Ply Orientation Research Articles

Maximum Bending Stress Analysis of Jute/Epoxy and Glass/Epoxy Polymer Composites

A surge inthe use of fibre reinforcedcomposites for biodegradable materials, which include both synthetic and natural fibres, to fulfil the strength requirements of composites while also being environmentally friendly has resulted in the use of these materials becoming increasingly popular. Researchers have been working to improve natural fibre qualities to partially replace synthetic fibre, even though not entirely. The research can be accomplished by modelling and simulation techniques, which are becoming more prevalent as technology advances. The approaches have the benefits of being efficient in addressing any material model, boundary conditions, and complicated form structure that may be encountered. This study uses ANSYS APDL, a finite element analysis tool, to carry out flexural test. These factors, as well as the fibre ply orientation, lay-up sequence, and fibre volume percentage, have an impact on the maximum stress of each composite, which are investigated in this study. In the lay-up sequence of [(+θ, -θ)2] s, with fibre ply orientation of 0 ̊ the maximum flexural stress obtains for glass/epoxy (vf=60%), glass epoxy (vf=30%), and jute/epoxy (vf=30%) is 214.64 MPa, 153.77 MPa, and 82.91 MPa and for fibre ply orientation of 90 ̊ the maximum bending stress is 55.41 MPa, 18.39 MPa and 8.37 MPa respectively. Furthermore, the impact of off-axis plies in the 0° fibre ply orientation can be observed in the maximum bending stress of the [θ4,04] s lay-up sequence, which is a function of the number of off-axis plies in the 0° fibre ply orientation. When using the lay-up sequence [904,04]s, the maximum flexural stress for glass/epoxy (vf=60%), glass/epoxy (vf=30%), and jute/epoxy (vf=30%) is 83.39 MPa, 23.04 MPa, and 17.92 MPa, respectively. When bending tests are performed, the 0° fibre ply orientation produces the highest maximum stress, followed by 45° and 90°. When comparing 0° plies composites with off-axis angles to plies composites, the lay-up sequence of 0° plies with off-axis angles exhibits the highest maximum stress.

Effects of Ply Orientations and Stacking Sequences on Impact Response of Pineapple Leaf Fibre (PALF)/Carbon Hybrid Laminate Composites.

This study investigated the impact response behaviours of pineapple leaf fibre (PALF)/carbon hybrid laminate composites for different ply orientations and stacking sequences. The laminates were manufactured using a vacuum infusion approach with various stacking sequences and ply orientations classified as symmetric quasi-isotropic, angle-ply symmetric, and cross-ply symmetric. The laminates were analysed using an IMATEK IM10 drop weight impact tester with an increment of 5 J until the samples were perforated. This investigation reveals that the overall impact properties of PALF and carbon as reinforcements were improved by a beneficial hybridised effect. The laminates with an exterior carbon layer can withstand high impact energy levels up to 27.5 J. The laminate with different stacking sequences had a lower energy transfer rate and ruptured at higher impact energy. The laminates with ply orientations of [0°/90°] and [±45°]8 exhibited 10% to 30% better energy absorption than those with ply orientations of [±45°2, 0°/90°2]s and [0°/90°2, ±45°2]s due to energy being readily transferred within the same linear ply orientation. Through visual inspection, delamination was observed to occur at the interfaces of different stacking sequences and ply orientations.

Effect of Carbon Nanotubes Volume Fraction on the Deflections and Stresses of Laminated Hybrid Composite Plates using First-Order Shear Deformation Theory

Carbon Nanotubes reinforced composite materials are widely used in aerospace engineering due to high strength-to-weight ratios, which can be tailored per requirements. The behaviour of the composite structures depends on various factors like, Lamination scheme, Ply orientation and loading conditions. In the present work, Static deflection and stresses analysis of a Carbon Nano Tube reinforced laminated hybrid composite plate extends the First Order Shear Deformation Theory with variable ply angles and volume fractions of CNT. A micromechanics model based on the Mori-Tanaka method is used to calculate the properties of CNT reinforced laminate. In this analysis, hybrid composite plates mainly consist of Graphite/epoxy, Kevlar/epoxy and CNT/ polystyrene sub-laminates. The lamination scheme and CNT volume fraction play a vital role in the non-dimensional deflections and stresses. The main intention of this work is to enhance the suitability of CNT reinforced Hybrid composite plates under static loading for structural applications.

