Cross-ply Panels Research Articles

Low velocity impact response of Automated Fiber Placement Advanced Placed Ply composites

This study explores the influence of the internal architecture in the low-velocity impact response of Automated Fiber Placement Advanced Placed Ply laminates. AP-PLY laminates with different lay-up are subjected to low velocity impact and compression after impact experiments. Different performance in terms of damage tolerance is obtained as a function of their internal architecture. Triaxial and quasi-isotropic AP-PLY configurations presented a reduced extension of the delamination in comparison to cross-ply panels. As a result, the cross-ply configuration exhibited a drastic loss in residual strength of 49.1% when subjected to 50 J of impact energy. Numerical simulations were employed to provide insight into the deformation and failure mechanisms (e.g., matrix cracking of directly impacted yarns, delamination or tow debonding), and assess the performance of AP-PLY against conventional angle-ply laminates, predicting larger delamination for the latter, showing the potential of the AP-PLY architecture to produce laminates with improved low-velocity impact performance.

Effects of Surface-Parallel Edge Restraints and Inter-laminar Shear on the Responses of Doubly Curved General Cross-Ply Panels

This study presents first a relatively lesser studied topic of the role played by surface-parallel restraints in determining the response of simply supported thick to thin doubly curved cross-ply panels of rectangular plan-form, modeled using a third order shear deformation theory, quantified by way of the difference between full and absent surface-parallel edge restraints. Mathematically speaking, this corresponds to the difference between complementary solutions to mixed boundary-value problems, resulting from two extreme sets of surface-parallel restraints.

Cylindrical Panel Like Response of Fully Surface Parallel Restrained Simply Supported Hyperbolic Paraboloidal Thick General Cross-ply Panels

An analytical (exact in the limit) solution to the boundary-value problem of deformation of a finite-dimensional general cross-ply thick hyperbolic-paraboloidal panel, modeled using a third order shear deformation theory, is presented. Of special interest is the issue of cylindrical panel-like response, in the presence of full surface-parallel constraints at all four edges of a thick antisymmetric cross-ply panel of negative Gaussian curvature.

Flattening Effect of Negative Gaussian Curvature on Simply Supported Thick Asymmetric Cross-Ply Panels in the Absence of Surface-Parallel Edge Restraints

AbstractThis paper investigated the flattening effect of negative Gaussian curvature on simply supported (SS) thick asymmetrically laminated cross-ply panels in the absence of surface-parallel edge...

Study of aeroelastic REsponse of cylindrical composite panels in A high-speed flow

This study aims to investigate the aeroelastic behaviors of cylindrical composite panels in a high-speed flow. A fluid-structure coupling program is applied to simulate the response of the interaction with the presence of both fluid and structural nonlinearities at [Formula: see text]. The cylindrical composite panels with different layer orientations, cross-ply and angle-ply are modeled by an assemblage of triangular finite elements and the nonlinearity caused by large displacement is described by an updated tangent stiffness matrix. The inviscid unsteady equations are discretized by an AUSMpw+ flux splitting scheme. The static divergence, flutter characteristic and post-flutter response are computed and analyzed with the increase of the dynamic pressure. The results show that static and dynamic responses vary with the layer orientation. Particularly, the dynamic response of the cross-ply panel presents as high-frequency resonant oscillation; on the contrary, the dynamic response of the angle-ply panel appears as low-frequency single mode oscillation. Nonlinearities involved with aeroelastic response, such as the movement of the multiple-shock structure, and large displacement in structure, are discussed.

Banana fiber/low-density polyethylene recycled composites for third world eco-friendly construction applications – Waste for life project Sri Lanka

In the framework of the waste for life Sri Lanka project, low value industrial low-density polyethylene waste plastics and banana fibers made from agricultural waste are upcycled into affordable eco-friendly building products. This creates income for the local communities while mitigating waste disposal and reducing ecological problems. Within this context, a robust manufacturing method using compression molding was developed. Panels with varying fiber content were manufactured using unchopped and chopped fibers. Low-density polyethylene characterization using Fourier transform infrared spectroscopy and differential scanning calorimetry to compare plastic sources was conducted. To reduce cost, no fiber treatments or compatibilizers were used. An estimate of critical fiber length was found to be around 1.45 cm to 2.5 cm. A trend of increasing strength with fiber content (up to 40 wt.%) was achieved by using longer fibers than in the previous research. Handling and dispersion of the fibers were increased by chopping the fibers to 20 cm lengths, which led to an increase in tensile strength due to easier manufacturing. Cross-ply panels made with fibers chopped to a length of 20 cm were found to be strongest peaking at around 40 wt.% with a tensile strength of 32.8 MPa, a fourfold increase compared to a raw low-density polyethylene (0 wt.%) panel.

