Ply Orientation Angles Research Articles

Vibration attenuation and dynamic control of piezolaminated plates with coupled electromechanical actuation

Vibration attenuation and dynamic control of the piezolaminated plate actuated with coupled electromechanical loading are aimed and achieved in the present work. Efficient finite element methodology with higher-order shear deformation theory is assisted to blend the effects of shear strains in the computational model. An isoperimetric eight-noded rectangular element is implemented through linear electric potential distribution along the thickness to set up the relations. Coupled electromechanical loading is considered in the formulation to consider the piezoelectric sensing and actuation mechanism. Piezolaminated plates with both cross-ply and angle-ply orientation of bonded substrate lamina are considered in the analysis. Vibration responses of multilayered composite plates with surface-mounted piezolaminates are evaluated for open-circuit and closed-circuit boundary conditions of the electric field. Results obtained from the analysis are well revealed for frequencies of various modes of simply supported piezolaminated plates. Dynamic vibrational response and effect of the control gain (Gv) in terms of velocity feedback on the dynamic characteristics of a piezoelectric laminated plate are examined. Another aim of proposing this FE model is to demonstrate the effect of placement of fibers in a different orientation for the PVDF layer to achieve active damping, and attenuation of vibrations of the laminated composite plate is also achieved and demonstrated.

Effect of ply orientation angle on residual stress in carbon fibre laminates

The mechanical performance of a composite structure is influenced by residual stresses induced during curing and post-processing. Therefore, residual stress evaluation is important especially as layers increase in laminated composites. The general aim of this study is to present a fundamental relation between residual stresses (due to manufacturing process) and the relative angle between plies (±θ) in a two-layered, carbon-fibre reinforced epoxy-resin laminate. The residual stresses along the loading direction were determined using the X-Ray Diffraction technique at different locations in a specimen. The maximum numeric value obtained was compared with the residual stress obtained from the Abaqus software using Universal Tensile Test data for failure.

Characterization of mechanical properties of stab-resistant angle-ply flexible composites

In this study, we fabricated para-aramid flexible angle-ply-laminated hybrid composites based on weft-knitted reinforcements. Here, four kinds of weft-knitted reinforcements with rib, interlock, punto di roma, and two-thread fleecy were prepared using para-aramid spun yarn. They were then compounded with silicone rubber and waterborne polyurethane–acrylate using the coating method. The layers were angle-plied to produce stab-resistant, weft-knitting-reinforced, flexible laminated hybrid composites. Tensile and tearing strengths of the para-aramid-knitted reinforcements were investigated. Relevant response analyses were chosen to evaluate the influence of three independent variables, including weft-knitted structures, matrix types, and ply orientations. The results showed that the mechanical properties of the composites were dependent on weft-knitted structures and matrix types. The fabric with high strength and the degree in approximate isotropy of stress in all composites was most suited for the reinforcement of the flexible stab-resistant composite. The optimum design with the best stab-resistant property was punto di roma/waterborne polyurethane–acrylate with a ply orientation angle of [0°/0°/0°/0°]. The interlaminar adhesion of flexible stab-resistant composite based on waterborne polyurethane–acrylate can be improved by increasing the surface roughness of fabric structure or modifying its surface.

Stochastic low-velocity impact analysis of sandwich plates including the effects of obliqueness and twist

Abstract This paper quantifies the influence of uncertainty in the low-velocity impact responses of sandwich plates with composite face sheets considering the effects of obliqueness in impact angle and twist in the plate geometry. The stochastic impact analysis is conducted by using finite element (FE) modelling based on an eight nodded isoparametric quadratic plate bending element coupled with multivariate adaptive regression spline (MARS) in order to achieve computational efficiency. The modified Hertzian contact law is employed to model contact force and other impact parameters. Newmark's time integration scheme is used to solve the time-dependent equations. Comprehensive deterministic as well as probabilistic results are presented by considering the effects of location of impact, ply orientation angle, impactor velocity, impact angle, face-sheet material property, twist angle, plate thickness and mass of impactor. The relative importance of various input parameters is determined by conducting a sensitivity analysis. The results presented in this paper reveal that the impact responses of sandwich plates are significantly affected by the effect of source-uncertainty that in turn establishes the importance of adopting an inclusive stochastic design approach for impact modelling in sandwich plates.

