| Abstract: | Improved Methods of Stress Analysis to Analyze and Prevent Failures The continuous rising demands on productivity and economy of modern processes, for example in the chemical or power generating industries, cause a tendency for permanent rise of the process parameters pressure and temperature. But for the engineer of a project rising process parameters mean an unproportional increase of the number of mechanical/thermal/chemical induced load collectives. During the basic design phase of a plant this aspect has to be taken into account with respect to the materials choice and the analysis of all mechanical, thermal and chemical induced load cases. In this article modern computer based stress analysis methods for the complex simulation of combined mechanical/thermal load cases are discussed using the example of pipe work. The emphasis was focussed on ?pipe work”? with respect to the new German pressure vessel code of April, 21 st., 1989. Since then within the framework of this code the integrity of pipe work has to be verified. Due to this demand a general discussion was initiated to validate the appropriate analysis method. In this article different examples were chosen to demonstrate the influence of complex load situations on the total stress level, for example the combination of external bending moments with stresses due to the mismatch of the physical properties of a selected material combination. Another goal of this paper is to show the demand for further investigations to transfer brand new scientific results to common engineering praxis. This aspect is discussed examining the failure behaviour of heat resistant steels under complex mechanical/thermal loading. It must be emphasized that the discussed analysis methods are not a paragraph in the German pressure vessel code. But these methods are necessary to assist the code in effective analysis and prevention of failures. |
