Response of a full-face motorcycle helmet FE model to the UNECE 22.05 chin bar impact test. Issue 6 (1st November 2016) - Whyte, Thomas
ABSTRACT: This study investigates the role of full-face motorcycle helmet components in reducing the severity of chin bar impacts to a motorcyclist. A finite element helmet model was created for chin bar impacts by carrying out component tests on the chin bar padding, helmet shell and the chinstrap. Addition of two composite layers to the chin bar, stiffening the shell, reduced the peak headform centre of gravity acceleration from 168.3 g to 122.6 g in the UNECE 22.05 chin bar impact test configuration. The presence of chin bar foam was necessary to avoid excessive headform responses but optimal foam stiffness was dependent on shell stiffness. The lowest peak headform acceleration of 113.1 g was achieved by stiffening the helmet shell and softening the chin bar foam padding in comparison to the validated helmet model. The chinstrap was also critical, causing peak acceleration increases of 27.3 g and 118 g when slightly loose and absent, respectively. The significance of the shell and chinstrap in chin bar impacts is in contrast to cranial helmet impacts which are predominantly controlled by the crushable foam liner. The fact that chinstrap pre-test tightness influences the headform acceleration response is important for the helmet test technician.