The on-load release tests were performed at various loadings for each load direction.

This can be seen for all three hooks in Table 4-5.

Table 4-5: On-load Offline Tests

Applied Load (kg)

Hook A

Hook B, Hook C

Direction of Pull

0, 500, 1000, 1500,

2000, 2500, 3000

0, 1000, 2000, 3000,

4000, 5000, 6000, 6600

Aft 50°

0, 500, 1000, 1500,

2000, 2500, 3000, 3300

0, 1000, 2000, 3000,

4000, 5000, 6000, 6600

Fwd 50°

0, 500, 1000, 1500,

2000, 2500, 3000, 3300

0, 1000, 2000, 3000,

4000, 5000, 6000

Side 20°

4.2.2 Static release tests

As with the on-load release tests, these loads were applied in a specific direction. The

cam however, was set to predetermined angles for each loading within each pull

direction. Tables 4-6 though 4-8 illustrate this process.

Table 4-6: Static Offline Tests for Hook A

Applied Load (kg)

Direction of Pull

Cam Angles

(degrees)

500

2, 10, 20, 30, 40, 50, 60

1000

2, 10, 20, 30, 40, 50, 60

1500

2, 10, 20, 30, 40, 50, 60

2000

2, 10, 20, 30, 40, 50, 60

2500

2, 10, 20, 30, 40, 50, 60

3000

2, 10, 20, 30, 40, 50, 51, 55, 60,

65, 70, 71, 71.5, 71.9, 72, 72.4,

72.8, 73, 74, 75, 78

3300

Aft 50°

2, 10, 20, 30, 40, 50, 60

500

2, 10, 20, 30, 40, 50, 60

1000

2, 10, 20, 30, 40, 50, 60

1500

2, 10, 20, 30, 40, 50, 60

2000

Fwd 50°

2, 10, 20, 30, 40, 50, 60

(20)

(Table 4-6 continued)

2500

2, 10, 20, 30, 40, 50, 60

3000

2, 10, 20, 30, 40, 50, 60

1000

2, 10, 20, 30, 40, 50, 60

2000

2, 10, 20, 30, 40, 50, 60

3000

Side 20°

2, 10, 20, 30, 40, 50, 60

500

11, 20, 30, 40, 50, 60, 70, 80, 90

1000

11, 20, 30, 40, 50, 60, 70, 80, 90

1500

11, 20, 30, 40, 50, 60, 70, 80, 90

2000

11, 20, 30, 40, 50, 60, 70, 80, 90

2500

11, 20, 30, 40, 50, 60, 70, 80, 90

3000

11, 20, 30, 40, 50, 60, 70, 80, 90

3300

Side 21°

11, 20, 30, 40, 50, 60, 70, 80, 90

Table 4-7: Static Offline Tests for Hook B

Applied Load (kg)

Direction of Pull

Cam Angles

(degrees)

1000

10, 20, 30, 40, 50, 60, 70, 80

2000

10, 20, 30, 40, 50, 60, 70, 80

3000

10, 20, 30, 40, 50, 60, 70, 80

4000

10, 20, 30, 40, 50, 60, 70, 80

5000

10, 20, 30, 40, 50, 60, 70, 80

6000

10, 20, 30, 40, 50, 60, 70, 80

6600

Aft 49°

10, 20, 30, 40, 50, 60, 70, 80

500 90

1000

2, 10, 20, 30, 40, 50, 60, 70, 80,

85, 90

1500 2

2000

10, 20, 30, 40, 50, 60, 70, 79, 80,

81, 82, 85, 90

3000

10, 20, 30, 40, 50, 60, 70, 80, 85

4000

10, 20, 30, 40, 50, 60, 70, 80

5000

10, 20, 30, 40, 50, 60, 70, 80

6000

Fwd 50°

2, 10, 20, 30, 40, 50, 60, 70, 80

4000

10, 20, 30, 40, 50, 60, 70

5000

10, 20, 30, 40, 50, 60, 70

6000

Side 23°

10, 20, 30, 40, 50, 60, 70

Table 4-8: Static Offline Tests for Hook B

Applied Load (kg)

