In the contemporary world, natural fibers reinforced polymer composite (NFRPC) materials are of great interest owing to their eco-friendly nature, lightweight, life-cycle superiority, biodegradability, low cost, noble mechanical properties. NFRPCs are widely applied in various engineering applications and this research field is continuously developing. However, the researchers are facing numerous challenges regarding the developments and applications of NFPRCs due to the inherent characteristics of natural fibers (NFs). These challenges include quality of the fiber, thermal stability, water absorption capacity, and incompatibility with the polymer matrices. Ecological and economic concerns are animating new research in the field of NFRPCs. Furthermore, considerable research is carried out to improve the performance of NFRPCs in recent years. This review highlights some of the important breakthroughs associated with the NFRPCs in terms of sustainability, eco-friendliness, and economic perspective. It also includes hybridization of NFs with synthetic fibers which is a highly effective way of improving the mechanical properties of NFRPCs along with some chemical treatment procedures. This review also elucidates the significance of using numerical models for NFRPCs. Finally, conclusions and recommendations are drawn to assist the researchers with future research directions.

Natural fiber reinforced composites: Sustainable materials for emerging applications

In-situ residual stress analysis during annealing treatments using neutron diffraction in combination with a novel furnace design

Model updating is concerned about the correction of finite element models by processing the record of dynamic response from test structures in order to have an accurate model for any simulated analysis. Finite element model updating had emerged years ago as an important subject in structural dynamics. It has been used frequently and has been successfully applied to many fields especially in detecting the dynamic stiffness of a structure. The purpose of this study is to perform model updating of a go-kart chassis structure in order to reduce the percentage of error between the experimental modal analysis (EMA) and finite element analysis (FEA). Modal properties (natural frequency, mode shapes, and damping ratio) of the go-kart chassis structure were determined using both EMA and FEA. Correlation of the modal parameters gathered in FEA and EMA was carried out before optimizing the data from finite element. By adjusting the selective parameters, incongruities between those two analyses are generally reduced. The sensitivity of selected parameters is also obtained. The significant reduction in percentageof error before and after model updating procedure was carried out in this study clearly shows that model updating technique is a reliable method in reducing the discrepancies between EMA and FEA. Therefore, in cases of high discrepancies between analytical and actual test data, model updating can be considered as an option in order to obtain better correlation between those two sets of data.

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Dynamics Properties of a Go-Kart Chassis Structure and Its Prediction Improvement Using Model Updating Approach

The hybridization of natural and synthetic fibers in
composite materials has gained the attention in the
research field due to environmental awareness. Therefore,
this study focuses on the effects of fiber stacking
configuration on the tensile and quasi-static penetration
of kenaf/glass hybrid fiber metal laminates (FMLs).
Kenaf/glass reinforced polypropylene FMLs with two different hybrid stacking configurations were prepared
using hot compression process. Non-hybrid kenaf and glass fiber reinforced metal laminates were also prepared
for comparison. The tensile test was conducted according to ASTM E8, while the quasi-static penetration test was carried out in accordance with ASTM D 6264 using 12.7 and 20 mm hemispherical indenters. The fractured surface of FMLs due to tensile loading was examined using scanning electron microscope, while optical micrograph was used to investigate the failure mechanism of quasi-statically penetrated laminates. From the results, FMLs with the glass plies at the outer layers of composite (H1) showed a positive hybrid effect as they displayed better tensile and penetration resistance, compared to the non-hybrid kenaf
and glass reinforced FMLs. Furthermore, it could be seen that the overall performance of FMLs decreased as the kenaf content in the laminates further increases for hybrid FML.

The Effects Of Stacking Configuration On The Response Of Tensile And Quasi-Static Penetration To Woven Kenaf/Glass Hybrid Composite Metal Laminate

The complex thermal histories in additive manufacturing (AM) of metals result in the presence of residual stresses in the fabricated components. The amount of residual stress accumulated during AM depends on the high temperature constitutive behavior of the material. The rapid solidification and repeated thermal cycles with each laser pass result in material contraction, and subject the surrounding, constrained material to both elevated temperatures and internal stresses, providing driving forces for stress relaxation. In this study, the stress relaxation behavior and mechanisms of conventionally processed and additively manufactured Inconel 625 (CP-IN625 and AM-IN625) at 600 °C and 700 °C were investigated via compression tests up to an engineering strain of 9% with in situ neutron diffraction characterization. The stress decayed to a plateau stress equivalent to 18% of the peak stress in CP-IN625 and 16% in AM-IN625 at 600 °C, and 39% in CP-IN625 and 44% in AM-IN625 at 700 °C. At the same temperature, the stress relaxation rate in AM-IN625 was twice as high as that in CP-IN625, and the magnitude of the plateau stress in AM-IN625 was slightly lower than that in CP-IN625, as the textured AM-IN625 had much larger grains than the texture-free CP-IN625. The stress relaxation in CP- and AM-IN625 was deduced to be controlled by dislocation glide and climb, where dislocations interact with grain boundaries, solute atoms, and secondary phases. The stress relaxation constitutive behavior reported here is a necessary input for the development of accurate thermomechanical models used to predict and minimize residual stresses and distortion in AM, as well as to predict the stress relaxation behavior of Inconel 625 in high temperature structural applications.

