Increased lightweight design via composite sandwich structures is a promising approach due to their exceptionally high weight-specific mechanical properties. The involved high cost when using sandwich composite structures has hindered applications in cost-sensitive markets up to now. However, full thermoplastic composite sandwich structures enable a cost reduction using novel processing routes based on fusion bonding of core and facesheet. In order to optimize such full thermoplastic composite sandwich structures and to ensure proper bonding of facesheet and core after manufacture, valid test methods for the quantification of skin-core interfacial bonding are required. This paper reviews existing test methods for the determination of Mode I dominant interfacial fracture toughness of sandwich structures. The main focus is set on cantilever beam tests as well as on peel tests. Based on a definition of requirements for suitable test methods, their applicability for full thermoplastic composite sandwich structures is evaluated. The Mandrel Peel Test results as most promising test method for thermoplastic sandwich structures, especially with thin facesheets.

Modern electric vehicle battery thermal management systems provide sophisticated means to control the temperature of its battery cells within the optimal temperature range. This is crucial as Lithium-Ion battery cells result in reduced lifespans if exposed to temperatures above 50°C. On the other hand, temperatures below 10°C lead to a reduced capacity and with respect to electric vehicles in reduced driving ranges. The OPTEMUS project therefore develops a thermal insulating battery module housing that thermally disconnects the battery cells from the ambient temperature, providing a more stable temperature profile and more efficient thermal management of the battery. Different housing materials and designs have been developed to provide thermal insulating properties while also withstanding mechanical forces. Based on a concept module design of Fraunhofer LBF, two different fiber reinforced plastic sandwich structures have been manufactured with insulating foam cores and analyzed with respect to their cellular structures and resulting thermal properties. The cellular structure was detected three-dimensionally via computer tomography analysis. The manufactured sub-module housings were tested in a climatic chamber at -10°C and compared to a benchmark housing design based on aluminum as construction material. Results showed that the cell temperatures decrease 250 to 400 % slower using foam core sandwich structures as housing material compared to an aluminum housing while providing large scale manufacturability via the injection molding process

No abstract

No abstract

Im Rahmen des EU-Projektes OPTEMUS beschäftigte sich das Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF mit der Entwicklung, der Herstellung und der Analyse eines Kompositmaterials. Dieses Material wurde in einem Armaturenbrett eines Elektrofahrzeugs eingesetzt. Der Schwerpunkt bei der Entwicklung des Kompositmaterials lag bei der Erhöhung der isotropen Wärmeleitfähigkeit und der Eignung zum Einsatz im Bereich des Armaturenbretts.