Uniaxial Tension and Compression Testing of （单轴拉伸和压缩测试）.pdf

Uniaxial Tension and Compression Testing of Materials Nikita Khlystov Daniel Lizardo Keisuke Matsushita Jennie Zheng 3.032 Lab Report September 25, 2013 I. Introduction Understanding material mechanics is critical for engineering. The uniaxial tension and compression tests provide a simple and effective way to characterize a materials response to loading. By subjecting a sample to a controlled tensile or compressive displacement along a single axis, the change in dimensions and resulting load can be recorded to calculate a stress- strain profile. From the obtained curve, elastic and plastic material properties can then be determined. Therefore, to investigate material mechanics and gain experience in uniaxial testing, we performed compressive and tensile tests on alloys, pure metals, and ceramics, and calculated their Young’s modulus, yield stress, ultimate tensile strength, and elastic strain energy density. 1.1 Uniaxial testing For uniaxial tests, the displacement is typically held at a constant rate, and displacement and resulting load are recorded. The load is measured by a series of strain gages, or “load cell,” while the displacement can be recorded as displacement of the crosshead, or the beam on which the specimen load frame is mounted. For more precise load measurements, strain gages or an extensometer can be directly fixed to the specimen. To make direct comparisons between materials, loading responses must be normalized against sample geometry. Therefore, the dimensions of each sample are noted to compute stress and strain from load and displacement, respectively. Engineering strain can be calculated as: εe = ΔL/Lo (1) Where ΔL is