Australia is considering allowing the use of lower anchorage systems for child restraints in motor vehicles. However, care needs to be taken to ensure that the mix of existing Australian child restraint systems and any proposed lower anchorage system does not pose safety risks for children. In addition, it is desirable to avoid unique requirements for an Australian lower anchorage system and hence an assessment of UNECE ISOFIX and US FMVSS LATCH requirements was undertaken.
A series of 28 frontal impact sled tests were conducted based on the Australian Standard AS/NZS 3629 child restraint dynamic test method. A further series of 15 tests were conducted in a vehicle body mounted on an impact sled with an acceleration-time history representative of a 56 km/h full frontal rigid barrier crash. Three different models of forward-facing child restraint were tested, with varying anchorage configurations including rigid ISOFIX, flexible LATCH strap and 3-point seatbelt. Top tethers were evaluated with anchorages directly behind the child restraint (0°) and offset at an angle of 20°. P3 and Hybrid III 3 year old dummies were used. Anchorage loads and safety performance of the restraint system were assessed. In tests in the vehicle body, maximum dynamic top tether loads were in the range of 7-8 kN and maximum dynamic lower anchorage loads are estimated to be in the range 13-14 kN. Tests using rigid ISOFIX anchorages generally produced lower head acceleration and forward excursion than other tested anchorage types. However, this was accompanied by increased chest deflections and neck flexion moments. These data suggest that lower anchorage systems may be acceptable in Australia, but that modifications to the UNECE and LATCH requirements may be required to ensure compatibility with existing Australian child restraint systems without a degradation of child safety.
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