Determination of Stresses and Time to Failure

Abstract

To assess the safety and life of a component or structure, it is essential to know the stresses in its critical parts. In Chapter 3, the characteristic features of stresses in two-layer bodies were discussed for the principal body shapes and configurations of loading. In practice, most problems are much more complex: the shape is complicated, the load or temperature may change with time, etc. Accurate determination of stresses in these cases is difficult. On the other hand, the magnitude of the load, conditions of heat transfer or material parameters are often not precisely known. In such cases, determining the stresses accurately is illusory. Generally, during strength design it is reasonable to proceed step by step. At first, we solve a simplified problem and try to ascertain the influence of the main factors. At the same time we evaluate the accuracy of the results. If the requirements are higher, the calculations may be repeated using better methods of analysis and more accurate values of the material and load parameters.