A Two-Dimensional Linear Elastic Crack Tip Element for Nastran

Linear elastic fracture mechanics has gained a substantial acceptance in industry and has become one of the most important design considerations. Many engineering structures such as airplanes, turbines, piping pressure vessels, bridges, etc. contain pre-existing flaws. As a result of even rather moderate service loads, crack propagation resulting from these flaws can have a dramatic effect on the service life of the component. To account for this reduction in service life, fracture mechanics analysis in conjunction with a fracture control plan is generally implemented. A new crack element has been developed and incorporated into COSMICNASTRAN. The element is considered linear, isotropic, and homogeneous. Mode I and II stress intensity factors are automatically calculated. Comparisons to theoretical plane strain solutions for several geometries are presented and demonstrate the accuracy of the developed element. Extensions of the element to three dimensions, anisotropic material, and plastic analysis are discussed. Keywords Singular Finite Elements.