Polymer plates subjected to impact: Experimental tests and numerical simulations A.H. Clausen 1,2 , M. Polanco-Loria 1,3 , R.T. Moura 4 , M. Alves 4 , T. Berstad 1,3 , M. Langseth 1,2 and O.S. Hopperstad 1,2 1 Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim, Norway 2 Structural Impact Laboratory (SIMLab), Centre for Research-based Innovation, Norwegian University of Science and Technology, Trondheim, Norway 3 SINTEF Materials & Chemistry, Trondheim, Norway 4 Group of Solid Mechanics and Structural Impact (GMSIE), University of Sa ˜o Paulo, Brazil Abstract. This paper presents quasi-static and dynamic tests on circular clamped plates made of a PEHD thermoplastic. A brief review of the main results from a material test programme, involving tension and compression tests at different rates, is also provided. The results from the material tests are used to identify the coefficients of a recently proposed hyperelastic-viscoplastic constitutive model for thermoplastics, also outlined here. Finally, the model is employed in numerical simula- tions of the impact tests. It is shown that the model represents the force-displacement response of the experimental tests fairly well. Also, considering the quasi-static tests, a localized failure mechan- ism around the impactor is captured. 1. INTRODUCTION Among the different classes of materials, i.e. metals, concrete, wood, polymers etc., few materials face the same world-wide increase in demand and use as polymers do. An important reason for the current growth is that polymers have several attractive properties: they are cheap, easy to form, have low density, and some of them are very ductile. In particular, such materials may have excellent energy absorption characteristics. Therefore, polymers are promising for use in several applications where other materials, e.g. metals, have been the common choice so far. The experience in using polymers in impact protection systems, however, is limited, and there are several challenges which call for an in-depth investigation. One of the most obvious is the lack of robust material models in commercial finite element codes, which are essential tools in today’s engineering design. Material models for polymers should be capable of handling large temperature and strain-rate effects, deformation-induced anisotropy, viscosity, and other features commonly observed for polymers. Development of new material models involves experimental efforts, including material tests and well-defined component tests. Material tests are required for two purposes. Firstly, they provide necessary information whose physical features a model should be able to represent. Moreover, material tests are required for calibration of the coefficients in a model. It is quite common to validate a proposed material model by doing numerical simulations of the material tests. A better choice, however, is to perform component tests, applying the calibrated material. These tests serve as an independent check of the capabilities of the model. This paper gives a brief presentation of material tests on a high-density polyethylene (PEHD), see Moura et al. [1] for further details. The results are used to calibrate the constitutive model described in details by Polanco-Loria et al. [2]. Subsequently, applying the FEM programme DYMAT 2009 (2009) 1537–1543 Ó EDP Sciences, 2009 DOI: 10.1051/dymat/2009217