Direction of Pull

Cam Angles

(degrees)

2000

2, 10, 20, 30, 40, 50, 60, 65, 66,

68, 70

4000

Aft 46°

2, 10, 20, 30, 40, 50, 60, 65, 67, 70

(21)

(Table 4-8 continued)

6000

2, 10, 20, 30, 40, 50, 60, 63, 65,

66, 70

2000

2, 10, 20, 30, 40, 50, 60, 70, 71,

73, 75, 80

4000

2, 10, 20, 30, 40, 50, 60, 65, 68,

69, 70

6000

Fwd 43°

2, 20, 30, 40, 50, 60, 65, 68, 69,

70, 71

1000

2, 10, 20, 30, 40, 50, 60, 70

2000

2, 10, 20, 30, 40, 50, 60, 65, 70

3000

2, 10, 20, 30, 40, 50, 60, 70

4000

2, 10, 20, 30, 40, 50, 60, 65, 70

6000

Side 22°

2, 10, 20, 60, 65

4.2.3 Damaged cable tests

The methodology for the damaged cable tests was the same as used in the static tests

with the exception of the disconnected release cable. The removal of the release cable

allows the cam to rotate if enough force is applied to it. Tables 4-9 to 4-11 below

illustrate the series of tests performed on hooks A, B and C.

Table 4-9: Damaged Cable Tests for Hook A

Applied Load (kg)

Direction of Pull

Cam Angles

(degrees)

1000

Aft 50°

10, 20, 30, 40, 50, 60,

71, 72, 74, 75, 76

1000

10, 20, 30, 40, 50, 60,

70, 71, 72

3000

Fwd 50°

0, 10, 20, 30, 40, 50, 60,

70, 71

1000

0, 10, 20, 30, 40, 50, 60,

70, 80, 86, 88, 89

3000

Side 21°

0, 10, 20, 30, 40, 50, 60,

70, 80, 86

Table 4-10: Damaged Cable Tests for Hook B

Applied Load (kg)

Direction of Pull

Cam Angles

(degrees)

2000

10, 20, 30, 40, 50, 60,

71, 72, 75, 80

6000

Aft 50°

10, 20, 30, 40, 50, 60,

72, 73, 75

2000

Fwd 50°

0

(22)

(Table 4-10 continued)

2000

6, 10, 20, 30, 40, 50, 60,

70, 74, 75, 77, 79, 80,

81

6000

Side 21°

8, 20, 30, 40, 50, 60, 70,

71, 73, 75, 80

Table 4-11: Damaged Cable Tests for Hook C

Applied Load (kg)

Direction of Pull

Cam Angles

(degrees)

2000

0, 10, 20, 30, 40, 50, 60,

70

6000

Aft 46°

0, 10, 20, 30, 40, 50, 60,

70

2000

0, 10, 20, 30, 40, 50, 60,

70

6000

Fwd 43°

0, 10, 20, 30, 40, 50, 60,

70

2000

0, 10, 20, 30, 40, 50, 60,

66, 68, 69, 70

4000

Side 22°

0, 10, 20, 30, 40, 50, 60,

64, 65, 68, 70

4.2.4 Wave loading tests

In this series of experiments, tests were performed to simulate the release mechanism

experiencing cyclic loading forces. Wind or waves or excessive ship/installation motions

can cause these types of forces. This test series was run first with the release cable in

place then again with the cable removed. Tables 4-12 and 4-13 illustrate the variety of

tests run for this condition.

Table 4-12: Wave Loading Tests for Hook A

Cyclic Load

Release cable

Mean

Load (kg)

Direction of

Pull

Amplitude (kg)

Period (sec)

Connected

Disconnected

1500

Fwd 50°

1500 5 Y -

1500

Fwd 50°

1500 10 Y -

2000

Fwd 50°

1000 5 Y -

2000

Fwd 50°

1000 10 Y -

Table 4-13: Wave Loading Tests for Hooks B and C

Cyclic Load

Release cable

Mean

Load (kg)

Direction of

Pull

Amplitude (kg)

Period (sec)

Connected

Disconnected

3000

Fwd 50°

3000 5 Y -

3000

Fwd 50°

3000 10 Y -

4000

Fwd 50°

2000 5 Y -

(23)

These tests were repeated for aft pulls at 50°, side pulls at 20° and with the release

cable disconnected.

