残余应力分析.pdfVIP

AUTOMATED RESIDUAL STRESS ANALYSIS X-ray Diffraction Residual Stress Measurement AN INTRODUCTION A world of solutions AN INTRODUCTION What is Residual Stress? Definition Residual stress is defined as “the stress resident inside a component or structure after all applied forces have been removed”. Compressive residual stress acts by pushing the material together, while tensile residual stress pulls the material apart. Mathematically, compressive stress is negative and tensile stress is positive. Stresses can also be characterized as normal stresses that act perpendicular to the face of a material and shear stresses that act parallel to the face of a material. There are a total of 6 independent stresses at any point inside a material (3 normal and 3 shear stresses). Units of Stress • SI unit for stress is the Mega Pascal (MPa). • US Customary unit for stress is kilo pound-force per square inch (ksi). 6.895 MPa = 1 ksi Stress components inside a material What Causes Residual Stress? Residual stresses are generated, upon equilibrium of material, after plastic deformation that is caused by applied mechanical loads, thermal loads or phase changes. Mechanical and thermal processes applied to a component during service may also alter its residual stress state. What is The Total Stress in a Component? The total stress experienced by the material at a given location within a component is equal to the residual stress plus the applied stress. Tensile residual stress opens crack and increases