Title: Validation of a new clamping solution for tensile testing of impregnated carbon and glass fiber rovings for applications in composites
Authors: S. Bhat, F.Pohlkemper, T. Schloemer, T. Gries
Abstract: The testing of fiber reinforced composites is associated with high costs and great effort. The characteristic values of tensile strength and modulus of elasticity are particularly relevant for component design and are of elementary importance. Tests on entire components in the development phase are very time-consuming and costly. For this reason, the tensile tests on impregnated roving are executed. This allows quick results and gives a good indication of the properties to be expected with the selected fiber matrix combination. Currently, for tensile testing of resin impregnated roving’s, resin tabs or cardboard tabs are attached at the ends of the impregnated roving specimens as force transmission elements. These prepared impregnated roving specimens are then tested in a universal testing machine. The production of the impregnated roving’s and their bonding with the force transmission elements is very time consuming and also does not guarantee repetitive and reliable results. This occurs due to frequent occurrence of clamp breaks before the impregnated roving fails. Therefore, in order to accelerate the testing procedure, a new clamping solution called “InnoGrip” is developed in the scope of the work presented for tensile testing of impregnated roving’s. The goal of this clamping and testing solution is to reduce the preparation time for the testing samples and provide valid and reproducible results during testing. Here, the glued-on force transmission elements are eliminated and clip-on sleeves are used instead. The specimens with the clip-on sleeves are held in position hydraulically, in a newly designed clamping device and are tested for their tensile properties directly on a universal testing machine. The validation tests carried out prove that the roving’s can be tested efficiently with the new clamping solution. The tensile stresses for the roving’s, reach the manufacturer's specifications and are thus approx. 31% higher than the achievable results with the established testing methods. The economic analysis carried out in this paper also approves that the new testing method can be used where a high demand for tensile tests is expected either during the design of composites or also for quick quality control roving’s during the manufacture of composites.
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Conference: CAMX 2023
Publication Date: 2023/10/30
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