# MECH lab 3.docx - Roque 1 Compression Test Alexis Roque...

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Roque 1Compression TestAlexis Roque[email protected]September 26th, 2018MECH 2120.102
Roque 2AbstractA compression test determines behavior of materials under crushing loads. The specimenis compressed and deformation various loads is recorded. Compressive stress and strain arecalculated and plotted as a stress-strain diagram which is used to determine elastic limit,proportional limit, yield point, yield strength, and, for some materials, compressive strength. Inour experiment, we used two samples PVC and acrylic. After analyzing the results, the sampleswere different from each other since one sample of each material was lubricated.IntroductionThe purpose of this experiment is to use compressive properties including modulus oelasticity, yield stress, deformation beyond yield point, and compressive strength (unless thematerial merely flattens but does not fracture) to analyze our data. Materials possessing a loworder of ductility may not exhibit a yield point.Principle TheoryThere are several basic concepts that are required to a perform a tensile test. Some basicconcepts include axial stress, strain, deformation, yield point, modulus of elasticity, stress-strain,deformation, yield point, modulus of elasticity, stress-strain curve, ultimate stress and fracturepoint.Axial stress:= P/A; Load (P) per cross-sectional area (A)Axial strain is the change in axial length (dL) per total original length (L) of the specimen.Axial strain:= S/LHooke’s Law shows that the axial strain is equal to the axial stress per the modulus ofelasticity (E). This s only valid in the linear portion of the curve.Hooke’s Law:=/EIf an axial stress is applied to the specimen and it has not reached its yield strength whenit is released, the specimen will return to its original shape. The test was a uniaxial compressiontest performed using an Instron Universal Testing System. BlueHill software was used forexperimental control and data acquisition. The system utilized two hardened steel plates that thespecimens were inserted between. The Instron machine then compressed the top plate toward thebottom one at a preset constant velocity. A load cell on the top plate measured the force of

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