Fatigue Life Estimation by Portable Data Acquisition and Damage Analysis Microcomputer System

A portable microcomputer system with the capability of acquiring strain data and estimating fatigue life to crack initiation has been developed. This briefcase sized equipment performs rainflow cycle counting of the input strain signal and a cumulative damage analysis which fully accounts for both plastic and elastic region effects and includes the effects of a strain concentration factor using Neuber's rule. The system responds interactively to English language commands, with all input and output in engineering units and scientific number notation. Appropriate values for material fatigue properties are entered by the user. These properties and other parameters, such as strain concentration factor and mean strain correction, may be altered after data is acquired and a revised analysis is immediately available. The system also provides a range of fatigue life estimates to suggest the sensitivity of the analysis to uncertainties in material properties.