Thermal buckling analysis of tapered laminated composite beam: Numerical and experimental investigation

AbstractThe present study focuses on the numerical modeling of the thermal buckling behavior of tapered laminated composite beams validated by experimentation. Lagrange's energy‐based governing differential expression was derived utilizing classical laminated plate theory and higher‐order shear deformation theory to analyze the tapered composite beam's thermal buckling property. The uniform temperature rise environment is employed to estimate the critical buckling temperature of the tapered laminated composite beam. The obtained results from the numerical approaches were validated with the experimental results and the previous results obtained from the literature associated with the fundamental frequencies of the structure and critical buckling temperature. The parametric study was incorporated in this present work to investigate the influence of the structural parameters and the geometrical parameters like taper angle, ply orientation, aspect ratio, and boundary constraints of the beam.

Numerical and Experimental Investigations on Nonlinear Buckling Response of a Laminated Composite Shell

In this study, a laminated composite shell with uniformly applied hydrostatic pressure on its external surface is investigated numerically and experimentally. A numerical buckling analysis is carried out on a laminated composite shell with various nonlinearities including geometrical nonlinearity, material nonlinearity and geometric imperfection to obtain the critical buckling pressure using the commercially available software ANSYSⓇ. The eigen mode shape imperfection in the geometry is considered for the nonlinear buckling analysis of composite shell. The force-induced inward dimple (FID) and eigen affine imperfections are also considered for the numerical analysis. The nonlinear governing differential equations of the buckling performance of the shell are solved using the arc-length method coupled with nonlinear finite element analysis. The developed nonlinear finite element modeling of the composite shell is validated by comparing the critical buckling pressures available in the literature obtained for the composite cylinder and prolate and oblate composite domes. Further, the effectiveness of the developed numerical modeling and analysis is demonstrated by performing an experimental investigation on a prototype shell made up of GFRP composites and subjected to external hydrostatic pressure. Various parametric studies are also performed to study the effect of aspect ratio of the shell and ply configuration of the composite shell. It was shown that the buckling pressure of the composite shell is decreased if the FIDs are located at the apex of the shell and eigen affine imperfection amplitude of the shell is increased. However, a substantial effect in the critical pressure of the composite shell could not be observed, if the position of FIDs is located towards the bottom of the shell. It is also found that the composite shell with all 90° ply orientation having aspect ratio of 0.5 yields higher critical buckling pressure.

Two-Level Weight Optimization of Composite Laminates Using Integer Programming

Optimization of composite laminates requires the satisfaction of constraints where the design ply thicknesses and orientations can only take discrete values prescribed by the manufacturers. Heuristics such as particle swarm or genetic algorithms are inefficient in such cases because they provide suboptimal solutions when the number of design variables is large. They also are computationally expensive in handling the combinatorial nature of the problem. In contrast, with the help of binary decision variables, mixed integer programming can be adopted to optimize such laminates efficiently. This paper presents an approach to reformulate lamination parameters and failure constraints as functions of binary decision variables. The buckling load maximization for a simply supported laminated plate is initially demonstrated using integer linear programming. Next, the laminate weight is minimized by varying the number of plies for a given external bi-axial compressive load and subjected to buckling and material failure constraints. A variation of laminate weight minimization is demonstrated by fixing the number of plies and assuming discrete changes in ply thicknesses. This is achieved using a sequential two-level optimization for laminates having uniform ply thickness. Finally, a scalability study is performed to evaluate the performance of mixed integer programming for different problem sizes. It is demonstrated that all three formulations with integer programming achieve significant performance gain and robustness over standard heuristic solvers.

