Showing papers in "Composites Science and Technology in 1992"

TL;DR: In this article, a model of fibrous composite laminate damage is modelled at the elementary-ply scale, where damage mechanics are used to describe the matrix microcracking and fiber/matrix debonding.

TL;DR: In this paper, a correction factor for the end-loaded-split (ELS) and end-notch-flexure (ENF) fracture toughness tests is described, which takes the form of correcting the crack length a, by a length χh, where h is the half thickness and χ is a constant that depends on the elastic parameters of the material.

TL;DR: In this article, two fabric composite models are presented for the on-axes elastic analysis of two-dimensional orthogonal plain weave fabric lamina, taking into account the actual strand cross-section geometry, possible gap between two adjacent strands and undulation and continuity of strands along both warp and fill directions.

TL;DR: In this article, a new approach for modelling the post-fatigue strength and stiffness of notched fiber composite laminates has been developed based on the observation of notch tip damage which can be quantified by the extent of individual failure processes, splitting in the 0° plies and delamination between the off-axis plies.

TL;DR: In this paper, carbon fiber surfaces were treated by cold plasmas of oxygen, nitrogen, argon, ammonia, and propylene, and the results showed that the results improved the compatibility and adhesion between the fiber and the polypropylene matrix.

TL;DR: In this article, thermoplastic and thermoset interleaves sandwiched between graphite/epoxy composite plies were investigated over a wide range of film thicknesses and the fracture process was initiated by the nucleation of microcracks ahead of the crack tip and continued with coalescence of micro-cracks that finally resulted in unstable fracture.

TL;DR: In this paper, a finite element computational procedure has been developed to find linear and nonlinear (von Karman) first-ply failure loads of composite laminates subjected to in-plane and transverse loads.

TL;DR: In this article, the fracture toughness of unidirectional continuous carbon fiber composites (CFRP) containing modified epoxy resin matrices has been studied in transverse impact fracture and Mode I delamination fracture tests.

TL;DR: In this article, micro-mechanical models based on a unidimensional load transfer approximation are used to predict the critical fiber length as a function of applied strain in the fragmentation testing of polymer matrix composites.

TL;DR: In this paper, a series of tests performed in eighteen laboratories with three specific aims: first, to establish the reproducibility of values from mode I and mode II tests carried out on two materials in different laboratories, secondly to investigate the differences between two data analyses; and finally to examine the influence of specimen thickness on mode I or mode II values.

TL;DR: In this article, a simplified improved beam model is proposed to analyze the cracked part of a double cantilever beam by means of shear-corrected classical beam theory and the uncracked part is analysed by considering Saint Venant effects and deformation of a beam on an elastic foundation.

TL;DR: In this article, a new material consisting of high-modulus polyethylene fibres in a polymethylene matrix (PE/PE) has been prepared and its properties evaluated.

TL;DR: In this article, an epoxy resin was reinforced by three-dimensional (3D) carbon fiber fabrices (orthogonal nonwoven type), and the effect of weave density and directional reinforcement on the mechanical fracture behavior of these 3-D composites was investigated.

TL;DR: In this paper, a detailed finite element stress analysis of both three-point and four-point short-beam bending specimens of a unidirectional glass-fibre/epoxy composite has been carried out.

TL;DR: In this paper, the stiffness tensor of the composite is calculated by globally averaging the approximate stresses in the representative fibers and matrix embedded in the composite, which admits the possibility of load transfer between the fiber ends and matrix.

TL;DR: In this article, a systematic study has been undertaken to examine the relationships between the matrix cracking initiation stress and the influencing factors in the microstructure for a class of fiber-reinforced ceramic matrix composites.

TL;DR: In this paper, a fatigue model was developed for damage growth at a notch tip in carbon fiber/epoxy laminates, which can explain the effect of cyclic tensile loading on the post-fatigue strength and stiffness of a notched laminate.

TL;DR: In this paper, a wide range of fiber/resin composites were tested and their failure mode versus loading-history relationships were examined, including graphite-, aramid-, and glass-fiber/expoxy composites prepared from different preform styles and stacking sequences.

TL;DR: In this paper, the effects of oxygen plasma treatment on polyethylene monofilaments were investigated with particular reference to their adhesion to epoxy resins, and the results of this investigation suggest that there are three contributions to the improvements in adhesion obtained from the plasma treatment.

TL;DR: In this paper, the authors used a double-lap shear model to determine the interlaminar shear strength of laminated composites under impact loading, where failure occurs on predetermined interfaces and the strain distribution along the failure plane is determined by using a finite element analysis.

TL;DR: In this paper, the deformation and fracture properties of glass-mat-reinforced thermoplastics ( GMT) have been studied as a function of fiber content and the results are discussed and related to the structural differences between the two materials.

TL;DR: In this article, the authors improved the analysis of the single filament pull-out test by adding a matrix compression contribution to the stored strain energy and by including the work of friction between the debonded fiber and matrix in the energy balance.

TL;DR: In this paper, a fracture mechanics approach was used to determine the fiber debond and frictional pull-out stresses in single fiber pullout experiments, and the difference in these stresses for three loading conditions (i.e., the fixed matrix bottom, fixed fibre and matrix bottom and the restrained matrix top conditions) has been identified in a newly developed analytical model that is based on fracture mechanics.

TL;DR: In this article, high modulus (M40) and high strength (T300) carbon fibers have been surface treated by argon and oxygen plasma to modify the fibre surfaces.

TL;DR: In this paper, the effect of various structures on such physical properties as tensile strength, flexural strength and short-beam shear strength of 3D fabric composites was investigated.

TL;DR: In this paper, the effect of strain rate on interlaminar shear properties of laminates is studied, and the results show that no influence of testing speed on interlinear properties was observed at low, intermediate and high strain rates.

TL;DR: In this paper, a pinned-end buckling rig that applied a combination of bending and compression was tested on a 26 ply unidirectional XAS/913 and it was suggested that the true ultimate compressive strain to failure of the material is in excess of 2·5%.

TL;DR: In this article, the results of an investigation into the multiaxial strength and stiffness properties of Toray T800/3900-2 fiber composites are presented, which is a high-strain-capability carbon fiber with a hightoughness epoxy-matrix system.

TL;DR: In this paper, a strength model of composites of the brittle fibre/metal matrix type is used to obtain statistical strength characteristics of fibres and to relate them to some details of the fabrication process.

TL;DR: In this paper, the tensile and flexural properties of the hybrid composites were predicted, from a theory formulated in this study, by using the strengths of the ABS/GB and ABS/GF composites alone.