Thermoplastic foams allow the manufacture of lightweight parts with good thermal and acoustic insulation properties, particularly suited for aircraft interior and cabins structures. Such foams can be combined with skin layers of organic sheet materials (e.g. glass fiber (GF) polycarbonate (PC)) forming sandwich structures, enhancing the mechanical properties, but which unfortunately do not fulfil strict FST (Fire, Smoke and Toxicity) standards. An alternative approach uses the foam itself to create an integrated sandwich structure of an unmodified core and two skins of high density from the same material.
In this study, various analysis and test activities are presented, which were carried out for the development of shock-mitigating floor mats. These impact-absorbing floor mats are produced from hyperelastic materials and are designed to absorb high-amplitude, short-duration shock loads in defense or civil applications. Throughout the study, the *MAT027 model is examined for its suitability in modeling hyperelastic materials in both static and dynamic analyses, conducted using the non-linear finite element code LS-DYNA®. The *MAT027 model accurately describes the behavior of hyperelastic materials and is often preferred for this type of material. To correctly apply this model, specific parameters pertaining to the hyperelastic material must be determined. This study primarily focuses on the determination of these material parameters through tests conducted on samples made of Thermoplastic Polyurethane (TPU) material. In the initial phase of the study, a literature review concerning TPU material was conducted, and material parameters were obtained using the test data presented in this study. The material parameters were then optimized using LS-Opt® to achieve the best material behavior. Following the determination of material parameters, dynamic simulations were performed using LS-DYNA®, and the simulation results were subsequently compared with experimental data. With the material parameters in hand, the second phase of the study involved the design of cellular structures with various geometric shapes. The force-displacement graphs of these newly designed shapes were analyzed through dynamic analyses.
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) [1]. 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 [2]. 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.
Simulating the hot press processing of structural thermoplastic foams