PSI - Issue 60

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Vaibhav Gangwar et al. / Procedia Structural Integrity 60 (2024) 123–135 Vaibhav Gangwar / StructuralIntegrityProcedia00(2024)000 – 000

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5. Charpy test Simulation by employing parameters extracted from strain gage tensile test results and parameters from tensile test results Charpy V-notch specimen is simulated at velocities 3 m/s and 4 m/s in ABAQUS Explicit FEA software. The material parameters are implemented through VUMAT code and plugged with software. The specimen was modelled according to the ASTM standard E23-12. The anvil or striker is made discrete rigid and sample is made 3d deformable. The velocity boundary condition is given to anvil and specimen is fixed in x-z direction with restricted rotation in y-direction. The simulation is done by parameters extracted from both the experimental results. From Fig.(16) it is clear that MJC_NP simulation results are very near to the experimental results for both the velocities. The peak force in the experiment is 23.11 KN, whereas MJ-C model predicted 25.02 KN, while MJC_NP predicted 24.3 KN which is very nearer to the experimental value. The relative error was only 5.14% in case of MJC_NP where as in case of MJC the value is 8.26% in prediction of peak force.

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Fig. 16. Experimental and simulated Charpy impact results obtained from both the parameters of MJC

6. Comparison between experimental methods of three type of test system The four main components of the high strain rate test system includes — input techniques, specimen geometry, clamping techniques, and measurement tools — are essential for accuracy of the test results. The detailed operational method of servo-hydraulic VHS (Bruce et al. 2004; P. K.C. Wood et al. 2007b, 2006; Huh, Lim, and Park 2009) and split Hopkinson are given in the literature (Yan et al. 2006; Ledford et al. 2015) here only INSTRON CEAST 9350 system described in detail. All three-machine comparison are listed in Table 3. According to the specifications outlined in the standards, the CEAST 9350 is a drop tower impact tester used to perform instrumented tests on plates, film specimens, and tridimensional parts. It is manufactured and designed with the modularity concept. The detailed dimension and function of the parts are mentioned in the manual (Impact, n.d.; Instron 2009). The strain gauge force sensor is used to capture the force. The specimen is attached in the two grips by four screws. The static grip is close to the force sensor and it is fixed as shown in Fig.(17). The dynamic grip, move with a certain velocity when the striker hits the dynamic grip. The global displacement is measured by the photocells. The energy required to fracture specimen is calculated by the Eq.(7). The equivalent impact height is calculated by Eq.(8). The grip section of the tensile sample must stay in the elastic deformation regime all over the tensile test because the strain gauge force sensors collect load data from the grip. In order to prevent the grip section from yielding during testing, the material of the grip and the width section of the testing sample were chosen carefully. The design of sample for servo hydraulic VHS is like one grip section end is longer than the other to allow uniform loading in the segment whereas for split Hopkinson and CEAST 9350 the geometry is like the traditional dog bone specimen but the sample size is small (Wang et al. 2019; Ledford et al. 2015).