4.3 Off-Load Test Series

Similar to the Inline Test Series, the off-load tests were done using the MTA to load the

hook along its vertical axis. Unlike the inline series however, there were no cam angle

variations. Since the off-load hook is designed to release only when the load is off, the

mechanism was tested to measure the torque required to release when the load is

being applied. A preset load amount was applied to the hook, at which point a torque

wrench was used to open the release mechanism. Initially, the torque was applied with

a torque wrench. For the latter tests, a 10-1 torque multiplier was used, and can be

seen along with the torque wrench in Figure 1. The loads applied are listed in Table

4-14. The top row lists the tests that used the torque wrench, and the bottom row applied

the 10-1 torque multiplier.

Table 4-14 Applied Loads for Hook D

Applied Load (kg)

Torque Wrench

200, 400, 600, 800, 1000, 1500, 2000, 2500, 3000, 3500

10:1 Torque Multiplier

1000, 2000, 2500, 3000, 4000, 5000

(24)

5.0 RELEASE MECHANISMS TEST RESULTS

5.1 On-Load Inline Test Series Results

In the following sections, the results for the on-load release mechanisms in the inline

configuration will be presented.

5.1.1 Normal on-load release test results

The on-load release mechanism tests series was conducted to ensure the hook was

operating as prescribed by regulation, to determine the cam angle at which the hook

would open while under load and to record the force required to rotate the cam so the

hook would open. The test data for hooks A, B and C was plotted as a moment of the

applied load resisting the opening movement and is shown in Figures 5-1 to 5-3,

respectively. In all three cases the force induced by the hook is resisting the opening

force, until the cam reaches approximately 45° for hook A, 58° for hook B and 62° for

hook C. After the cam moves past these values the moment to resist opening starts to

decrease until the cam is at 49° for hook A, 71° for hook B and 74° for hook C, when the

hook finally releases. Until opening neither the hooks nor the cams move a measurable

amount, only the applied forces change. One may conclude that the hooks are stable.

The cam-opening rate for hook C at 5.03 deg/s is more gradual than for hooks A and B,

5.95 deg/s and 6.19 deg/s, respectively. One may infer from these results that hook C

has a higher degree of stability than the other two sample hooks.

-20

-15

-10

-5

0

5

10

15

20

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Inline Pull

Hook Load = 1500 kg

Cam Opening Rate = 5.95 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

(25)

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Inline Pull

Hook Load = 3000 kg

Cam Opening Rate = 6.19 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-2: Hook B: Inline On-load Release Test - 3000 kg Load

80

70

60

50

40

30

20

10

0

-10

-20

-30

-40

-50

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Inline Pull

Hook Load = 3000 kg

Cam Opening Rate = 5.03 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-3: Hook C: Inline On-load Release Test - 3000 kg Load

5.1.2 Static load tests results

The results of this test series determined the load on the cam from applying a known

force to the hook at a specific cam angle setting. Table 5-1 shows the results for the

three hooks at 50% of total load and a full range of cam settings, that is, 1500 kg for

hook A and 3000 kg for hooks B and C.

(26)

Table 5-1: Static Tests Results at 50% of Total Load

Hook A

Hook B

Hook C

Cam Setting

(degrees)

Force

(N)

Cam Setting

(degrees)

Force

(N)

Cam Setting

(degrees)

Force

(N)

0 -5.12 0

-26.78

0 -

10 - 10

-39.07

10

-30.34

20 -13.52 20 -18.38 20 -16.44

30 -8.03 30

-24.52

30 -21.93

40 -8.67 40

-23.23

40 -8.03

45 -119.28 50 -55.25 50 -30.02

48 -474.07 60 -88.56 60 -24.52

48.5 -685.58

66 -28.73

67

-247.03

69

-876.72

70

-1069.47

Note: positive force = closing, negative force = opening

The release cable load remains low until 45°, for hook A, 60° for hook B and 66° for

hook C. After these thresholds the force in hooks A, and C increase rapidly. No results

are available for hook B, beyond the 60° cam angle setting. These results show that the

cam has low opening forces induced on it through its equivalent dynamic operating

region.

