Crashworthiness

Crashworthiness is the ability of a structure to protect its occupants during an impact. Crashworthiness may be assessed either prospectively, using computer models (e.g., LS-DYNA, MSC-Dytran, MADYMO) or experiments or retrospectively by analyzing crash outcomes. Several criteria are used to assess crashworthiness prospectively, including the deformation patterns of the vehicle structure, the acceleration experienced by the vehicle during an impact, and the probability of injury predicted by human body models. Injury probability is defined using criteria, which are mechanical parameters (e.g., force, acceleration, or deformation) that correlate with injury risk. A common injury criterion is the Head impact criterion (HIC). Crashworthiness is assessed retrospectively by analyzing injury risk in real-world crashes, often using regression or other statistical techniques to control for the myriad of confounders that are present in crashes.


 Types of Impact

• Frontal-impact tests: which is what most people initially think of when asked about a crash test. These are usually impacts upon a solid concrete wall at a specified speed, but can also be vehicle-vehicle tests. SUVs have been singled out in these tests for a while, due to the high ride-height that they often have.

• Offset tests: in which only part of the front of the car impacts with a barrier (vehicle). These are important, as impact forces (approximately) remain the same as with a frontal impact test, but a smaller fraction of the car is required to absorb all of the force. These tests are often realized by cars turning into oncoming traffic. This type of testing is done by the Insurance Institute for Highway Safety (IIHS), EuroNCAP and Australasian New Car Assessment Program (ANCAP).

• Side-impact tests: these forms of accidents have a very significant likelihood of fatality, as cars don't have a significant crumple zone to absorb the impact forces before an occupant is injured.

• Roll-over tests: which tests a car's ability (specifically the pillars holding the roof) to support itself in a dynamic impact. More recently dynamic rollover tests have been proposed as opposed to static crush testing (video).

• Roadside hardware crash tests: are used to ensure crash barriers and crash cushions will protect vehicle occupants from roadside hazards, and also to ensure that guard rails, sign posts, light poles and similar appurtenances do not pose an undue hazard to vehicle occupants.

Front Impact Side Impact Rear Impact

Roof Impact

MUHAMMAD RUZAINI BIN SAMSU@SHAMSUDIN