Tensile testing

Tensile testing, also known as tension testing, is a fundamental materials science and engineering test in which a sample is subjected to a controlled tension until failure. Properties that are directly measured via a tensile test are ultimate tensile strength, breaking strength, maximum elongation and reduction in area. From these measurements the following properties can also be determined: Young's modulus, Poisson's ratio, yield strength, and strain-hardening characteristics. Uniaxial tensile testing is the most commonly used for obtaining the mechanical characteristics of isotropic materials. Some materials use biaxial tensile testing. The main difference between these testing machines being how load is applied on the materials. Tensile testing might have a variety of purposes, such as: Select a material or item for an application Predict how a material will perform in use: normal and extreme forces. Determine if, or verify that, the requirements of a specification, regulation, or contract are met Decide if a new product development program is on track Demonstrate proof of concept Demonstrate the utility of a proposed patent Provide standard data for other scientific, engineering, and quality assurance functions Provide a basis for Technical communication Provide a technical means of comparison of several options Provide evidence in legal proceedings The preparation of test specimens depends on the purposes of testing and on the governing test method or specification. A tensile specimen usually has a standardized sample cross-section. It has two shoulders and a gauge (section) in between. The shoulders and grip section are generally larger than the gauge section by 33% so they can be easily gripped. The gauge section's smaller diameter also allows the deformation and failure to occur in this area. The shoulders of the test specimen can be manufactured in various ways to mate to various grips in the testing machine (see the image below).