Now showing 1 - 4 of 4
  • Publication
    Electrical discharge coating of NiTi alloy in deionized water
    Shape memory alloys, specifically nickel-titanium (NiTi), exhibit excellent technical properties that suited them for biomedical applications. However, the release of nickel ions into human body is a drawback because it results in severe adverse health effects as well as degrades the biocompatibility of the alloys. In this work, surface modification through adaptation of electrical discharge machining was used to develop a deposition layer of titanium oxide on NiTi alloy surface. The adaptation was through electrical discharge coatings (EDC) parameters such as polarity, gap voltage, and erosion depth that were set up to study their effects on the experimental performance. The experiment was parameterized by implementing 2 level of full factorial design with ANOVA analysis to measure the surface roughness of that machined surface. One-factor-at-a-time, OFAT method is applied for XRD analysis by adopting the previous parameters approach. The EDC process was aided with deionized water and pure titanium rod as the dielectric fluids and electrodes, respectively. It was determined that the high level of gap voltage provided some major constituents on the surface of NiTi alloy based on XRD analysis. As apparent, this substantiated the presence of the tool materials and their oxide layer phases. The interaction of polarity and gap voltage also indicated a significant effect towards the surface roughness.
  • Publication
    Effects of machining conditions on the specific cutting energy of carbon fibre reinforced polymer composites
    ( 2017-10-29) ;
    Syahmi A.
    ;
    Naquib M.
    ;
    ; ;
    Khalil A.
    This article presents an approach to evaluate the effects of different machining conditions on the specific cutting energy of carbon fibre reinforced polymer composites (CFRP). Although research works in the machinability of CFRP composites have been very substantial, the present literature rarely discussed the topic of energy consumption and the specific cutting energy. A series of turning experiments were carried out on two different CFRP composites in order to determine the power and specific energy constants and eventually evaluate their effects due to the changes in machining conditions. A good agreement between the power and material removal rate using a simple linear relationship. Further analyses revealed that a power law function is best to describe the effect of feed rate on the changes in the specific cutting energy. At lower feed rate, the specific cutting energy increases exponentially due to the nature of finishing operation, whereas at higher feed rate, the changes in specific cutting energy is minimal due to the nature of roughing operation.
  • Publication
    Experimental and analytical study of drilling hybrid glass/carbon fibre reinforced epoxy composite
    Hybrid composites have become increasingly attractive in research and development activities in recent times due to the capabilities to tailor their mechanical performance or characteristics to specific needs. Current research and innovation in the field of hybrid composites include processing, development and testing of metal matrix hybrid composites as well as the synthetic and natural fibre hybrid composites. Nonetheless, a number of complications arise in the manufacturing processes, particularly in machining such as drilling, of these multiphase laminated materials. The fact is that machining of composites or hybrid composites presents a great challenge due to anisotropic nature of the material, lack of plastic deformation and abrasiveness of the fibre reinforcements. According to the previous statistic studies, unqualified holes leads to approximately 60 % part rejections during the final assembly process. Therefore, this research study pursues an experimental and analytical approaches to extend the fundamental knowledge in drilling hybrid fibre reinforced polymer (FRP) composites. Prior to the drilling tests, the evaluations of the mechanical performance of hybrid FRP composite have been attempted. Specifically, the hybrid effect of the plain woven carbon and E-glass fibres hybrid composites within an epoxy polymer matrix was experimentally evaluated. It was evident that the physical properties and mechanical strength of monolithic fibres composite were enhanced 48 % by hybridising carbon fibres into the glass FRP composites. In addition, theoretical analysis through the rule of mixture reveals that the hybrid FRP composites have exhibited a positive hybrid effect in term of tensile and flexural behaviors. Even though fabrication technology for the hybrid FRP composites has well advanced in the production of near-net shape components, the secondary machining process is vital for completing the postmanufactured of these materials. Thus, the desired setting for minimising the delamination damage and surface roughness were determined using the Taguchi methodology and statistical analyses.
  • Publication
    Translaminar fracture toughness of discontinuous, aligned flax fibre composites
    ( 2020-01-01)
    Canturri C.
    ;
    Tran L.Q.N.
    ;
    ;
    Teo W.S.
    This paper describes the results of an investigation into Mode I translaminar critical strain energy release rate of continuous laminates and slit-cut laminates. The aims of the work were to define the fracture properties of flax-epoxy prepreg laminates for component design and to investigate the active fracture mechanisms. Compact tension tests were performed using cross ply unidirectional laminates, one with continuous 0° plies and one with slit cuts in the 0° plies. The behaviour of the material observed during the test revealed a lower initiation critical energy release rate for the discontinuous laminates. The R-curve was only established for the discontinuous laminates and showed a rising behaviour due to bridging of the interfaces. It was found that different fracture mechanisms acted in the two laminates, single fibre pull-out was observed in the continuous laminates and bundle pull-out was observed in the discontinuous laminates.