Angle-ply Layups Research Articles

Bone healing under different lay-up configuration of carbon fiber-reinforced PEEK composite plates.

Secondary healing of fractured bones requires an application of an appropriate fixator. In general, steel or titanium devices are used mostly. However, in recent years, composite structures arise as an attractive alternative due to high strength to weight ratio and other advantages like, for example, radiolucency. According to Food and Drug Administration (FDA), the only unidirectionally reinforced composite allowed to be implanted in human bodies is carbon fiber (CF)-reinforced poly-ether-ether-ketone (PEEK). In this work, the healing process of long bone assembled with CF/PEEK plates with cross- and angle-ply lay-up configurations is studied in the framework of finite element method. The healing is simulated by making use of the mechanoregulation model basing on the Prendergast theory. Cells transformation is determined by the octahedral shear strain and interstitial fluid velocity. The process runs iteratively assuming single load cycle each day. The fracture is subjected to axial and transverse forces. In the computations, the Abaqus program is used. It is shown that the angle-ply lamination scheme of CF/PEEK composite seems to provide better conditions for the transformation of the soft callus into the bone tissue.

Effect of stitching on the static and fatigue properties of fibre-dominated and matrix-dominated composite laminates

The paper reports the results of an experimental investigation into the effect of stitching on the static and fatigue response of fibre-dominated and matrix-dominated laminates. The tests were conducted on Kevlar stitched carbon/epoxy laminates with quasi-isotropic ([0/±45/90]s) or angle-ply ([+302/−302]s, [+452/−452]s, [+602/−602]s) layups. The analyses show that stitching significantly reduces both the static and the fatigue strength of fibre-dominated [0/±45/90]s laminates, owing to the presence of localized fibre damage introduced during the stitching process. On the other hand, stitching does not affect the fatigue response of [+602/−602]s laminates but significantly improves the fatigue strength of [+302/–302]s and [+452/−452]s laminates. The effectiveness of stitching on the fatigue performance of the angle-ply layups was found to be directly related to the specific damage mechanisms preceding the ultimate failure, which are controlled by edge delaminations in [+302/–302]s and [+452/−452]s and transverse matrix cracking in [+602/−602]s laminates.

Investigation of bamboo-based vertical axis wind turbine blade under static loading

Bamboo fiber composites are recyclable, low cost, high strength, and biodegradable compared to synthetic composites. Fiber-reinforced polymer composites such as glass and carbon fibers are extensively used as wind turbine blades followed by a major challenge of recycling and waste disposal etc. The present work investigates the suitability of bamboo-epoxy composite for vertical-axis wind turbine blades. The NACA 0015 and NACA 4415 blade profile has been chosen for study. The static structural analysis of blades is performed using various cross-ply and angle-ply layups. Results demonstrated that layup [45°/90°/0°/-45°]S obtained the minimum values of stress and deflection. The effect of shear webs is also analyzed. It is observed that the blade with two shear webs showed the minimum values of stress and deflection. The unidirectional strength of the composite material is also compared with the maximum design stress and found under acceptable limits. Additionally, the stress and deflection of the bamboo composite blades are compared with conventional blade materials. The stress and deflection on the non-symmetric bamboo-epoxy composite blade with double shear webs are obtained as 15.84 MPa and 4.45 mm which is observed to be decreased by 70.98% (stress) and 1.11% (deflection) respectively in comparison with glass-epoxy blade. Through the structural analysis, it is recommended that the designed blade with natural bamboo composite is acceptable for structural safety.

Experimental investigation on Compression-After-Impact (CAI) response of aerospace grade thermoset composites under low-temperature conditions assisted with acoustic emission monitoring

Low-velocity impact (LVI) can provoke catastrophic failure depending on the impact energy, lay-up configuration, and the operating temperature in fiber-reinforced composite structures via damage accumulation during the service. Additionally, extreme operating temperature is an important factor affecting the damage initiation and growth mechanism and understanding the compression-after-impact (CAI) response is a promising way to predict the damage-growth dynamics. For this purpose, this study investigates the LVI response and CAI strength of composite laminates under the −55 °C temperature considering the low-temperature (LT) service conditions of aerospace applications. The experiments are performed on cross-ply ([0/90°]4s) and angle-ply ([±45°]4s) lay-up composites for impact energy levels of 1.4 J and 10 J. After LVI tests, the occurred damages are examined by infrared thermography (IRT). Furthermore, the effect of the impact damage on the failure mechanism under compression loading is elaborated using acoustic emission (AE) inspection. The CAI test results reveal that the LT increases the compressive residual strength. However, this change is directly related to the load and lay-up configuration. The alternation in the damage growth mechanism of angle-ply laminates under LT operating temperature is more significant compared to the cross-ply laminates.

