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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1. Introduction Composite stiffened laminate panels offer high specific strength, high specific stiffness, good fatigue resistance, and good designability (Witik et al., 2012). Because of its various benefits, such as high bearing efficiency and a simple molding process, it has been widely utilized in aircraft structural engineering, such as fuselage skins, wing webs, and fuel tank panels (Rezasefat et al., 2021; Damnjanović et al., 2017). In practice, composite panels are frequently subjected to compression, shear, compression-shear combinations, and other stresses that can create local instability without losing bearing capacity. However, because the interfacial strength between the fabric layers is heavily dependent on the polymer matrix, which has a low toughness, composite stiffened panels are prone to interlaminar damage, typically delamination, when subjected to out-of-plane loadings, such as impact loads, compromising mechanical performance and even causing serious structural failure (Cao et al., 2016; Prabowo et al., 2016;2018; Ravindran et al., 2021; Do et al., 2023). Despite buckling is the predominant failure mode of the stiffened plates, unlike most thin-walled constructions, the stiffened laminated plates with variable degrees of buckling damage may nevertheless bear external stresses (Huang et al., 2020; Teter and Kolakowski, 2022; Mejdi and Atalla, 2012). As a result, the residual strength and complicated failure process of stiffened panels with varied stiffening forms under diverse loading forms have captured the interest of researchers, who have studied theory (Piculin and Može, 2021; Zhao et al., 2020), experiments (Sahoo and Barik, 2020; Jiang and Yang, 2020), and simulation (Ma and Wang, 2021; Li et al., 2021). Furthermore, to address the issue that the computational efficiency of the simulation was limited for large damaged stiffened plates, a methodology for simulating low velocity impact and compression after impact was described and applied to a composite stiffened panel with visible impact damage (Soto et al., 2018). The stiffened panel may be subjected to varied positions with varying degrees of impact load under actual operating situations. The stiffened panel's ability to be utilized after impact is determined by the impact damage's effect on the buckling and post buckling behavior of the stiffened panel. Composite structures are vulnerable to impact, and low-velocity impact (LVI) during aircraft maintenance and servicing can cause substantial inter- and intra-laminar damage (Sun et al., 2018; Ouyang et al., 2018). The influence of different impact locations on shear behavior was discovered that pre-debonding reduced the buckling load (Feng et al., 2017). In a previous study, a researcher utilized stiffeners to separate the specimens into four sections (Zhou et al., 2022). The impact energy level was chosen to 30 J to cause barely visible impact damage (BVID) to the specimens, since BVID is commonly used in practice to assess the damage tolerance of composite constructions (Tan et al., 2018). In addition, a photoelectric sensor was used to quantify the impact and rebound velocities. The impactor weighed 7.329 kg in total and had a 12.7 mm diameter hemispherical snout. It is vital in the aviation industry to have a structure capable of absorbing energy, especially in crash occurrence situations. In the vehicle and aerospace sectors, composite materials have shown to be one of the most effective ways to boost energy absorption capabilities. Composite constructions, for example, can be utilized as the outer skin of an aeroplane or as the primary component of a fuselage. In most aircraft crash occurrence situations, the first impact will be on the skin and the structure behind it. It is critical, however, to study the structure's crashworthiness performance during drop mass impact occurrences. Many studies used a drop mass impact event to evaluate crashworthiness by varying mechanical characteristics such as drop height variation, mass or load bearing, and impactor form. In this paper, the impact behavior of a composite stiffened panel, which represents a fuselage structure, is investigated. The composite stiffened panel was modeled using ABAQUS 6.23. The effect of varying impact velocities and impactor mass on the composites was simulated. The material properties for this study were taken from a previous study conducted by Ge et al. (2022). Before the main analysis, a benchmarking study and mesh convergence analysis was carried out to verify the model robustness. 2. Numerical model and simulation In this section, the finite element models are described in the scope of drop mass impact simulation within ABAQUS. The simulation setup will be reviewed comprehensively. In this study, the material properties are referred to the studies conducted by Ge et al. (2022), which represent a woven carbon fiber. In order to analyze the failure of the panel, the damage evolution standard output identifiers available in ABAQUS are employed.