5.2 On-Load Offline Test Series Results

In the following sections, the results for the on-load release mechanisms in the offline

configuration will be presented.

5.2.1 On-load release tests results

The offline on-load release mechanism tests series was similar to the inline test series

with the exception that pulls were performed from the forward, aft and side sections of

the hook. These tests were conducted to ensure the hook could still operate when the

hook load was acting at approximately 50° in a forward and aft orientation and 20°, in a

side orientation. The test data for hooks A, B and C was plotted again as a moment of

the applied load resisting the opening movement and is shown in Figures 5-4 to 5-6, for

the aft pulls, Figures 5-7 to 5-9 for the forward pulls, and Figures 5-10 to 5-12 for the

side pulls. All the examples will again show results at 50% of the total hook load. In the

aft pulls the cam opening rate reaches a high of almost 30 degrees per second for hook

A, and down to about 20 degrees per second for hook C, with hook B having a rate

half-way in between at about 25 degrees per second. Worth noting that in this configuration,

hook A has a small negative moment as the hook is released while hook B has a large

negative moment and hook C a small positive moment. Also, the moment resisting

opening for hooks A through C is in the range of 60° to 70°.

(27)

-30

-25

-20

-15

-10

-5

0

5

10

15

20

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Aft Pull

Hook Load = 1500 kg

Cam Opening Rate = 28.64 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-4: Hook A - Offline On-load Release Test Aft Pull - 1500 kg Load

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

Mo

me

nt (N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Aft Pull

Hook Load = 3000 kg

Cam Opening Rate = 24.25 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

(28)

80

70

60

50

40

30

20

10

0

-10

-20

-30

-40

-50

Mo

me

nt (N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Aft Pull

Hook Load = 3000 kg

Cam Opening Rate = 19.16 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-6: Hook C - Offline On-load Release Test Aft Pull - 3000 kg Load

The forward pulls show a slightly different cam opening range and opening rate. Hook C

again has the largest range and the lowest cam-opening rate. Hooks A and B have a

negative release moment while hook C maintains a positive hook moment through out

the test.

-20

-15

-10

-5

0

5

10

15

20

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Fwd Pull

Hook Load = 1500 kg

Cam Opening Rate = 29.28 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

(29)

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Forward Pull

Hook Load = 3000 kg

Cam Opening Rate = 21.54 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-8: Hook B - Offline On-load Release Test Forward Pull - 3000 kg Load

-50

-40

-30

-20

-10

0

10

20

30

40

50

Mo

men

t (N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Forward Pull

Hook Load = 3000 kg

Cam Opening Rate = 19.02 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-9:

Hook C - Offline On-load Release Test Forward Pull - 3000 kg Load

In the side pulls the opening range for hooks A and B drop to about 50° and 65° down

from 60°, 70°, respectively. Hook C maintains a closing moment through the entire

process and the range remains the same as for the two previous pulls, aft and forward.

(30)

As in the previous pulls the cam-opening rate varies from about 30° for hook A down to

about 20° with hook B attaining an intermediate cam-opening rate of approximately 25°.

