Key Engineering Materials Vols. 471-472

Abstract: This paper discusses about the simulation of the process of injection moulding for thermoset materials namely Bulk Moulding Compounds (BMC). BMC is a polyester resin based compound with glass fibre additives. In this paper a complex part was used to simulate and obtain the parameters for moulding BMC. Autodesk Moldflow Plastics Insight was used to run the simulation. Two main parameters i.e. Injection time and mould temperature were considered. Six different sets of parameters were used and the settings were optimized. The obtained optimized settings are 15.08 seconds and 145°C. The obtained parameters were then applied and the actual part was tested using an injection-moulding machine. After the simulation, changes were also made to the actual mould to improve the moulding conditions. Extra air vents were added at the problematic areas to ease the flow. There was an average variance of 7% which was thought to be acceptable as the simulation considers the ideal condition, where as there may be external factors such as the machine wear and tear during the actual moulding of the part. It can be said that the simulation was run successfully and tested during actual moulding.

Abstract: The aeroelastic flutter of a laminated hybrid composite wing was investigated. The composite wing was modelled as composite plates and the aeroelastic analysis has been carried out in the frequency-domain. Pre-determined fiber orientation of a 3-layers carbon/epoxy and glass/epoxy laminated plate has been employed with various aspect ratios. The modal approach and the Doublet-lattice Method (DLM) have been used herein to calculate the normal modes and the unsteady aerodynamics of the plate. The structural and aerodynamic models were connected using surface splines and the flutter speed has been calculated using the p-k method that provides the eigenvalues at different air densities and airstream velocities. The study showed that it is imperative that the carbon/epoxy should be employed in the outermost layers in order to improve the flutter speed and flutter frequency.

Abstract: In new era in marine industries especially in fibreglass boat construction, a proper material need to be consider for the product perfomance and economical. This paper ilustrate how the selection has been perform to select most suitable material for related body and structure component of fibreglass boat. Expert System has been using as a tool of selection and polymeric based material reinforced with different composition of fibreglass as candidate material. Ranking system has been implemented according to various factors to reveal the best polymeric based material composite for each fibreglass boat component.

Abstract: This work aims to enhance thermal conductivity of thin film without compromising the other properties of polymer. In this study, three types of fillers in nano size with high thermal conductivity properties were studied; silicon nitride, boron nitride and synthetic diamond. The contents of fillers were varied between 0-2 vol. %. Epoxy nano-composite solution filled with high thermal conductivity fillers was spun at 1500-2000 rpm to produce thin film in the thickness of 40-60 µm. Thermal conductivity properties were measured by using hot disc technique. It was found that the thermal conductivity increases as filler loading increases. The mechanical properties of the thin film epoxy composites were determined by using tensile test (ASTM D882). As predicted, the tensile modulus was found increasing with the addition of fillers and reasonable agreements were obtained from the SEM images of the fracture surfaces.

Abstract: At present, aircraft structural integrity is a concerned due to heavy usage of composite materials and cost saving on the operational. Structural health monitoring system is one of condition based monitoring introduced to supplement the current aircraft maintenance non destructive inspection. One approach is to embed or attach sensors such as lead zirconate titanate (PZT) to detect the anomalies either passively or actively. Due to the aircraft operational environment the defects and damage are likely to occur. Repair has to be carried out as per recommended and the requirement to replace back the sensors are important in order to monitor back the structure at post repair situation. The Lamb waves generated by using the PZT sensor can be used to monitor the surface structural integrity for damage or pristine condition. The effect of the lamb wave signals when surface condition of the aircraft component changes is concerned. One hundred data sets were recorded for the undamaged, damage and repair condition. An outlier analysis was used to analyze the situation by overlaying the isolated signal spectrum and the range of the voltage peak to peak (Vpp) mean values. Different signals were observed for different type of structural condition tested and more tests were required to make a conclusive solution.

Abstract: The purpose of this research is to investigate the effect of filler loading and using coupling agent on tensile and impact properties of thermoplastic polypropylene composite with oil palm ash (OPA) powder. This research is intended to discover the dependant various effect of loading percentage weight of filler OPA and coupling agent maleated anhydrate polypropilene (MAPP) on tensile and impact properties of thermoplastic composite. This materials is weighed as OPA loading percentage 0%, 1%, 3%, 5% and 7% while the loading percentage of coupling agent MAPP 0%, 3%, 6%, 10% and 12% affect the mechanical properties of thermoplastic composite. Mixture process has been carried out using double-screwed extruder machine at constant speed and temperature,while board manufacturing of PP/OPA composite are made used hot press and cold press machine. Loading OPA and MAPP effect on polypropylene composite were tested through mechanical testing , specifically for tensile and impact properties. All testing methods are predicated from ASTM's standard (American Society for Testing and Material). Results showed lower OPA content and highest MAPP in ratio giving the highest tensile and impact strength of the composite.

