Enhancing Shoulder Joint Biofidelity in the VIVA+ Human Body Model and Evaluating its Response

Sammanfattning

Previous versions of the VIVA+ human body models have demonstrated excessive shoulderstiffness compared to experiments conducted on postmortem human subjects. This studyaims to enhance the biofidelity of the shoulder in the VIVA+ model. Data from studiesinvolving postmortem human subject experiments were extracted and applied to twoseparate models of the acromioclavicular and sternoclavicular joint. Different verificationtests were implemented to ensure that the mechanical properties of the joints wereimplemented correctly. The data from the studies were also used to construct biomechanicalresponse corridors. The model modifications were implemented and evaluated in LS-DYNA,and the corridors were constructed in Python using principal component analysis andBayesian regression. Initially, a force-deflection corridor was intended, but limitations inthe deflection data restricted the final corridor construction to the force-time response.Analysis of the corridors showed that the choice of principal components affected thephysical reasonability. The final validation of the updated model involved comparing itwith the previous iteration and the response corridors. By implementing the joints in anupdated model in LS-DYNA and comparing the simulated VIVA+ response with thesecorridors, it was possible to assess how closely the updated model was to the experimentalhuman response. The results showed that the updated model was less stiff than the originalVIVA+ model, for all model types. The comparison to the corridors showed that themodified model was closer to the corridors at lower impact speed, while the response athigher speeds still differed from the experimental range. This indicates that the updatedshoulder joints improved the response of the model, but further development is still neededto fully represent the biomechanical behaviour of the shoulder.