Roof Crush Analysis

One of the tests used in occupant safety analysis is a roof crush test.

Roof crush analysis.

216 fmvss 216 first published in 1971 specified the test requirements and configurations of roof crush process. Used for quasi static roof crush analysis. Static and it was simulated in ls dyna shown in fig. Roof crush simulation federal motor vehicle safety standard no.

A safer car does not deform as much providing the occupant a larger survival space during this kind of accident. The roof strength is measured by the resistance force required to push a rigid plate into the roof structures. It is used to evaluate how a car will deform during a rollover accident. Objective of the test roof crush is the failure and displacement of an automobile roof into the passenger compartment during a rollover accident.

Quasi static roof crush analysis was carried out on a car roof by a more or less rigid contact body with a flat surface with low velocity i e. The relationship between injury levels and intrusion or roof crush has been statistically established but the mechanism has been thought sometimes to be somewhat obscure. The analysis procedure consisted of examining the case summary crash diagrams and photographic documentation to observe general roof damage patterns. The reason for such low roof crush resistance is the reduced model which does not include all of the components of the biw to offer proper geometric resistance to the impactor displacement.

A and b pillars tended to remain virtually straight. The recently released nhtsa study roof crush analysis using 1997 2001 nass case review which has been in the works for nearly four years reviewed nass rollover crashes in an effort to determine whether roof deformation patterns identified in an earlier agency study were still valid for current vehicle designs see upgraded rollover roof crush protection. Material approach is preferred over the geometric approach due to space constraints in the passenger compartment as well as weight limitations. Vehicle damage is mostly influenced by vertical velocity not roll rate or lateral velocity.

Roof crush and roll velocity loss are however largely independent of lateral velocity. Rollover test and nass case analysis nhtsa june 1992. Each case was evaluated against the deformation patterns observed from the previous analysis. The acceleration induced by the tripping motion itself may be sufficient to eject unbelted occupants before rollover habberstad 1986.