Browsing by Author "Ghasemnejad, Hessammaddin"

Now showing 1 - 5 of 5
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    Analysis of the effect of impact damage on the repairability of composite panels
    (Elsevier, 2017-05-25) Alzeanidi, Nasser; Ghasemnejad, Hessammaddin
    The present paper aims to provide further understanding of the behaviour of Carbon Fibre Reinforced Plastic (CFRP) composite panels under high velocity impact and develop design guideline for repair of damaged composite panels in order to increase the aircraft survivability. This work consists of two parts: part one is a combination of experimental investigation and numerical simulation to evaluate the impact of a woven CFRP laminate which were subjected to selected impact velocities (100 m/s–500 m/s) in order to evaluate the induced impact damage in two different thicknesses of CFRP composite panels (4.125 mm and 2.625 mm). In part two a finite element model is developed to design a guideline for repairing of a composite panel. In order to achieve this an optimised repair models with variable parameters such as number of steps and length of steps in the stepped lap joints are investigated. The penetration process and also change of kinetic energy absorption characteristics have been used to validate the finite element results. Finite element results were in close agreement with experimental data obtained from different sources.
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    Effect of multi stitched locations on high speed crushing of composite tubular structures
    (Elsevier, 2016-06-20) Rabiee, Ali; Ghasemnejad, Hessammaddin
    The present paper experimentally investigates progressive energy absorption of fibre-reinforced polymer (FRP) composite tubular structures under high speed loading conditions. Various multi stitched locations are studied to find a correlation between single and multi-locations of stitches and energy absorption capabilities of composite absorbers. The through-thickness reinforcements are applied into locations of 10 mm, 20 mm, 30 mm, 10–20 m, 10–30 mm, 20–30 mm, 10–20–30 mm and 10–15–20–25–30–35 mm from top of the tubes. It is shown that multi-stitched location can cause several increase of crushing load and consequently increase of energy absorption of composite tube absorbers. The idea would be expanded to other designs which are followed by increase of stitched locations and reduction of the distance between stitches to improve the mean force with a smooth and progressive pattern of crushing load.
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    Effect of stitching pattern on composite tubular structures subjected to quasi-static crushing
    (2016-10-31) Rabiee, Ali; Ghasemnejad, Hessammaddin
    Extensive experimental investigation on the effect of stitching pattern on tubular composite structures was conducted. The effect of stitching reinforcement through thickness on using glass flux yarn on energy absorption of fiber-reinforced polymer (FRP) was investigated under high speed loading conditions at axial loading. Keeping the mass of the structure at 125 grams and applying different pattern of stitching at various locations in theory enables better energy absorption, and also enables the control over the behaviour of force-crush distance curve. The study consists of simple non-stitch absorber comparison with single and multi-location stitching behaviour and its effect on energy absorption capabilities. The locations of reinforcements are 10 mm, 20 mm, 30 mm, 10-20 mm, 10-30 mm, 20-30 mm, 10-20-30 mm and 10-15-20-25-30-35 mm from the top of the specimen. The effect of through the thickness reinforcements has shown increase in energy absorption capabilities and crushing load. The significance of this is that as the stitching locations are closer, the crushing load increases and consequently energy absorption capabilities are also increased. The implementation of this idea would improve the mean force by applying stitching and controlling the behaviour of force-crush distance curve.
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    Post impact analysis of damaged variable-stiffness curved composite plates
    (Elsevier, 2017-01-18) Arachchige, Buddhi; Ghasemnejad, Hessammaddin
    This research studies the post impact response of damaged area of variable stiffness curved composite plates. Varying thicknesses of sections is widely found in aerospace and automotive composite sub structures. In this regard, the impact response of this geometry characteristic has to be studied in thin-walled structures. In our model, a removal of ply technique is used to represent damaged region within a curved panel, thus degrading the stiffness in that area is considered in the theoretical models. A summation of spring-mass systems is used in the modelling of damaged variable stiffness plate to analysis post impact behaviour of these structures. The theoretical force-time results are also compared with the relevant finite element outcomes in LSDYNA. The comparison establishes a good prediction capability of the proposed model.
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    Progressive Crushing of Polymer Matrix Composite Tubular Structures: Review
    (Scientific Research Publishing, 2017-01) Rabiee, Ali; Ghasemnejad, Hessammaddin
    The present paper reviews crushing process of fibre-reinforced polymer (FRPs) composites tubular structures. Working with anisotropic material requires consideration of specific parameter definition in order to tailor a well-engineered composite structure. These parameters include geometry design, strain rate sensitivity, material properties, laminate design, interlaminar fracture toughness and off-axis loading conditions which are reviewed in this paper to create a comprehensive data base for researchers, engineers and scientists in the field. Each of these parameters influences the structural integrity and progressive crushing behaviour. In this extensive review each of these parameters is introduced, explained and evaluated. Construction of a well-engineered composite structure and triggering mechanism to strain rate sensitivity and testing conditions followed by failure mechanisms are extensively reviewed. Furthermore, this paper has mainly focused on experimental analysis that has been carried out on different types of FRP composites in the past two decades.