Functions of Tensile Testing Machine

Functions of Tensile Testing Machine Points : Functions of Tensile Testing Machine, Different Functions Tensile Testing Machine, Proportional limit, Elastic Limit, Yield Strength, Yield Point, Tensile Strength, Rupture Strength, Elongation, Reduction of Area, Modulus of Elasticity, Ductility, Stiffness, Resilience Tensile testing machine or universal testing machine is used to test different properties of materials. Sonic of functions of the tensile test are as follows: (i) Proportional limit It is the maximum stress at which stress remains dir proportional to strain. The proportional limit is determined from the stirs strain carver drawing straight line managing at the origin and noting first deviation of the plot from the. The proportional limit has limited engineering significance because of its great depends upon the precision, available for its determination. (ii) Elastic Limit The elastic limit is the maximum stress which the material can with without causing permanent deformation which remains after removal of stress. For engineering usages the elastic limit has little significance. (iii) Yield Strength The yield strength is the stress at which a material exhibits a species limiting permanent set. The yield strength of a metal is a property of considerable significance. The tensile strength indicates resistance to permanent deformation produced by tensile loads. It is relating resistance to permanent deformation by shearing bending, compressive, and computer combination of forces. Because of this and the ease of its, measurement the tensile yield strength is used widely as a factor of design it is preferable in most instances to the use of tensile strength. The yield strength also is indicative, of the ease of forming or shaping metals by mechanical means. (iv) Yield Point The yield point is the stress at which there first occurs a marked increase in strain without an increase in stress. The yield point can be determined nothing the first at which there is visible increase in the distance between two gauge marks on a tensile specimen. This is conveniently accomplished by checking the length with a pall of dividers. If extensometer is used, the length can be observed to increase rapidly without an increase in lode Still a third method is to coat the specimen with lacquer which cracks when the yield point reached, the yield point most commonly is observed in mild steel, although it has been detector in a few other alloys as well. (v) Tensile Strength (Ultimate or maximum strength): It is calculated by dividing maximum load carried by the specimen during a tension test by the original cross-sectional of the specimen. (vi) Rupture Strength It is determined by dividing the load at the time of fracture by original cross-sectional area. If the rupture load is divided by the actual cross-section at the time of fracture, the time rupture strength is obtained. The rupture strength is of indirect and limited interest to engineers. It provides the terminals point of the stress-strain curve and makes possible a computation of static toughness. (vii) Elongation Elongation of a example after fracture may be determined by placing the broken specimen closely together and holding them in place by a vice. The distance gauge marks may be measured by means of dividers. Elongation has considerable engineering significance because it indicates ductility or the deform appreciable without rupture. Ductility is essential in forming operation for metals, is desirable to achieve as much deformation as possible in one operation without danger rupture. Ductility is also essential to avoid local failures leading to overall failures in members which are locally highly stressed as a result of design or fabricating techniques. (viii) Reduction of Area After the metal has fractured the percentage reduction in area is by measuring the lest piece diameter at the point of fracture, calculating the cross-area at this point, and expressing it as a percentage of original area. (ix) Modulus of Elasticity Below the proportional limit stress and strain are related to one a constant of proportionality known as modulus of elasticity. (x) Ductility Ductility of a material cannot be expressed exactly from a tensile test. However, valuable information’s are obtained by overall form of the test curve and by the percentage elongation (i.e., strain) and percentage reduction in area of the test piece. (xi) Stiffness The modulus of elasticity is a measure of stiffness of the material. (xii) Resilience It is the ability of a material to absorb energy when deformed elastically and to return is when unloaded. This usually measured by the modulus of resilience which is the string energy per unit volume required to stress the material from zero stress to the yield stress.