Warping deformation analysis of angle-ply fiber metal laminates with slippage during manufacturing

Abstract Thermal residual stress generated during the manufacturing process may induce the warping deformation of fiber metal laminates (FMLs). An analytical model considering slippage effect due to thermal residual stress is developed to study the warping deformation for angle-ply FMLs, which is also validated by the measurement of warping deformation for angle-ply [Al/-45/45/Al] FML. The warping deformations for angle-ply FMLs are greatly associated with the geometry parameters. The effect of laminate length, metal layer thickness, aspect ratio and ply orientation angle on the warping deformation of angle-ply FMLs are investigated. The analytical results show that the ply orientation angle of FMLs does not influence the bifurcation point but change the final stable shapes. By calculating the contribution of the thermal strain energy and slippage strain energy to the total potential energy, it is shown that the slippage effect cannot be neglected in the prediction of the warping deformation for angle-ply FMLs.

Effect of matrix material and orientation angle on tensile and tribological behavior of jute reinforced composites

Abstract Environmental friendly natural fibers have been used instead of petroleum-based synthetic fibers as reinforcements because of the depletion of oil resources, plastic waste disposal problems and the emissions generated during combustion. In these natural fibers, thermoplastic or thermoset materials are used as matrix material because of their low cost, light weight and durability. In this study, the effects of ply number (2 and 3 layer) and orientation angle of reinforcement (0/90° and ± 45°) and matrix type (thermoset and thermoplastic) on the tensile strength of jute reinforced composites were investigated. Also, the effect of the reinforcement orientation angle, sliding time (600, 1200 and 1800 s) and applied load (5, 10 and 15 N) on tribological characteristics were determined. Adhesive and abrasion wear tests were carried out at 0.15 m × s−1 sliding speed. It was observed that the matrix material and the reinforcement are very important in tensile and wear tests, while the ply number and the orientation angle only exert an influence in the tensile strength of composites. It was determined that an increase in load and sliding time is the most effective parameter on wear experiments.

Analytical solutions for the natural frequencies of rectangular symmetric angle-ply laminated plates

Analytical solutions, based on the Ritz method, are derived for the lowest natural frequency of rectangular symmetric angle-ply laminated plates. Since symmetric angle-ply plates have nonzero cross-elasticity constants, the solutions are approximate. The accuracy of these solutions is tested with a convergence study using the Rayleigh quotient iteration method. With the solutions available in symbolic form, parameter studies are presented that establish the effect of plate aspect ratio and ply orientation angle for a number of stacking geometries. The results are also verified through a comparison with numerical Ritz solutions, showing a maximum error of 5% in our approximate solution.

Influence of ply angle and length on buckling behavior of composite shells under hydrostatic pressure

This paper is devoted to the buckling problem of the composite cylindrical shell subjected to hydrostatic pressure. Both analytical and numerical methods are applied to investigate the buckling behavior. Based on the study of analytical formulas, it is found that the composite cylindrical shells with the same length-to-diameter ratio, diameter-to-thickness ratio, and type of layup have the same buckling pressure. Thus, a scale model experiment method is then proposed, which uses the scale model to replace the full-scale model in pressure test experiment to reduce the manufacturing cost of the test specimen. The feasibility of this method is verified by numerical calculation. The influences of ply orientation angle and length of shell on buckling shape and critical buckling pressure have been investigated numerically and demonstrated by several examples. Based on the study of the influence of shell length on critical buckling pressure, a modified finite element model, which can overcome the conservatism of optimization result due to the stress concentration caused by boundary conditions, is combined with the genetic algorithm to optimize the laminations for mass reduction.

