Attachment J.1 - Appendix D - Upper Legform PADI.pdf

APPENDIX D

Procedures for Assembly, Disassembly, and Inspection

(PADI)

of the Pedestrian Upper Legform Impactor

December 2019

Brian Suntay David Hyder

Transportation Research Center Inc.

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Table of Contents

List of Figures

List of Tables

1. Introduction

1.1. Purpose

1.2. Part Numbers

2. Construction

3. Clothing

4. Instrumentation

5. Procedures for Assembly and Disassembly

5.1. Assembly

5.1.1. Setting the Torque Limiting Joint

5.1.2. Assembling the Load Transducer Components

5.1.3. Fitting the Flesh and Cover

5.1.4. Additional Weights

5.2. Disassembly

5.3. Inspection

6. External Dimensions and Mass Specifications

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List of Figures

Figure 1. Assembly drawing of the upper legform impactor Figure 2. Exploded view of the upper legform impactor and select calibration components Figure 3. Setting the torque limiting joint (adapted from TRL User Manual v2.8) Figure 4. Insertion of cork sleeve and load transducer adaptor into the front member Figure 5. Insertion of the pin into the side of the front member and through the adaptor Figure 6. Installation of sliding washer and centering sleeve Figure 7. Installation of load transducer of stud and centering sleeve Figure 8. Installation of the rear member onto the front member with load transducers in place .. 9 Figure 9. Securing the rear member to the front member using an M8 washer and nut Figure 10. Use of cable tie to secure and prevent mechanical noise between front and rear members Figure 11. Assembled upper legform impactor (without flesh/cover) Figure 12. Flesh (blue Confor foam) and cover Figure 13. Assembly of skin, studs and spacers on one side of legform Figure 14. Insertion of studs through the rear member and insertion of opposite side spacers Figure 15. Upper legform impactor with flesh and cover Figure 16. Assembled upper legform impactor with additional weights installed

List of Tables

Table 1. Upper legform impactor parts list Table 2. Major dimensions of the upper legform impactor

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1. Introduction

This document was prepared for the National Highway Traffic Safety Administration (NHTSA) under the title “Procedures for Assembly, Disassembly, and Inspection (PADI) of the Pedestrian Upper Legform Impactor.”

1.1. Purpose

This document contains the procedures for assembly and disassembly of the upper legform for the purpose of inspection and preparation for testing. Certification tests are specified in a UNECE Addendum 126 Regulation Number 127 Revision 1 Annex 6 Section 2. The details of this test are also specified in the NHTSA companion document “Qualification Procedures for Pedestrian Test Devices December 2019.” The upper legform user will periodically perform the qualification tests to assure that the legform is maintained at the specified performance levels.

1.2. Part Numbers

All part numbers in this document refer to the drawing package entitled “Pedestrian Upper Legform Drawing Package December 2019”.

2. Construction

Figure 1 shows an assembly drawing of the upper legform impactor.

Figure 1. Assembly drawing of the upper legform impactor

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Some of the design highlights of the pedestrian upper legform impactor include:

• Bending and force measurements that correspond to the two principal modes of serious injury to pedestrians in contact with upper bumper and hood leading edge: femur fracture due to bending and pelvis fracture due to high forces.

• Torque limiting joint (consisting of the pivot bolt and clutch plates in Figure 1) that provides protection to the impactor and propulsion system.

3. Clothing

The upper legform impactor utilizes two layers of blue Confor foam to mimic flesh and a thin layer of rubber to mimic skin. This is described in more detail in the assembly section 5.1.3.

4. Instrumentation

Standard instrumentation of the upper legform impactor includes three channels to measure bending moments and two channels to measure forces. All channels are intended for injury assessment.

To measure bending moments, the backside of the front member of the upper legform contains three full-bridge strain gages: one at the centerline, one 50 mm above the centerline, and one 50 mm below the centerline – as shown in Figure 1. To calibrate these bending moment strain gages, please refer to the TRL User Manual1.

