Experimental characterization, analytical and numerical investigations of metal/polymer/metal sandwich composites – Part 1: Deep drawing

Thermoplastic fibre metal laminates: Stiffness properties and forming behaviour by means of deep drawing

Metallic (M) and polymer (P) materials as layered hybrid metal-polymer-metal (MPM) sandwiches offer a wide range of applications by combining the advantages of both material classes. The interfaces between the materials have a considerable impact on the resulting mechanical properties of the composite and its structural performance. Besides the fact that the experimental methods to determine the properties of the single constituents are well established, the characterization of interface failure behavior between dissimilar materials is very challenging. In this study, a mixed numerical–experimental approach for the determination of the mode I energy release rate is investigated. Using the example of an interface between a steel (St) and a thermoplastic polyolefin (PP/PE), the process of specimen development, experimental parameter determination, and numerical calibration is presented. A modified design of the Double Cantilever Beam (DCB) is utilized to characterize the interlaminar properties and a tailored experimental setup is presented. For this, an inverse calibration method is used by employing numerical studies using cohesive elements and the explicit solver of LS-DYNA based on the force-displacement and crack propagation results.

A Mixed Numerical-Experimental Method to Characterize Metal-Polymer Interfaces for Crash Applications

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was also observed that an increase in the rolling temperature increases bonding strength because the polymer penetrates the AA5052 surface irregularities more easily, the PP-g-MAH molecules move more smoothly toward the AA5052 surface, and finally there are more chemical interactions among the layers. An Increase in ...

Roll bonding of AA5052 and polypropylene sheets: Bonding mechanisms, microstructure and mechanical properties

Resistance element welding (REW) is an appropriate thermal-based joining method for joining hybrid materials with other structural steel grades, e.g. high-strength steels. Due to insufficient knowledge on the application of this joining process in combination with these new hybrid materials, deeper investigations were done regarding the suitability of the process and specific boundary conditions. This article introduces by giving a summary of the material properties, the boundary conditions and the welding process itself. Afterwards, the pre-assembly step of the elements and the resulting handling strength of the pre-assembled elements are discussed for two different hybrid material thicknesses. Weldability lobes are compared for REW with and without additional adhesives so that appropriate process parameters are defined. Due to a possible industrial application, relevant production-related disturbance variables are addressed as well. Therefore, the impact on the resulting joint properties, e.g. nugget size, is evaluated for different offsets of the electrodes and different gap sizes between the sheets as well as for both orientations of the polarity. The article closes with a comparison of the resulting load-bearing capacities of the REW-joints with those manufactured by resistance spot shunt welding and self-pierce riveting with semi-hollow rivets.

Process characteristics and influences of production-related disturbances in resistance element welding of hybrid materials with steel cover sheets and polymer core

Numerical and experimental investigations on HYLITE sandwich sheets as an alternative sheet metal

Focus of this paper is the sustainable lightweight design of a composite seat shell and the development of a fully-automated high-volume production process for lightweight-optimized automotive structures made from fibre-reinforced thermoplastics. It was shown, that the lightweight component was able to meet all static and crash-relevant requirements in combination with a weight reduction of nearly 50 %. Accompanying analyses of the economical and ecological key figures pointed out that the designed lightweight seat shell can be produced at equal costs with less resource demands than the original steel part.

Enhancing Sustainability Through the Targeted Use of Synergy Effects Between Material Configuration, Process Development and Lightweight Design at The Example of a Composite Seat Shell

T. Weber

Papers

Numerical and experimental investigations on HYLITE sandwich sheets as an alternative sheet metal

Enhancing Sustainability Through the Targeted Use of Synergy Effects Between Material Configuration, Process Development and Lightweight Design at The Example of a Composite Seat Shell