Ahmad Mubarak Tajul Arifin

Behavioural observation of laminated polymer composite under uniaxial quasi-static and cyclic loads

In this study, we investigate the mechanical performance of woven glass fiber reinforced polymer composite laminates subjected to quasi-static and cyclic loading at room temperatures using the unnotched and open hole specimens. The mechanical behaviour and damage in composite laminates are greatly affected by the existence of notches with different parameters such as the size of the holes, number of layers and stacking sequences. The objective of this study is to investigate and evaluate the mechanical behavior of composite lamination structures using unnotched and notched specimens by experimentally and numerically. The materials selected for the studies were chopped strand mat (CSM)/woven roving fabric (WR) as the reinforcement and epoxy resin as the matrix. The hand lay-out technique was used to fabricate these composites. Fractured surfaces were comprehensively examined in a optical microscope and scanning electron microscope (SEM) to determine the microscopic fracture mode and to characterise the microscopic mechanism governing fracture. A numerical procedure based on the finite element method was then applied to evaluate the overall fatigue behaviour of the unnotched and open hole polymer laminate composites using the experimentally applied load. The predicted results based on the FEM analysis were found to be in reasonable agreement with experimental observations.

Failure characterisation in polymer matrix composite for un-notched and notched (open-hole) specimens under tension condition

This paper presents an investigation of the influences causing failure in the materials comprising polymer matrix composites. Structures with differences in stacking sequences and design configuration are analysed. The objective of this study is to investigate and evaluate the reasons for the failure of composite lamination structures in terms of stress, strength, strain, and Young modulus within a morphology observation of composite materials. The materials selected for the study were a chopped strand mat (CSM) and a woven roving (WR) fabric. These materials are used as reinforcement and are produced by the hand lay-up technique using epoxy and polyester matrix resin. The experiment was performed using specimens made of notched (open-hole; OH) tension and un-notched (UN) shapes. The characteristics of different shapes, materials, and lamination structures are studied in this research. The results showed the failure phenomenon in the structure of the polymer matrix composite is dependent on the characteristics of the material used and the design configuration of both structures.

The Effect of Cutting Speed and Feed Rate on Surface Roughness and Tool Wear when Machining Machining D2 Steel

Machining parameters is a main aspect in performing turning operations using lathe machines. Cutting parameters such as cutting speed, feed rate and depth of cut gives big influence on the dynamic behavior of the machining system. In machining parts, surface quality and tool wear are the most crucial customer requirements. This is because the major indication of surface quality on machined part is the surface roughness and the value of tool wear. Hence, to improve the surface roughness and minimize the forming of tool wear, the optimum feed rate and cutting speed will be determined. The input parameter such as cutting speed, feed rate and depth of cut always influence the tool wear, surface roughness, cutting force, cutting temperature, tool life and dimensional accuracy. The D2 steel was being investigated from the perspective of the effect of cutting speed and feed rate on its surface roughness and tool wear. The results show that cutting speed is the main parameter which affects the surface roughness where the most optimum parameter would be at cutting speed of 173, 231 and 288 m/min with feed rate of 0.15 mm/rev. The tool wear strongly affected by feed rate where at 0.15 mm/rev the tool wear value is the lowest. The combination of high cutting speed and low feed rate was the best parameter to achieve smooth surface roughness.

Behavior of Chopped Strand Mat and Woven Roving under Bending

Abstract In this study, lamination panels were fabricated using chopped strand mat (CSM) and woven roving fabric (WR) as reinforcement for two different types of specimens, type Eb and type Pb, respectively. By a combination of plain materials composite lamination structures were formed, with [CSM/0/90/CSM]2s as an orientation layer for the structures. In this research study, the structural panel was produced by hand lay-up technique with a combination of unsaturated epoxy and polyester resin, separately. Therefore, with this publication, a characteristic combination of chopped strand mat/woven roving fabric, are presented. The experimental work for both types of specimens were performed by bending until the structure fails. The characteristics of different materials, i. e. the chemicals used and the composite lamination structure, were studied, because there are different types of damages in the structure of composite materials, such as delamination, matrix cracking, fiber-matrix damage and fiber pull-out. Furthermore, it can affect the behavior of composite materials in the whole structure. As a result, this process contributes to failure prevention, as the capabilities of the structures are known, before it can be used for any part, component or area. It was also shown that different configuration lamination layers influence the strength properties of the composite materials.

Investigating the fatigue phenomenon of CSM-woven roving composite materials lamination

This paper presents the investigation of composite materials lamination using a combination of chopped strand mat (CSM) glass and glass fabric materials in the structure of lamination. The purpose of the study is to evaluate the behavior of characteristics in composite materials subjected to difference of fatigue loading on tension-tension condition, whereby to understand the criteria that influence the behavior of composite lamination structure. The orientation structure of lamination used in this research is 0°/90° and the material selected for the study were CSM and woven roving fabric (WR) as reinforcement materials with combination of epoxy resin. The 0°/90°, means the orientation degree of woven roving fabric in the stacking sequence of lamination, and CSM as an additional material in a lamination structure of composite. The composite lamination structure has been produce using hand lay-up technique. It is suggested that, with a difference of composite materials used and the amount of matrix produced various material characteristics respectable to material elasticity. It should be noted that, composite have a difference behavior if the difference material, orientation and stacking sequence used. In this case, the investigation of fatigue phenomenon is on the combination of CSM and WR with 5 layers lamination system in a 2 (two) symmetry of stacking sequence. With a combination of 2 (two) types method used to predict the fatigue life of composite materials, it shows a correlation result with an experimental and prediction result and showed the characteristic of composite materials for this type of specimen in a fatigue failures condition before it fractured. An implication of this study show and proven with difference of lamination structure system of composite materials, it showed a difference behavior of composite life.

