Ghalib Rzayyig Ibrahim

This review presents a comprehensive study of recent advances in the fracture behavior of functionally graded porous materials (FGPMs), with a specific focus on application, fracture mechanism, and mechanical characteristics. The mechanism of mechanical fracture involves two stages: the first is the formation of a crack or defect in the material, and the second is the growth of the crack under loads until the material separates and total failure occurs. The most important characteristic of functionally graded porous materials is their very good strength-to-weight ratio; they also possess sound and thermal insulation and impact absorption. The study is based exclusively on data gleaned from published literature, database resources, and previous research reports. The components of functionally graded materials (FGMs), from production techniques to stress analysis and their performance, have already been the subject of a sizable body of work because they have huge potential to be useful in a wide variety of important structural applications, especially when thermo-mechanical loading is applied. The current study concentrates on developments in structural composites derived from FGMs, particularly crack formation and fracture behavior. The review showed that finite element analysis (FEA) is used to simulate the mechanical behavior of functionally graded porous materials (FGPMs), enabling accurate prediction of crack growth, the effect of porosity ratio, and improved structural design to resist crack growth under external loads. Such a review provides useful information on the main issues that have been faced previously and lays the groundwork for future solutions to evaluate the structural integrity of this type of material when cracks are present

This study considers the intra-laminar damage mode in composite structures and its effect on delamination prediction. The progressive damage models for matrix cracking and fibre failure in ABAQUS, based on Hashin's model, are only available for shell elements. The results presented here show that the predicted matrix cracking based on the damage model presently available in ABAQUS diverges from experimental results. A new model based on strain failure criteria, which can be used with both shell elements and 3D solid elements, has been developed. The effect of friction coefficient and enhancement factor on the delamination lobes within the delamination area was investigated, and it is shown that the intact zone can be captured in laminate [0₃/90₃]_s and [90₃/0₃]_s subjected to low-velocity impact, by using an enhancement factor of η = 0.75, and friction coefficient [ ], together with the new model proposed here.

This article presents a comparison between empirical mode decomposition (EMD) and smoothed pseudo-Wigner–Ville distribution (SPWVD) methods based on vibration signature and energy calculation procedure for monitoring gearbox systems. The simulation and experimental work were carried out using two-stage helical gears for a healthy pair of gears and a pair suffering from a tooth breakage with severity fault 1 (25 per cent tooth removal), fault 2 (50 per cent tooth removal), fault 3 (75 per cent tooth removal), and fault 4 (100 per cent tooth removal) under loads (0, 20, 40, 60, and 80 per cent of the total load) and speeds (10, 30, 50, 70, and 90 per cent of full speed). This article illustrates that the calculation of energy using EMD techniques offers a more effective way to detect early faults than that computations using the SPWVD method, and that the computation of energy using the EMD technique is faster than the calculations done using the SPWVD method.