Investigation on mechanical properties of basalt/epoxy fiber reinforced polymer composite with the influence of turtle shell powder

AbstractThe research article deals with the efficacy of turtle shell powder (TSP) as an attempt at a novel perspective vision, used as a filler material in the fabrication of basalt‐epoxy composites preparation for us as a first opportunity. The fiber reinforced polymer composite made of basalt‐epoxy matrix was fabricated by filling TSP powder with different weight percentage levels of 1%, 3%, and 5% by hand lay‐up process continued by a compression molding technique. In addition, the single laminate basalt fiber ply orientations were configured by symmetric‐quasi‐isotropic. Density, tensile, flexural, impact, and hardness tests were performed to analyze the composite strength and modulus. The morphological traits and TSP elemental composition were analyzed by scanning electron microscope and EDAX, respectively. Results elucidate that the incorporated TSP particle in basalt‐epoxy composite enhanced the mechanical properties. Overall compared with the B0 composite, the B3 composite exhibits the optimal result, the tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength increased by 98.4%, 68.9%, 70.73%, 53.12%, and 76.85% performance explicates, respectively, except hardness, which shows 43.5% higher in 5 wt% composite. The interfacial bonding of basalt‐epoxy composites has been improved by the TSP particle curtailed the microvoids. The basalt‐epoxy characteristics were adversely affected by TSP aggregation that occurred at 5 wt% laminate. The laminated composites are heavily bolstered by the performance of TSP particles and with the addition of ply orientation increased the strong interfacial bonding of TSP‐epoxy‐basalt interactions.

Interlayer interaction characteristics of multi‐layered plain woven glass fabric in hemisphere forming

AbstractCharacterizing the interlayer interaction is beneficial to mitigate the manufacturing defects in the multi‐layered fabric forming of composite. However, the interlayer interactions including the force and sliding distance, and their effects on the defect generation have not been reported yet. Here, the monolayer and multi‐layered fabric hemisphere forming were conducted by experiments. Firstly, the forming force and deformation modes at different hemisphere regions are confirmed in the monolayer fabric forming as a reference. Then, in the multi‐layered forming, the interlayer interaction is confirmed to still exist in the configuration with the same ply orientations, whereas the forming force, forming force rate, and interlayer sliding are smaller than that in the configuration with different ply orientations. In addition, with the increase of layer number, the extent of interlayer interaction is improved, which intensifies the defect from the out of plane yarn buckling to the macro wrinkle in the tensile direction. Especially, it is revealed that the tensile direction of lower layer should be avoided under the shear direction of upper layer to reduce the interlayer sliding. These results obtained here provide an important reference to the multi‐layered plain woven fabric forming.

Numerical study to investigate the influence of CNTs on delamination resistance in broken ply carbon/epoxy composites

In fibre reinforced polymer (FRP) composite laminates subjected to low velocity impact, one of the common mode of failure is ply breakage followed by interfacial delamination at the site of ply break. Improving the delamination resistance at the interface is therefore important and the present work examines quantitative understanding of how the addition of CNTs to epoxy might enhance the resistance to such delamination at the interface. A laminate made of plies with CNT-epoxy as the matrix and carbon fibre as the reinforcement has been considered to be broken through the full width. A full three dimensional FE analysis was carried out for such a carbon/CNT-epoxy laminate for different wt% of CNTs. Resistance to delamination has been assessed by computing critical strain energy release rate (Gc ) using quadratic stress criterion (QSC) and virtual crack closure integral (VCCI). From the results, by adding CNTs to epoxy, a significant improvement in the delamination resistance could be observed. However, the improvement is till a certain specific CNT wt% and adding CNTs further leads to a significant reduction in delamination resistance. In addition, the effect of various factors such as fiber orientation of the adjacent continuous ply and resin layer thickness on critical strain energy release rate (Gc ) have been studied. The results show that Gc also depends upon the fiber orientation of the adjacent ply and on the resin layer thickness. As the resin layer thickness increases, a significant increase in Gc is observed.