Free vibration analysis of laminated cylindrical panels using discrete singular convolution

Based on three-dimensional theory of elasticity, semi-analytical solutions for free vibration of cross-ply laminated cylindrical panels are derived applying the state space approach (SSA) and discrete singular convolution (DSC) algorithm. One pair of opposite edges are assumed to be with simply supported and the other pair of edges arbitrary boundary conditions. The thickness direction of panels is chosen as the transfer direction in SSA, and the DSC is employed to discretize the axial direction of panel. Hence, the original partial differential equations are transformed into a state equation consisting of first-order ordinary differential equations. The application of DSC can deal with various boundary conditions, which cannot be solved in the conventional SSA. Accuracy and convergence for laminated cross-ply panels are validated through numerical examples.

Ballistic impact response of Ultra-High-Molecular-Weight Polyethylene (UHMWPE)

In this paper we report findings from ballistic experiments conducted on Ultra-High-Molecular-Weight Polyethylene (UHMWPE) flat panels. We measured ballistic limit velocities, V50 of panels of different thicknesses using a fragment simulating projectile (FSP) and characterized back face deformation (BFD) using a spherical projectile. UHMWPE panels with different architectures (hybrid and non-hybrid) were evaluated. For the back face deformation (BFD) experiments, the thickness of post-impact intact material and interior delamination were characterized using X-ray Computer Tomography method. These measurements were used to evaluate the effects of fiber orientation and boundary constraints on material deformation and failure response to ballistic loading conditions. The expansion rate of the back face deformation zone in the transverse direction (to the direction of impact) decreased with time. This transverse expansion speed was higher in hybrid panels compared to the [0/90] cross-ply panels, which resulted in earlier influence of boundary constraints on back face deformation for hybrid panels. One major delamination occurred in the hybrid panels at cross-ply [0/90] and non-cross ply interface. The lateral extent of this delamination was larger when the panel edges were clamped as compared to the free panel edge case.

Effect of Bimodularity on Dynamic Response of Cross-ply Conical Panels

The effect of bimodularity ratio on free vibration characteristics of cross-ply conical panels of various geometry and lamination scheme is studied. Forced vibration response is also studied for a typical case. The formulation is based on first order shear deformation theory and Bert’s constitutive model. An iterative eigenvalue approach is employed to obtain the positive and negative half cycle free vibration frequencies. Galerkin’s approach in time domain is used to obtain the frequency response. It is interesting to note that there is a significant difference between positive and negative half cycle frequencies depending on panel parameters. Also, there is a significant difference in positive and negative half cycle forced response amplitudes due to bimodularity. Bimodularity, the different behavior of material in tension and compression, affects the static and dynamic response of structures. Few studies on static analysis of bimodulus laminated cross-ply composite shells and dynamic analysis of cross-ply panels have been presented [1-4]. To the best of the authors’ knowledge, the work on the analysis of bimodular laminated cross-ply conical shell panels is not dealt in the literature. The effect of bimodularity ratio on free and forced vibration characteristics of cross-ply conical panel is important for design of such structures under dynamic loading condition. Here, the dynamic analysis of cross-ply laminated conical panels of bimodulus material is carried out using finite element method and Bert’s constitutive model. The effect of semi-cone angle, number of layers and bimodularity ratio (E 2t /E 2c ) on free vibration frequencies and frequency response is investigated. 2. FORMULATION The geometry and dimensions of a conical panel is shown in Fig. 1 with total thickness h, small end radius r 1 , large end radius r 2 , meridional length L, circumferential length b at small end, sector angle y, and semi-cone angle a. Displacements u, v, w at a point (s, q, z) are expressed as functions of middle surface displacements u 0 , v 0 , w 0 and independent rotation b s , b q of the meridional and hoop sections, respectively, as: u (s, q, z, t) = u 0 (s, q, t) + z b s (s, q, t) v (s, q, z, t) = v 0 (s, q, t) + z b q (s, q, t) (1) w (s, q, z, t) = w 0 (s, q, t)

Active damping of laminated thin cylindrical composite panels using vertically/obliquely reinforced 1–3 piezoelectric composites

This paper deals with the analysis of active constrained layer damping (ACLD) of laminated thin composite panels using vertically and obliquely reinforced 1–3 piezoelectric composite materials as the material of the constraining layer of the ACLD treatment. A finite element model has been developed for analyzing the ACLD of laminated antisymmetric cross-ply and antisymmetric angle-ply thin composite panels integrated with the patches of such ACLD treatment. Both in-plane and out-of-plane actuations of the constraining layer of the ACLD treatment have been utilized for deriving the finite element model. The analysis revealed that the vertical actuation dominates over the in-plane actuation. Particular emphasis has been placed on investigating the performance of the patches when the orientation angle of the piezoelectric fibers of the constraining layer is varied in the two mutually orthogonal vertical planes. The analysis revealed that the vertically reinforced 1–3 piezoelectric composites which are in general being used for the distributed sensors can be potentially used for the distributed actuators of high performance light-weight smart thin composite panels.