To measure force, two piezo-electric load transducers (Kistler Part No. 9021A) are located between the front and rear members, one at the top of the legform and one at the bottom of the legform – as shown in Figure 1. The impactor is designed for use with the load transducer components listed in Table 1. No other type of load transducer is recommended for use with this design. However, it is possible to use alternative charge amplifiers with suitable cables to connect to the load transducers.2 Use a power supply that is suitable for the load transducers and charge amplifier. The load transducers and charge amplifier should be recalibrated as a system on an annual basis. Please refer to the TRL User Manual3 for the calibration process.

1 TRL Upper Legform Impactor User Manual Version 2.6a September 2015, p. 6 2 NHTSA used Kistler Part No. 5039A331 or 5073A221 in this procedure.

3 TRL Upper Legform Impactor User Manual Version 2.8a November 2016, p. 8

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5. Procedures for Assembly and Disassembly

Figure 2 shows an exploded view of the upper legform impactor with parts labeled as listed in Table 1.

Figure 2. Exploded view of the upper legform impactor and select calibration components

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Table 1. Upper legform impactor parts list Assembly Item # Item Description Quantity

Front Member 1 Front Member 1 2 Adaptor Pin 2 3 Cork Sleeve 2

Rear Member

4 Rear Member 1 5 Weight, Large, 10 mm Thick 12 6 Weight, Large, 5 mm Thick 2 7 Weight, Large, 3 mm Thick 2 8 Weight, Large, 2 mm Thick 2 9 Weight, Large, 1 mm Thick 2

10 Weight, Small, 2 mm Thick 2 11 Weight, Small, 1 mm Thick 2 12 Screw, M8 x 90 8 13 Screw, M8 x 80 8 14 Screw, M8 x 70 8 15 Screw, M8 x 60 8 16 Screw, M8 x 50 8 17 Screw, M8 x 40 8 18 Screw, M8 x 30 8 19 Screw, M8 x 20 8 20 Washer, M8 8

Load Transducer Assemblies

21 Load Transducer Adaptor/Stud 2 22 Sliding Washer 2 23 Load Transducer, 9021A 2 24 Centering Sleeve, 9524 2 25 Charge Amplifier, 5039A (Not Shown) 1 26 Cable, 1633C5 (Not Shown) 2 27 Connector, 1500A57 (Not Shown) 2 28 Washer, M8 2 29 Nut, M8 2 30 Cable Tie 2

Torque Limiting Joint

31 Friction Disc 2 32 Clutch Plate 2 33 Pivot Bolt 1 34 Pivot Nut (Extra High Tensile) 1 35 Washer, M12 2

Flesh and Skin

36 Flesh, Inner 1 37 Flesh, Outer 1 38 Skin 1 39 Studding 4 40 Spacer 8 41 Washer, M5 8 42 Nut, M5 4 43 Nut, Self-Locking, M5 4

Calibration and Certification

44 Calibration Lever 2 45 Calibration Mount 1 46 Load Distribution Cap 1 47 Certification Tube 1

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5.1. Assembly

5.1.1. Setting the Torque Limiting Joint

To assemble the torque limiting joint, place a friction disc (Item #31) on either side of the central hole of the rear member (Item #4). Keep the friction disc surfaces clean and free from oil. Next, place a clutch plate (Item #32) on top of both friction discs. Insert the pivot bolt (Item #33) through a lightly greased M12 washer (Item #35), then through the clutch plates and friction discs, and then through the center of the rear member. Place another lightly greased M12 washer over the end of the pivot bolt and loosely fasten the extra high tensile pivot nut (Item #34).

Before fastening, make sure that the thread of the pivot nut is oiled (e.g., gearbox or engine oil).

