Shengbin Lin

ACCELERATED DURABILITY TESTING AND DATA ANALYSIS FOR PRODUCTS WITH MULTIPLE FAILURE MECHANISMS

Durability and reliability performance is one of the most important concerns of ground vehicle systems, which usually experience cyclic fatigue loadings and eventually fail over time. Creep and oxidation caused damages at elevated temperature conditions further shorten the life of a system and make the life assessment even more complex. One of the key challenges posed to design engineers is to find a way to accelerate the durability tests for products with multiple failure modes and to validate designs within development cycle to satisfy customers and markets requirements. The accelerated testing procedures for products with single failure modes have been studied for several decades and essentially well established even though some fundamental issues are still unsolved. By contrast, much is needed to do for the accelerated testing procedure of products with multiple failure modes and their interactions. In this paper, a new accelerated testing and data analysis procedure suitable for products with linear homoscedastic data pattern is proposed. Examples related to durability life of high temperature components with single failure modes such as fatigue, creep, and oxidation are provided to demonstrate the procedure developed. Durability life assessment of components with multiple failure modes is also investigated and demonstrated with creep-fatigue and fatigue-oxidation damage analyses.

A Probabilistic Life, Damage, and Uncertainty Assessment Method for Engineering Components and Systems

Fatigue life and damage assessment is crucial to the durability and reliability performances of engineering components and systems, especially at early design and validation stages. However, durability and reliability assessment of engineering components and systems is difficult due to, partially, the large uncertainties introduced from many sources. How to quantitatively measure the uncertainties is an important task in engineering probabilistic analysis. Recently, based on fatigue failure data, a new procedure has been developed to assess the durability, reliability and uncertainty of components under constant amplitude loadings. An uncertainty measure, which is very similar to those used in computational complexity, classical statistical physics and information theory, has been proposed. In this paper, two new developments are reported: (1) the uncertainty measure is modified in such a way that the uncertainty measure can be normalized, (2) the durability, reliability and uncertainty analysis procedure is extended to system level. Several examples are provided to demonstrate the effectiveness of the new probabilistic life, damage, and uncertainty assessment approach.Copyright