Effect of nanoscale interface modification on residual stress evolution during composite processing

The interface characteristics of the matrix and fibers significantly influence the evolution of residual stress in composite materials. In this study, we provide a methodology for reducing the residual stress in laminated composites by modifying the thermomechanical properties at the fiber–matrix interface. A hydrothermal chemical growth method was used to grow Zinc Oxide nanowires on the carbon fibers. We then utilized a novel digital image correlation approach to evaluate strains and residual stresses, in situ, throughout the autoclave curing of composites. We find that interface modification results in the reduction of residual stress and an increase in laminate strength and stiffness. Upon growing ZnO NWs on the carbon fibers, the maximum in situ in-plane strain components were reduced by approximately 55% and 31%, respectively, while the corresponding maximum residual stresses were decreased by 50.8% and 49.33% for the cross-play laminate [0°/90°] layup in the x and y directions, respectively. For the [45°/-45°] angle ply layup in the x-direction, the strain was decreased by 27.3%, and the maximum residual stress was reduced by 41.5%, whereas in the y-direction, the strain was decreased by 166.3%, and the maximum residual stress was reduced by 17.8%. Furthermore, mechanical testing revealed that the tensile strength for the [45°/-45°] and [0°/90°] laminates increased by 130% and 20%, respectively, with the interface modification.

A Simplified Analytical Solution for the Computation of Machine Path in Filament Winding of Cylindrical Angle-Ply and Double-Double Structures

This paper presents a simplified computation approach for the machine path (or winding trajectory) of grid structures and tubes with a circular cross-section and angle-ply or double-double layup. The solution for the machine path is given through controllable degrees of freedom of a low-cost two-axis filament winding machine (FWM): mandrel rotation and translation of the delivery eye along the axis of the mandrel. The efficiency of the analytical solution for the machine path of the FWM was ascertained by automated laying the cotton thread over the geodesic and non-geodesic groove imprinted on the surface of a cylindrical polylactide mandrel. These results validated the possibility of manufacturing cylindrical composite structures with an angle-ply layup or double-double stacking sequence, without the need for expensive software, making the winding technology accessible to society and promoting university extension.

Static and Vibration Analyses of a Composite CFRP Robot Manipulator

This paper reports analyses of a 5-degrees-of-freedom (5-DOF) carbon fiber-reinforced polymer (CFRP) robot manipulator, which has been developed for farm applications. The manipulator was made of aluminum alloy (AA) and steel materials. However, to check the effectiveness of CFRP materials on the static and free-vibration performance of the manipulator, the AA parts were replaced with CFRP. For this purpose, the effects of various cross-sections and layups on three design criteria—deflection, load-carrying capacity, and natural frequency—were investigated. Two types of thin-walled laminated sections, specifically the I section and rectangular tubular sections, were used for the composite parts. These parts were made from three hollow square section (“SSS” section) beams and three I section (“III” section) beams. These multi-cell beams were modeled using the finite element (FE) method. Three configurations were selected for analysis based on the manipulator’s most common operating conditions. The results indicated that the use of CFRP increased the manipulator’s natural frequencies, increased the load-carrying capacity, and decreased the manipulator’s tip deflection when compared with its AA counterpart. An analysis showed that using CFRP in the manipulator’s structure could improve static and vibrational performances. It was observed that the “SSS” section beams were 1.17 times stiffer, could carry a 1.20 times higher load, and were 1.40 times heavier than the “III” section beams. Also, decreasing the fiber direction in angle-ply layups from 90° to 0° and adding 0° plies, while keeping the total number of layers constant, decreased the manipulator’s tip deflection and increased its natural frequencies.