Abstract: Numerical investigations were performed to determine the influence of the spherical convex shape ceramic - alumina composite in reference to the standard double layer panel. All versions of the target were verified in an impact test including influence upon the position of the AP (Armor Piercing) 7,62x51HHS impact. The crucial parameter which was used for this verification was change in time of the PROJECTILE kinetic energy. The problem has been solved with the usage of the modeling and simulation methods as well as finite elements method implemented in LS-DYNA software. Space discretization for each option was built by three dimension elements guarantying satisfying accuracy of the calculations. For material behavior simulation specific models including the influence of the strain rate and temperature changes were considered. Projectile’s core made of HHS and aluminum plate material were described by Johnson-Cook model and ceramic target with Johnson-Holmquist model. In the studied panels the area surrounding back edges was supported by rigid wall. The obtained results show interesting properties of the new structures considering their ballistic resistance. However only certain places were chosen for tests, the protection ability against projectile attack is in general higher than the reference model. What is particularly interesting during the 6.6mm from the sphere center impact the sphere surface trajectory deviation effect is present. A projectile is not stopped here by material strength but the front layer shape. Moreover it can be assumed that this phenomenon will take place on majority of points on the sphere surface. Despite this fact, a ceramic multi sphere layer is less susceptible to overall destruction, depending on the impact point. The results of those numerical simulations can be used for designing of modern armor protection systems against hard kinetic projectiles.

Abstract: The paper presents a numerical study of a double layer composite panels impacted by a AP (Armor Piercing) 51WC projectile. The standard panel is built with aluminum and Al2O3 ceramic continuum layers while the studied model consists of the same aluminum plate but the front one is built with a set of hexagonal ceramic bars. The bar width and the impact position influence on the ballistic resistance are analyzed and compared with the reference solution. The problem has been solved with the usage of the modeling and simulation methods as well as finite elements method implemented in LS-DYNA software. Space discretization for each option was built by three dimension elements guarantying satisfying accuracy of the calculations. For material behavior simulation specific models including the influence of the strain rate and temperature changes were considered. Projectile Tungsten Curbide and aluminum plate material were described by Johnson-Cook model and ceramic target by Johnson-Holmquist model. In the studied panels the area surrounding back edges was supported by a rigid wall. The obtained results show interesting properties of the examined structures considering their ballistic resistance. All tests has given clear results about ballistic protection panel response under WC projectile impact. Panels consisting of sets of hexagonal ceramic bars are slightly easier to penetrate, reference model is stronger by 19% for smaller bars and by only 7% for bigger rods. Despite this fact, the ceramic layer is much less susceptible to overall destruction what makes it more applicable for the armor usage. Furthermore, little influence of the projectile impact point and consequently a part of the bar which is first destroyed is proved.

Abstract: The aim of this study is to investigate the effect of impregnation time on physical and tensile properties of sugar palm (Arenga pinnata) fibres. The fibre was impregnated with phenol formaldehyde (PF) and unsaturated polyester (UP) with various impregnation times (0, 5, 10, 15, 20, 25 min) at constant impregnation pressure of 1000 mmHg, before it was released within 30 s. Significant improvement in physical properties was observed after being impregnated for 5 min especially for fibre impregnated with PF due to its low moisture content (MC) and water absorption (WA). However, no significant changes in specific gravity for both impregnated fibres were observed. Fibre impregnated with UP for 5 min shows notable improvement in tensile strength and better fibre toughness while the fibre impregnated with PF showed lower tensile strength and elongation at break and higher tensile modulus than un-impregnated fibre. Since the PF-impregnated fibre become brittle and results in lower fibre toughness as shown in the stress strain behavior, this causes for poor fibre properties. However, there was no significant difference (p≤0.05) between all impregnated fibres in physical and tensile properties after impregnation time was extended from 10 to 25 min. In general, by increasing time of impregnation did not give much effect in improving physical and tensile properties of fibres.

Abstract: The aim of this study is to investigate the effect of impregnation pressure on physical and tensile properties of sugar palm (Arenga pinnata) fibres. The fibre was impregnated with phenol formaldehyde (PF) and unsaturated polyester (UP) with different impregnation pressures (1000, 900, 800, 700, 600 and 500 mmHg) at constant impregnation time of 5 min. Significant improvement in physical properties was observed due to reduction of moisture content (MC) and water absorption (WA) after being impregnated from 1000 to 500 mmHg while PF-impregnated fibre was showing more superior. Improvement in mechanical properties was also observed after being impregnated where much better tensile properties and toughness were found at UP-impregnated fibres while PF-impregnated fibres were found to be very much lower in toughness. This study concluded that in order to obtain a high toughness and better physical properties of sugar palm fibre, the fibre should be impregnated with UP resin with impregnation pressure of 600 mmHg.