Optimization Method of Injection Molding Parameters for Vinyl-Based Polymer Composites

Abstract The utilization of biocomposites from waste agricultural residues as reinforcing fillers has been getting more attention nowadays as more industries aim to achieve green technology and address environmental issues. They are often obtained from oil palm plantations and other agricultural industries like rice husk, rice straw, pineapple, sugarcane, banana, and coconut. Agricultural wastes lead to vast amounts of biomass often known as natural fibers. Until now, only 10% of these are utilized as alternative raw materials for various industries. Waste agricultural residues have normally been a problem due to their resistance to ground decomposition, low nutritional value, and difficult digestion in animals. Thus, many researchers focused on developing and studying these natural fibers and their potential as reinforcing fillers in composites. To enhance their mechanical properties, inorganic materials and fibrous reinforcing fillers were mixed with polymer matrix. Previous studies have incorporated fillers and materials in polyethylene and polypropylene. The studies revealed that the polymeric materials were able to enhance the tensile strength, impact strength, flexural strength, and hardness of the composites. The most suitable processing operation to produce the composite is via injection molding. To optimize the process, parameters need to be at their optimum levels to ensure an acceptable performance. Optimizing the parameters in injection molding process is vital in enhancing productivity. Taguchi method is considered as one of the optimization methods. In this method, an orthogonal array is produced based on the experimental design.

Introduction to Natural Fiber Reinforced Vinyl Ester and Vinyl Polymer Composites

Abstract In recent years, the polymer industry has intensified its efforts to produce renewable material based polymer. Therefore, the use of natural fiber composites has been widely considered in various engineering sectors to replace conventional synthetic composite usage. This is because natural fiber composite properties are easily disposed and environmentally friendly in generating economic and sustainability societies. Vinyl polymer is a group of matrices comprising of thermosets and thermoplastics that are normally preferred as matrices with natural fibers. Both groups have their own unique features in benefiting their applications. The composite made of thermoset resin cannot be reprocessed or recycled. The composites of the thermoset matrix tend to provide good mechanical strength, are fragile and have low tensile effects. This is in contrast to the properties of the thermoplastic polymer that can be formed and diluted without changing its physical properties. Thermoplastic has excellent impact resistance and ductile. However, various approaches continue to be carried out by researchers to meet the requirements of natural fiber composites in different applications.

Characteristics on Treated Kenaf Fiber Reinforced Polypropylene Composites

Nowadays natural fiber and polymer matrix are being extensively used as alternatives in producing furniture like ceiling, floor and etc. to fulfill society demand instead of environmental friendly and saving cost. The objective of this study is to investigate the effects of maleic anhydride grafted polypropylene (MAPP) as a coupling agent for reinforcement between kenaf fiber (KF) and polypropylene (PP). The ratio of MAPP between 3% and 5% was observed to determine which composition ratio is better. The tensile strength for both 30% KF and 40% KF was treated through the alkali treatment process with 5% sodium hydroxide (NaOH). Kenaf fiber reinforced polypropylene (PP/KF) composites were melt blended and then used hydraulic molding test press machine for characterization to observe their tensile strengths by measuring their threshold. Tensile test was carried out to determine the tensile stresses of the composite at the best composition ratio of kenaf fiber that are 30% KF and 40% KF instead of MAPP ratio. The result shows 40% KF (5% MAPP) lead to better tensile performance compared to 40% KF (3% MAPP), 30% KF (5% MAPP) and 30% KF (3% MAPP). Meanwhile, Scanning electron microscopy (SEM) is used to observe the morphological comparison between untreated KF and treated KF as well as PP/KF. The good interfacial bonding between KF and PP was 5% MAPP rather than 3% MAPP due to the optimum strength received. Overall 5% MAPP with 40% PP/KF had shown the best result compared to others with the estimated tensile strength value of 21.38 MPa.

An Evaluation of Mechanical Properties on Kenaf Natural Fiber/Polyester Composite Structures as Table Tennis Blade

Nowadays, natural fibers getting attention from researchers and industries to optimize the use it, with combination of polymers as composite structure, due to environmental awareness. Furthermore, it show a few advantage, such as biodegradability, light in weight and non-toxic characteristic. In this study, kenaf natural fibers was used as reinforcement material, with combination of polyester as matrix material, known as polymer matrix composites. The main purpose of this study is to analysis the mechanical properties of kenaf natural fiber/polyester composite structure, in order to know the suitability of kenaf natural fibers as replacement material for table tennis blade structure, instead of using wood. The structural panel of composite laminates has been produced using hand lay-up technique. The experimental works are performed in tension, impact (Charpy) and shear condition. The characteristic of different condition on kenaf composite structure was studied. Based on the result, it found the properties of kenaf composite structure, and it will used as a benchmark, to compare with initial properties of table tennis blade made by wood. In addition, the strength and a weakness of that particular materials and lamination structure will be identified.

Numerical modelling of steel tubes under oblique crushing forces

This paper presents the numerical assessment of crushing responses of elliptical tubes under crushing forces. Based on the literature survey, tremendous amount of works on the axial crushing behaviour can be found. However, the studies on the oblique crushing responses are rarely found. Therefore, this work investigates numerically the elliptical tubes under compressions. The numerical model of the tubes are developed using ANSYS finite element program. Two important parameters are used such as elliptical ratios and oblique angles. The tubes are compressed quasi-statically and the force-displacement curves are extracted. Then, the area under the curves are calculated and it is represented the performances of energy absorptions. It is found numerically that the introductions of oblique angles during the crushing processes decrease the crushing performances. However, the elliptical-shaped tubes capable to enhance the energy absorption capabilities. On the other hand, the elliptical-shaped tubes produced the enhancement on the energy absorption capabilities.