Free Vibration of Angle-ply Laminated Conical Shell Frusta with Linear and Exponential Thickness Variations

Free vibration of laminated conical shell frusta of variable thickness is studied using spline approximation. This problem includes first order shear deformation and considers shells as antisymmetric angle-ply orientation. The governing differential equations of the shells are resolved in terms of displacement functions and rotational functions. These functions are approximated using splines and the method of collocation is adopted for simultaneous algebraic equations. These equations become generalized eigenvalue problems and are solved numerically to avail eigenfrequencies and the corresponding eigenvectors. The variation of frequencies is analysed with respect to the cone angle, aspect ratio, material properties, number of layers, and thickness variation.

Damping of carbon fibre and flax fibre angle-ply composite laminates

The damping behaviour of continuous carbon fibre and flax fibre reinforced polymer (CFRP and FFRP) composites was studied by comparing angle-ply laminates. Using logarithmic decrement measurements, dynamic mechanical analysis and vibration beam measurements, the damping was described as the specific damping capacity ψ in order to compare data using the different methods.Our results show approximately 2–3 times better damping of FFRP compared to CFRP at low frequency and low strain. We show that the damping of both materials increases with increasing angle-ply orientation below 300Hz. While the matrix and interface seems to contribute mainly to damping at lower frequencies, the fibre shows an increasing contribution with ψ = 64.4% for unidirectional FFRP at 1259Hz in the 5th mode of vibration, without a notable change in the elastic modulus. This work demonstrates that the FFRP may be simultaneously stiff and efficient at damping.

On Bending-Twisting coupled laminates

The definitive list of stacking sequences is presented for Bending-Twisting coupled (ASB0DF) laminates, with up to 21 plies. This class of laminate arises from the ubiquitous balanced and symmetric design rule, but symmetry is shown to be a sufficient rather than a necessary constraint. Each stacking sequence configuration is derived in symbolic form together with dimensionless parameters from which the extensional and bending stiffness terms are readily calculated for any fibre/matrix system and angle-ply orientation. Expressions for ply orientation dependent lamination parameters are also given, together with graphical representations, which demonstrate the extent of the design space. Pseudo Quasi-Homogeneous (ASB0DF) laminates are introduced as an important laminate sub-set, since such laminates have concomitant orthotropic properties, i.e. matching orthotropic or isotropic stiffnesses in extension and bending, from which the isolated effects of Bending-Twisting coupling can be studied. These coupling effects are quantified for compression buckling of Angle-ply and Quasi-Isotropic laminated plates with simply supported and clamped edges.

Analytical solution for buckling of embedded laminated plates based on higher order shear deformation plate theory

In this research, buckling analysis of an embedded laminated composite plate is investigated. The elastic medium is simulated with spring constant of Winkler medium and shear layer. With considering higher order shear deformation theory (Reddy), the total potential energy of structure is calculated. Using Principle of Virtual Work, the constitutive equations are obtained. The analytical solution is performed in order to obtain the buckling loads. A detailed parametric study is conducted to elucidate the influences of the layer numbers, orientation angle of layers, geometrical parameters, elastic medium and type of load on the buckling load of the system. Results depict that the highest buckling load is related to the structure with angle-ply orientation type and with increasing the angle up to 45 degrees, the buckling load increases.

Bottom up surrogate based approach for stochastic frequency response analysis of laminated composite plates

This paper presents an efficient uncertainty quantification (UQ) scheme for frequency responses of laminated composite plates. A bottom up surrogate based approach is employed to quantify the variability in free vibration responses of composite cantilever plates due to uncertainty in ply orientation angle, elastic modulus and mass density. The finite element method is employed incorporating effects of transverse shear deformation based on Mindlin’s theory in conjunction with a random variable approach. Parametric studies are carried out to determine the stochastic frequency response functions (SFRF) along with stochastic natural frequencies and modeshapes. In this study, a surrogate based approach using General High Dimensional Model Representations (GHDMR) is employed for achieving computational efficiency in quantifying uncertainty. Subsequently the effect of noise is investigated in GHDMR based UQ algorithm. This paper also presents an uncertainty quantification scheme using commercial finite element software (ANSYS) and thereby comparative results of stochastic natural frequencies are furnished for UQ using GHDMR approach and ANSYS.

