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.

Report Date:

1994-09-01

Pagination or Media Count:

45.0

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 models 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