Computational human rigid body model with applications to landing falls and injury prevention

• Main Author: Thornton, D. A.
• Published: Swansea University 2005
• Subjects: 612
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639234

A three-dimensional computational human body model, named CHRIS (<b>C</b>omputational <b>H</b>uman <b>R</b>igid-Body <b>I</b>mpact <b>S</b>imulator), was developed to study the mechanical behaviour of the body in low and high acceleration environments. CHRIS is constructed from 15 rigid ellipses, which are connected by 14 kinematic joints, and has 34 degrees of freedom (DOF). Various human limbs and joints can be attached to CHRIS, so as to determine stresses and strains in specific body regions during impacts. Within this thesis a three-dimensional knee joint and lower leg are connected to CHRIS, and the stresses within the ligaments and bones are analysed. Biological materials, present within the human body, generally consist of an elastin ground substance and bundles of collagen fibres. Subsequently, hyperelastic transversely isotropic constitutive models are employed in this thesis. Bone is modelled using a general transversely isotropic hyperelastic function, which recovers the linear transversely isotropic constitutive matrix in the linear regime. Soft biological materials, such as tendons and ligaments, exhibit a high degree of stiffening for lower strains; thus, an exponential based function is used to stimulate this phenomenon. Although, soft biomaterials fundamentally display viscoelastic material properties, the time-dependent effects can be neglected when studying short impacts; hence, a purely hyperelastic response is sufficient. In the future, it is hoped that this research will prove to be a valuable tool in the automobile and aerospace industries, where the ability to predict injuries within the human body (and thus design safety systems) would be of use.