-20

-15

-10

-5

0

5

10

15

20

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Side Pull

Hook Load = 1500 kg

Cam Opening Rate = 28.17 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-10: Hook A - Offline On-load Release Test Side Pull - 1500 kg Load

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Forward Pull

Hook Load = 3000 kg

Cam Opening Rate = 24.93 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

(31)

80

70

60

50

40

30

20

10

0

-10

-20

-30

-40

-50

Moment (

N

-m)

80

70

60

50

40

30

20

10

0

Angle (deg)

Moment Required to Rotate the Cam

Offline - Side Pull

Hook Load = 3000 kg

Cam Opening Rate = 18.21 deg/s

Start of Rotation of Cam

Hook Beginning to Release

Hook Released

Opening Moment

Closing Moment

Figure 5-12: Hook B - Offline On-load Release Test Side Pull - 3000 kg Load

In all three pulling direction cases and hook designs the force induced by the hook is

resisting the opening force, until the cam reaches some nominal value after which it will

start opening. The cam opening rate for hook A is the highest followed by hook B and

finally hook C. The cam opening rates for offline pulls are 6 times those of the inline

pulls for hook A, five times for hook B and 4 times for hook C.

As from the inline on-load tests, one may infer from the results for offline on-load test for

aft/forward and side pulls that hook C appears to have higher degree of stability than

the other two sample hooks.

5.2.2 Static release tests results

These tests were completed at various loading angles (aft, forward and side) and at

predetermined cam angles. Figures 5-13 to 5-15 show the aft, forward and side loading

at two-thirds (66.7%) of the total load. This means that hook A shows a 2000 kg load,

while hooks B and C show a 4000 kg load. Note that the positive release moment

indicates a closing moment and a negative release moment indicates opening.

In Figure 5-13, it can be seen that for the aft pulls, hooks B and C initially have a

positive moment through various cam angles. Hook B does not cross into the negative

area, indicating that it remains in a closing moment throughout this testing. Hook C

crosses into the negative (opening) area with a 60° cam angle, and stays negative for

the remainder of the tested cam angles. Hook A has an opening moment for the entirety

of the aft testing, however these values are very close to zero.

(32)

Release Moment vs. Cam Angle

-4

-3

-2

-1

0

1

2

3

4

0

5

10 15 20 25 30 35 40 45 50 55 60 65 70

Cam Angle (degrees)

Release Mom

e

nt (N-m

)

Hook A

Hook B

Hook C

Figure 5-13: Aft Pulls at 2/3 of Total Load

For the forward pulls in Figure 5-14, each hook experienced an opening moment

throughout the testing, with the exception of hook B that had a slight closing moment at

70°.

Release Moment vs. Cam Angle

-4

-3

-2

-1

0

1

2

3

4

0

5

10 15 20 25 30 35 40 45 50 55 60 65 70

Cam Angle (degrees)

Release Mom

e

nt (N-m

)

Hook A

Hook B

Hook C

(33)

With the exception of hook C, a negative moment was seen on the hooks during the

side pulls in Figure 5-15. The moments recorded for hook A however, tended to

oscillate from near zero to just after 1°. Hook C initially saw an opening moment, but

experienced a closing moment for the majority of the testing, crossing into the negative

area at 60° and remaining negative for the rest of the testing. Note that due to the

instability of hook B, the scale for the release moment in Figure 5-15 had to be

lengthened to accommodate the data.

Release Moment vs. Cam Angle

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

3

4

0

5

10 15 20 25 30 35 40 45 50 55 60 65 70

Cam Angle (degrees)

Release Mom

e

nt (N-m

)

Hook A

Hook B

Hook C

Figure 5-15: Side Pulls at 2/3 of Total Load

For the aft pulls, the highest positive and therefore closing moment seen was that of

hook C. It can therefore be said that hook C would be the most stable in an aft loading

situation, followed by hook B and then hook A. Although all three hooks had negative

moments during the majority of the forward pulls, hook A had negative moments that

were closest to zero, indicating that it would be more stable than the other two hooks

during forward loading. Hook C again had positive moments for the side pulls, while the

other hooks had negative moments. This shows that hook C has a higher degree of

stability during side as well as aft loading.

5.2.3 Damaged cable tests results

The results from this series of tests simulate a broken or detached release cable and

the effect on the hook as a load is applied. The tests were performed on the three hook

types for the aft, forward and side offline pulls at angles of 50°, 50° and 20°,

respectively.