Investigation and prediction of mechanical properties of hot water treated jute/poly(lactic acid) composite laminates using response surface methodology and genetic algorithm

AbstractThe main objective of this work was to estimate the usefulness of response surface methodology (RSM) and genetic algorithm (GA) in modeling and predicting the strength of jute/poly(lactic acid) (PLA) composite laminates. Firstly, the impact of the hot water treatment on the thermal, molecular structure, and morphological characterizations as well as kinetic analysis of jute fibers were performed by Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM). The FTIR results showed that the hot water treatments reduced the content of lignin, hemicellulose, and impurities of the fibers. Hot water treated fibers exhibited higher thermal stabilities compared with untreated fibers as shown with TGA results. The SEM results showed effect contact surface area improved after the hot water treatment, leading to better mechanical properties of bio‐composites. Secondly, the influences of the ply orientation, plies and fiber content on the tensile strength and flexural strength of the hot water treated fibers composites were evaluated by RSM. RSM with the Box Behnken Design was utilized to establish the quadratic models of two objectives in response to input parameters. Analysis of variance (ANOVA) was used to determine percentage contribution of various parameters on two quality objectives. According to the ANOVA results, ply orientation had the most important impact on tensile strength while the ply orientation‐fiber content interaction had the most important impact on flexural strength. Finally, multi‐objective optimization was carried out to maximize tensile strength and flexural strength using the desirability function and GA. The optimized results both showed an acceptable relative error between experimental and optimized values.

Experimental and numerical damage characterization of glass/polypropylene multidirectional laminates under quasi-static loading condition

Polypropylene (PP) as a commodity thermoplastic, when reinforced with continuous glass fibers provides cost-effective composites. However, the low glass transition temperature and fabrication induced semi-crystalline morphology of PP set challenges for the experimental characterization especially when the quantification of damage mechanisms in multidirectional laminates is concerned. This paper is aimed at performing in-situ experimental observation, quantification and theoretical modeling of damage mechanisms in glass fiber reinforced polypropylene multidirectional laminates subjected to uniaxial quasi-static loading conditions. Two Stereo Digital Image Correlation systems (3D-DIC) are applied to measure the full-field strains and quantify the extent of damage mechanisms from the specimen's edge. The effects of ply thickness, off-axis ply orientation and location on damage initiation and growth are studied by testing different lay-ups. To validate the experimental measurements, a recent physics-based modeling technique is implemented that can predict the evolution of damage modes as well as their effects on the laminate properties. Good agreements are observed between the experimental measurements and simulation results which verify the accuracy of both analyses.

Investigation of mechanical properties of hybrid stainless steel/acrylic and carbon fiber reinforced epoxy composite

Hybrid composite specimens were produced with stainless steel-acrylic (SSA) and carbon fiber reinforcement in order to achieve ductile behavior compared to CF reinforced epoxy composites. Laminated composites containing CF and SSA fabrics in with different ply configurations were manufactured using vacuum infusion method. In addition, CF fabric was used in two different ply orientations (0–45°). In both the flexural and tensile test results, composites having CF oriented at 0° showed higher strength and modulus but lower strain than composites having CF oriented at 45°. When the number of carbon fiber layers increased, the composites showed high strength and modulus, but low strain. Increasing the number of SSA significantly increased the flexural and tensile strains of laminated composites. After the mechanical tests, the fracture surfaces of the specimens were examined with an optical microscope and matrix cracks, fiber breakage, fiber pull-out and delamination failures were observed.

UHBR Open-Test-Case Fan ECL5/CATANA

The application of composite fans enables disruptive design possibilities but increases sensitivity to multi-physical resonance between aerodynamic, structure dynamic and acoustic phenomena. As a result, aeroelastic problems increasingly set the stability limit. Test cases of representative geometries without industrial restrictions are a key element of an open scientific culture but are currently non-existent in the turbomachinery community. In order to provide a multi-physical validation benchmark representative of near-future UHBR fan concepts, the open-test-case fan stage ECL5 was developed at Ecole Centrale de Lyon. The design intention was to develop a geometry with high efficiency and a wide stability range that can be realized using carbon fibre composites. This publication aims to introduce the final test case, which is currently fabricated and will be experimentally tested. The fan blades are composed of a laminate made of unidirectional carbon fibres and epoxy composite plies. Their structural properties and the ply orientations are presented. To characterize the test case, details are given on the aerodynamic design of the whole stage, structure dynamics of the fan and aeroelastic stability of the fan. These are obtained with a state-of-art industrial design process: static and modal FEM, RANS and LRANS simulations. Aerodynamic analysis focuses on performance and shows critical flow structures such as tip leakage flow, radial flow migration and flow separations. Mechanical modes of the fan are described and discussed in the context of aeroelastic interactions. Their frequency distribution is validated in terms of resonance risk with respect to synchronous vibration. The aeroelastic stability of the fan is evaluated at representative operating points with a systematic approach. Potential instabilities are observed far from the operating line and do not compromise experimental campaigns.