Stress relaxation in a nickel-base superalloy at elevated temperatures with in situ neutron diffraction characterization: Application to additive manufacturing

This document contains the formatting information for the papers presented at the International conference on “4th International Conference on Recent Advances in Automotive Engineering & Mobility Research (ReCAR IV)”. The conference would be held at Hotel Bangi-Putrajaya during August 8-10, 2017. Fibreglass composites are one of the materials that can be used in manufacturing of the vehicles part due to their excellent lightweight properties. Composite structures may undergone the fatigue failure when subjected to a certain numbers of cyclic loading, which is normally occurs below the ultimate strength of material. However, there still lack of studies on the effect of fibre orientations on the fatigue strength of glass fibre reinforced composites (GFRC). Therefore, the purpose of this study is to determine which orientation would have the highest fatigue strength. The fibre materials used in this study is unidirectional glass fibre with [0/90]°, [ ±45]° orientation and chopped strand mat (CSM). The composite is fabricated from glass fibre and polyester resin using a hand lay-up technique according to ASTM D3039 for tensile test and ASTM D3479 for fatigue test. The results were presented in the form of S-N curve. The results show that the mechanical properties and fatigue behavior were significantly affected by the fibre orientation of the GFRC  

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Tensile and Fatigue Behaviour of Glass Fibre Reinforced Polyester Composites

This paper presents effects of heat treatment on toughness, hardness and fatigue strength of aluminum alloy 6061. The alloy specimens were heat treated in the furnace at different temperature levels and holding times; and then cooled in different media (water and oil). The mechanical properties such as hardness, impact and fatigue were examined using standard method. Result shows that mechanical properties of aluminum alloy can be improved by the heat treatment. It was found that through ageing processes at temperature 160 °C for one, three and five hours, decreased the hardness, while increased the toughness. The fatigue strength was decreased when the number of cycles increased. The fracture surfaces between specimens have a different appearance before and after heat treatment.

Influence of Heat Treatment on Impact, Hardness and Fatigue Strength of 6061 Aluminium Alloy

The question of “what type of elements should be us ed?” never fails to pop up in the minds of analysts when carrying out finite element analysis (FEA). Indeed, the selection of el ements from a variety of different types of element s is part and partial of FEA. Initially, only one-dimensional (1D) elements were developed. The introduction of two-dimensional (2D) and three dimensional (3D) elements, which came later, greatly increase the ca pability of finite element (FE) programs to model a nd solve complex engineering problems. Not only do these elements provide improv ement in accuracy of the results but also brought a bout new challenges which include evaluation of numerical errors, validity of results, setup and execution time as well as large computer memory capacity. The outcome of the analysis is very much dependent of t he type of element chosen. The aim of this paper i s to investigate the factors influencing the selection of elements in FEA by con sidering the effects of different types of elements on the results of FEA. A simple case study of an I-beam subjected to an asymmetric load is carried out by FEA. Three different models of the I-beam were prepared and analyzed separately using 1D elements, 2D eleme nts, and 3D elements. The results of these models w ere compared with the mathematical model of the I-beam. The FEA results o f these models showed good agreement with the theor etical calculation despite the small and negligible errors in the analysis. Si nce the aim of FEA is an effective and efficient so lution to engineering problems, it becomes a necessity to consider factors such as str uctural shape, desired analysis results, and comput er capability while choosing the right element for the analysis.

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Effect of elements on linear elastic stress analysis:a finite element approach

The stress relaxation behaviour of heat treated nickel-base superalloy Inconel 718 at high temperature was investigated. Solution treatment was applied on the as-received material at 980 oC for 1 hour before water quenching followed by double aging treatments at 720 oC for 8 hours and 621 oC for 8 hours, then cooled in air. The stress relaxation test was conducted at 1 % strain at different test temperatures of 550 oC, 650 oC and 750 oC. The tests were carried out for a total of 72 hours. The tests were interrupted at 3 hours and 48 hours to investigate the evolution of microstructure and changes in material properties by using Scanning Electron Microscope (SEM) and X-Ray Diffractometer (XRD). The results showed that thermal dependent stress increased with decreasing temperature. In contrast, stress relaxation rate increased with increasing temperature. Microstructure observation by SEM showed that recovery process occurred. This was further supported by the decrease in dislocation density with increase in time and temperature, which is in-line with the Vickers micro-hardness results.

Omar Bapokutty

Papers

Tensile and Fatigue Behaviour of Glass Fibre Reinforced Polyester Composites

Influence of Heat Treatment on Impact, Hardness and Fatigue Strength of 6061 Aluminium Alloy

Effect of elements on linear elastic stress analysis:a finite element approach

Stress relaxation behaviour and mechanism of heat treated inconel 718 in high temperature environments