Sensitivity of the response of thick cross-ply doubly curved panels to edge clamping

A heretofore unavailable analytical solution to the problem of deformation of a finite-dimensional general cross-ply thick doubly-curved panel of rectangular plan-form, modeled using a higher order shear deformation theory (HSDT), is presented. A solution methodology, based on a boundary-discontinuous generalized double Fourier series approach, is used to solve a system of five highly coupled linear partial differential equations, generated by the HSDT-based laminated shell analysis, with the C3-type clamped boundary condition prescribed at all four edges. The numerical accuracy of the solution is ascertained by studying the convergence characteristics of deflections and moments of a cross-ply spherical panel. The primary focus of the present study is to investigate the effect of edge clamping on the response of a thick laminated doubly-curved panel, while keeping the surface-parallel edge constraints unaltered. Important numerical results presented include sensitivity of the predicted response quantities of interest to lamination, material property, thickness and curvature effects, and edge clamping as well as their interactions.

Three-dimensional elasticity solution for laminated cross-ply panel under localized moment

Three-dimensional elasticity solutions have been presented for thick laminated crossply circular cylindrical panel. The panel is under localized patch moment in axial direction and is simply supported at all edges with finite length. Ordinary differential equations with variable coefficients are obtained by means of Fourier series expansion for displacement field and loading in the circumferential and axial directions. Resulting ordinary differential equations are solved using Taylor series. Numerical results are presented for (0/90°) and (0/90/0°) lay-up, and compared with the results for simple form of loading published in literatures.

Nonlinear Response of Axially Compressed Laminated Cylindrical Shell Panels

A kinematics-based geometrically nonlinear thin-shell approach is presented. Reddy-Levinson-Murthy displacements have cubic distributions through the shell thickness for the in-plane shell displacements and result in parabolic transverse shear strain. Strains are assumed to be small and of the order of θ 2 , where θ 2 is a small quantity compared with unity. The nonlinearity allows moderate rotations by retaining terms of the order of θ 3 and larger in the strain-displacement relations. Each of the shell strains is nonlinear in displacement. A second, simpler, intermediate nonlinearity of the von Karman type results by retaining all terms of the order of θ 2 and larger. The von Karman type approach has displacement nonlinearity in the in-plane strains, yet is linear in displacement for the transverse shear strains. For solution of the shell equations, the finite element method using a 36-degree-of-freedom curved shell element is developed. The nonlinear response of axially compressed laminated cylindrical shell panels is examined and compared with existing experimental results. The influence of the nonlinear transverse strain-displacement terms of the moderate rotation approach is illustrated in a numerical simulation of an axially compressed unsymmetrically laminated cross-ply panel.

Nonlinear Static Response and Free Vibration Analysis of Doubly Curved Cross-Ply Panels

In this paper, the nonlinear static and free vibration analyses of doubly curved cross-ply laminated panels subjected to thermomechanical loading are examined. The shell theory adopted in the present case is an extension of Reissner’s shallow shell simplifications that accounts for parabolic distribution of the transverse shear strains through thickness of the shell and tangential stress-free boundary conditions. A multiterm Galerkin’s method is adopted to solve the governing nonlinear partial differential equations. The static equilibrium paths are traced using the Newton-Raphson method in conjunction with the Riks approach to overcome the limit points. The free vibration frequencies about a static equilibrium state of a deformed panel are reported by solving the linear eigenvalue problem. Analytical results are presented for symmetric [0/90/0] and antisymmetric [0/90] cross-ply laminated doubly curved panels that illustrate the influence of geometric properties, in-plane edge boundary conditions, latera...

Elasticity solution for the free vibration analysis of laminated cylindrical panels using the differential quadrature method

Based on the three-dimensional theory of elasticity, a new approach combining the state space method and the differential quadrature method (DQM) is presented in this paper for the free vibration analysis of the cross-ply laminated cylindrical panels. The panel has one pair of opposite edges with simply supported and the other pair of opposite edges arbitrary boundary conditions. Applying the differential quadrature method to the state space formulations along the axial or circumferential directions of panel, new state equations about state variables at discrete points are obtained. Eigenfrequency equation is obtained by using edges boundary condition in this state equation. Natural frequencies of the panel are obtained by solving the frequency equation. Numerical results for laminated cross-ply panel with arbitrary edges condition are performed. Results are verified by comparing for the simply supported edges with the available published results.

