PSI - Issue 71

Deepak Kumar et al. / Procedia Structural Integrity 71 (2025) 380–387

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Several studies were conducted on the low velocity impact analysis of hybrid composites. Mohammad Reza Karamooz et al. (2020) examined woven basalt-Kevlar/epoxy hybrid composites under low velocity impacts (30J, 40J, 60J) across six configurations. Anni Wang et al. (2021) analyzed carbon-flax hybrid composites to enhance damping and energy absorption using impact tests (10J, 15J, 20J, 25J) and material characterization. Periyasamy Manikandan et al. (2014) analyzed metal-composite hybrid laminates under low-velocity impacts (6J) using ABAQUS ® software. L. Maio et al. (2013) used the MAT162 model in LS-DYNA to predict delamination in composites under low-velocity impact (1.75 m/s), matching with experimental results. Atiqah Afzaluddin et al. (2019) studied sugar palm and glass fiber reinforced TPU composites. Sisal fibers, known for their robustness and coarse texture, are hard fibers with tensile strengths of 340-600 MPa, show promise for biodegradable composites. Flax fibers exhibit tensile strengths of 343-2000 MPa and crucial for maintaining composite stability. There is a research gap in understanding carbon-sisal-flax composites combination for impact resistance. Carbon fiber-flax-sisal composites are rarely studied for low-velocity impact resistance, despite the promise of these natural fibers for real-world applications. This research investigates if these hybrid laminates can replace synthetic fibers while maintaining mechanical properties. These composites combine the benefits of high strength and affordability from natural fibers with the lightness of carbon fiber. Low velocity impacts, in particular, often result in visible surface damage such as dents, fiber breaking, matrix cracking and delamination. According to the principle of energy conservation, the energy absorbed by the sample during impact will equal the energy needed to induce damage. Hence, this study aims to assess the impact properties like absorbed energy, reaction force, and damage area of hybrid composites composed of sisal, flax, and carbon fibers. The numerical impact analysis in finite element method-based software ANSYS ® - LS-DYNA ® is initially simulated and verified for the existing numerical impact analysis given in literature L. Maio et al. (2013). 2. Validation case based on the study of L. Maio et al. (2013) ANSYS ® - LS-DYNA ® software is used to simulate the impact response of composite plates. Some simplifying assumptions are made that includes no friction, no material damping, and no gravity. The simulated plate is rectangular (12.5 cm x 7.5 cm, 1 mm thick) with clamped edges and a specific layer arrangement. A steel ball (0.412 kg, 6.35 mm radius) struck the center of the plate. The ball is modeled as a rigid body and the plate with shell elements. The model has 1243 nodes and 1114 elements, and the materials properties used are referred from L. Maio et al. (2013). 2.1. Results validation based on the study of L. Maio et al. (2013) The carbon/epoxy (HTA/6376 epoxy) composite laminate is subjected to an impact at 0.67 J energy level. The impact energy gets absorbed by the composite material is shown in Fig. 1 (a). This absorption causes damage and increases the material's internal energy. However, some energy is lost due to a numerical effect called "hour-glassing " that causes zero-strain deformation modes in first-order reduced-integration elements leads to spurious results. The continuous slope changes in Fig. 1 (b) suggests that after initial failure some fluctuations are observed due to the matrix failure then subsequently crack propagation occurs before reaching to critical damage. The reaction force values obtained are closely matching with the corresponding results from literature L. Maio et al. (2013).

(b)

(a)

Fig. 1: (a) Absorbed energy vs time (b) force reaction vs time graph for [45 /-45 /90 /0] s laminate sequence of 0.67 J.