Journal of Reinforced Plastics and Composites

This study includes experimental and numerical investigations on fibre-metal laminate structures containing adhesive joints under static bending loads. Experimental tests were carried out on Glare® 4B specimens manufactured in-house and containing doubler joint features. Numerical analyses were performed using Abaqus software including damage in the glass fibre reinforced polymer layers, ductile damage in the resin pockets (FM94 epoxy) and plasticity in the metal layers. A new cohesive zone model coupling friction and interfacial shear under through-thickness compressive stress has been developed to simulate delamination initiation and growth at the metal/fibre interfaces with the adhesive joint under flexural loading. This model is implemented through a user-defined VUMAT subroutine in the Abaqus/Explicit software and includes two main approaches, firstly, combining friction and interfacial shear stresses created in the interlaminar layers of the fibre-metal laminate as a result of through-thickness stresses and secondly, considering elastic-plastic damage behaviour using a new cohesive zone model based on the trapezoidal law (which provides more accurate results for the simulation of toughened epoxy matrices than the commonly used bilinear cohesive zone model). Numerical results have been validated against experimental data from 4-point bending tests and a good correlation observed with respect to both crack initiation and evolution. Delamination and shear failure were noted to be the predominant failure modes under bending stresses as expected. This is due to the higher mode-II stresses introduced during bending which cause different damage evolution behaviour to that seen for axial stresses. Finite element results revealed that both friction and shear strength parameters generated from through-thickness compression stresses have a significant effect in predicting damage in fibre-metal laminate structures under this type of loading.

Although surface grinding is reported to be capable of precision material removal in carbon fibre reinforced epoxy polymer composites (CFRPs), it is highly limited by deprived cutting temperature dissipation, tool wear and sensitivity to undesired cutting defects. Continuous engagement of abrasive grains and successive accumulation of heat at cutting interface in conventional surface grinding results in severe surface damages. Though the controlled application of cutting fluids exhibited improved surface integrity, entrapment of fluid droplets into the defective zones/cracks of fibre, matrix and its interfaces are shown to be stimulating further defect propagation. Present paper investigates the feasibility of improving cutting fluid application in CFRP grinding, establishing a minimum surface defect condition through eccentric sleeve grinding (ESG). The reduction of post-grinding surface defects through an intermittent-progressive cutting scheme in ESG is demonstrated and the efficacy of cutting fluids in such a grinding scheme is illustrated through the comparison of grinding forces and surface characteristics.

Market demands for lightweight and lower cost products drive manufacturers to improve current product portfolios. In the case of electronic devices, the most significant weight originates from the enclosure, traditionally in steel or aluminum, that ensures excellent mechanical and electromagnetic shielding performance. The use of thermoplastics filled with electrically conductive fibers, such as carbon or stainless steel, was investigated as a lightweight and cost-effective alternative to steel sheet for creating electromagnetic interference (EMI) shielding enclosures for electronic devices. This paper presents an EMI shielding analysis workflow for the development of plastic enclosures for an electronic device. The workflow starts by measuring the fiber-reinforced thermoplastic compounds shielding effectiveness (SE) with an experimental method in the 30 MHz–3 GHz frequency band. This analysis helps to filter a vast list of materials with a wide range of shielding performance, 20–100 dB, and allows to obtain empirical data for the second phase of the workflow, computer simulations. Simulations with experimentally adjusted material properties were used to validate the design concept of an enclosure in its early development phase. Results from this study showed that the selected material has better EMI SE performance than a steel sheet venting grid.

In the mineral processing, mining, oil and gas industries, it is not uncommon to find mechanical components exposed to degradation and wear from slurries. Polymeric matrix composites (PMCs) are considered as potential alternatives to replace metallic materials in such severe environments because of their high strength to weight ratio, ease of production, high wear resistance and good corrosion/chemical resistance. Often, seemingly erratic wear behaviour is observed making preventive maintenance and time-to-failure difficult to manage. A major culprit is the complex physical and chemical interaction with the slurry, such as exposure to high temperatures, high alkalinity, high slurry density, insoluble inorganic contents, high hardness of suspended particles and humidity. It is well understood that the addition of reinforcing fibres greatly improves the stiffness and strength of polymeric matrix composites. However, the effect the reinforcement has on the wear performance is far less established and a framework to analyse the effect of fibre volume fraction is yet to be established. The difficulties in establishing such a framework lay in the multi-factorial contributions and the potential trade-offs with mechanical performance. This makes it much more difficult to isolate clear trends. The objective of the present work is to present a comprehensive review on the influence reinforcing fibres play on wear behaviour of PMCs. The influence of fibre volume fraction on wear performance of polymeric composites reinforced with man-made fibres is presented. The applied load, fibre length, coefficient of friction and chemical treatment of fibres are analysed with respect to wear performance of PMCs. Future trends in the use of fibre-reinforced polymeric composites in wear critical applications are identified. Research gaps in designing composites for wear applications are explained, aiming at motivating future research to address these gaps.