Abstract: A Reddy type, third order shear deformation theory of shells is applied to the development of two versions of finite strip method (FSM), namely semi-analytical and spline methods, to predict the parametric stability and instability regions in the case of cylindrical moderately thick composite laminated panels. The structures are assumed to be under harmonic in-plane loads in the context of the so-called parametric loading. The linear strain terms are expressed in terms of the Koiter-Sanders theory of shallow shells. In order to demonstrate the capabilities of the developed methods in predicting parametric behavior of the subject structures, some representative results are obtained and compared with those in the literature wherever available.
Abstract: The effect of silane treatment on tensile properties and morphology of recycled acrylonitrile butadiene rubber(NBRr)/polypropylene(PP)/rice husk powder(RHP) composites has been studied. Polypropylene/recycled acrylonitrile butadiene rubber/rice husk powder (PP/NBRr/RHP) composite were prepared by melt mixing technique at 180º C for 9 minutes and 50rpm rotor speed using an internal mixer. Five different composites compositions (70/30/0, 7030/5, 70/30/10, 70/30/15 and 70/30/30), with silane treated RHP(treated) and without silane treatment(untreated) was studied. The specimens were analyzed by different techniques i.e. tensile test and scanning electron microscopy (SEM). The result obtained showed lower tensile properties with increasing amount of NBRr content. Lower tensile strength and tensile modulus was exhibited with increasing NBRr content. However higher tensile strength, greater tensile modulus and lower elongation at break in PP/NBRr/RHP was exhibited for silane treated RHP composites compare with untreated RHP. PP/NBRr/RHP composite was found to become more brittle with strong attachment between PP/NBR matrix and RHP filler with silane treatment. Good adhesion between silane treated RHP filler and PP/NBRr matrix was confirmed by the morphological studies.
Abstract: The effect of silane treatment on processing characteristic and swelling behavior of recycled acrylonitrile butadiene rubber (NBRr)/polypropylene (PP)/rice husk powder (RHP) composites has been studied. Polypropylene/recycled acrylonitrile butadiene rubber/rice husk powder (PP/NBRr/RHP) composite were prepared by melt mixing technique at 180º C for 9 minutes and 50rpm rotor speed using an internal mixer. Five different composites compositions (70/30/0, 7030/5, 70/30/10, 70/30/15 and 70/30/30), with silane treated RHP (treated) and without silane treatment RHP (untreated) was studied. The specimens were analyzed for swelling behavior with ASTM oil No.3 and processing torque of composites was obtained during composite preparation. The results showed that swelling percentage for both composites increased with NBRr content. However the treated composites exhibited lower swelling characteristics. Processing torque of both composites also showed higher torque reading with increasing NBRr content. However the treated composite with silane exhibited much higher torque value for similar composition composites. Better interaction between RHP filler and PP/NBRr matrixs was obtained with treated composites.
Abstract: The parametric study of automotive composite bumper beam subjected to frontal impact is presented and discussed in this paper. The aim of this study is to analyze the effect of steel and composite material on energy absorption of automotive front bumper beam. The front bumper beams made of e-glass/epoxy composite and carbon epoxy composite are studied and characterized by impact modeling using LS-DYNA V971, according to United States New Car Assessment Program (US-NCAP) frontal impact velocity and based on European Enhanced Vehicle-safety Committee. The most important variable of this structure are- mass, material, and Specific Energy Absorption (SEA). The results are compared with bumper beam made of mild steel. Three types of materials are used in the present study which consists of mild steel as references material, Aluminum AA5182, E-glass/epoxy composite and carbon fiber/epoxy composite with three different fiber configurations. The beams were subjected to impact loading to determine the internal energy and SEA and to reduce mass of the conventional bumper beam. The in-plane failure behaviors of the composites were evaluated by using Tsai Wu failure criterion. The results for the composite materials are compared to that of the reference material to find the best material with highest SEA. LS-DYNA Finite Element Analysis software was used. The results showed that carbon fiber/epoxy composite bumper can reduce the bumper mass and has highest value of SEA followed by glass fiber/epoxy composite.
Abstract: The development of nanoclay-epoxy nanocomposite material requires a suitable blending process to be employed. Amongst blending techniques, sonication has been one of the promising means for polymer-clay nanocomposite fabrication. In this study, epoxy-clay nanocomposites with 2, 4 and 5% clay loadings were fabricated using different sonication periods ranging from 5 to 60 minutes. The effect of sonication time and clay loading on the nanocomposite structure was investigated using Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Scanning Electron Micropscope (SEM) and Energy Dispersive Spectroscopy (EDS). Differential Scanning Calorimetry analysis indicated that while clay loading reduced the glass transition temperature (Tg), sonication time did not alter Tg significantly. Upon examining the structure of the resulting nanocomposites both exfoliation and intercalation structures were present, yet, neither structure was fully achieved; evident by the XRD patterns. Nonetheless, the predominant structures for most of the nanocomposites were intercalation. Intergallery spacing of the nanocomposites were enhanced with increased sonication time mainly at 2%wt loading; whereas further increase in nano-clay loading resulted in a reduction of the d-spacing. SEM analysis showed that clay agglomerates were present in the nanocomposites irrespective of the sonication time. However, the analysis revealed that dispersion of clay was better in the nanocomposite fabricated at higher sonication time. From the EDS analysis, the different sites in the nanocomposites’ microstructure were identified which were then correlated with the observation made in the fractographic analysis.
