Small Specimen, Accelerated Fracture Mechanics Test Methods for Failure Analysis

摘要

Innovative methods of extracting test specimens while minimizing the compromises in fracture mechanics analysis often requires imaginative and creative loading conditions to duplicate the in-service fracture conditions. Accelerated test methods to conduct time dependent crack growth measurements in a short time also becomes a critical requirement. The purpose of this paper is to provide an overview of the modified fracture mechanics test methods with specific examples of how modified specimens were fabricated and utilized in the analyses. It will be explained how an accelerated test methods developed on a government funded Small Business Innovative Research Program (SBIR) is utilized to measure fracture toughness with small specimens and life parameters of crack initiation threshold, K_(ISCC), and K_(threshold) for fatigue in a very short time. These techniques have been applied to conduct failure analyses of welded HY 130 steel structures, turbine bolts, gas regulator springs, and chrome-plated aircraft pistons.