Simulation of thermoplastic 3D-printed parts for crash applications

Abstract

The rapid development of additive manufacturing techniques in aeronautic and automotive industry opens new possibilities in the design of metallic or composite parts compared to traditional subtractive processes. In particular, 3D printing allows the design of complex parts with a high lightweight potential through optimal use of material along the load paths. In the composite field, various printing techniques emerged in the last decade such as Selective Laser Sintering (SLS) or Fused Deposition Modelling (FDM). On the downside, 3D printing is confronted to the large influence of process parameters on the geometrical and optical quality as well as on the mechanical properties of the manufactured structures. Moreover, simulation techniques with finite-element methods are still at their very beginning and improvements should be achieved to predict structural performances in crash applications. This paper focuses on the characterization and simulation of structures manufactured with the Screw Extrusion Additive Manufacturing (SEAM) technique presented in Figure 1. The material investigated is a combination of PA6 resin reinforced with 30% carbon fibres in weight. The mechanical behaviour under various loadings (tension, compression, shear) is first investigated in different material directions relative to the building direction with help of coupon specimens extracted from printed structures. The obtained properties are then fed in an anisotropic material card *MAT157_ANISOTROPIC_ELASTIC_PLASTIC and the respective performances studied by reproducing numerically the experimental tests. This contribution illustrates potential numerical solutions to recreate the mechanical behaviour between the printed layers and gives an insight into their advantages and drawbacks. Finally, an application of the suggested approach to generic honeycomb structures is presented and the gaps in simulation technique are analysed.