Abstract: Epoxy-clay nanocomposites have recently gained considerable attention due to their interesting physical, thermal and mechanical properties. These properties, however, depend on a number of parameters such as the clay type, clay modifying agent, polymer matrix and the adopted mixing process. In the current work, epoxy-clay nanocomposites were prepared from Araldite GY6010 CRS and Nanomer I.30E nanoclay using different sonication (mixing) periods (5 to 60 minutes) and different concentrations of clay (2 to 5%wt). The effect of sonication time and clay loading on the tensile and hardness properties of the resulting nanocomposites were investigated. The results showed that the ultimate strength and fracture strain of the nanocomposites were below that of the neat epoxy, but the elastic modulus was generally enhanced by the addition of the nano-clay content. Increasing the sonication time enhanced the tensile strength on the expense of reducing the modulus of elasticity. Hardness of the nanocomposites did not show significant change with either the addition of clay or processing under different sonication times.
Abstract: This investigation is done to select the best composite on bending strength and stiffness derived from different parts of sugar palm fibre reinforced unsaturated polyester composites. Sugar palm tree is one of the most popular natural fibres. The fibre was obtained from the sugar palm tree and mixed with unsaturated polyester (PE). All of the composites are labelled as SPF/PE for sugar palm frond composite, SPB/PE for sugar palm bunch composite, SPT/PE for sugar palm trunk composite and ijuk/PE for black sugar palm fibre composite. The bending strength and stiffness tests were done according to ASTM D 790-(2000). The higher value of bending strength and stiffness obtained by SPT/PE which is 41.906 MPa and 3.363 GPa respectively followed by SPF/PE (38.906 MPa and 3.001 GPa), SPB/PE (35.168 MPa and 2.749) and ijuk/PE (33.742 MPa and 2.424 GPa)
Abstract: Combination of lignocellulosic fiber with thermoplastic is leading to the new areas of research in plastic composite field. Due to the problem of petroleum shortages and encouragement for reducing the dependence on fossil fuel products, thus increased the people interest in maximizing the utilize of renewable materials like kenaf fiber. By adding optimum natural fiber to thermoplastics could provide some cost reduction to the world of plastic industry as well as to dominance the agro-based industry. With a view to identifying the effect of fiber content and effect of coupling agent in kenaf fiber reinforced unplasticized poly (vinyl chloride) (UPVC) composite on the mechanical properties, the fiber and matrix mixture were mixed with poly [methylene poly (phenyl isocyanate)] (PMPPIC) using thermal mixing process followed by compression molding technique for the composite preparation that required for tensile characteristic (ASTM D638). The fiber loading were 10%, 20%, 30%, and 40% in weight. Since the kenaf fiber and UPVC are chemically different, the compatibility and dispersability of kenaf fiber in UPVC can be improved by lowering the surface energy of the fiber to make it less polar, consequently more similar to the plastic matrix. Generally, PMPPIC act as a bonding agent that facilitates the optimum stress transfer at the interface between fiber and matrix which gives an optimal mechanical performance of kenaf fiber reinforced UPVC composites. Meanwhile, the addition of 30% fiber contents with PMPPIC was successful to enhance the tensile properties and the efficiency of PMPPIC was verified using Fourier Transform Infra-Red (FTIR) spectroscopy.
Abstract: In evaluating thermoplastics for their effective performance during processing, rheology properties are very useful. Similarly, in designing processing apparatus, knowledge of rheological behavior of composite melt is critical. In this study, melt flow and viscosity behavior of polypropylene/kenaf fibre composite was investigated using a single-screw extruder. Subsequently, flow behavior of the compounded formulation were evaluated by comparing the melt flow index, flow curve and viscosity curve of the PP and that of the composites at 190oC processing temperature and varying the fibre size. There appears to be a positive linear increase of the apparent shear stress with increase in the apparent shear rate and, as expected, viscosity values for the composite samples are much higher than the PP especially at larger fibre size. The additional of kenaf fibre in composite reduces the MFI value basically because of the hindrances in the plastic flow of the polymer. In addition the increase in viscosity with increase in fibre loading might contributed to the high specific area of the fibre in the matrix thereby increasing the shear stress in the composite. Moreover loading of polymer system with fibre tends to disturb or disorganize the normal free movement of the polymer and certainly hindered the mobility chain segments in flow.
Abstract: Polyamide (PA6) is an engineering plastic with wide range of applications and the development in the field of montmorillonite (MMT) filled polymer nanocomposites has resulted in the development of PA6/MMT nanocomposites. However, MMT filled PA6 nanocomposites are notch sensitive and brittle at low temperatures, which posed as a major setback for many of its applications. The main objective of this study is to enhance the toughness of PA6/MMT (100/4) nanocomposites with epoxidised natural rubber-25 (ENR25). The ENR-25 content in the composites ranged from 15 to 30 wt%. The PA6/ENR/MMT nanocomposites were extruded and injection molded into tensile and impact test samples. The addition of ENR25 into PA6/MMT nanocomposites improved the impact strength of the nanocomposites while tensile modulus and tensile strength decreased with increasing ENR25 content. The thermal properties of PA6/ENR/MMT nanocomposites were also investigated via thermal gravimetric analysis (TGA). Both T10% and derivative thermal analysis (DTA) determined the lower thermal stability of PA6/MMT nanocomposites after addition of ENR.