Tables 5-2 to 5-4 show the aft pulls for hooks A, B and C, while tables 5-5 to 5-7 show

forward pull results and tables 5-8 to 5-10 show side pull results. The tables present the

initial and final cam angles (columns 1 & 2) as the load is applied and the difference

(34)

between the two (column 3). Also on the tables a horizontal red line separates the range

of stable cam angles beyond which the hook begins to open, i.e. cam rotation starts.

Figures 5-16 to 5-23 show the release of the hook with the associated cam angle

change at the stable threshold limit and the force experienced at that point.

The tables present results for the one-third and full load, i.e. 1000 kg and 3000 kg for

hook A and 2000 kg and 6000 kg for hooks B and C, while the figures only present the

results for the one-third of total load.

The aft pull cam angle for Hook A had minimal change until a cam angle of 74°-75°

,

after which the cam moved 9°-11°. This is a significant change in cam angle given that

the changes previous to this were minimal, i.e. all less than 0.5°. Figure 5-16 shows the

applied load (blue line) drops after reaching only about 750 N, coinciding with the

significant change in cam angle, indicating a release.

Table 5-2: Change in Cam Angle for Hook A Aft Pull

Applied Load of 2000 kg

Applied Load of 6000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

10

9.96

-0.04

No data Available

10 10.45

0.45

20 20.14

0.14

30 30.07

0.07

40 40.50

0.50

50 49.99

-0.01

60 59.99

-0.01

71 71.45

0.45

72 71.94

-0.06

74 74.18

0.18

75 84.03

9.03

75 86.57

11.57

76 85.32

9.32

(35)

Figure 5-16: Hook A Change in Cam Angle Aft Pull

Hook B shows a large change in cam angle of 10°-13° at the low end (cam angle 10°)

for both applied loads (i.e. 2000 kg and 6000 kg) and then stabilizes at 2.5° to 5.0°. The

graphical data in Figure 5-17 shows a cam angle change of 22°

 from an initial cam

angle of 71°, with release at an applied load of approximately 2700 N.

Table 5-3: Change in Cam Angle for Hook B Aft Pull

Applied Load of 2000 kg

Applied Load of 6000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

10 20.69

10.69

10 23.43

13.43

20 22.52

2.52 20 23.37

3.37

30 32.77

2.78 30 33.16

3.16

40 42.82

2.82 40 44.08

4.08

50 52.95

2.95 50 52.55

2.55

60 63.51

3.51 60 63.17

3.17

70 73.81

3.81 70 73.76

3.76

70 73.75

3.75 72 75.08

3.08

71 76.65

5.65 73 77.36

4.36

72 75.80

3.80 75 79.78

4.78

75 79.34

4.34

80 84.23

4.23

80 83.52

3.52

(36)

Figure 5-17: Hook B Change in Cam Angle Aft Pull

Hook C aft pull results show a similar patter to those of hook A. Up to a cam angle of

60°,

the change from initial to final cam angle variation is around 0.5°. Beyond this point

however, the change in cam angle increases to 2°-3°. The cam angle changes are

similar for the two applied loads (i.e. 1/3 and full load capacity). The increase in cam

angle is much smaller than that observed in the previous two cases. After the 60° cam

angle threshold, the load drops after reaching a maximum of 1600 N in Figure 5-18.

Table 5-4: Change in Cam Angle for Hook C Aft Pull

Applied Load of 2000 kg

Applied Load of 6000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

0 0.16

0.16

0 0.34

0.34

10 10.26

0.26 10 10.09

0.09

20 20.33

0.33 20 20.13

0.13

30 30.45

0.45 30 30.60

0.60

40 40.01

0.01 40 40.24

0.24

50 50.01

0.01 50 50.42

0.42

60 59.95

-0.05 60 60.10

0.10

70 72.83

2.83 70 72.48

2.48

(37)

Figure 5-18: Hook C Change in Cam Angle Aft Pull

The forward pull tests started with hook A that lost its stable cam angle threshold about

4°-5° earlier than in the aft pull tests. In these tests the threshold was crossed between

70° and 71°, corresponding to the applied loads of 1000 kg and 3000 kg. The change in

cam angle registered values between 33° and 38°.

