Car-to-car side impacts : development and validation of mathematical models and their usability for protective system design. Thesis Chalmers University of Technology, Göteborg.

The objective of the present work is to develop and use mathematical models to establish principals for protective systems for occupants in car-to-car side impacts. The efforts in this work are concentrated on the protection of the thorax and abdomen. The chosen approach is to develop general-purpose mathematical models since developing occupant protection system by means of mechanical tests is very costly and time consuming. The models were subsequently used to evaluate a large number of design parameters. The mathematical models developed and implemented are: (1) a model of the BIOSID dummy; and (2) a hybrid model consisting of occupant, vehicle and impacting barrier. The BIOSID model is used in sled simulations to evaluate the potential injury-reducing benefits of padding or airbags in side impacts. The hybrid model is used in crash simulations to evaluate the effects of barrier type and vehicle modifications on injury response. Models of the EUROSID-1 and US-SID dummies and a model of the human body are used as occupants. Models of the EEVC foam and NHTSA honeycomb side-impact barriers are the impacting object. The sled model, including the BIOSID dummy model, is used to establish the occupant protection system that would result in the efficient protection of the occupant. The hybrid model is used to establish the most violent barrier for the occupant. It is found that significantly reduced injury measures are obtained with the addition of thick padding at higher impact velocities. At lower impact velocities, padding produce no injury-reducing benefits. Impact with the EEVC barrier is more violent for the occupant than impact with the NHTSA barrier; thus, higher dummy readings are obtained with the EEVC barrier. It is shown that vehicle improvement to reduce injury risks in side impacts did not necessarily entail the stiffening or strengthening of the structure. The advantage of mathematical modelling approach is that it provides a quick and economical means of developing principles for occupant protection systems.