Thermo-mechanical Interlaminar Stress and Dynamic Stability Analysis of Composite Spherical Shells

Three-dimensional Finite Element Method (FEM) based thermo-mechanical stress analysis of a laminated Fibre Reinforced Polymer (FRP) composite made spherical shell structure subjected to an elevated thermal filed has been carried out. FE simulation has been carried out through ANSYS 14.0, using Brick 8-node solid 185 layered elements. Shell structures due to curvature effect show thermo-mechanical stress concentration effects not only at the edges but also at various other critical locations in its domain. Appropriate FE mesh size has been adopted to capture these stress concentration effects and has been established through validation with analytical results. Out-of-plane thermo-mechanical interlaminar stresses (σrr, τθr, τɸr) has been assumed to be responsible for damage initiation and hence have been analysed in details in order to reveal the critical ply-interface. In order to study dynamic stability of the shell structure under thermal environment, different lamination schemes have been adopted ([0/θ]4, θ 00, 150, 300, 450, 600,750, and 900). It has been observed that, plies oriented parallel to the cantilevered edge of the shell structure are providing minimum deformation under an elevated thermal environment. However, the laminated shell shows a geometrically non-linear behaviour as the ply-orientation angle has been varied.

Analysis of Stress Concentration in Orthotropic Laminates

The current paper presents a comprehensive finite element analysis on stress concentration in orthotropic laminates. This research investigates the Stress Concentration Factor (SCF) in isotropic and orthotropic plates due to presence of a central cutout with respect to ply orientation angle (θ). The numerical simulations are carried out by using an 8 node shell element in ANSYS APDL environment. It is established from the simulations that the SCF is dependent upon the orientation the fibers. For orthotropic laminates, SCF depends on material properties. It increases with increase in Ey/Ex ratio and decreases with increase in μxy.

Efficient methodologies for reliability-based design optimization of composite panels

The main factors governing the design of composite laminates are the geometrical dimensions, the stacking sequence –including ply thickness and orientation angles–, the mechanical properties of the materials, the applied loads and the performance requirements. Most of these factors are commonly affected by uncertainty and this should be taken into account when designing these structures. Thus, uncertainty quantification should be used to evaluate the performance requirements and a reliability-based procedure is advisable when the design is optimized. However, these methods present several drawbacks, like the lack of trustworthy information about the uncertainty present in the variables of the model or the high computational cost required to apply the algorithms to medium to large models. This paper evaluates several methodologies for design optimization of composite panels under uncertainty. The uncertainty quantification is performed using stochastic expansion and limit state approximation methods. Monte Carlo sampling is also used to verify reliability results. The optimization process is carried out using gradient-based and genetic algorithms, with either continuous or discrete design variables. Surrogate methods, including polynomial, kriging, multivariate adaptive regression splines, and artificial neural networks, as well as parallel computing, have been leveraged to keep analysis times under acceptable levels. An application example of a stiffened composite panel of an aircraft fuselage is presented to demonstrate the computational performance and the accuracy of the methods. Results show major improvement in analysis time without compromising on precision.