Sparse Polynomial Chaos Expansion for Uncertainty Quantification of Composite Cylindrical Shell with Geometrical and Material Uncertainty

The geometrical dimensions and mechanical properties of composite materials exhibit inherent variation and uncertainty in practical engineering. Uncertainties in geometrical dimensions and mechanical properties propagate to the structural performance of composite cylindrical shells under hydrostatic pressure. However, traditional methods for quantification of uncertainty, such as Monte Carlo simulation and the response surface method, are either time consuming with low convergence rates or unable to deal with high-dimensional problems. In this study, the quantification of the high-dimensional uncertainty of the critical buckling pressure of a composite cylindrical shell with geometrical and material uncertainties was investigated by means of sparse polynomial chaos expansion (PCE). With limited design samples, sparse PCE was built and validated for predictive accuracy. Statistical moments (mean and standard deviation) and global sensitivity analysis results were obtained based on the sparse PCE. The mean and standard deviation of critical buckling pressure were 3.5777 MPa and 0.3149 MPa, with a coefficient of variation of 8.801%. Global sensitivity analysis results from Sobol’ indices and the Morris method showed that the uncertainty of longitudinal modulus has a massive influence on the critical buckling pressure of composite cylindrical shell, whereas the uncertainties of transverse modulus, shear modulus, and Poisson’s ratio have a weak influence. When the coefficient of variation of ply thickness and orientation angle does not surpass 2%, the uncertainties of ply thickness and orientation angle have a weak influence on the critical buckling pressure. The study shows that the sparse PCE is effective at resolving the problem of high-dimensional uncertainty quantification of composite cylindrical shell with geometrical and material uncertainty.

Compression-After-Impact analysis of carbon fiber reinforced composite laminate with different ply orientation sequences

This article explores the experimental and numerical study in ABAQUS/explicit of the post-impact damage progression in carbon/epoxy composite laminate under compression. LVI (Low-Velocity Impact) tests at three different energy levels followed by CAI (Compression-After Impact) tests are carried out as per ASTM standards. Damage envelopes are studied by NDE (Non-Destructive Evaluation) technique, using X-ray computed tomography. The results of the numerical study match well with the experimental study. It is seen that the CAI strength depends on the factors like properties of the constituent material, ply orientations and stacking sequence, and thickness of the laminate. It has been observed that even with the barely visible impacts, the compressive strength of the laminate has been reduced drastically. The mode of failure observed is buckling of the laminates in the damaged zone due to impact, especially at the back face of the specimen where damage was more. The size of the damaged zone increases as the impact energy increases and reduces the CAI strength of the laminate.

Holistic determination of physical fracture toughness values and numerical parameters for delamination analysis considering multidirectional-interfaces

Delaminations are a concern for the structural integrity of fibre composite structures. The decisive material parameter for delaminations is fracture toughness. Structures usually have a multidirectional ply stacking. However, interface orientation dependant fracture toughness values and R-curve effects are neglected in numerical delamination analysis. This work investigates interface orientation specific fracture toughness values and considers R-curve effects in mode I to improve simulation accuracy. Therefore, mode I, mode II and mixed mode fracture toughness values of different interface ply orientations are determined experimentally and verified using numerical analysis of the characterisation specimens with cohesive zone modelling. In this way, an engineering methodology is provided for the experimental characterisation and comprehensive numerical modelling of delaminations in mesoscale progressive damage analysis of multidirectional composite structures. In addition, a full parameter set for the simulation of four different interfaces of M21-T700GC prepreg material is given. It can be shown that the use of standard 0°//0°-values leads to very conservative results. The use of interface specific values increases the accuracy. Ultrasonic scans of the DCB specimens are used to compare the crack front shapes for validation. Not only the load displacement curves of the characterisation specimens are well captured, but also the crack front shapes. This demonstrates that by smearing the microscale effects, the material behaviour can be captured phenomenologically correct by mesoscale modelling suitable for industrial use.

