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Unformatted text preview: EGR75L: Tensile Test for Tinius Olsen H50KS Load Frame Joseph Nadeau Civil & Environmental Engineering Duke University September 25, 2006 During the course of this laboratory a material specimen (see Fig. 1) is going to be gradually loaded in tension—until it fails—while collecting load and elongation, i.e., change in length, data. The reader is referred to Appendix A for fundamental information about the tension test; you are encouraged to read Appendix A at this time. Some “common” problems that could arise during this lab, and how to fix them, are presented in Ap pendix B. Figure 1: Tensile specimen. 1 Objective The objective of this laboratory is to introduce students to the tensile test and to evaluate a number of material properties relevant to the tensile test. Young’s modulus E , which is one of two material properties that completely characterize the elasticity of any linear elastic isotropic material, will be determined. A second linear elastic isotropic material property, namely the shear modulus G , will be determined when the torsion experiment is performed later in the semester. Additional material properties, namely, (tensile) yield stress σ y and ultimate (tensile) stress σ u will also be evaluated. 1 Figure 2: TiniusOlsen H50KS load frame. Tension/compression load capacity of 10,000 lbs. 2 Equipment The various instruments needed to conduct the tensile test are listed below: 1. Tinius Olsen load frame H50KS (see Fig. 2): Applies tensile load to sample; measures the load using a load cell. The maximum capacity of the load cell is 10,000 lbs. Rate of loading can be controlled. 2. Tinius Olsen LS4%2A Extensometer (see Fig. 3): Measures elongation over a 2 inch gauge length. Maximum elongation is 4% of the gauge length, or 0.08 inch. 3. Computer and MATLAB Data Acquisition Toolbox software: Acquires raw data from the load cell and the extensometer via instructions from the MATLAB mfile, CollectTensionData H50KS.m , which is included in Appendix C. NOTE: CollectTensionData.m collects 3 pieces of data at each sampling time and this data is output to a file, the name of which you get to choose. Only two of the three pieces of collected data are specifically required for this lab, namely, the load (column 1 of the data file) and the strain, as measured by the extensometer in units of percent (column 3 of the resulting data file). The second column in 2 Figure 3: TiniusOlsen LS4%2A extensometer. Measures change in length over a 2 inch gauge length, up to a maximum of 4% strain. the data file is the displacement of the crosshead. What can be confusing is that this crosshead displacement is what is being referred to on the H50KS control panel as “Extension” (see Fig. 7)....
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 Spring '08
 VIRGIN
 Environmental Engineering, Tensile strength, specimen, extensometer

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