PSI - Issue 59

Ilham Bagus Wiranto et al. / Procedia Structural Integrity 59 (2024) 230–237 Wiranto et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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3.3. Impact response Simulations were conducted to assess the impact performance of a crossbar stiffened composite panel as a representation of fuselage structure with varying impact velocity and impactor mass. This study investigated the influence of impact velocity and impact mass on the crossbar stiffened composite panel. The impact velocity was representative of the height drop within the impact experimental setup where the impact velocities of 4.43, 6.26, and 7.67 m/s are equal to the height drop of 1, 2, and 3 m, respectively. Evaluation of the composite panel's impact response focused on impact force and displacement. The contact force data was taken in the center node of the composite panel where the impactor and panel had first contact. In addition, the displacement data was to capture the deformation of the panel during an impact event. Figure 4 illustrates the relationship between impact force and displacement in drop tests, showcasing the impact of varying velocities and impact mass. From the diagram, it is known that, once the impactor hit the panel, a sudden rise of contact force occurred. After that, the contact force value is decreased drastically, which indicates the failure of the stiffened composite panel. Following this event, the force decreases gradually to zero, which indicates the impactor is leaving the panel and resulting in the panel deforming after impact.

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Fig. 4. Contact force vs displacement diagram: (a) mass = 50 kg with impact velocity variation, and (b) v = 6.26 m/s, with impactor mass variation.

Figure 5 shows the deformation of all axial impact loading variations at maximum displacement. furthermore, the impact energy (e) of a falling mass can be calculated by multiplying mass (kg), gravity (m/s 2 ), and drop height (m). This equation is based on the gravitational potential energy formula, where the potential energy gained by an object is converted into kinetic energy as it falls. From the simulation, it is known that the lowest displacement occurred when the 50 kg of impactor mass and 4.43 m/s velocity were applied. Furthermore, the maximum displacement was achieved when 150 kg impactor mass was subjected to the panel with a velocity of 7.67 m/s. 4. Conclusions In conclusion, a numerical study to investigate the behavior of carbon fiber-reinforced polymers (CFRP) composite stiffened panel under axial impact loading subjected to varying impact velocities and impact mass has been developed. The results reveal valuable insights into the dynamic response of these composite materials. In terms of benchmark study, the continuum shell element was developed and shows good agreement. The mesh convergence test analysis was conducted to determine the optimal mesh size before the main analysis. A uniform mesh size of 10mm was selected due to its computing time efficiency and accuracy. The simulations clearly demonstrate that with an increase in impact velocity and impact mass, both the impact force and the maximum displacement of the stiffened panel composite rise in a corresponding fashion. In addition, the shear damage variable was occurred in most of stiffened panel area. This research contributes to a better understanding of the behavior of these stiffened composite materials and provides essential data for engineers and designers working