Informal Group on Child Restraint Systems | Session 54 | 27 Oct 2015
Brussels
Agenda Item 6.3.
Feedback from TRL study (Chest deflection measurement,…)

6.3.1. CRS-54-08e on abdomen and submarining on Q10, Q6 & Q3 dummy with different input conditions (R129 conditions, UMTTRI installation method and higher test pulse) and with / without poor lab belt guidance CRS. In summary, some works still to do and the following question can be asked :

  • Review of 1.2 bar limit?
  • R129 adopts UMTRI positioning procedure?
  • Investigate on submarining for Q3?
  • New severe frontal pulse?

Pierre CASTAING (UTAC & Chairman) suggests keeping the 1.2 bar limit, as we now do not have scientifically supported & sufficient data (only one test per configuration).

6.3.2. CRS-54-09e on chest behaviour results. The Q-series dummies are able to measure chest deflection (P-series dummies are not) but the shoulder belt tends to move towards the neck. The maximum deflection is due to chin to chest contact. Chest deflection limits are proposed but still not validated. We can see some potential solutions to solve previous problems by creating a test environment that prevents belt slippage from occurring, propose an assessment procedure for the static belt lie & useful injury threshold limits. For this study, deflections were measured on the clavicle for the Q3 & Q6 dummy.

However, during testing a bottoming-out was observed; there was a hard contact between clavicle and neck bracket. Two input conditions were tested (R129 & extreme D ring position) without CRs, with booster seat & with booster cushion.

In conclusion and for summary:

  • the shoulder belt tends to slip toward the neck with Q3 & Q6 dummy,
  • Confirmed clavicle to neck bracket contact affects chest deflection measurements,
  • CRS seem safe using R129 setup with Q3,
  • For Q6 an extreme upper anchorage position can influence belt path and interaction,
  • The belt stays on Q10 shoulder.

Recommendations for TRL are:
  • To test with modifications to upper anchorage position,
  • Can we “fix” the Q3 dummy shoulder & clavicle?
  • Need a static belt path assessment, if nothing else exercises belt guides

Documentation
CRS-54-04/Rev.1 Working draft UN Regulation No. 129 incorporating Phase I and Phase II non-integral CRS provisions (CRS-54 updated)
CRS-54-05 Presentation: Cumulative 3ms Not Consistent in R129 (Tass)
CRS-54-08 TRL EC child safety project–summary of abdomen results (TRL)
CRS-54-09 TRL EC child safety project–summary of chest behaviour results (TRL)
CRS-54-11 CRS booster seat width development (CLEPA)