Make sure that the rear member is free from the load transducers and the front member. Bolt the rear member to a long lever using the holes for the load transducer studs. Next, attach the rear member via the clutch plates to a mount held in place with a clamp or vice – as shown in Figure 3.

Figure 3. Setting the torque limiting joint (adapted from TRL User Manual v2.8)

Put a known torque not exceeding 160 Nm on the pivot nut while using the alignment marks on the rear member and clutch plates to ensure that the rear member is perpendicular to the guidance

D8 system. Then, pull on the far end of the lever through a load transducer until the joint moves.

Repeat this process (increasing or decreasing the force as necessary) until the torque required to move the joint (force exerted multiplied by lever length, L, to centerline of rear member) is 675 Nm ± 25 Nm.

If a minimum joint torque of 650 Nm cannot be obtained, then disassemble and inspect the joint and clean the clutch plates and friction discs. Ensure that the thread of the pivot nut is oiled and reassemble and repeat the process for setting the joint torque. If a proper joint torque is still unobtainable, the inner surfaces of the clutch plates and friction discs may need to be roughened with 120 grit wet and dry paper. To roughen the friction discs, rub them just enough to remove any surface glazing. To roughen the clutch plates, rub their inner surface with a figure eight motion until all but the deepest score marks are removed. Finally, clean and reassemble the torque limiting joint.

Once the appropriate joint torque is obtained, remove the lever arm from the rear member and unfasten the clutch plates from the mount.

5.1.2. Assembling the Load Transducer Components

When reassembling the impactor, the end of the front member labeled “TOP” should be uppermost. In addition, the same combination of load transducer and stud should be used for calibration and testing. Note that the stud should not be removed from the load transducer adaptor as the stud is held in its correct position by a thread-locking adhesive.

Insert a cork sleeve (Item #3) into the hole at the top of the front member (Item #1). Next, insert the load transducer adaptor with attached stud (Item #21) into the hole. Center the adaptor to the hole using the alignment marks on the adaptor and front member – as shown in Figure 4.

Figure 4. Insertion of cork sleeve and load transducer adaptor into the front member

Front Member

Stud

Transducer Adaptor

Cork Sleeve

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Insert the adaptor pin (Item #2) into the side of the front member and through the load transducer adaptor – as shown in Figure 5.

Figure 5. Insertion of the pin into the side of the front member and through the adaptor

Install a sliding washer (Item #22) that is lightly greased on both sides and centering sleeve (Item #24) over the load transducer stud – as shown in Figure 8.

Figure 6. Installation of sliding washer and centering sleeve

Next, install the top load transducer (Item #23) that is lightly greased on both sides over the stud and over the centering sleeve – as shown in Figure 7.

Pin

Sliding Washer

Centering Sleeve

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Figure 7. Installation of load transducer of stud and centering sleeve

Repeat the previous steps for the bottom load transducer.

Insert the top and bottom load transducer studs into the holes at the top and bottom of the rear member – as shown in Figure 8.

Figure 8. Installation of the rear member onto the front member with load transducers in place

Place an M8 washer and an M8 nut over the studs. Pre-tension the elastic load transducer stud to a force of about 10 kN. Use the load transducer output to set the pre-tension as follows: 1) Start

Load Transducer

Rear Member

Front Member

Stud

Load Transducer

D11 with the nut loose; 2) Reset the charge amplifier; 3) Tighten the nut while monitoring the output until 10 kN is obtained; and 4) Reset the charge amplifier – as shown in Figure 9.

Figure 9. Securing the rear member to the front member using an M8 washer and nut

Lastly, fit cable ties around the front and rear members as shown in Figure 10. Trim off the ends of the cable ties. The cable ties are fitted to take up slack in the slotted holes, hold the adaptor pins in contact with the adaptors, and prevent contact between the components that may cause spikes in the load transducer outputs.

Figure 10. Use of cable tie to secure and prevent mechanical noise between front and rear members

The assembled upper legform impactor without flesh and cover is shown in Figure 11.