Effect of compression and tension types of concentrated edge loads on buckling and vibration behavior of interlaminar hybrid fibre metal laminates

The present study deals with the numerical investigation on the buckling and vibration behaviour of interlayer hybrid fibre metal laminates (HFMLs) subjected to different types of concentrated edge compression and tension loads. The term interlayer hybrid represents carbon and glass fibre laminates are sandwiched in between aluminum face sheets. Totally six different hybrid configurations are taken into consideration separately for cross-ply and angle-ply layup schemes. To serve this purpose a finite element code using MATLAB is developed to examine the effects of hybrid configuration, aspect ratio, fiber orientation, type of loading and boundary conditions have been considered to study the buckling responses of HFMLs. The plate is modelled by using 9-noded heterosis elements by considering the effect of shear deformation and rotary inertia. It is revealed from the investigation that the hybrid configurations and loading conditions significantly affect the buckling and vibration characteristics of HFMLs.

Deriving unidirectional lamina properties from testing on cylindrical laminated specimens

The present work aims to derive the mechanical properties of a unidirectional (UD) lamina from experimentally measured properties of non-flat (cylindrical) laminated specimens. The specimens were cut from carbon fiber-epoxy tubes having cross-ply and angle-ply layup configurations. Special tests were designed and applied on these specimens to measure the mechanical properties of the laminate, Ex, Ey, νxy, Gxy, as well as tensile and shear failure strength. By using the classical laminate theory (CLT), the mechanical properties of UD lamina, E1, E2, ν12 and G12 were expressed explicitly as functions of the measured properties of the cross-ply laminate and in form of effective mechanical properties of general lamination configuration like the angle-ply layup. A new shear test fixture was designed in order to obtain the in-plane shear modulus and shear strength of ring-shaped composite specimens. This shear test fixture has proved to be advantageous, especially when one bears in mind that there are very few shear test methods for cylindrical components. The outcomes of this work would be useful for material characterization and quality control when standard flat coupons are not available.

Comparison of fracture behaviour of a composite laminate with Cross-ply & Angle ply lay-up subjected to Thermal rise loading

Abstract There is an increased usage of advanced composite structures due to several inherent benefits that they offer in comparison with the monolithic materials. But the application of these materials is being limited by the fact that the knowledge about the crack propagation and strength behaviour under application of loads and environmental conditions is not extensive. So, undertaking research in this direction is still very much important. In this paper, a circular crack which is present in the middle of a composite laminate made up with a cross-ply (0/90) and Angle-ply (-45/+45) was modelled and then subjected to thermal loading conditions where the temperature was considered to be rising to study the fracture behaviour. The fracture behaviour of the composite laminate was studied using the strain energy release rate (SERR) value calculated using Virtual crack closure technique (VCCT). Comparison of fracture behaviour between the cross-ply and angle-ply layups the thermal loading conditions on the SERR value in the 3 different modes of fracture with a circular crack located in the middle of the composite laminate was studied and the influence of these parameter was discussed in this paper

Crushing and energy absorption mechanisms of carbon fiber-epoxy tubes under axial impact

The energy absorption capability of carbon fiber-epoxy tubular specimens having closed circular and open C-shape cross-sections was investigated using experimental tests when focusing on the effect of the layup configuration. Specimens were subjected to a wide range of loading rates ranging from axial quasi-static compression to axial impact loading in order to reveal the deformation mechanism of CFRP samples. Several different combinations of mass and velocity of the striker were selected to study the possible effects on the crushing behavior of composite specimens. C-section specimens were used to investigate the effects of the cross-section shape on the crushing performance of carbon fiber material and to provide a better step-by-step visual understanding of the damage initiation and propagation in each layer due to quasi-static compression. It was observed that, in general, the different stacking sequences and loading conditions had minor effects on the SEA value of full-tube specimens while a significant difference between SEA values of C-section specimens with different layups was found. The calculated SEA value of C-section cross-plied specimens was lower than the SEA value of the full circular tubes having the same stacking sequence while an insignificant difference between the SEA values of C-section and full circular tube specimens of angle-ply layup configuration was observed. It was established experimentally that the removal of the outer layer with fibers oriented along the tube axis has no significant effect on the crushing force value under quasi-static compression. As a sequence, the SEA value increased due to the decrease of the total absorber weight.

