THUMS (Total human model for safety) [Watanabe et al] is a finite element model of human body developed to study various injury mechanisms and for use as a substitute for crash test dummies. The development team of Toyota Central R&D Labs (TCRDL) has validated different parts of this model against experimental data available in literature. Neck response data for different impact conditions is available in Mertz and Patrick, and McElhaney et.al. A preliminary validation of the neck model in Thums, against some of these tests, has been presented by the TCRDL group [Oshita et.al] but no extensive validation has been reported for the variety of test conditions reported in literature. Typically, frontal, side and rear end impacts are of interest and these cause bending, axial as well as torsional loading on the cervical spine. A computational model can be expected to validate against multiple BCs and initial conditions. Therefore, validation of a computational model (THUMS) in varying test conditions is of significance. Thus the objective of the current work is to independently investigate the fidelity of the neck model of THUMS under varying impact conditions.
 

From the initial seating position the Thums model has been modified to match the initial position in the tests. The impact test conditions used in the experiments have been then recreated in PAMCRASH^TM and simulations have been carried out to validate the neck model. The models and the material properties have then been iterated and the performance of the Thums model has been investigated vis-à-vis the experimental results.
 

In this paper we have verified the THUMS cervical spine model against three sets of experimental data available in literature. The model validates well in some cases but is found lacking in some others. The reasons for the same have been discussed and possible directions for improvement have been suggested. These include better material models for soft tissues, better muscle model, better failure / rupture models, better contact interfaces and inclusion of more details in the neck model, to name a few. We are currently investigating most of these issues and would have more suggestions in these areas in the months to come.

                     Movements in THUMS after 0.025, 0.05, 0.075 and 0.092 msec.    (Chawla A et al., 2005)

 Final Sitting Position of THUMS for frontal  (Chawla A et al., 2005)   Sled Model using Shell Element (Chawla A et al.,2005)                                                     

        Initial Position of THUMS (Chawla A et al., 2005)        THUMS with chest restraint system (Chawla A et al., 2005)

Front, side and Top view of the neck model prepared for simulating Human cervical spine to torsion. (Chawla A et al., 2005)

Movements in THUMS after 0 msec, 100 msec, 150 msec, 200 msec and 250 msec respectively.   (Chawla A et al., 2005)

Movements in THUMS neck after 0 msec, 100msec, 200 msec and 300 msec respectively.   (Chawla A et al., 2005)

                     Super imposed view of neck