PATHOLOGIES ASSOCIATED WITH THE NUMERICAL-ANALYSIS OF HYPER-ANISOTROPIC MATERIALS

The rise in popularity of composite materials has brought to light the necessity of analysing materials exhibiting the kinematic constraint of directional inextensibility. Numerical phenomena associated with th e analysis of such hyperanisotropic materials are described herein. Th e phenomena include: element locking dependent on fibre orientation, s purious tension modes and difficulties associated with elements posses sing large material parameter ratios. To facilitate the present descri ption, these phenomena are compared to, and contrasted with the well-d ocumented problems associated with the analysis of incompressible or n early incompressible media. Based on the results of eigenvalue analyse s, elements satisfying the Babuska-Brezzi condition for incompressible media are found to perform rather poorly when analysing hyperanisotro pic materials. These findings are supported by the results of a simple example.