Open-mode delamination stress concentrations in horseshoe and elliptic composite curved bars subjected to end forces

The multilayer theory of anisotropic elasticity and a finite element method were used to analyze the open-mode delamination stress concentrations in horseshoe and elliptic laminated composite curved bars. Two types of laminations, solid laminations and sandwich laminations, were analyzed. It was found that the open-mode delamination stress concentration could be greatly increased in these two types of curved bars by decreasing their aspect ratios. The open-mode delamination stress concentration generated in the solid laminations was found to be far more severe than that generated in the sandwich laminations. The horseshoe curved bar may be used to determine both the open-mode delamination strength of solidly laminated composites and the open-mode debonding strength of sandwiched laminated composites. However, the elliptic curved bar is only good for determining the open-mode delamination strength of solidly laminated composites

Fiber Orientation and its Influence on the Flexural Strength of Glass Fiber and Graphite Fiber reinforced Polymer Composite

This paper investigates the effect of fibre orientation on the flexural strength of fibre reinforced -epoxy laminated composite material, with the variation in the orientation of the reinforced fibres there will be a substantial variation in the flexural strength of the laminated composites. In the present paper fabrication of glass fibre reinforced laminated composites and graphite fibre reinforced laminated composites with varying orientation of reinforced fibres were prepared using the hand layup, vacuum baggage technique and these specimens are subjected to 3 point static bending testing the investigations are carried out as per the ASTM standards. Using the load -deflection graph the maximum load, maximum deflection and the flexural strength of the specimen for different laminated composites is evaluated and the appropriate conclusions are drawn

Preparation of graphene film reinforced CoCrFeNiMn high-entropy alloy matrix composites with strength-plasticity synergy via flake powder metallurgy method

Inspired by the design principle of pearl structure, a bottom-up flake powder self-assembly arrangement strategy, flake powder metallurgy, is used to prepare graphene films (GFs) reinforced CoCrFeNiMn high-entropy alloy (HEA) matrix composites with a pearl laminated structure. Flaky HEA powder was prepared by ball milling method and homogeneously mixed with Ni plated GFs. Vacuum hot-press sintering (VHPS) technique was carried out to solidify the mixed powders to obtain composites with uniform distribution of GFs(Ni) and flaky HEA. The results show that the bottom-up preparation strategy can effectively fabricate bionic laminated HEA matrix composites, and the composites have a distinct pearly laminated structure. The tensile strength of the composites with 5 vol% GFs(Ni) content reached 834.04 MPa, and the elongation reached 26.58 %. The compressive strength in parallel and perpendicular laminar directions reached 2069.66 MPa and 2418.45 MPa at 50 % strain, respectively. The laminated GFs(Ni)/HEA matrix composites possessed excellent strength and maintained good plasticity. In this study, the strengthening and toughening mechanism of the laminated GFs(Ni)/HEA matrix composites is discussed in detail, and the results show that the laminated structure and GFs(Ni) are favorable for the hardening and strengthening of the HEA matrix

Multiscale Hierarchical Structure and Laminated Strengthening and Toughening Mechanisms

Metal matrix composites with multiscale hierarchical structure and laminated structure have been developed to provide a novel route to achieve high strength, toughness and ductility. In this chapter, a lot of scientific research has been carried out in the preparation, processing, properties and application of metal matrix composite. Many toughening mechanisms and fracture behavior of composites with multiscale hierarchical structure and laminated structure are overviewed. It is revealed that elastic property and yield strength of laminated composites follow the “rule of average.” However, the estimation of fracture elongation and fracture toughness is complex, which is inconsistent with the “rule of average.” The fracture elongation of laminated composites is related to the layer thickness size, interface, gradient structure, strain hardening exponent, strain rate parameter and tunnel crack, which are accompanied with crack deflection, crack blunting, crack bridging, stress redistribution, local stress deformation, interfacial delamination crack and so on. The concept of laminated composites can be extended by applying different combination of individual layer, and provides theoretical as well as experimental fundamentals on strengthening and toughening of metal matrix composites

Wood polymer composite bonded veneer based hybrid composites

Wood veneer based composites have a great demand in present market as the material can  utilize small diameter plantation timbers grown at short rotation cycle. This paper presents preparation and characterization of hybrid composites made of wood veneer and wood polymer composite. The study explored utilization of wood polymer composite as an adhesive for bonding veneers replacing formaldehyde-based adhesives. Wood polymer composite containing 40 % bamboo particles embedded in the matrix of polypropylene was used in sheet form to bind the veneers of Melia dubia wood. The composites were prepared in both laminated veneer lumber and plywood configurations. The assessment of physical and mechanical properties indicated that the properties of wood polymer composite contribute significantly to the properties of the hybrid composites. The density of the resultant composites was significantly higher (0,69 g/cm3 – 0,75 g/cm3) than conventional plywood or laminated veneer lumber. Among mechanical properties, there was no statistical difference in tensile and flexural strength of plywood and laminated veneer lumber configuration. Modulus of elasticity and compressive strength of laminated veneer lumber configuration were significantly higher than plywood. Glue shear strength and internal bond strength of the composites indicated acceptable bonding properties of wood polymer composite which suggests the potential application of these composites as a binding agent for wood veneers. These composites could be a special class of laminated composites with no formaldehyde emission hazards

Comparison of motor stator teeth built of soft magnetic composite and laminated silicon steel sheets in an axial flux permanent magnet synchronous machine

This paper compares the iron losses generated by the concentrated excitation windings for the axial flux permanent magnet synchronous machine stator core elements constructed with laminated silicon steel sheets and soft magnetic composites. The two types of eddy current losses for laminated silicon steel sheets are taken into account. A 3D nonlinear finite element method in the time domain is used to calculate all flux density distributions for various frequencies and different magnitudes. Experimental measurements are also performed to validate the 3D model

Contact law and impact responses of laminated composites

Static identation tests were performed to determine the law of contact between a steel ball and glass/epoxy and graphite/epoxy laminated composites. For both composites the power law with an index of 1.5 was found to be adequate for the loading curve. Substantial permanent deformations were noted after the unloading. A high order beam finite element was used to compute the dynamic contact force and response of the laminated composite subjected to the impact of an elastic sphere. This program can be used with either the classical Hertzian contact law or the measured contact law. A simple method is introduced for estimating the contact force and contact duration in elastic impacts

Selection of natural fibre for hybrid laminated composites vehicle spall liners using analytical hierarchy process (AHP)

Natural fibres with variable properties are found in many engineering applications because of its low cost and biodegradability .The selection of suitable fibres involves the evaluation of a number of alternatives based on certain criteria. The purpose of this study is to suggest the use of analytical hierarchy process (AHP) in the selection of natural fibres for hybrid laminated composites. It was found that the most suitable natural fibre to be used with Kevlar 29 in hybrid laminated composites is kenaf fibre. It is expected that this finding will significantly contribute to the development of hybrid laminated composites for vehicle ballistic protection

Application of Binary Firefly Algorithm (BFA) in tuning PID parameters for couple tank system

This paper presents the application of the Binary Firefly Algorithm (BFA) in tuning PID parameters for a coupled tank system. The agent position in the BFA represents the potential combination the PID parameters. This agent position is modelled using a string of 32 binary bits where each eight bits represents the value o