Static strength and fatigue life of optimized hybrid single lap aluminum–CFRP structural joints

ABSTRACT Hybrid bolted/bonded joints are used to assemble structural components, commonly made by carbon fiber reinforced plastics (CFRP), with aluminum frames. Hence, they have become common solutions in a number of modern structural applications in the industrial fields, as well as civil constructions. Unfortunately, due to the lack of understanding of the relationships between the multiple parameters of influence that characterize their mechanical performance, only limited improvement have been achieved so far over classical bonding approaches, in terms of static and fatigue strength. As a result, further studies are needed in order to better exploit the potential of hybrid bolted/bonded joints and identify optimum joint configurations. This paper describes an optimization procedure of the joints, achieved through a systematic experimental analysis of hybrid single lap aluminum–CFRP structural joints. This, analyzing the effect of overlap length, stiffness imbalance, adhesive curing as well as of size, positioning and preload of the bolt, results in a significant rise of the strength, especially in presence of high cycles fatigue loading. Also, micrographic analysis and related numerical simulations have allowed to gain a better insight into the damage mechanisms occurring during the in-service tensile loading, corroborating the highest mechanical performance of the angle-ply lay-up proposed for the CFRP adherent.

Thermoelastic Solutions for Flexure of Anisotropic Cylindrical Shells

Solutions within the framework of linear uncoupled thermoelasticity, are presented here for simply supported infinitely long anisotropic cylindrical shell panels subjected to thermal gradient. Benchmark numerical results in the form of displacements and stresses are tabulated for certain angle-ply layup useful for the assessment of improved shell theories.

Three-Dimensional Tailored Vibration Response and Flutter Control of High-Bypass Shroudless Aeroengine Fans

