PSI - Issue 25

Wojciech Danek et al. / Procedia Structural Integrity 25 (2020) 19–26 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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The analysis of the results obtained from these numerical simulations indicated that the method of supporting revealed the influence on the calculation result. The surface area where the damage occurs is much bigger for the case of the support using the additional element. However, in the case of von Misses stress the difference between both results is insignificant. 3.3. Mesh density In order to investigate the influence of the mesh density on the results, simulations for three different FE size were carried out (Fig. 6). For the coarse mesh the FE size equals 3.5 mm, whereas in the second and third iteration the mesh is more dense, which allowed obtaining the FE size of 1.75 mm and about 0.9 mm, respectively.

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Fig. 6. Sizes of the finite element meshes.

Based on the results obtained from the numerical simulations the influence of mesh density on values of the damaged surface area was analyzed. For the case with the coarse mesh the damaged surface area is equal to 240 mm 2 . For the more dense meshes the damaged surface area is 269 mm 2 and 124 mm 2 , respectively for the cases where the FE size is 1.75 mm and 0.9 mm. Based on the results obtained from the comparison of the damaged surface area it can be noticed that the mesh density have a very big impact on the results of the numerical simulation of impact damage in composite structures. In addition, maps of von Misses stress for all the cases are illustrated in Fig. 7. The analysis of the results indicated that the finer mesh the higher values of von Misses stress it is. The von Misses stress distribution on the specimen’s surface caused by impact loading is similar between the analyzed cases, however, for the case with the smallest element size the higher values of the von Misses stress are observable only on the boundaries of removed elements due to exceedance of the critical stress value. 4. Conclusions In order to initially verify the numerical model of impact damage in the CFRP composite plate the influence of three selected parameters of numerical modeling was investigated. Based on the simulations carried out it can be concluded that the biggest influence on the results has the mesh density, where the value of the surface area where damage occurs changes in the range of 124-269 mm 2 . The lower bound of the compartment was obtained for the model where the size of FE was the smallest. In the case of von Misses stress the biggest differences were obtained when compared the different ways of modeling the composite plate. For the case where the plate was modeled as one layer the maximal value of von Misses stress is more than two times higher than in the case with modeling the composite plate as 10 separate layers. Such a big difference in the obtained results may be caused by not taking into account the delamination process occurring during impacts. The results of the initial studies on parameters of numerical modeling of impact damage in composite structures presented in this paper will allow for performing a deeper analysis planned in the research project being realized by the authors. A big influence of the considered parameters on the results revealed the necessity of performing additional studies that will show which modeling approaches are the most suitable for adequate simulating BVID in