Reliability analysis for components under thermal mechanical loadings

Environmental and Operational Stress Testing is the most common approach to precipitating structure latent defects before the manufacturing of products. This testing consists of applying environmentally induced stresses to the product. Typically, these environmental stresses for mechanical structural automotive components consist of vibration loading based on road input and/or self-induced vibration with cycling temperatures between a high and low extreme. Many components in most fields of engineering are subjected to fatigue at elevated temperatures. High - temperature fatigue is mainly a concern at temperatures above 30 or 40 percent of the absolute melting temperature. Since some of these components are costly and safety-critical, it is understandable that there is a significant interest in proper characterization of fatigue behavior at high temperatures. On most cases strain life characteristic is not known for a given application and or a given material. To further complicate the component application can be in an environment where more than one failure mode due to the application type can be observed. This paper presents a practical testing methodology used to determine product´s operational life given high temperature operational application and results are compared with field observations.