Modeling of Thick UD Composites for Type IV Pressure Vessels

Increasing energy costs, limitation of crude oil resources as well as constantly intensifying emission targets (especially w.r.t. CO 2 ) are a pivotal driver for current automotive research and development [1]. In this regard alternatively powered vehicles (APV) with drive-trains, that differ from conventional internal-combustion engines (ICE) supplied with petrol or diesel fuel, show high potential for energy economical and environmentally friendly propulsion [2]. On the other hand lightweight structures are a fundamental requirement in order to achieve a low demand of energy and to compensate possible higher structural masses of alternatively powered drive-trains [3]. An alternatively powered drive-train that is on the one hand cost efficient since it requires comparatively minor design changes to conventional vehicles (primarily ignition and valve-train system) and on the other hand has a perspective to evoke low CO 2 emissions, is an ICE operated with compressed natural gas (CNG) [4], [5]. This energy source requires high-pressure storage tanks that have to withstand the high mechanical demands of internal pressures of 200 bar to 250 bar. In order to achieve energy storage that is simultaneously light and safe, pressure vessels of the Type IV that are entirely made of fibre reinforced polymers (FRP) are currently state of the art [6]. For the proper and optimal integration of the tanks into the vehicle during the APV design and development process at industrial level, moreover the predictability of the material and component behaviour using the finite element method (FEM) is indispensable [7]. To make a step forward in the capability of the automotive industry to model, predict and optimise the crash behaviour of vehicles equipped with Type IV tanks, a virtual testing methodology (VTM) was developed within the project MATISSE funded by European Commission’s 7 th Framework Programme. As a demonstrator a belly mounted CNG tank consisting of a combined carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP) wet wound structure with a polyamide (PA) liner and aluminium bosses was used. The reference structure was provided by the MATISSE partner Xperion Energy & Environment GmbH and is presented in Fig.1.