Accession Number : ADA288343

Title :   Life Prediction Methodology for Composite Laminates. Part 1. Constant Amplitude and Two-Stress Level Fatigue.

Descriptive Note : Interim rept. 15 Jan 93-30 Aug 94,

Corporate Author : WRIGHT LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Schaff, Jeffery R. ; Davidson, Barry D.

PDF Url : ADA288343

Report Date : SEP 1994

Pagination or Media Count : 45

Abstract : A strength-based wearout model is presented for predicting the residual strength and life of composite laminates subjected to constant amplitude or two-stress level fatigue loadings. It is assumed that the laminate undergoes proportional loading, that its residual strength is a monotonically decreasing function of the number of loading cycles, and that the probability of failure after an arbitrary number of cycles may be represented by a two parameter Weibull function. The model also incorporates a "cycle mix factor" to account for the degradation of strength and life that may be associated with frequent changes in the stress amplitude of the loading. Experimental results from two-stress level loadings are used to evaluate the model's predictive capability for sequencing effects, as in a low-high or high-low test, and for cycle mix effects, as in a low-high-low-high repeating test. Good correlation between theory and experiment is obtained for all loadings and laminates studied.

Descriptors :   *LAMINATES, *SHEAR STRESSES, *WEAR, TEST AND EVALUATION, MATHEMATICAL MODELS, WEIBULL DENSITY FUNCTIONS, DEGRADATION, PREDICTIONS, PARAMETERS, COMPOSITE MATERIALS, PROBABILITY, FAILURE, STRENGTH(MECHANICS), CYCLES, RESIDUALS, RESIDUAL STRESS.

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE