Ply Failure Load Research Articles

A simplified approach for predicting last ply failure load of VO-notched laminated composite components

In this study, the last ply failure (LPF) load of composite laminates with VO-notches under pure mode I and mixed mode I/II was investigated experimentally, analytically, and numerically. The efficiency of the virtual isotropic material concept (VIMC) in combination with a new combined failure criterion was also evaluated. The J-integral and average strain energy density failure criteria were combined with VIMC. Using analytical expressions for the J-integral and the average strain energy density (ASED), the prediction of the fracture load of notched components was simplified and expedited. The experimental fracture loads of notched specimens were determined for quasi-isotropic and cross-ply laminates under mode I and mixed mode I/II. The fracture loads were predicted using analytical expressions for the J-integral and ASED, combined with VIMC. The VIMC-ASED and VIMC-J-integral failure criteria demonstrated good accuracy in predicting the LPF, with the highest accuracy for mode I, slightly reduced accuracy for mixed mode I/II. VIMC, in combination with energy-based failure criteria, effectively predicts the fracture load. The use of analytical expressions further simplified and expedited the prediction process without losing accuracy, making it a practical approach for engineering applications. Additionally, this approach significantly reduces the time and cost associated with extensive experimental testing.

Prediction of last ply failure load of keyhole notched laminated composites using the virtual isotropic material concept

Composite laminates have become increasingly popular in industries like aerospace and shipbuilding. In practical applications, the creation of notches in composite laminates is often necessary to enable assembly and modifications. This rise in the use of notched composite laminates highlights the need for reliable methods to predict potential failures in these components. With these predictions, the safety and reliability of composite structures can be ensured by preventing catastrophic failures. The present paper investigates the use of the Virtual Isotropic Material Concept (VIMC) combined with the Finite Fracture Mechanics (FFM) criterion to predict the Last Ply Failure (LPF) load in keyhole notched composite laminates and under mode I loading conditions. Experimental tests were conducted to measure the LPF load of E-glass/Epoxy keyhole notched specimens, and the results were compared with the predicted results using the VIMC-FFM criterion. The paper also derives an expression for the Stress Intensity Factor (SIF) function for a crack that emanates from the keyhole notch tip under mode I loading conditions. The derived equation matches very well with numerical data and have a mean absolute error about 2% in the studied domain. The study shows that the VIMC-FFM criterion predicts the LPF load of keyhole notched composite laminates with acceptable accuracy and in a simple and low-cost manner.

Micro-mechanical analysis of the effect of ply thickness on curing micro-residual stresses in a carbon/epoxy composite laminate

During the manufacturing of thermoset-based carbon fiber reinforced polymers (CFRPs), micro-residual stresses are developed in the material, due a mismatch of the chemical-thermal-mechanical properties of the fibers and the polymer matrix. This ultimately leads to a reduction in the mechanical performance of the composite material. In this work, a representative volume element (RVE) of a composite sub-laminate with a 90° ply discretized at micro-scale level, stacked within homogenized plies, is proposed to study the micro-residual stresses and the ply mechanical response considering the in-situ effect caused by the constraining adjacent layers. A model framework is developed using finite elements in Abaqus®/Standard with user-subroutines. The retrieved micro-residual stresses in the 90° layer are generated by the dissimilar chemical shrinkage and thermal expansions, plus the additional residual meso-scale stresses caused by the constraining effect of adjacent plies. The residual stresses in the constrained condition can achieve almost 80 % of the ply failure load for the 0/90/0 sub-laminate, meaning lower sub-laminate strain to failure. Thick laminates retrieve more residual stresses in the transverse 90° layer and exhibit lower constrained strength and more unstable post-failure response, demonstrating that thin-ply laminates exhibit beneficial constraining effects during the curing process.

Failure Analysis in a Multilayerd Glass Fiber Reinforced Polyester Composite Plates under Flexural Loading

The usage of laminated glass fiber reinforced polyester composites in aerospace applications helps to reduce overall weight of the aerospace structures. The flexural strength of the laminated glass fiber reinforced composites becomes more important when they are employing for aeroplane wings. In this work, a laminated glass fiber polyester composite with two distinct sets of six different woven lamina stacking sequences is manufactured via hand layup technique. The effect of stacking sequence over the total ply failure load are investigated through universal testing machine. Finally, the progressive failure of the lamina in composites is also examined using ANSYS software.

