1. OBJECTIVE
The tensile test consists of determining the properties of materials when subjected to tensile stress. This experiment also demonstrates the use of a manual pump, caliper, manometer and dial indicator, which are fundamental instruments for carrying out mechanical tests on materials. This practice will be carried out using a universal material testing machine containing a manual pump attached to apply load and a dial indicator on its moving part to measure the displacement that the application of the load generates in the test piece. As part of the activities, you must measure the initial and final dimensions of the test specimen, in order to check its elongation and determine the modulus of elasticity for the different materials tested.


At the end of this experiment, you should be able to:

Determine the modulus of elasticity of materials;

Analyze the elastic modulus of materials, identifying the characteristics inherent to each of these materials that influence the presented elastic modulus values;

Build and interpret the “stress x strain” curve of materials for tensile tests;

Associate the modulus of elasticity with the tensile strength.

2. WHERE TO USE THESE CONCEPTS?
The tensile test allows us to understand how materials react to tensile efforts, what are the tensile limits, modulus of elasticity and the applied load at which the body breaks. From this test, it is possible to obtain information regarding the hardness, ductility and tensile strength of the material. This information is extremely important for the use of materials in certain applications. We can visualize these concepts in many moments in our daily lives, such as in a simple game like “tug of war”, where the cable is tensioned by the people pulling it and it has to resist this effort without breaking. Another example is the support cables of an elevator, where the cable needs a tensile strength that supports the load applied by the weight of the cabin and the people being transported.


3. THE EXPERIMENT
In this experiment you will make use of the following instruments: universal machine for testing materials, clamping clamps, manual pump, test specimens, caliper and dial indicator. The tensile strength of the material is determined by fixing the test piece by the claws and the caliper is used to measure the dimensions before and after carrying out the test.

By activating the manual pump, the load is applied to the test specimen by moving the piston of the universal machine. The load is applied, generating an elongation in the length of the specimen until it reaches total or partial rupture. This variation in length is measured by the dial indicator throughout the test. And when rupture occurs, the applied load is removed so that the final dimensions of the specimen can be measured.


4. SECURITY
The experiment was designed not to bring physical risks, so you will use objects that are not very harmful and light. Even with these precautions, the use of personal protective equipment (PPE) is extremely important for safety during experiments. In this experiment, the use of a lab coat is recommended.


5. SCENARIO
The experiment features the following materials: universal machine for testing materials, manual pump, dial indicator, test specimens, clamping claws and caliper.