Crash-induced Loads in Liftgate Latching Systems 2018-01-1333

Automotive liftgate latches have been subject to regulation for minimum strength and inertial resistance requirements since the late 1990’s in the US and globally since the early 2000’s, possibly due to liftgate ejections stemming from the first generation Chrysler minivans which employed latches that were not originally designed with this hazard in mind. Side door latches have been regulated since the 1960’s, and the regulation of liftgate, or back door latches, have been based largely on side door requirements, with the exception of the orthogonal test requirement that is liftgate specific.

Based on benchmarking tests of liftgate latches, most global OEM’s design their latches to exceed the minimum regulatory requirements. Presumably, this is based on the need to keep doors closed during crashes and specifically to do so when subjected to industry standard tests. The focus of this paper is to understand the specific loads seen by center-mounted liftgate latches when exposed to various industry standard tests, as well as some foreseeable crash conditions currently not addressed by the standard tests. This paper explores the use of CAE analysis to understand the specific structural and inertial loads liftgate latches are exposed to in various rear and side crash tests, in order to better understand the design requirements for liftgate latches to ensure passenger compartment integrity and minimize the risk of occupant ejection through the liftgate closure. Various standard crash tests, vehicle body types and cargo load cases are explored as well. A methodology is presented which shows how the various load cases can be obtained and used for development of new liftgate latches.

This paper does not deal with roll over load cases, which is a subject of ongoing research and will be presented in a subsequent paper.