A Continuous Biomechanical Model of the Face: A Study of Muscle Coordination for Speech Lip Gestures

International audienceA 3D finite element face model which geometry has been extracted from CT data is being used for implementing orofacial speech gestures and studying underlying muscle activations. This model consists of 3 layers of full and degenerated hexahedral elements. The simplified 5-parameter Mooney-Rivlin hyperelastic law has been used to account for nonlinear elastic properties of face tissues. Contact elements model the contacts between upper and lower lip and between lips and teeth. Muscle fibres are modelled by macrofibres which are implemented in reference to anatomical key points, independently of the mesh structure, by cable (tension only) elements. The muscles themselves are determined by a proximity algorithm through face elements surrounding the cable elements. The effect of some muscle activations on lip shaping has been studied. It is shown that in particular muscle stiffening associated with muscle activation has a noticeable influence on lip protrusion and rounding. The effect of muscles coordination for producing realistic lip shapes has been investigated