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Natural fibre waste is a material with high material resistance, including fibres derived from coconut fruit. Coconut fruit waste is frequently underutilised and can contribute to environmental pollution if not handled correctly. This study's objective is to convert waste from coconuts into fibres, incorporate them into composite mixtures, and produce robust materials. Using coconut fibre presents a significant advantage in that it is easily biodegradable, reducing environmental pollution. The aim of this research is to produce a composite board material using HDPE plastic and coconut fibre, which is resistant to corrosion, through the hot felting method. This method of producing composite materials results in minimal voids and high material density, effectively reducing the chances of material failure. The composite specimens were subjected to testing following the ASTM D 638-01 standard. Technical abbreviations used throughout the text will be explained upon first use. The study achieved an excellent average tensile strength, strain, and elastic modulus of 22.45 MPa, 7.15%, and 5.13 MPa, respectively. The manufacture of composite materials using coconut coir fibre combined with HDPE plastic through the hot felting method resulted in high material strength, corrosion resistance, and reprocessability.

This study successfully explored and evaluated the impact of notches modification in U, V, and square shapes on both tensile and shear strength using Arcan fixture. ASTM D 5379 was incorporated to evaluate the model then compared with FEA simulation. Composite material featuring a U-shaped notch possesses a notable advantage in terms of its tensile strength and shear strength values, which measure at 276.3 MPa and 14.9 MPa, respectively. 3D Hashin's damage model also employed to compare and validate the shear damage resulting from each notch of the experimental work. The composite with a U-shaped notch demonstrates excellent capacity for withstanding both tensile and shear loading without compromising its strength and fracture resistance in shear. the failure mode analysis was showed that the matrix failure tent to make weaker of the specimen, although the fiber still stands and kinked. The present study can be used as the leading method to evaluate the hybrid laminates applied in wind turbines, automotives body structures, and aircraft structures.

This paper presents research on the use of anisogrid lattice structures in fighter wing applications. While the anisogrid lattice structure has been widely used in spacecraft structures, its implementation in main aircraft structures is still limited. The study is aimed at investigating the feasibility of utilizing an anisogrid lattice structure in fighter wing design. The analysis and optimization focus on determining the optimal weight of the composite wing structure, considering static, buckling, and flutter failure constraints. Various lift distributions, including triangular, Schrenk, and constant, are applied to evaluate the structure’s response to static failure caused by aerodynamic loads. The anisogrid structure design incorporates inclined lattice elements between ribs and spars, with spar arrangement in the wing box featuring an anisogrid configuration. The anisogrid lattice structure is expected to produce higher bending and torsional stiffness compared to conventional orthogonal structures, producing better flutter and buckling characteristics. The optimized wing structure successfully meets static, buckling, and flutter load requirements at speeds below 500 m/s. The study showcases triangular, Schrenk, and constant load distributions resulting in half-wing masses of 504, 571, and 707 kg, respectively. The results show that flutter and buckling loads are no longer the critical loads in wing structural design but static load.

Due to their anisotropic behavior, composite structures are weak in transverse direction loading. produces transverse cracks, which for a laminated composite, may lead to delamination and total failure. The transition from transverse crack to delamination failure is important and the subject of recent studies. In this paper, a simulation of transverse crack and its transition to delamination on cross-ply laminate was studied extensively using a cohesive element Finite Element Method (FEM). A pre-cracked [0/90] composite laminate made of bamboo was modeled using ABAQUS/CAE. The specimen was in a three-point bending configuration. Cohesive elements were inserted in the middle of the 90° layer and in the interface between the 0° and 90° layer to simulate transverse crack propagation and its transition to delamination. A load–displacement graph was extracted from the simulation and analyzed. As the loading was given to the specimen, stress occurred in the laminates, concentrating near the pre-cracked region. When the stress reached the tensile transverse strength of the bamboo, transverse crack propagation initiated, indicated by the failure of transverse cohesive elements. The crack then propagated towards the interface of the [0/90] laminates. Soon after the crack reached the interface, delamination propagated along the interface, represented by the failure of the longitudinal cohesive elements. The result of the numerical study in the form of load–displacement graph shows a consistent pattern compared with the data found in the literature. The graph showed a linear path as the load increased and the crack propagated until a point where there was a load-drop in the graph, which showed that the crack was unstable and propagated quickly before it turned into delamination between the 0o and 90° plies.