Numerical Failure Analysis of Laminated Beams Using a Refined Finite Element Model

AbstractIn the present investigation, laminated composite beams subjected to a bending static loading are studied in order to determine their failure mechanisms and the first ply failure (FPF) load. The FPF analysis is performed using a refined rectangular plate element. The present element is formulated based on the classical lamination theory (CLT) to calculate the in-plane stresses. To achieve this goal, several failure criterions, including Tsai-Wu, Tsai-Hill, Hashin, and Maximum Stress criteria, are used to predict failure mechanisms. These criterions are implemented within the finite element code to predict the different failure damages and responses of laminated beams from the initial loading to the final failure. The numerical results obtained using the present element compare favorably with those given by the analytic approaches. It is observed that the numerical results are very close to the analytical results, which demonstrates the accuracy of the present element. Finally, several parameters, such as fiber orientations, stacking sequences, and boundary conditions, are considered to determine and understand their effects on the strength of these laminated beams.

Effect of Stacking Sequence Variation on First Ply Failure Load of Laminated Composite Skew Plate

The present work aims to study and report the first ply failure load of laminated composite skew plate of different laminations and stacking sequences with a practical boundary condition. The finite element model is developed using eight noded isoparametric curved quadratic shell element with five degrees of freedom per node (with three translations and two rotations). Numerical experiments are conducted considering skew plates of varying skew angles, laminations and stacking patterns. First ply failure loads are evaluated for seven different failure criteria such as maximum stress, maximum strain, Tsai-Wu, Tsai-Hill, Hoffman, Puck and Hashin’s failure criteria. The minimum value of load obtained from different failure criteria is chosen as the governing first ply failure load value. Benchmark problems are solved to validate the correctness of the present approach of evaluation of first ply failure load and incorporation of skew geometry in the present model. The results of authors’ own problems are finally studied meticulously and relative performance matrix of skew plate options of different combination of skew angle and stacking sequences are reported.

Analytical solution for first ply failure analysis of laminated plates using Reddy–Legendre higher-order theory

The existing finite element formulation generally leads to overestimation on the first ply failure (FPF) load. Reasons of this phenomenon have been less cleared in detail. Therefore, it requires to propose an analytical solution to provide an accurate prediction of the FPF with the high efficiency-cost ratio. To this end, the following work has been carried out: (1) Legendre polynomials as local terms are first introduced into Reddy-type higher-order theory, which provide a novel alternative form of global-local displacement field. (2) Compared with the classical first-order and higher-order shear deformation theories, the proposed model can predict transverse shear stresses directly by constitutive equations which is close to the results obtained by the three-dimensional finite element method (3D-FEM). Therefore, the accuracy and efficiency of the FPF analysis can be improved, attributing to the accurate prediction of the quasi-three-dimensional stress field. (3) The static response and the FPF of laminated composite plates are analyzed, which have been compared with the results of selected models in the published literature and 3D-FEM. Influences of different failure theories, transverse loads, stacking sequence on prediction of the FPF loads are also explored. (4) By visualizing full-field displacement, stress and damage variables rather than those obtained from key points, it is easier to find the failure tendency and the failure modes. As a result, it is necessary to propose an analytical solution for predicting the FPF of composite laminated plates, which can provide a reference for other investigators.

Probabilistic Progressive Failure of Multiwall Carbon Nanotube-Reinforced Composite Plate Under Transverse Patch Loading

Second-order statistics of progressive failure response of multiwall carbon nanotube-reinforced composite (MWCNTRC) plate subjected to the transverse loading is presented. The mathematical model is based on the higher-order shear deformation theory (HSDT) and von Karman nonlinear kinematics through the mechanics of the material approach. Second-order perturbation technique (SOPT) and polynomial chaos (PC) methods are used for the uncertainty quantification. The properties of the MWCNTRC plate are obtained by using the Halpin–Tsai model. Epoxy-matrix reinforced with multiwall carbon nanotube (MWCNT) is considered as a new matrix and boron fiber is reinforced with this new matrix in an orthotropic way to get MWCNTRC. The distribution of volume fraction of carbon nanotube (CNT) in the epoxy matrix is considered in the functionally graded (FG) manner for thermo-mechanical loading. Stochastic progressive failure analysis (PFA) along with the probability of failure of MWCNTRC plate is performed by using the progressive damage model incorporated in the ply discount method and considering randomness in the material properties, the geometry of plate and loading. The conclusions are based on the effect of the parameters like stacking sequence, fiber volume fraction, temperature, CNT distribution, fiber material and number of CNT on the mean of first and last ply failure loads (FPFL and LPFL) and coefficient of variance (COV) of MWCNTRC plate. Stochastic failure analysis of MWCNTRC plate up to last ply failure by considering patch loading, nonlinearity and FG distribution of CNT is unique in this work.

