Determining Polyurethane Elastic Parameters at Large Strains Using Torsion and Tensile Test Results

The problem of increasing the reliability of calculations of polyurethane elements of constructions is associated with the development of reliable mathematical models of elastic behavior of the material. Within the framework of the phenomenological approach, the authors propose various models of elasticity for elastomers. The choice of the law of elasticity and the determination of elasticity parameters for a specific material based on sample testing is an important problem to consider. The results of static torsion and tensile tests performed on the cast polyurethane specimen SKU-PFL-100 with the hardness of 92…95 units according to the Shore A scale are presented in the article. To identify elastic potential of the polyurethane, the axially symmetric stress-strain state of a cylindrical sample is analyzed using a model of incompressible material. When performing calculations for rubber parts, the two-parameter Mooney–Rivlin constitutive model is often used.  Taking into account the positive experience of using this model, it is applied to describe polyurethane elasticity. The parameter values of the strain energy potential are determined on the basis of the test results by minimizing the function of deviations of the stress theoretical values from the experimental ones. It has been shown that the selected model describes polyurethane elastic behavior with a satisfactory accuracy.

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