Showing papers in "Composites Engineering in 1991"

TL;DR: In this article, an efficient algorithm is outlined for solving boundary-value problems involving laminated composite materials and structures that require satisfaction of both continuity of tractions and displacements along common interfaces.

TL;DR: In this article, the elements of a theory for elastic composites with a changing microstructure, such as microcracking, are reviewed and a formulation, which uses internal state variables and potentials like strain energy and work, is illustrated by mathematically characterizing and predicting the damage and deformation behavior of particle-filled rubber under axial straining and confining pressure.

TL;DR: In this article, the authors present an overview of the problem of matrix cracking in laminated composite materials, and the parameters governing the onset and accumulation of internal damage under several types of loadings are reviewed.

TL;DR: In this paper, three micromechanical models for estimating complex viscoelastic moduli in aligned short fiber reinforced three-phase polymer composites have been developed, and the effects of the fiber aspect ratio, and damping and stiffness properties of fiber, matrix and interphase are analyzed and discussed.

TL;DR: In this article, an elasticity solution for the fiber pull-out-type problem is developed using sets of orthogonal functions and compared with two approximate methods, and the most interesting features of the solution are the nature of the stress field in the neighborhood of the interface at the free surface of the cylinder.

TL;DR: In this article, a leaky Lamb wave (LLW) technique was used to estimate the phase velocity and amplitude of a composite laminate in a broad range of frequencies and velocities.

TL;DR: In this article, an analytical model based on the internal state variable (ISV) concept and the strain energy method is proposed for characterizing the monotonic and cyclic response of laminated composites containing matrix cracks.

TL;DR: In this article, local elastic fields in the unit cell of a periodic composite are examined numerically with an integral equation approach, using techniques of Fourier series and Green's functions to construct the integral equations.

TL;DR: In this paper, the conditions for subsequent interfacial debonding and fiber fracture associated with elastic bridging fibers are discussed, and probable bridging mechanisms are deduced by the consideration of the calculated bridging stresses and comparison of the evaluated fracture toughness increment with the measured R -curve behavior.

TL;DR: In this article, an interlaminar-shear-stress analysis was developed for deformation and progressive damage in biaxially-loaded bidirectional three-layer composite laminates.

TL;DR: In this article, a higher-order theory was developed for a laminated cylindrical configuration, under the actions of lateral pressure, axial compression and torsion, which includes initial geometric imperfections and transverse shear effects.

TL;DR: In this paper, a nonlinear finite element for layered fiber-reinforced composite shells is presented which has been developed by the author, implemented into a commercial finite element code (ABAQUS), and tested extensively.

TL;DR: In this paper, impact damage tolerance is evaluated for three different graphite-epoxy composite material systems which were fabricated as 92-ply composite plates and tested in an instrumented dropweight impact tower or in a high-velocity impact device (gas gun).

TL;DR: In this article, first-order orthotropic shear deformation equations for the nonlinear elastic bending response of rectangular plates are introduced and their solution using a computer program based on a noninterlacing finite-difference implementation of the Dynamic Relaxation (DR) method is outlined.

TL;DR: In this paper, the effects of embedding hard particles in a soft matrix upon the opening, growth and stress intensity factor (SIF) of cracks in a particulate composite are studied from a combination of surface measurements and a "first-cut" three-dimensional finite element model, the latter for assessing the projection of the observed surface effects in the thickness direction.

TL;DR: In this article, an analytical method to handle thermal buckling of laminated composite circular cylindrical shells is presented, where an eighth-order governing differential system for predicting this response is formulated from an energy approach.

TL;DR: In this article, a cantilever beam of a [0m90n]s cross-ply laminate with a cracked 90° layer was analyzed and the relationship obtained between the shear modulus and transverse crack density was in complete agreement with predictions from a pure shear analysis.

TL;DR: In this paper, the authors analyzed the mechanism of crack arrest in a composite with long fibers by using the inclusion method and found that the bridging action reduced the energy release rate for the crack extension.

TL;DR: In this paper, a set of linear reference carrier fringe patterns is used to detect debonds embedded in a glass-fibre-reinforced plastic (GRP) plate.

TL;DR: In this paper, an experimental and analytical study was conducted on the force-indentation relations of composite materials with a rigid, conical-tip indenter, and the analytical analysis was developed based on two models: transversely isotropic elastic, and perfectly plastic.

TL;DR: In this article, a simple analytical formulation is used to predict the interlaminar stresses in a symmetric laminate under extension, bending, torsion and their combined effect, based on a shear deformation theory and a sublaminate approach.

TL;DR: In this article, the mechanical performance of Spectra 900 and Spectra 1000 fibers subjected to either glow-discharge or chemical etch treatments was evaluated with respect to untreated control fibers.

TL;DR: In this paper, the effect of the σ-alumina fibers on physical and mechanical properties in the temperature range 293-573 K was studied and the highest hardness was exhibited by composite materials containing 30 vol. % of reinforcement.

TL;DR: In this paper, the impact response of a series of IM6 6376 carbon fiber composite beams was examined using a fully-instrumented drop-weight impact rig, where a piezo-electric load cell and a newly-developed laser-light displacement transducer were used to determine the load-deflection histories of a number of centrally-loaded multi-directional composite beams.

TL;DR: In this article, the effects of fiber orientation on the dynamic deflection of shallow composite shells under lateral pressure pulse were investigated, and it was found that the optimal fiber orientation depends not only on the shell curvature but also on the frequency of the applied load.

TL;DR: In this paper, a failure criterion based on the strain energy density function is proposed for the purpose of predicting the strength of laminated fiber-reinforced composites, and application of the theory to the case of uniaxially-loaded off-axis laminates is investigated.

TL;DR: In this paper, the authors summarized the current state-of-the-art in the modeling of brittle deformation of solids containing a large number of microcracks and suggested that an appropriate phenomenological model can be derived from micromechanical considerations.

TL;DR: In this paper, the bending and buckling of cylindrically-orthotropic circular and annular plates are considered and the solutions are obtained in a closed form for arbitrary boundary conditions.

TL;DR: In this article, closed-form constitutive relations for the homogenized behavior of unidirectional composites damaged by slipping at interfaces between constituents are given, where the interface degradation is modelled by one or two parameters according to its behavior: elastic, viscous or viscoelastic.

TL;DR: In this article, Vlasov's semi-membrane isotropic shells theory is extended to composite cylindrical shells and the resulting theory can be used to obtain closed-form solutions for the statics and dynamics of composite cylinders.