Effect of Cutout on the Stability and Failure of Laminated Composite Cylindrical Panels Subjected to In-Plane Pulse Loads

In this investigation, the nonlinear dynamic buckling analysis and the failure analysis of laminated composite cylindrical (LCC) panel with different shapes of cutouts under the action of rectangular in-plane pulse loads are performed in the finite element framework. Cross-ply laminates which are balanced symmetric are considered in the investigation. The first ply failure load (FPFL) of the panel is evaluated and checked whether it occurs before the nonlinear dynamic buckling phenomenon considering Tsai–Wu failure criterion. Convergence and validation studies are undertaken, and the results are compared with those from the existing literature. The effects of loading duration, cutout area and cutout geometry on the panel are investigated in detail and results are reported. The results indicate that for the panel with cutout, its dynamic buckling load (DBL), in certain cases, compared to the static buckling load (SBL), can be lower even if the loading duration is half of its first natural period. Additionally, the vibration and the static buckling analyses of the panels are carried out as and when required.

Predicting the Nonlinear Damage Response of Imperfect Laminates Using Linear Material Degradation Model and a Semi-Analytical Technique

This paper investigates nonlinear damage response and ultimate collapse of laminates under in-plane and lateral pressure loadings. The in-plane loading was in the form of end-shortening strain, while the lateral pressure was sinusoidal. The plates had initial geometric imperfection to which simply-supported boundary conditions were applied. Ritz techniques with nonlinear strain terms in kinematic relations as well as the first-order shear deformation theory were applied. Hashin and Rotem failure criteria were used for failure analysis. Two models were also employed for degradation of material properties in the plates. The complete ply degradation model was implemented along with the ply region degradation model, in which stiffness reduction was applied only to one region of the ply in which failure had occurred. Note that the stiffness degradation after the failure was investigated as both instantaneous and linear models. In both complete ply and region ply degradation models with instantaneous degradation of material properties, at any location in a ply or region, which has exceeded the given stress criterion, the corresponding stiffness properties are instantaneously degraded throughout that ply or region but with linear material degradation model, the stiffness diminishes gradually and linearly. Finally, the results were then validated against the findings of different references as well as finite element analysis. According to the results, it was seen that in the ply region degradation model, last ply failure loads are generally larger than those of the complete ply degradation model.

A Numerical Approach to Estimate First Ply Failure of Fibre Metal Laminate

Fibre Metal Laminates (FMLs) are laminates consisting of metal layers and fibre reinforced composite layers. These laminates are designed to improve some specific properties of constituent metals and composites layers. Estimation of First Ply Failure (FPF) Loads of these FMLs is a part in the broad characterization of these materials. A numerical method is developed for the estimation of FPF when these laminates are used as simply supported plates subjected to uniformly distributed load. Various failure criterions are used to identify these loads. The proposed method has been validated with the results of exact (Navier) solution available in the literature. FPFs are estimated for different groups of FMLs based on Aluminum, Titanium and Magnesium layers. The results are presented in the form of non-dimensional FPF and deformation values for various aspect ratios.

Progressive failure analysis of laminated composite plates

Failure of laminated composite plates has been a crucial issue that numerous researches have been conducted on the matter. Several modes of failure of laminated composites include fibre failure in tension, matrix failure in tension, fibre failure in compression, matrix failure in compression and delamination. This paper analyses failures of the composites to determine the first ply failure load (FPL) and last ply failure load (LPL) using the progressive failure approach that combines the effect of several modes of failure. Finite element method (FEM) was used via the commercial software of ANSYS APDL where the laminated composite plates were first modelled. Validation of the analysis was firstly conducted through a simple stress and deflection analysis. Progressive analysis was then conducted as the composite is loaded with an incremental combined tensile and transverse loading. The Tsai-Wu failure and the maximum stress criteria have been used to detect the FPL. With the failure occurred in an element, the degradation of that element mechanical properties was applied. As the load was further increased, more elements will fail and be degraded until the LPL was reached. A parametric study was conducted on the effect of varying angles of orientation of the composite. The results showed that the FPL and the LPL of the composites due to the Tsai-Wu criterion and the maximum stress criterion were in good agreement. The progressive failure behaviour of laminated composite plates subjected to uniaxial load and combined uniaxial load and transverse load was successfully established.

