Abstract

The application of polymers is spread in many sectors, and these materials are increasingly replacing metals. It is therefore crucial to develop the constitutive model of these polymers in order to perform predictive numerical simulations for industrial structures under different types of loading. An elasto-viscoplastic behavior law taking into account hydrostatic pressure, based on the model proposed by Grandidier et al [1] has been devolved for a Polyethylene. All material constants were determined, from experimental data of six tensile tests at different constant real strain rates, by inverse problems coupling to the simulation software (Abaqus©) an optimization software (DAKOTA [2]). The validation of the behavior law is performed by comparing tests and numerical simulations of 3 and 4 point bending tests for different specimen thicknesses. In a 3-point bending test, the combination of tension, compression, and shear occurs in the material, whereas in the 4-point bending test, pure bending occurs in the specimen between the two moving rollers, which allows the model to be evaluated under different types of loading. The effect on the simulation results of different parameters such as the hydrostatic pressure coefficient, the friction coefficient, and the geometrical dimension of the specimens are studied. Mesh convergence was performed, different 3D elements were used to see the influence on the numerical responses. Bending test simulation results were in good agreement with the experimental results. Finally, a correlation between the experimental results of a test on a polyethylene reference structure subjected to an internal hydraulic pressure which generates complex loading conditions, and the corresponding numerical simulation is presented. The confrontation of the 3D displacement fields obtained on the one hand by a non-contact optical method during the test and on the other hand by numerical simulation confirms the predictivity of the numerical tool. [1] J. C. Grandidier and É. Lainé, “Identification by genetic algorithm of a constitutive law taking into account the effects of hydrostatic pressure and speeds,” Oil Gas Sci. Technol., vol. 61, no. 6, pp. 781–787, 2006. [2] J. G. Adams, B.M., Bohnhoff, W.J., Dalbey, K.R., Ebeida, M.S., Eddy, J.P., Eldred, M.S., Hooper, R.W., Hough, P.D., Hu, K.T., Jakeman, J.D., Khalil, M., Maupin, K.A., Monschke, J.A., Ridgway, E.M., Rushdi, A.A., Seidl, D.T., Stephens, J.A., Swiler, L.P., and Wi, “‘Dakota, A Multilevel Parallel Object-Oriented Framework for Design Optimization, Parameter Estimation, Uncertainty Quantification, and Sensitivity Analysis: Version 6.12 User’s Manual,’ Sandia Technical Report SAND2020-12495, November 2020.” .