Papers by Keyword: Fiber Reinforced Thermoplastics

Abstract: This work presents sensitivity analyzes of the influence of deviations in the shear stress vs. shear angle curves of bias extension tests of fiber-reinforced thermoplastics on the results of forming simulations. The investigations are carried out on the basis of a double dome benchmark geometry from the Ford Motor Company. Its experimental results of shear angle values and wrinkling are compared to the simulation results. The initial values for sensitivity analyzes are the shear stress-shear angle curves determined within further preliminary investigations on the basis of different sample sizes and cutting directions. Then these are gradually scaled. Finally, it will be discussed which deviations in the shear stress-shear angle curve are permissible in order to achieve a maximum deviation of 20% between simulation results and the real part. This is assumed to be the target value for this study.

Abstract: Growing mechanical, economic and environmental specification lead to multi-material designs. Based on an extensive basic research, more achievements and experiences regarding the manufacturing technologies and mechanical properties of hybrid laminates were achieved in the Institute of Lightweight Structures and Polymer Technology. The present study shows the development, characterization and forming of novel hybrid laminates, made of steel sheets (HC220Y+ZE, t = 0.25 mm) and carbon fiber reinforced polymers (Polyamide 6). The interface-optimization of the hybrid laminates was carried out with two different bonding agents. The results of a three point bending test underline the potential of the innovative material. A hybrid roof crossmember was formed on a hydraulic Tryout-Press successfully.

Abstract: Bending of multilayered sheets like lightweight sandwich sheets or fiber reinforced thermoplastics is dominated by the mechanism of interply-slip. FE-analysis is performed to predict defects depending on this mechanism. The shear and damage behavior of the adhesive layer of sandwich sheets can be modeled by cohesive elements in Abaqus. Forming simulation of fiber reinforced thermoplastics requires coupled thermo-mechanical analysis methods due to temperature dependence. For this, alternative modeling strategies for the inner layer of adhesive or polymer matrices will be tested in this paper that are able to transfer heat. The layer will be presented by solid elements with enriched property definitions or viscoplasticity. Furthermore the thickness of the layer will be neglected and replaced by contact formulations or spring elements.

Abstract: For high temperature applications of laminated composite structures, viscoelastic behavior of laminated composite structures is investigated by multi-scale analysis based on a homogenization theory. Effective viscoelastic properties of the laminas are evaluated by a boundary integral method at a micro-scale level, and viscoelastic analysis for laminated composite structures is performed by a finite element method at a macro-scale level using the effective viscoelastic properties of lamina obtained by the micro-scale analysis. In the multi-scale analysis, the Laplace transformation is adopted and the correspondence principle between elastic and viscoelastic solutions in the Laplace domain is applied. The inverse Laplace transform is formulated by the Duhamel integral, and is calculated numerically. As a numerical example, a laminated composite plate with a hole is treated and the viscoelastic behavior of the laminated composite structure is elucidated.