Fourier analysis of thick cross-ply Levy type clamped doubly-curved panels

A hitherto unavailable Levy type analytical solution to the problem of deformation of a finite-dimensional general cross-ply thick doubly-curved panel of rectangular plan-form, modeled using a higher order shear deformation theory (HSDT), is presented. A solution methodology, based on a boundary-discontinuous generalized double Fourier series approach is used to solve a system of five highly coupled linear partial differential equations, generated by the HSDT-based laminated shell analysis, with the C4-type simply supported boundary condition prescribed on two opposite edges, while the remaining two edges are subjected to the SS3-type constraint. The numerical accuracy of the solution is ascertained by studying the convergence characteristics of the deflection and moment of a cross-ply spherical panel, and also by comparison with the available FSDT (first-order shear deformation theory) based analytical solution. Additionally, numerical results pertaining to flat symmetric and antisymmetric cross-ply plates with the same boundary conditions have also been reproduced. Hitherto unavailable important numerical results presented include sensitivity of the predicted response quantities of interest to shell geometry (cylindrical and spherical), lamination, lamina material property, and thickness effects, as well as their interactions. Comparison with their SS2 counterparts demonstrates the effect of end clamping on the deflections and moments of thin to thick singly- and doubly-curved cross-ply panels.

Effect of boundary constraint on the frequency response of moderately thick doubly curved cross-ply panels using mixed fourier solution functions

A hitherto unavailable analytical solution to the boundary value problem of free vibration response of shear–flexible cross-ply laminated doubly curved panels is presented. The laminated shell theory formulation is based on the first-order shear deformation theory (FSDT) including rotatory and surface-parallel inertias. The governing equations of the panel are defined by five highly coupled partial differential equations in five unknowns — three displacements, and two rotations. The assumed solution functions for the eigen/boundary-value problem are selected in terms of mixed-type double Fourier series. Extensive numerical results that are presented in this study include (1) convergence characteristics of computed natural frequencies, and (2) effects of length-to-thickness ratio, radius-to-length ratio, lamination sequence, boundary constraint and shell geometry on the normalized natural frequencies of interest. Also numerically investigated is the highly complex interaction among bending–stretching type coupling effect, membrane action due to shell curvature, surface-parallel end constraints (or lack thereof), and the effects of transverse shear deformation, rotatory inertias and surface-parallel inertias.

Experimental and theoretical investigations on stiffened and unstiffened composite panels under uniform transverse loading

An experimental investigation on fibre-reinforced stiffened and unstiffened panels under transverse uniform pressure has been carried out. The deflections and strains measured inside the laminate are compared with a finite element analysis. The effect of one or two stiffeners within the panel is small since the stiffener fail at small loads. In contrary to this, the effect of a different lay-up is big, because the angle-ply panels [+45°/−45°] 2 carried higher loads than the cross-ply panels [0°/90°] 2. The failure of the panels near the centre of the long edge at the clamping is correctly predicted by the FEA. In addition, calculated and predicted stresses are close to each other.

Exact two-dimensional piezoelasticity solution for buckling of hybrid beams and cross-ply panels using transfer matrices

Two-dimensional exact piezoelasticity solution is presented for buckling of simply supported symmetrically laminated hybrid beam and cross-ply panel with elastic substrate and piezoelectric layers. Buckling is considered under axial strain and actuation potentials for movable inplane end conditions and under actuation potential alone for immovable inplane end conditions. The governing equations for buckling mode are formulated in terms of six variables: displacements u, w, potential φ, stresses σ z , τ zx and electric displacement D z . These entities are expanded in Fourier series that satisfy the end conditions. The governing equations reduce to differential equations in z with coefficients dependent on the axial load and actuation potentials. The solution has six constants for each layer. The transfer matrix is derived relating the six primary variables at the top and bottom of a layer. The six conditions σ z = τ zx =0, φ=0 at the top and bottom of the beam are used to set up three homogeneous equations for u, w, D z at the bottom. The determinant of their coefficient matrix is set to zero to obtain the buckling axial strain/potential. The present benchmark solution would help assess one-dimensional theories for buckling of hybrid beams.

Creep deflection of viscoelastic laminated cylindrical panels with initial deflection under axial compression

Abstract The viscoelastic behaviors of symmetric cross-ply and antisymmetric angle-ply cylindrical panels under axial compression are examined. The laminates considered are simply supported and have various amplitudes of initial imperfection. The analysis is based on the geometrically nonlinear viscoelastic approach. The stress function is obtained by solving the compatibility equation using the Laplace transform and a numerical integration scheme. Deflections are calculated by employing the generalized Galerkin method in conjunction with the numerical integration. The characteristics of creep deflection behaviors are illustrated, and a numerical procedure for tracing the post-snapping paths is provided. Effects of initial imperfection and the magnitude of loading on the creep buckling are studied. Numerical results for deflection histories and critical time for glass reinforced epoxy and glass reinforced vinyl ester laminates are presented. Solutions based on the quasi-elastic approach are also presented for comparison.