SEDL / STP / STP569-EB / STP33180S

Realism in Fatigue Testing: The Effect of Flight-by-Flight Thermal and Random Load Histories on Composite Bonded Joints

Wilkins, DJ
Senior structures engineer, senior structures engineer, and project test engineer, General Dynamics, Fort Worth Division, Forth Worth, Tex.

Wolff, RV
Senior structures engineer, senior structures engineer, and project test engineer, General Dynamics, Fort Worth Division, Forth Worth, Tex.

Shinozuka, M
Professor, Columbia University, New York, N.Y.

Cox, EF
Senior structures engineer, senior structures engineer, and project test engineer, General Dynamics, Fort Worth Division, Forth Worth, Tex.

Pages: 16    Published: Jan 1975

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Abstract

Current military specifications call for increased realism in fatigue testing. Criteria are discussed which recognize those portions of a spectrum that should be random and those that should be deterministic.

This paper documents a research program which included spectrum development, test facility setup, and a limited test series. The spectrum was a flight-by-flight random load history including realistic mission temperature exposures. The test facility utilized a small digital computer for closed-loop control of load and temperature.

Results of tests on three sets of five boron-epoxy-to-titanium bonded joints are discussed, and the effects of temperature exposure and time acceleration are investigated.