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Taylor Castagna MANE 6963 – Friction and Wear of Materials Prob 3. Copper Assumed properties used were yield strength of 365 MPa and a linear tangent modulus of 552 MPa. The tangent modulus will mimic a linear isotropic hardening Reference: http://www.journalamme.org/papers_vol24_1/24127.pdf. Figure 1 – Elastic Figure 2 - Elastoplastic With a constant displacement, the results show a decrease in stress between Figure 1 and Figure 2. This is due to the change in rate of stress/strain once the material has reached the proportional limit. Unloading of the flat punch will show a significant amount of permanent plastic strain. Aluminum Assumed properties used were yield strength of 55 MPa and a linear tangent modulus was estimated using Figure 3. The rate of strain hardening for aluminum is particularly low. Figure 3 – Tension Test of Aluminum Taylor Castagna MANE 6963 – Friction and Wear of Materials Figure 4 – Elastic Figure 5 – Elastoplastic Due the low yield strength of aluminum and the high displacement (1e-3) used as an input in this simulation, the surrounding material on the punch began yielding to an extreme extent before the punch reached its maximum depth. The stress in Figure 5 is an entire factor smaller than the elastic model used in Figure 4. This is due to the very low strain hardening rate of the aluminum.