PSI - Issue 52

Dong Xiao et al. / Procedia Structural Integrity 52 (2024) 667–678 Dong Xiao et al. / Structural Integrity Procedia 00 (2023) 000–000

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3. Finite element modelling

Figure 4 illustrates the composite plate and its corresponding FEM model that are employed for the simulations. The composite plate utilized in the study is composed of M21 / T800 material and has dimensions of 290 × 200 × 4 mm and layup of [0 / + 45 / − 45 / 90 / 0 / + 45 / − 45 / 90] s . The plate is instrumented with a total of 8 PZT sensors on its surface, but only the 4 sensors located at the outside vertices were utilized in this study. To ensure fixed boundaries, the plate was clamped along the longitudinal edges, preventing any movements or rotations at these boundaries. The simulation of impact events on a fiber-reinforced composite plate was performed using ABAQUS commercial FE software with explicit solver. The plate was modeled using 3D deformable solid part, while the PZT sensors were represented as shell parts bonded to the plate surface using tie constraints. The explicit continuum shell SC8R mesh was utilized to discretize the plate, generating a total of 9280 elements with a global size of 2.5 mm. Similar to the experimental setup, the longitudinal edges of the plate were constrained without allowing any movement or rotation. Detailed material properties of the plate and PZT sensor can be found in the reference Hami Seno and Ferri Aliabadi [2023]. To realize precise control of impact force in the simulation, the impact force was implemented as a point load instead of modelling an explicit impactor. This point load representation is advantageous for the impact identification process, as it provides precise control over the magnitude and location of the applied force. In contrast, explicitly modelling an impactor would introduce additional uncertainties and challenges in precisely controlling the impact force. For example, the interaction between the impactor and the plate could introduce complexities might a ff ect the accuracy of impact force simulation.

(a) Composite plate

(b) FEM model

Fig. 4: FE model for simulating impacts

To validate the accuracy of the FEM model, an experimental impact test was conducted using a drop tower machine with a 5.5 kg impactor and an energy of 6 J. The same impact scenario was simulated using the FEM model. Figure 5 presents a comparison between the experimental and FEM-simulated impact forces. The results demonstrate that the FEM model accurately predicts the impact force history, as the impact duration and peak force are well-matched between the experimental and simulated data. This validation confirms the reliability of the FEM model for simulating impact events on the composite plate. Regarding the impact identification process, the FEM model was used to simulate the local impact structural responses by inputting the experimental impact force history at a given location. The FEM model considers the same 8 PZT sensors as in the experimental setup, but only the 4 sensors located at the outside vertices were utilized to record the simulated impact structural responses. Figure 6 illustrates the impact locations considered in this study, with 4 employed sensors labelled as S1-S4 and 4 impacts labelled as I1-I4. All the impacts I1-I4 are excited with the experimental impact force history shown in Figure 5. These impacts will be identified by the proposed surrogate assisted e ffi cient global optimisation.