Documents (Latest posted on 4 Mar 2021)
Related Meetings : Informal Group on GTR 7 (Phase II) | Session 13
Documentation Discussion/Report

Document – GTR7-13-03.
Bernd Lorenz updated the group on the output of a workshop held at BASt at the end of March. The details of this work, which included consideration of an alternative to the use of the 3D H machine method for backset measurement, were dealt with under specific agenda items during the meeting.

The TEG documents from the TEG group are available from:

Paul Depinet– Presentation covering further work on certification testing.
Document – GTR7-13-04.

Spine Bumper compression.

A test rig that will permit bumpers to be inspected individually but without a requirement to disassemble the spine was in design and expected to be built “within the next month” (May 2013). The test procedure will require the cables to be fully slackened to isolate the bumpers and the process is expected to take around 2 hours to perform. The chair asked whether bumper testing might be required as part of each certification, at least in the immediate future, to help establish an appropriate bumper servicing schedule. Paul suggested that in the short term a lot of tests could be needed but that as experience was gained the frequency of testing could be reduced.

Full back support mini sled.

Work has been done using a full back support mini sled with the purpose of improving repeatability. These tests are detecting bumper and jacket variation.

An FE study suggests the full back support test improves ramping and also indicates that changes in lumbar bumper stiffness have a noticeable effect (the same indication as testing in the car seat).

It was noted that there is a lack of consistency in the field with regard to the head contact switch. Humanetics had noted that variations of friction between the head and the head restraint affected some measurements – particularly My. It was noted that the range of μ values used (0.15 to 0.7) to arrive at this conclusion was quite wide, certainly greater than seen in Euro NCAP tests, and could be exaggerating the point.

It was noted that the interest was in respect of calibration/certification and that the frictional value used should be representative of that seen in seat certification tests. It was suggested the seat suppliers could help with finding suitable friction coefficient.

Timeline – Preliminary results available at the end of May, finalised work plan by August 2013. Take into TEG in August.