Unformatted text preview: TENSILE TEST IN MATERIALS OVERVIEW Today we will compare steel and aluminum in a tensile test. Identical specimens of each material will be provided for testing. They are about 4 inches long in the gauge length,
1/8 inch thick and 0.530 inches wide. As they are loaded in the testing machine, both load and deformation will be recorded. In the first stage there is elastic behavior where stress is linearly related to strain. If
unloaded in this range there would be no permanent strain. But when yielding occurs,
stress stops being proportional to strain and unloading results in permanent strain. This
deﬁnes the yield point which is very obvious in steel but harder to discern in aluminum. The modulus of elasticity is the slope of the stress —strain plot before yielding. TEST PROCEDURE 1 i ix) DJ 4 5 6 Verify the test specimen dimensions.
Mount the test specimen in the machine and seat the grips. Begin monitoring load and deformation in the elastic range. The xy recorder will
print deformation against load. . You can convert load to stress using the relation, Stress : Load / Cross section area
. Approximate strain is given by deformation / gauge length . At failure determine the true stress and fracture strain. QUESTIONS TO BE ANSWERED IN YOUR REPORT 1. 2 4 .7. 4 What properties did you determine in the test ?
. How do steel and aluminum compare in these properties ?
How do strength to weight and stiffness to weight ratios compare ? . What does this infer as to their structural applications ? REPORT OUTLINE: Introduction
Test procedure observations
Data collected and analysis Results and Conclusions
Supporting information ( any sketches, photos, plots you wish to include ) DENSITIES: Steel 0.284lb/cu.in. Aluminum 0.097lb/cu.in. 7* ...
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- Spring '11