Constitutive response and failure mechanisms of off-axis metal matrix composites

Although, considerable information is available an the deformation and failure characteristics of longitudinal and transverse MMC lamina a clear understanding of the controlling deformation processes and the nature of damage evolution is Inciting far off-axis MMC lamina. In this thesis damage evolution and failure characteristics were investigated for SiC/Ti unidirectional metal matrix composite (MMC) lamina subjected to a variety of off-axial monotonic loading at room temperature and elevated temperature. Test data regarding 0°, 10°, 15°, 30°, 45°, 90° off-axis loading at room temperature and at elevated temperature of 427°C on MMC we provided in this thesis. As an important component of multi-axial plane stress, pure shear constitutive response of class of the materials was investigated by conducting Iosipescu tests on 90° MMC, its matrix and quasi-isotropic, [0/+45/–45/90]s. The primary objective was to systematically determine the constitutive responses of MMCs in relation with off-axial loading angles their in-plane shear properties and the mechanical behavior of MMCs under multi-axial plane stresses. Microstructure analysis technique was used to reveal the role of damage and plasticity in the development of inelastic deformation. The research was going to provide an insight into the off-axis material response for MMC lamina and associated inelastic deformation Finite element analysis based on a modified MMC inelastic deformation model in literature was conducted to predict the pure shear response of quasi-isotropic MMC subjected Iosipescu loading. Unit cell modeling and analysis were employed for the determination of MMC fundamental constitutive responses as of 0°, 90° and pure shear loading. A damage associated anisotropic Continuum modeling and analysis on MMC were conducted and correlated with experimental data. An effort was also made to establish a comparatively accurate yield stress prediction function based on a modification of an existing MMC J_2A theory. The ultimate purpose of this research was to provide an insight into inelastic deformation and failure mechanisms subjected to multi-stress loading, particularly, under off-axis and Iosipescu loading and furthermore to establish a multi-axial constitutive model and failure criteria for MMC design purpose.