| Summary: | 碩士 === 國立成功大學 === 工程科學系碩博士班 === 91 === On the basis of theory of Endochronic cyclic viscoplasticity and “A systematic Method of Determining Material Function in the Endochronic Plasticity” proposed by Lee, this thesis provides a Endochronic cyclic viscoplastic constitutive model for 60Sn/40Pb solder material. All material parameters and the material function are determined from the cyclic stress-strain curve of 60Sn/40Pb solder material. By incorporating the temperature effect and rate effect into material parameters and the material function, this model can account for the cyclic stress-strain response of 60Sn/40Pb solder material under thermal cycle test.
The applicability of this constitutive model is evaluated with the simulations of material tests conducted by Sasaki et al., includes (1)Uniaxially constant strain amplitude cyclic test, (2)Fast in tension/Slow in compression constant strain amplitude cyclic test, (3)Slow-fast-slow constant strain amplitude cyclic test, (4)Cyclic strain with tensile hold time test. Simulations based on this constitutive model have a good agreement with (1), (2) and (3), proofs that it can describe the cyclic stress-strain behavior of 60Sn/40Pb solder very well. To Simulate (4), this thesis provides a method which integrates theory of Endochronic cyclic viscoplasticity with creep deformation kinetics proposed by Valanis and Lee, and shows it can account for the response of material well with suitable material parameters. In the future, it could be a great aid to the application of Strain Range Partitioning method(SRP) in predicting the fatigue life of 60Sn/40Pb solder material.
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