These values are shown in tabular

form in Table 5.5 and graphically in Figure 5-19. From the figure we can also estimate

that an applied load of 2600 N was registered before the hook released.

Table 5-5: Change in Cam Angle for Hook A Forward Pull

Applied Load of 1000 kg

Applied Load of 3000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

10 10.23

0.23 0 1.68

1.68

20 20.30

0.30 10 11.01

1.01

30 29.91

-0.09 20 20.20

0.20

40 40.51

0.51 30 29.87

-0.13

50 50.23

0.23 40 39.97

-0.03

60 60.43

0.43 50 50.65

0.65

70 70.06

0.06 60 60.61

0.61

71 104.60

33.60 70 70.73

0.73

71 86.76

15.76

71

108.99

37.99

72 82.90

10.90

71 71.29

0.29

(38)

Figure 5-19: Hook A Change in Cam Angle Forward Pull

There is no forward pull data for hook B. At the time of the testing there were several

technical problems with the testing apparatus and this series of tests were delayed and

eventually never completed.

The forward pull tests confirmed the observations made earlier on the aft pull tests in

which there was very little change in the cam angle (refer to Table 5-6). It is worth

noting the fact that for the maximum allowable load (i.e. 6000 kg) at the initial angle of

0°, a large change of approximately 25°

is observed however in subsequent cam angles

the difference is minimal and around 1° or less until after 60°. In other applied load

conditions the change in cam angle remains small until after the 60° threshold. Figure

6-20 shows the hook C forward pull release load of just over 4000 N for a cam angle of

70°.

Table 5-6: Change in Cam Angle for Hook C Forward Pull

Applied Load of 2000 kg

Applied Load of 6000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

0 1.46

1.46

0

24.56

24.56

10 10.57

0.57 10 11.18

1.18

20 20.24

0.24 20 20.45

0.45

30 30.26

0.26 30 30.95

0.95

40 40.32

0.32 40 40.37

0.37

50 50.32

0.32 50 50.14

0.14

(39)

(Table 5-6 continued)

60 59.81

-0.19 60 59.89

-0.11

70 74.64

4.64 70 74.66

4.66

Figure 5-20: Hook C Change in Cam Angle Forward Pull

In general, the side pulls cam angle stable threshold was larger for all hooks tested.

For hook A the stable threshold reached 86° for the 1000 kg applied load. For the 3000

kg applied load case, the hook seemed to stay stable throughout with a change in angle

of less than 1°. Figure 5-21 illustrates graphically the cam rotation after the 88° level to

approximately 16° after which the hook releases. The force attained before release was

9300 N.

Table 5-7: Change in Cam Angle for Hook A Side Pull

Applied Load of 1000 kg

Applied Load of 3000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

0 -1.17

-1.17

0 0.28

0.28

10 10.28

0.28 10 9.90

-0.10

20 19.59

-0.41 20 19.60

-0.40

30 30.52

0.52 30 29.45

-0.55

40 40.44

0.44 40 39.76

-0.24

50 50.03

0.03 50 49.89

-0.11

60 60.13

0.13 60 60.11

0.11

(40)

(Table 5-7 continued)

80 79.20

-0.80 80 80.28

0.28

86 85.46

-0.54 86 85.51

-0.49

88 105.02

17.02

89 98.94

9.94

Figure 5-21: Hook A Change in Cam Angle Side Pull

Hook B showed a considerable change in cam angle (initial to final) at cam angles of

less than 20° but seemed to stabilize to less than 2° in the range 20° to 70°, after which

the change in cam angle started to increase again. These results are representative of

the 2000 and 4000 kg applied loads and are presented in tabular form in Table 5-8. The

corresponding graphical presentation is illustrated in Figure 5-22, in which a cam angle

change of 18° at an applied load of 1100 N represents the cam rotation leading to hook

release.