Progressive Failure Analysis of Composite Laminates Subjected to Transverse Loading with Augmented Finite Element Method

In this paper, two-dimensional (2D) orthotropic augmented finite element method (A-FEM) is applied to account for progressive failure of composite laminates under transverse loading, which considers all major cracking modes (delamination, fiber kinking/rupture matrix cracking). High-fidelity simulations of different stacking composite laminates under transverse loading are implemented. Both predicted load−deflection curves and damage evolution are in good agreement with that of experimental results, which demonstrates the numerical capability of A-FEM. In addition, the influence of stacking sequence on the failure mechanism is also studied by predicted damage evolution of laminates with different stacking sequence [Formula: see text], [Formula: see text] and [Formula: see text]. Results show that the tensile matrix crack in the bottom laminar is always the first damage mode for the composite laminate, and the subsequent crack propagation is related to ply orientation of adjacent plies which have a blocking effect on crack propagation.

Optimal design of vibro-impact resistant fiber reinforced composite plates with polyurea coating

This paper studies on optimal design of vibro-impact resistant fiber reinforced composite plates (FRCPs) with polyurea coating. Initially, a theoretical model for the coated FRCP structures under elastic boundary conditions is proposed, through which dynamic stiffness and impact damage area are predicted. Here, based on the first-order shear deformation theory and the Rayleigh-Ritz method, the dynamic stiffness of coated FRCP structures is calculated, which is taken as an index of vibration suppression performance. Regarded as an index of anti-vibration performance, the impact damage area is identified by employing the Hertz contact law and the predefined delamination threshold load. After validation of the proposed model against a series of experiments on coated and uncoated FRCP specimens, optimization analysis is then conducted based on the Non-dominated Sorting Genetic Algorithm, where the maximum dynamic stiffness, the minimum impact damage area and structural mass are defined as objective functions, and thickness ratio, elastic modulus ratio and ply orientation angle are taken as design variables. It has been found that to possess the desired vibration and impact resistant capabilities together with maintaining lightweight property, it is recommended to choose design variables associated with the turning point of Pareto-optimal solutions as the final optimal results.

Vibration and buckling behaviour of delaminated composite plates subjected to localised edge loads

Laminated composite plates are usually a part of complicated structures. Most of the cases these components may undergo delamination due to the transferring of various complicated loads. In this investigation the effect of extent of delamination on the vibration and buckling characteristics of laminated composite plate is studied by using FE method. Towards this, an eight-noded plate element has been used, by incorporating the effect of shear deformation. In this work two types of boundary conditions are used for calculating pre buckling in-plane stresses and buckling loads respectively. Matlab code has been developed to carry out various parameters like extent of delamination, ply orientation, plate thickness, width and position of load and boundary conditions.

Effect of interlayer adherend inclusions on strength of composite bonded joints

Foreign objects such as backing tapes may get embedded between the plies of a laminated polymer composite during its fabrication which can compromise the composite panel or the adjacent bond joint. This paper investigates the effect of such inter-layer inclusion defects in laminated carbon fiber composite adherends, on the strength of an adjacent single lap bonded joints, using both experimental and computational methods. Composite laminates composed of 0° unidirectional lamina were fabricated with Polytetrafluoroethylene (PTFE) strips embedded between the first two plies closest to the bond line. Three different inclusion positions were investigated and the location of the inclusion defect yielding the lowest strength was identified. The inclusion location in the most compromised joint was then used to study the effect of this type of defect in adherends having different ply orientations. Finite Element (FE) stress analysis was performed to understand the variation in the shear and peel stresses due to the presence of the inclusion. FE analysis revealed higher shear and peel stresses in bonded joints adjacent to inclusion defects.