Tensile Tst - Lab Report Example

The intention of this experiment is to find out what kind of material should be used in different loading conditions depending upon the kind of construction and the criticality of the work structure. In the experiment, 4 samples of different metals were used –Aluminum, Brass, Steel and Cast-Iron. The experiment involves application of axial loads to four different specimens of identical dimensions till it breaks. A Universal Testing Machine (UTM) is used for this purpose and corresponding stress, strain and extension undergone by each specimen prior to breakage is observed and suitable conclusions drawn.

Preparing the specimen is also an important aspect of testing as both ends of the specimen should have ample length so as to be properly gripped during loading. There is specific gauge length that is standardized and is directly related to the diameter of the round specimen. The testing machine also comes in various combinations with simple screw driven machines to hydraulically actuated machines. Modern machines also have a computer generated feedback which displays all the required information on our screen.

After preparing the specimen it is loaded onto the UTM machine and loaded according to a specific gradual extension rate till the specimen breaks. (Gere and Timoshenko, 2004) The outputs results from the range of stress that the specimen goes through during the process of loading till its breakage gives us valuable information regarding the yield strength, allowable stress and Young’s Modulus of the material. The uniform plastic deformation continues till the specimen starts to experience necking which gives the ultimate tensile strength.

On further increase of loading non-uniform plastic deformation starts. This progresses till a point of fracture which gives the fracture strength of the specimen. (Gere and Timoshenko, 2004) Specimen 1 (aluminum) and specimen 2 (brass) showed lower