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Applied Composite Materials: An International Journal for the Science and Application of Composite Materials (v.6, #6)
The Experimental Study of the Strain-Rate Dependence of a Unidirectional Reinforced Gr/Al Metal Matrix Composite by Yuanxin Zhou; Yuanmin Xia (pp. 341-352).
Loading and loading-unloading tests of a unidirectional reinforced Gr/Al metal matrix composite have been carried out using a self-designed tensile impact apparatus, and quasi-static tensile tests have been performed on the Shimadzu-5000 testing apparatus. The stress/strain curves of composites have been obtained in strain rate range from 0. 0005 s− 1 to 1300 s−1. The experimental results show that complete stress/strain curves of the material can be divided into two parts: the nonlinear elastic brittle deformation and residual deformation. The tests results also clearly indicate that the Gr/Al composite is a rate-sensitive material; namely the strength, failure strain and residual strength of composite all depend on strain rate. Statistical analysis and models were used to obtain the mechanical parameters for composites and their relationship with strain rate from experimental results. The simulated stress/strain curves from the model are in good agreement with the test data. The theoretical model and test results show that the shape parameter β and the scale parameter σ0 are both independent of strain rate. The constituent, Gr fibers in Gr/Al composites, can be regarded as a rate-insensitive material, and the strain rate effect of Gr/Al composites is mainly caused by the Al alloy matrix.
Keywords: Gr/Al tensile impact; strain rate
The Influence of Fibre Volume Fraction on the Mode I Interlaminar Fracture Toughness of a Glass-Fibre/Vinyl Ester Composite by P. Compston; P.-Y. B. Jar (pp. 353-368).
This paper investigates the influence of fibre volume fraction on the mode I interlaminar fracture toughness G Ic of a glass-fibre/vinyl ester composite. Two fibre volume fraction parameters are defined; a global value for the composite specimen and a value for the fibre-dense intralaminar regions. The range of global fibre volume fraction studied was 32–52 %. Results show that G Ic values for crack initiation are independent of fibre volume fraction and similar to matrix resin G Ic . Variations in the G Ic for steady-state crack propagation, and the amount of fibre bridging, are not completely explained by changes in global fibre volume fraction. Instead they are consistent with fibre volume fraction in the fibre-dense intralaminar regions, through which the crack preferred to grow. It is concluded that this latter parameter is more relevant for G Ic characterisation as a function of fibre volume fraction.
Keywords: mode I; interlaminar fracture toughness; fibre volume fraction; intralaminar; fibre bridging
Finite Element Calculation of a Press Fit Joint between a Composite Materials Tube and an Aluminium Cylinder by C. Millán; M. A. Jiménez; A. Miravete (pp. 369-380).
This paper presents the design and calculation of a press fit joint between a fibre reinforced plastic tube and an aluminium cylinder. This joint is used for connecting the several tube portions that form a crane structure.The calculation has been carried out by means of finite element analysis. The corresponding finite element model has been experimentally validated by testing of tube sections under compression. The behaviour of the tube section in these tests is highly dependent on the elastic and strength material properties of the tube in the hoop direction, as it occurs in the press fit joint between the aluminium part and the composite tube.Once that the finite element model is validated, the calculations allow the determination of the maximum diameter of the cylindrical part to be used in the joint in order to prevent failure of the composite tube.
Finite-Element Analysis of Laminated Stiffened Cylindrical Shallow Shell by Ezgi Günay (pp. 381-395).
A finite-element solution for a geometrically nonlinear fiber composite shallow shell with Stringer-type stiffeners is presented. A laminated, anisotropic thin/thick shallow stiffened shell finite element is developed and applied for the solution of several static problems. Geometrically, a nonlinear finite-element model is based on the nonlocking shear deformable theory. Stiffened composite cylinders are subjected to mechanical loading and the shallow shell theory is used for the geometric representation and formulation of the axially stiffened cylinders. A new, two-sided meshing system is generated to represent a cylindrical shell with stiffeners in a three-dimensional coordinate system.
Keywords: Shallow shell; stiffened laminated cylinder; geometrically nonlinear; finite element analysis; nonlocking phenomenon