Mechanical behaviour and constitutive modelling of an additively manufactured stereolithography polymer
Ruben Løland Sælen, Odd Sture Hopperstad, Arild Holm Clausen
Abstract
Additive manufacturing enables the production of complex structures not possible with traditional methods. Such structures are attractive for use in various engineering applications. It follows that knowledge about the mechanical response of additive manufactured materials, and how to model it numerically, is required. In this work, a polymer manufactured with the stereolithography (SLA) method was studied through tensile and compression testing of smooth and notched specimens. The material exhibited an initial linear elastic behaviour followed by strain-rate- and pressure-dependent inelastic flow before failing at rather large strains in a brittle fracture mode. Motivated by the observed material behaviour, a hyper-viscoelastic constitutive model with a brittle fracture criterion was developed, implemented in a commercial finite element software, and calibrated to the material tests. Compression tests of lattice structures were performed and simulated to validate the model’s capabilities at complex stress states. The model captured the experimentally observed nonlinear stress–strain behaviour, and predicted the fracture initiation and a failure mode similar to the experimental results.