Table 5-8: Change in Cam Angle for Hook B Side Pull

Applied Load of 2000 kg

Applied Load of 6000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

6 20.15

14.15

8 20.92

12.92

10 20.13

10.13 8 21.35

13.35

20 22.44

2.44 20 22.76

2.76

30 31.56

1.56 30 32.95

2.95

(41)

(Ta

contin

50 51.61

52.367

2.37

ble 5-8

ued)

1.61 50

60 61.30

1.30 60

62.2512

2.25

70 71.96

1.95 70

72.6417

2.64

74 77.27

3.27 71

73.4956

2.50

75 79.77

4.77 73

79.8054

6.81

77 81.80

4.80 75

83.3646

8.36

77 80.55

3.55 80

84.7324

4.73

79 92.93

13.93

79 92.77

13.77

80 82.94

2.94

81 93.75

12.75

Figure 5-22: Hook B Change in Cam Angle Side Pull

Hook C like hook A

experienced a wider stable threshold range in the

side pull tests (i.e.

≈ 5° over the aft and forward pulls. The cam angle threshold after which the cam started

to rotate was 68° for the 2000 kg applied load and about 68° for the 4000 kg applied

load from Table 5.9. The data for this trial only extended as far as 4000 kg rather than

6000 kg as the technical staff advised not to exceed 4000 kg during this test due to

limitations of the machine. Illustrated in Figure 5-23 is the 2000 kg applied load example

in which the cam started to rotate at 69° (i.e. 12° change) at a load of 9700 N.

(42)

Table 5-9: Change in Cam Angle for Hook C Side Pull

Applied Load of 2000 kg

Applied Load of 4000 kg

Cam Angle

(degrees)

Final Angle

(degrees)

Delta

Cam Angle

(degrees)

Final Angle

(degrees) Delta

0 0.55

0.55

0

-1.13

-1.13

10 9.16

-0.84

10 9.22

-0.78

20 20.09

0.09 20 21.16

1.16

30 29.26

-0.74 30 29.09

-0.91

40 41.00

1.00 40 40.37

0.37

50 51.44

1.44 50 50.31

0.31

60 60.67

0.67 60 60.97

0.97

66 66.58

0.58 64 64.68

0.68

68 68.02

0.02 65 82.83

17.83

69 81.90

12.90

68 82.25

14.25

70 76.67

6.67 70 77.45

7.45

Figure 5-23: Hook C Change in Cam Angle Side Pull

The results for the damage cable offline pulls (i.e. aft, forward and side) indicate that

hook B exhibits the lowest degree of stability of the three on-load hooks tested. Hook C

showed the greatest degree of stability (i.e. smallest cam angle changes from initial to

final angle) even though hook A had a wider threshold range. In summary, with the

release cable disconnected hook C is the least likely to open followed by hook A and

finally hook B.

Figure

Figure 2-1: On-Load Release System
Figure 3-3: Hook C Set Up for Inline Tests
Table 4-14 Applied Loads for Hook D  Applied Load (kg)
Figure 5-2: Hook B: Inline On-load Release Test - 3000 kg Load
+7

Références

Documents relatifs

Avant que vienne le crépuscule Celui qui précède la nuit Et que s'arrête la pendule Qui bat le rythme de nos vies, Je voudrais profiter encore D'être avec toi tout simplement

A and B, examples (A) and number (B) of multinucleated TRAP-positive cells formed in M-CSF-, M-CSF/sRANKL-, M-CSF/LPS-, and M-CSF/sRANKL/LPS-treated cultures after 14 days of

Below room temperature the easy axis in DyFe3 does not overlap any of the principal crystallographic axes. This necessitates the off- diagonal elements of the EFG tensor to be

structure persists throughout the gap, (iv) at any non-zero shear rate there is secondary flow (i.e., flow normal to the plane of applied shear) which is a direct consequence of

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

As illustrated with the drug release experiments the kinetic of release can be controlled by both the nature of the nucleobase and the presence of salts.. Their nucleic

The purpose of this experiment is to mix several simple tasks items in a complex sequence of behav- iors, the combination of those simple tasks being taught to the robot by

Les féculents sont le riz, le blé, les pâtes, le pain, les céréales du petit déjeuner, les légumineuses (haricots blancs, flageolets, pois chiches, lentilles…) et les pommes