A new reduced-order design synthesis technology has been developed for vibration response and flutter control of cold-stream, high-bypass ratio, shroudless, aeroengine fans. To simplify the design synthesis (optimization) of the fan, a significant order reduction of the mechanical response and stiffness-shape design synthesis has been achieved. The assumed cyclic symmetric baseline fan is modeled as a cascade of tuned, shroudless, arbitrarily shaped, wide-chord laminated composite blades, each with a reduced order of degrees of freedom using a three-dimensional (3D) elasticity spectral-based energy model (McGee et al., 2013, “A Reduced-Order Meshless Energy Model for the Vibrations of Mistuned Bladed Disks—Part I: Theoretical Basis, ASME J. Turbomach., in press; Fang et al., 2013, “A Reduced-Order Meshless Energy Model for the Vibrations of Mistuned Bladed Disks—Part II: Finite Element Benchmark Comparisons, ASME J. Turbomach., in press). The uniqueness of the mechanical analysis is that the composite fan was modeled as a “meshless” continuum, consisting of nodal point data to describe the arbitrary volume. A stationary value of energy within the arbitrarily shaped composite fan annulus was achieved using an extended spectral-based Ritz procedure to obtain the dynamical equations of motion for 3D free vibration response of a rotating composite high-bypass fan. No additional kinematical constraints (as in beam, plate, or shell theories) were utilized in the 3D elasticity-based energy formulation. The convergence accuracy of the spectral-based 3D free vibration response predictions was nearly one percent upper-bounds on the exact mechanical response of the baseline composite fan, particularly in the lowest five modes studied closely in this work, as typically seen with spectral-based Ritz procedures employed in the analysis. The spectral-based 3D predictions was validated against those predicted using a general purpose finite element technology widely used by industry. In off-design operation, the frequency margins of the lower flex-torsion modes of a fan may be dangerously close to integral-order resonant and empirical stall flutter boundaries. For a given baseline composite fan, it is proposed that to reduce the likelihood of resonant response and flutter on a Campbell diagram, design analysts can efficiently unite the newly developed reduced-order 3D spectral-based energy reanalysis within a novel reduced-order spectral-based Kuhn–Tucker optimality design synthesis procedure to fairly accurately restructure the Campbell diagram of a composite high-bypass ratio fan using stiffness optimization (by means of proper choices of angle-ply orientations of the blade laminates) and mass-balancing (shape) optimization (by way of blade thickness variation tuning of the lower aerodynamic loading portion of the blades between the dovetail root section and the midradial height section of the composite fan annulus). Fan design optima is summarized that (1) achieves multiple frequency margins and satisfies multiple empirical stall flutter constraints, (2) controls the twist-flex vibratory response in the lowest (fundamental) mode, and (3) ensures the mechanical strength integrity of the optimized angle-ply lay-up under steady centrifugal tension and gas bending stresses. Baseline and optimally restructured Campbell diagrams and design sensitivity calculations are presented, comparing optimum solution accuracy and validity of the proposed reduced-order spectral-based design synthesis technology against optimum solutions generated from open-source nonlinear mathematical programming software (i.e., NASA’s general-purpose sequential unconstrained minimization technique, Newsumt-A) (Miura and Schmit, Jr., 1979, ”NEWSUMT–A, Fortran Program for Inequality Constrained Function Minimization—Users Guide,“ NASA CR-159070). Design histories of fan stiffness and mass balancing (or shape) along with nondimensional constraints (i.e., frequency margins, reduced frequencies, twist-flex vibratory response, first-ply failure principal stress limits, and dovetail-to-midblade height thickness distribution) show that a proper implementation of fan stiffness tailoring (via symmetric angle-ply orientations) and mass-balancing (thickness) optimization of the fan assembly produces a feasible Campbell diagram that satisfies all design goals. An off-design analysis of the optimized fan shows little sensitivity to twist-flex coupling response and flutter with respect to small variability or errors in optimum design construction. Industry manufacturing processes may introduce these small errors known as angle-ply laminate construction misalignments (Graham and Guentert, 1965, “Compressor Stall and Blade Vibration,” Aerodynamic Design of Axial-Flow Compressors, Chap. XI, NASA SP-36; Meher-Hornji, 1995, “Blading Vibration and Failures in Gas Turbines, Part A: Blading Dynamics and the Operating Environment,” ASME Paper 95-GT-418; Petrov et al., 2002, “A New Method for Dynamic Analysis of Mistuned Bladed Disks Based on the Exact Relationship Between Tuned and Mistuned Systems,” ASME J. Eng. Gas Turbines Power, 124(3), pp. 586–597; Wei and Pierre, 1990, “Statistical Analysis of the Forced Response of Mistuned Cyclic Assemblies,” ASME J. Eng. Gas Turbines Power, 28(5), pp. 861–868; Wisler, 1988, “Advanced Compressor and Fan Systems,” GE Aircraft Engines, Cincinnati, Ohio (also 1986 Lecture to ASME Turbomachinery Institute, Ames Iowa)).

About the influence of temperature and matrix ductility on the behavior of carbon woven-ply PPS or epoxy laminates: Notched and unnotched laminates

Could thermoplastic-based composites be used to replace thermosetting-based composites in high-temperature secondary aircraft structures? The purpose of this work is to establish the ability of a material system to be used in aircraft engine nacelles when subjected to static loadings, with a key upper temperature of 120 °C. In order to provide answers to this question, the thermo-mechanical behaviors of carbon fiber fabric reinforced PPS or epoxy laminates have been compared specifically within the temperature change with 120 °C at the upper bound. The temperature-dependent ductile behavior of laminates is more or less exacerbated, depending on polymers glass transition temperature, and laminates stacking sequence. For both materials, the degree of retention of tensile mechanical properties is quite high in notched and unnotched quasi-isotropic laminates. A Digital Image Correlation technique has been used in order to understand the influence of temperature and matrix ductility on the mechanisms of overstresses accommodation near the hole. In fabric reinforced laminates, the high-temperature results suggest a competition between the mechanisms of damage, and the mechanism of plasticization, enhanced in angle–ply lay-ups. Thus, the highly ductile behavior of TP-based laminates, at temperatures higher than their T g, is very effective to accommodate the overstresses near the hole.