M8 Washer & Nut

Cable Tie

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Figure 11. Assembled upper legform impactor (without flesh/cover)

5.1.3. Fitting the Flesh and Cover

The flesh and cover for the upper legform impactor are shown in Figure 12. The flesh consists of two layers of blue Confor foam. The inner foam layer (Item #36) is smaller in width and has a notch cut out on either side (320 mm x 180 mm x 25.4 mm, R. 45 mm). The outer foam layer (Item #37) is slightly wider (320 mm x 230 mm x 25.4 mm). A small dab of glue may be applied between the two layers of foam at the top and bottom in order to keep the foams together and aid in installation. The cover skin (Item #38) consists of a thin rubber sheet that is flanked by two brackets to fasten it to the impactor.

Figure 12. Flesh (blue Confor foam) and cover

Strain Gages Load Cell

Centerline Top Bottom

Load Cell

Rear Member

Front Member

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Fasten an M5 washer and nut to the end of each of the fours studs (Item #39). Then, insert the four studs through one side of the cover. Next, insert a spacer (Item #40) over each of the studs

– as shown in Figure 13.

Figure 13. Assembly of skin, studs and spacers on one side of legform

Insert each of the studs through the four holes in the rear member. Then, insert another spacer over each of the studs as shown in Figure 14.

Figure 14. Insertion of studs through the rear member and insertion of opposite side spacers

Cover

Stud

Spacer

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Place the foam assembly over the front member and make sure that the smaller, notched inner foam is in contact with the front member. Center the foam over the front member and pull over the cover. Insert the cover over the four studs and fasten an M5 washer and nut. Hand tighten it

– as shown in Figure 15.

Figure 15. Upper legform impactor with flesh and cover

5.1.4. Additional Weights

The upper legform itself has a mass of 5.725 ± 0.125 kg. Depending on the application (qualification versus vehicle testing), ballast may be added to the legform as shown by the added mass in Figure 16. There is available space behind the rear member for the installation of various weights of appropriate size. The total effective impactor mass (upper legform plus attached propulsion/guidance system components) is specified to be 12.0 ± 0.1 kg for qualification testing. The total effective impactor mass (upper legform plus attached propulsion/guidance system components) is specified to be 10.5 ± 0.105 kg for vehicle testing following the 775 mm wrap around distance (WAD 775) procedure in the European New Car Assessment Programme (Euro NCAP) Pedestrian Testing Protocol (V8.3, December 2016).

Depending on the mass of the attached propulsion/guidance system components, the addition of extra masses might be necessary to meet the specified mass requirement. At VRTC, the guidance system components have a mass of 3.759 kg. Therefore, ballasts of approximately

2.516 kg and 1.016 kg were added for qualification testing and vehicle testing, respectively.

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Figure 16. Assembled upper legform impactor with additional weights installed

5.2. Disassembly

To disassemble the upper legform impactor, reverse the process described in section 5.1.

5.3. Inspection

Inspect the skin for tears or cracks and replace if necessary. Ideally, always use new flesh foam.

However, if the flesh is not to be replaced after a test, inspect the foam for any visible splits or cracks and check if the foam feels abnormally soft. Finally, check that the rear member and clutch plates are aligned via the alignment marks to ensure that the rear member is perpendicular to the guidance system. Realign if necessary.

Added Weight

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6. External Dimensions and Mass Specifications

Major dimensions of the upper legform impactor are shown in Table 2. The assembled upper legform impactor (not including propulsion system components or added ballast) has a mass of

5.725 ± 0.125 kg.

Table 2. Major dimensions of the upper legform impactor

Item Nominal

(mm) Overall Width 187 Front Member Height 351 Rear Member Height 345 Inner Flesh Height 320 Inner Flesh Width 180 Inner Flesh Radius 45 Outer Flesh Height 320 Outer Flesh Width 230

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6. External Dimensions and Mass Specifications