A MADYMO MODEL OF NEAR-SIDE HUMAN OCCUPANTS IN SIDE IMPACTS

The protection of automotive occupants against broadside collisions is of current interest due to the implementation of a new Federal standa rd on side impact. There is controversy as to the validity of the stan dard, the best criterion to assess injury to the thorax and the type a nd manner in which padding should be used. Although it has been shown in a series of 17 cadaveric tests that paper honeycomb can reduce thor acic injuries dramatically, there are still concerns regarding the los s of air space between the door and the occupant due to the presence o f the padding and regarding the loss of protection for the thorax when there is no engagement of the shoulder with the intruding side struct ure of the car. This paper describes the development of a three-dimens ional rigid body model to simulate cadaveric experiments carried out a t Wayne State University. Model parameters were chosen to yield human- like responses at the level of the shoulder, thorax, abdomen and pelvi s. The model was then used to study the effect of padding on injury pa rameters related to the near-side occupant when a relatively thick pad ding is used (up to 100 mm). It was also used to study the increase in force on the thorax when shoulder engagement is lost. Laboratory test s were conducted with full shoulder engagement but in the field most c ars have a low beltline (window sill) which effectively eliminates sho ulder contact if the arms are outstretched in a normal driving posture . If a sufficiently soft padding was used, the model did not predict a n increase in thoracic force level or any of the injury parameters. Th is result contradicted those from previous models which either used a dummy as the near-side occupant or did not take into account the accel eration of the target vehicle. The model also predicted that the shoul der can provide substantial protection to the thorax and that without shoulder engagement, the force on the thorax can be approximately 45 p ercent higher. A door design which can lower its first velocity peak t o match the second peak and which has 75 mm of soft padding is predict ed by this model as being able to provide protection to the near-side occupant for moderate impacts. Additional cadaveric testing is needed to confirm these results.