Boundary-layer hygrothermal stresses in laminated, composite, circular, cylindrical shell panels

Free-edge effects in laminated, circular, cylindrical shell panels subjected to hygrothermal loading are studied by utilizing displacement-based technical theories. Starting from the most general displacement field of elasticity for long, circular, cylindrical shells, appropriate reduced displacement fields are determined for laminated composite shell panels with cross-ply and antisymmetric angle-ply layups. An equivalent single-layer shell theory is used to analytically determine the constant parameters appearing in the reduced displacement fields. A layerwise shell theory is then employed to analytically determine the local displacement functions and the boundary-layer interlaminar stresses in cross-ply and antisymmetric angle-ply shell panels under hygroscopic and/or thermal changes. Several numerical examples for the distributions of transverse shear and normal stresses in various shell panels under a uniform temperature change are presented and discussed.

Free-edge effects analysis of angle-ply laminates under transverse loading using layer-wise finite-element method with semi-analytical shear stress calculation

Free-edge stress fields are of an utmost localized nature exhibiting steep stress gradients and they rapidly decay with increasing distance from the laminates’ edges. Layer-wise theory has already been used to analyse the stress field at the free edges of the laminates. In this investigation, the layer-wise theory in finite-element method (FEM) is used to analyse the stress field of the laminates’ free edges. In this study, apart from the conventional FEM in which the stresses are calculated from the constitutive laws, the shear stress components along the thickness are calculated from the equilibrium equations by employing a semi-analytical approach. It is shown that the obtained stresses from the current investigation are very close to those available from the three-dimensional elasticity solution for a square laminate under transversely double sinusoidal pressure distribution. To investigate the free edge influence on shear stress distribution of laminates under transverse loading, the analyses are performed for three angle-ply lay-ups with clustered and alternating sequences. It is shown that the free edge effects of angle-ply laminates with different stacking sequences under transverse pressure loading could be considerably different from laminates with in-plane loading conditions.

An experimental investigation on the effect of multi-angle filament winding on the strength of tubular composite structures

Computer-controlled winding procedures are a state-of-the-art production method for tubular structures with filament reinforced polymer composites. Such structures are often subjected to complex states of stress during installation and/or operation. Modern computerised equipment allows for the design and production of multi-angle lay-up configurations. Using internal pressure and axial force, experiments under biaxial tensile stress ratios were carried out to investigate the performance of multi-angle filament wound structures. Results in terms of stresses at failure, observable modes of failure and stress-strain curves were compared to those of a baseline configuration made from a ± α angle-ply lay-up. Multi-angle wound structures exhibited an overall better performance in resisting damage when subjected to a variety of loading conditions. Thus, the present investigation concludes that multi-angle winding technology may provide considerable advantages over pure angle-ply lay-ups.

Buckling analysis of composite laminates under end shortening by higher‐order shear deformable finite strips

AbstractA higher‐order shear deformable finite strip is developed and employed in the buckling analysis of laminated composite plates when subjected to uniform end shortening. This enables the transverse shear deformation to be accurately incorporated. The permitted laminate material properties are quite general, encompassing anisotropy and full coupling between in‐plane and out‐of‐plane behaviour. Results with respect to the number of plies, thickness of laminate and ratios of E11/E22 are presented for unsymmetric cross‐ply and angle‐ply lay‐ups and for laminates with arbitrary lay‐up arrangements. Copyright © 2002 John Wiley & Sons, Ltd.

A new postprocessing method for laminated composites of general lamination configurations

A new postprocessing method is developed for the deformation and stress recovery of laminated plates of general layup configurations. After obtaining first-order shear deformation plate solutions, deformations and stresses are recovered by utilizing displacement field of higher-order plate theory. The previous developed postprocess method for symmetric cross-ply layup is extended for various layup configurations. For the general layup configurations, not only shear angles but also reference in-plane displacement matchings are needed between higher-order theory and first-order shear deformation theory. Additionally, in-plane equilibrium equations of higher-order shear deformation theory are utilized to satisfy the transverse shear free conditions at the top and bottom surface of the laminates. The basic framework of the postprocess method is preserved. To treat general lamination configurations, the reference plane of the in-plane displacement of an efficient higher-order theory is defined at the bottom surface. Numerous examples demonstrate the accuracy and simplicity of the present method for various layup configurations including anti-symmetric cross-ply and angle-ply layups.