Use of Cantilever Specimens to Determine Microcreep Properties

Abstract

Abstract Cantilever beams were employed to determine the microyield strength (MYS) and the microstress relaxation (MSR) behavior of composites for stable member applications. Cantilever beams were designed and the compliance determined using resistance strain gages. Two different composites were tested: 2124-T6/30% SiC and Al-2.5Mg/20% SiC. A 2124-T6/30%SiC composite, previously tested under axial compression, was used to compare its data with the results of this study using bend specimens. The latter material was chosen because of its lower yield strength and modulus. The cantilever beam geometry is a significantly easier configuration to test and obtain over one per million resolution in strain than equivalent axial compression specimens. This allows cost-effective development of microcreep data using readily available standard mechanical test equipment. Additional test development work may permit this technique to be developed into an ASTM standard. It also offers the opportunity to measure the elastic, plastic, and anelastic strain components to develop engineering materials with improved MYS and MSR properties.