Investigation into testing approaches for material characterisation of filament-wound components for hydrogen storage
Topic(s) : Special Sessions
Co-authors :
Jordan FORBES-THOMAS (UNITED KINGDOM), Chris HUNT , Janice M. DULIEU-BARTON (UNITED KINGDOM), Marcus WALLS-BRUCK , Neha CHANDARANAAbstract :
Research into hydrogen storage is necessary to meet global climate targets. A mature method of storing hydrogen is in high-pressure vessels, with recent designs using composite shells as the key load carrier. Simulation is an important part of the composite pressure vessel (CPV) design process to predict burst pressure and failure locations. To provide accurate predictions of the CPV behaviour, it is essential that well-characterised properties for the composite material are used. Hence, defining a reliable, accurate method for obtaining material properties that can accommodate realistic test pieces produced from representative manufacturing procedures is vital. CPVs are often manufactured using filament winding, which produces hollow, cylindrical structures. It is possible to produce ‘flat panels’ to cut coupons, but this is challenging and requires an appropriately designed mandrel and winding process. Therefore, in general, standard material characterisation methods, such as ASTM D3039, are not appropriate.
A variety of approaches that go some way to address filament wound (FW) material have been described in the literature. These include split disk tests (ASTM D2290) and FW flat panels. Split disk testing is a standardised procedure that can be used to obtain the apparent tensile properties of ring structures. However, the method induces bending stresses in the specimen, which reduces the measured tensile strength. For the reasons mentioned above, flat FW panels produce material that is not representative of cylindrical FW parts. Pressurised ring and pipe tests are more promising methods for characterising materials produced by FW. Pressurised ring testing was first demonstrated by Cohen et al. [1] to link coupon and full-scale vessel testing. Methods of open-ended pipe testing have been demonstrated by Hull et al. [2] and Soden et al. [3], which allow a 1:0 hoop to axial stress state. This pure hoop stress state means that the hoop tensile properties of materials can be obtained directly from the as manufactured part. The work presented in [1]-[3] use different fixture and specimen designs and the method has not been standardised. The aim of this research is to examine the current state-of-the-art in the characterisation of FW material and to identify an appropriate test procedure. The intention is to then design a testing methodology based on internal pressurisation that can provide material properties directly from FW parts to improve the accuracy of current CPV design methods, leading to lighter and lower cost CPVs.
A variety of approaches that go some way to address filament wound (FW) material have been described in the literature. These include split disk tests (ASTM D2290) and FW flat panels. Split disk testing is a standardised procedure that can be used to obtain the apparent tensile properties of ring structures. However, the method induces bending stresses in the specimen, which reduces the measured tensile strength. For the reasons mentioned above, flat FW panels produce material that is not representative of cylindrical FW parts. Pressurised ring and pipe tests are more promising methods for characterising materials produced by FW. Pressurised ring testing was first demonstrated by Cohen et al. [1] to link coupon and full-scale vessel testing. Methods of open-ended pipe testing have been demonstrated by Hull et al. [2] and Soden et al. [3], which allow a 1:0 hoop to axial stress state. This pure hoop stress state means that the hoop tensile properties of materials can be obtained directly from the as manufactured part. The work presented in [1]-[3] use different fixture and specimen designs and the method has not been standardised. The aim of this research is to examine the current state-of-the-art in the characterisation of FW material and to identify an appropriate test procedure. The intention is to then design a testing methodology based on internal pressurisation that can provide material properties directly from FW parts to improve the accuracy of current CPV design methods, leading to lighter and lower cost CPVs.