Showing papers in "Composites Engineering in 1992"

TL;DR: In this paper, a variationally and asymptotically consistent theory is developed in order to derive the governing equations of anisotropic thin-walled beams with closed sections.

TL;DR: In this article, an asymptotically exact methodology based on geometrically nonlinear, three-dimensional elasticity is presented for analysis of prismatic, nonhomogeneous, anisotropic beams.

TL;DR: In this article, the use of genetic algorithms (GAs) for the design of composite laminates is presented, where the design variables are the lamina orientations and stacking sequence required for maximum laminate strength and/or stiffness with minimum weight.

TL;DR: In this article, a thin-walled anisotropic composite beam model is adopted to analyze the static aeroelastic response and divergence instability of swept-forward aircraft wing structures constructed of anisotropy composite materials.

TL;DR: In this article, the structural behavior of coupled, thin-walled, composite beams of open as well as closed section was analyzed using Vlasov theory and then the results were validated by experiment.

TL;DR: In this article, the authors report on the development and characterization of fiber-optic strain gauges that have been embedded within composite materials and used to measure the internal strain field or detect loadinduced acoustic emission from within composite specimens, and explore the feasibility of undertaking optoacoustic cure monitoring.

TL;DR: In this article, a rule is developed that is intended to provide a convenient method of classifying impact problems, based on the calculation of an equivalent structure mass that can be considered to be lumped at the impact site, and then uses the ratio of impact mass to equivalent lumped structure mass to establish the limits of applicability of the quasi-static solution procedure.

TL;DR: In this article, a mathematical model for the deformation of a curved and twisted anisotropic beam is presented, which can take into account any kind of elastic coupling due to the material properties and the curved geometry.

TL;DR: In this paper, the authors investigated the long-term creep and short-term failure of a plane portal frame structure constructed entirely of pultruded fiber-reinforced plastic (FRP) components.

TL;DR: In this article, the effect of intentional electrical heating of a selected subset of the NITINOL fibers on the overall dynamics of the composite was investigated, and the effects of the associated thermal energy propagating through the composite on the unintentional thermal activation of additional subsets of the fibers was accounted for.

TL;DR: In this article, the Rayleigh-Ritz method was used for free vibration analysis of generally laminated composite skew plates having arbitrary edge conditions, such as clamped, simply supported or free.

TL;DR: In this article, the authors used the finite difference method to solve the differential equation for the critical loading associated with a specific lateral-torsional buckling test configuration for thin-walled composite doubly symmetric I-beams made from midplane symmetric, fiber-reinforced laminated panels.

TL;DR: In this paper, the thermally-induced geometrically nonlinear response of symmetrically laminated composite plates was investigated using variational methods in conjunction with a Rayleigh-Ritz formulation.

TL;DR: In this paper, the effect of a penny-shaped crack in the fiber in the single-fiber fragmentation test is shown to be one of the parameters governing the interfacial failure mode, and it is shown that loading conditions, meniscus formation, and fiber free length have a large effect on the distribution of interfacial stresses in the case of the microbond.

TL;DR: In this article, a variational mechanics analysis of stresses in embedded single fibers has been applied to the analysis of the stresses in a microdrop debond specimen, which is more accurate than the commonly applied shear-lag or elastic-plastic analyses.

TL;DR: A review of the application of embedded optical fibres as damage detection sensors based on fracture of the sensor is presented in this paper, where critical matrix cracking occurring under tension and shear is shown to be fundamental to the mechanics of embedded damage sensors.

TL;DR: In this article, a simple formulation of the stiffness matrix for an anisotropic, 3-node, thin triangular flat shell element in global coordinates is presented, where an Allman triangle (AT) is used for membrane stiffness.

TL;DR: In this paper, the use of imbedded active piezoelectric materials to change the aeroelastic stiffness of a lifting surface to allow this surface to control the aircraft is discussed.

TL;DR: In this paper, a one-dimensional finite element formulation based on a higher-order displacement model has been developed, which accounts for geometric nonlinearities, a parabolic shear strain distribution through the thickness, and satisfies the shear stress free boundary conditions at the upper and lower surfaces of the beam.

TL;DR: In this article, a finite element analysis was conducted to determine the interlaminar stress states near the ply drop closest to the root of the taper, and four different internal ply drop configuration were examined which achieved the same transition in thickness.

TL;DR: In this paper, the impact response of thin imperfect laminated plates subjected to impact loads is studied using a 48 DOF finite element based on the classical laminated plate theory and the modified Hertzian law is incorporated to evaluate the impact loads due to a projectile.

TL;DR: In this paper, a two-phase elastic fiber composite consisting of boron fibers in an epoxy matrix with various fractions of the two phases is studied by means of the homogenization method.

TL;DR: In this paper, a new concept of the three-dimensional stress concentration factor for notches in plates is suggested. But this concept is based on the concept of average stresses, which has been widely accepted in analytical mechanics and was adapted in general engineering design and testing, including various procedures of experimental stress analysis.

TL;DR: In this article, the influence of free-edge effects on stiffness measurements comprises a finite-element model which is based on a so-called quasi-three-dimensional finite element, a simple theory that follows from the boundary-layer nature of the free edge problem and predicts the width influence on measured stiffness values, and the comparison with experimental data.

TL;DR: In this article, limit loads under plane stress and plane strain are found for a circumferentially reinforced elastoplastic ring subjected to interior pressure, which are used as bounds on an estimate of the failure pressure of a SiC/Ti test rig that is being fabricated and tested.

TL;DR: In this paper, the effects of SiC whisker and SiC platelets on the mechanical properties of Al 2 O 3 composites have been investigated using the four-point bend test.

TL;DR: In this paper, the authors presented a comprehensive report on results obtained during the past year on large deflections of beams, although their recent efforts have also covered plates and shallow shells, and derived simple dynamical models for beams of various types, by considering the effects of transverse shear and buckling as well as large deflection.

TL;DR: In this article, a three-dimensional glass epoxy angle-ply laminate of the type [±55°] containing matrix cracks and two types of matrix-crack-induced interlaminar local delaminations has been numerically analyzed by the finite element method.

TL;DR: In this paper, secondary loads associated with typical composite structure design and corresponding laminate failure modes are discussed and the significance of these failure modes and critical environmental conditions corresponding to each failure mode are emphasized as a key to predicting an initial failure for composite structures.

TL;DR: In this article, a proof-of-concept investigation is presented on a class of macroscopically smart composite laminated structural materials and also monolithic materials containing voids filled with electro-rheological (ER) fluids.