Influence of Material Anisotropy on the Compressive Strain Capacity

Assessment of compressive strain capacity forms one of the critical components of the strain-based design. For pipeline-specific capacity assessments, detailed finite-element (FE) models are generally employed. However, the modelling approach taken to represent pipeline material anisotropy in the FE analysis may have a considerable influence on the computed compressive strain capacity. This study presents a new approach for the representation of material anisotropy in FE models and demonstrates the influence of material anisotropy on the compressive strain capacity with the aid of two case studies using pipeline materials for X60 and X80 grade steel. Results indicate that material anisotropy reduces the compressive strain capacity by up to 30% compared to the capacity prediction using axial tension material properties. If material anisotropy is to be ignored, in order to assess the lowest value of compressive strain capacity it is recommended that the material representation with highest yield strength and yield to tensile strength ratio be selected among the hoop tension, axial tension, and axial compression coupon test results.