Mohd. Sultan Ibrahim Shaik Dawood

Effects of Adhesive Bond on Active Repair of Aluminium Plate Using Piezoelectric Patch

Research activities on active repairs and stress control of structures using piezoelectric actuators and adhesive bond have received much attention in recent years. The function of the adhesive bond on active repair is to transmit the induced stresses by the piezoelectric actuator to the host structure in order to reduce the stress intensity on the crack front. Assessment of repair performance of adhesive bonds is done based on the transfer of the shear and peel stress concentration in the adhesive layer. In the present work, three dimensional finite element analyses have been carried to understand the effects of adhesive properties on active repair performance of a cracked aluminium plate under mode I. Adhesive efficiency is evaluated by the stress intensity factor (SIF) as a fracture criterion. The results show that SIF varies inversely with the adhesive layer’s shear modulus.

Numerical Analysis of Kraft Paper Honeycomb subjected to uniform compression loading

The objective of this study is to investigate the crushing strength of Kraft paper honeycomb with different thickness of cell wall and different cell size subjected to compression loading. At first, experimental tests were carried out on Kraft paper honeycomb with 10mm cell size and 0.6mm thickness of paper with different mass density (RO). Then, a finite element model was developed in order to study the effect of cell size and thickness of cell wall on crushing properties of Kraft paper honeycomb. Based on the simulation results, the cell size and thickness of cell wall of Kraft paper honeycomb influence the crushing properties of the honeycomb. Crushing strength increases with decreasing the cell size which for the range of the study, cell size 10mm shows the highest strength. Meanwhile, 0.4mm thickness of cell wall results the higher crushing strength of honeycomb. Also, higher density gives higher crushing strength where in this study is found for 2.236× 106 kg/mm3.

Effect of stitching on the tensile mechanical property of empty fruit bunch oil palm fiber reinforced epoxy composites

Stitching has proven to be an effective reinforcement for improving through-thickness (out-of-plane) mechanical properties with the incorporation of z-direction reinforcements of synthestic fiber. There are drawbacks to stitching as it may cause focal stress concentration, and fiber misalignment and breakage, but at the same time, it can also improve the tensile performance of the composite. Tensile properties, such as tensile strength and modulus of elasticity, were obtained from tensile tests performed on both stitched and unstitched oil palm fiber composites as per ASTM D638 specifications using Universal Testing Machine INSTRON 5582. The test results indicated that stitching natural, short, untreated and random empty fruit bunch oil palm fiber reinforced epoxy composites improve the tensile strength and elastic modulus due to the increase in matrix volume percentage and additional tensional resistance.

A study on the parameters affecting the properties of coated paper honeycomb

In this study, three parameters, namely the density of Kraft paper, the thickness of cell wall and the cell size of honeycomb were evaluated. A statistical analysis was performed to investigate the effect of the parameters on the specific compression strength(SCS) and specific energy absorption (SEA) of Kraft paper honeycomb. Based on the design of experiment, 27 configuration of Kraft paper honeycomb with different cell sizes (10mm, 15mm, 20mm), thicknesses of cell wall (1ply, 2ply, 3ply) and paper densities (80gsm, 120gsm, 175gsm) are subjected to quasi static compression loading. An analysis of variance (ANOVA) was used to examine the effect of each parameters and to obtain the optimum configuration of Kraft paper honeycomb. As a result, the thickness of cell wall shows as the most prominent parameter for specific energy absorption and specific compression strength. Meanwhile, the Kraft paper honeycomb with density 175gsm, 3 ply thickness of paper and 10mm cell size of honeycomb shows the optimum configuration with 724.80 J/kg of SEA and 9.35 MPa/kg of SCS.

Experimental Investigation on the Energy Absorption Capability of Foam-Filled Nomex Honeycomb Structure

The effect of low density filler material comprising polyurethane foam on the axial crushing resistance of Nomex honeycomb under quasi-static compression conditions was analyzed. Honeycombs with two different densities, two different heights and similar cell size, along with five different densities of polyurethane foams were used in the research. A total of 14 unfilled Nomex honeycombs, 15 polyurethane foams, and 39 foam-filled Nomex honeycombs were subjected to quasi-static compression loading. The crushing load and capability of foam-filled Nomex honeycomb structure in absorbing the energy were found to increase significantly since the cell walls of honeycomb were strengthened by the foam filler; the walls did not buckle at the very beginning of compression loading. The failure mechanism of the foam-filled honeycomb was analyzed and compared with the unfilled honeycomb.