Fuzzy uncertainty propagation in composites using Gram–Schmidt polynomial chaos expansion

The propagation of uncertainty in composite structures possesses significant computational challenges. Moreover, probabilistic descriptions of uncertain model parameters are not always available due to lack of data. This paper investigates on the uncertainty propagation in dynamic characteristics (such as natural frequencies, frequency response function and mode shapes) of laminated composite plates by using fuzzy approach. In the proposed methodology, non-intrusive Gram–Schmidt polynomial chaos expansion (GPCE) method is adopted in uncertainty propagation of structural uncertainty to dynamic analysis of composite structures, when the parameter uncertainties represented by fuzzy membership functions. A domain in the space of input data at zero-level of membership functions is mapped to a zone of output data with the parameters determined by D-optimal design. The obtained meta-model (GPCE) can also be used for higher α-levels of fuzzy membership function. The most significant input parameters such as ply orientation angle, elastic modulus, mass density and shear modulus are identified and then fuzzified. The proposed fuzzy approach is applied to the problem of fuzzy modal analysis for frequency response function of a simplified composite cantilever plates. The fuzzy mode shapes are also depicted for a typical laminate configuration. Fuzzy analysis of the first three natural frequencies is presented to illustrate the results and its performance. The proposed approach is found more efficient compared to the conventional global optimization approach in terms of computational time and cost.

Vibration analysis of a tapered laminated thick composite plate with ply drop-offs

In this study, vibration characteristics of a tapered laminated thick composite plate have been investigated using finite element method by including the shear deformation and rotary inertia effects. The governing differential equations of motion of a tapered laminated thick composite plate are presented in the finite element formulation based on first-order shear deformation theory for three types of taper configurations. The effectiveness of the developed finite element formulation in identifying the various dynamic properties of a tapered laminated thick composite plate is demonstrated by comparing natural frequencies evaluated using the present FEM with those obtained from the experimental measurements and presented in the available literature. Various parametric studies are also performed to investigate the effect of taper configurations, aspect ratio, taper angle, angle ply orientation and boundary conditions on free and forced vibration responses of the structures. The comparison of the transverse free vibration mode shapes of the uniform and tapered composite plates under various boundary conditions is also presented. The forced vibration response of a composite plate is investigated to study the dynamic response of tapered composite plate under the harmonic force excitation in various tapered configurations. It is concluded that the dynamic properties of laminated thick composite plates could be tailored by dropping off the plies to yield various tapered composite plate.

Influence of Angle Ply Orientation on the Flexural Strength of Basalt and Carbon Fiber Reinforced Hybrid Composites

In this paper the influence of fiber orientation of basalt and carbon inter-ply fabrics on the flexural properties of hybrid composite laminates was experimentally investigated. Four types of basalt/carbon/epoxy inter-ply hybrid composite laminates with varying angle ply orientation of reinforced basalt fiber and fixed orientation of carbon fiber were fabricated using hand lay-up technique. Three point bending test was performed according to ASTM 7264. The fracture surface analysis was carried out by scanning electron microscope (SEM). The results obtained from the four laminates were compared. Lay-up pattern of (0B/+30B/-30B/0C)S exhibits the best properties in terms of flexural strength and flexural modulus. Scanning electron microscopy results on the fracture surface showed that the interfacial de-bonding between the fibers and epoxy resin is a dominant fracture mode for all fiber lay-up schemes.

Base Line Study for Determination of Effect of Stacking Sequence on Vibration Characteristics of Composite Propeller Blade

An investigation of a conventional propeller made from composite materials was conducted in which its vibration characteristics were studied. Optimized designing of a composite propeller was performed for various constrained and unconstrained design objectives. Only symmetric ply stacking sequences were considered. Results show that the ply stacking sequence has an effect on the characteristics of a conventional propeller. Proper stacking sequence of the composite propeller improves its performance as compared to its metallic counterpart. The finite element method is used to calculate the resulting natural frequency and mode shapes of the propeller blades. In the present study the shapes of the propeller blade is modelled as cantilever discretized into various number of hexahedral and pentahedral finite elements. Propeller vibration characteristics are calculated by ply orientation angles, for achieving the desired objectives Ansys and Radiosis solvers are used. From the results it can be made clear that by proper selection of optimum number of layers from 8 to 16 and tailoring the ply orientation angles operational frequencies of composite materials can be further enhanced and can be made much stiffer than metallic one.