Mechanical testing Introduction
Mechanical testing plays an important role in:
Evaluating fundamental properties of engineering materials In developing new materials and Controlling the quality of materials for use in design and construction.
For example:- If a material is to be used as part of an engineering structure that will be subjected to a load, it is important to know that the material is strong enough and rigid enough to withstand the loads that it will experience in service. As a result engineers have developed a number of experimental techniques for mechanical testing of engineering materials subjected to tension, compression, Fatigue, bending or torsion loading. Tension test
Tensile strength is defined as a stress, which is measured as force per unit area. The most common type of test used to measure the mechanical properties of a material is the Tension Test. Tension test is widely used to provide basic d esign information on the strength of materials. The major parameters that describe the stress-strain curve obtained during the tension test are
the tensile strength (UTS), yield strength or yield point (σy), elastic modulus (E), percent elongation (ΔL%) and The reduction in area (RA%).
Some materials will break sharply, without plastic deformation, in what is called a brittle failure. Others, which are more ductile, including most metals, will experience some plastic deformation and possibly necking before fracture. The UTS is usually found by performing a tensile test and recording the engineering stress versus strain. The highest point of the stress-strain curve is the UTS. It is an intensive property. Tensile strengths are rarely used in the design of ductile members, but they are important in brittle members. They are tabulated for common materials such as alloys, composite materials, ceramics, plastics, and wood.
Tensile strength is defined as a stress, which is measured as force per unit area. Concept
Many materials display linear elastic behavior, defined by a linear stress-strain relationship. For many applications, plastic deformation is unacceptable, and is used as the design limitation. The UTS is not used in the design of ductile static members because design practices dictate the use of the yield stress. It is, however, used for quality control, because of the ease of testing. It is also used to roughly determine material types for u nknown samples. Objective
Tension test is carried out; to obtain the stress-strain diagram, to determine the tensile properties and hence to get valuable information about the mechanical behavior and the engineering performance of the material.