Examination of selected failure criteria with asymmetric shear stresses in the collapse analysis of laminated shells

The paper is concerned with failure analysis of composite shells performed with the usage of the nonlinear 6-parameter shell theory with drilling rotation degree of freedom. This special theory embodies naturally unlimited translations and rotations and is suitable for analysis of irregular shells for instance with various, particularly orthogonal, intersections. The presence of the drilling rotation is inherently accompanied with asymmetry of in-plane shear stresses and strains which must be taken into account in the composite failure criteria. In the paper in general two failure measures are applied: Hashin criterion and Tsai-Wu criterion which are appropriately modified to accommodate the stress asymmetry. It is shown, that depending on the used failure criterion, it is possible to obtain slightly different damage zones and values of the first ply failure and ultimate load. These values are compared with those obtained experimentally.

Nonlinear first ply failure study of laminated composite skew plates

The present work reports the first ply failure investigation of laminated composite clamped skew plates subjected to uniformly distributed transverse static load considering geometric linear and nonlinear strains. An eight-noded isoparametric curved quadratic plate element based on Sanders’ and Von Karman's nonlinearity is employed to develop the finite element code used in the present research. The first ply failure loads are evaluated based on various well-acknowledged failure theories like maximum stress, maximum strain, Hoffman, Tsai – Hill, Tsai – Wu, Hashin and Puck failure criteria. Effect of variation of skew angles on first ply failure loads of laminated composite skew plates for various stacking pattern is reported and studied in depth. The failure criterion corresponding to which the failure load value is minimum, for each skew angle, is only reported in this paper. The effects of skew angle on the first ply failure load are summarised in the form of charts and working equations. The engineers and researchers may use the charts and equations directly to predict the first ply failure load provided the geometry of the plate is known. Besides first ply failure loads the failed plies as well as the failure modes are also reported in the present paper.

Ply-by-Ply Failure Analysis of Laminates Under Dynamic Loading

Ply-by-ply failure analysis of symmetric and anti-symmetric laminates under uniform sinusoidal transverse dynamic loading is performed for a specified duration. The study investigates the first ply failure load, followed by t... | Find, read and cite all the research you need on Tech Science Press

Non-linear stability and failure of laminated composite stiffened cylindrical panels subjected to in-plane impulse loading

In this article, the non-linear dynamic buckling behavior and failure of laminated composite stiffened cylindrical (LCSC) panel is performed in the finite element framework when subjected to sinusoidal and rectangular in-plane pulse loading. Balanced symmetric cross-ply laminates and balanced symmetric angle ply laminates are considered in this study. The first ply failure load (FPFL) of the panel is evaluated and checked whether it occurs before the non-linear dynamic buckling phenomenon considering four different failure theories. Convergence and validation studies are carried out using the present mathematical formulation and compared with the results from the existing literatures. The effect of loading duration, loading function, aspect ratio of stiffener and the ply orientation of the skin and stiffener on the non-linear dynamic buckling of LCSC panel is studied in detail and the results are reported. It is observed that the non-linear dynamic buckling load (DBL) of balanced and symmetric angle ply (45°/−45°/−45°/45°) stiffened panel is lower than those of unstiffened composite cylindrical panel upto aspect ratio of the stiffener (ds/bs) equal to 8 when subjected to rectangular pulse load. In case of balanced and symmetric cross ply (0°/90°/90°/0°) stiffened panel the DBL of stiffened panel is lower than those of unstiffened panel when the aspect ratio of the stiffener is less than 4 with rectangular pulse load. Further, the free vibration, static buckling and static post-buckling analyses of the panels are carried out as and when required.

Hole integrity of carbon fibre reinforced epoxy composites using combined punching and drilling techniques

Drilling is the most common technique in the hole making of composite panels. Based on the previous study, punching was proposed to replace drilling. This study aims to investigate the effect of hole-making techniques, i.e. new combined technique and conventional drilling technique to the hole quality and performance by conducting experiment based on surface roughness and bearing strength, respectively. The surface roughness measurement was performed oversampling with 3.6-mm thickness at four quadrant points along the hole wall. A bearing test was conducted according to ASTM D5961 procedure-A double shear with a single-pin fastener. The failure modes resulting from an experiment are quantified and compared. It was found that there is a slight difference in the initial ply failure load (IPFL) between the conventional drilling and both combined technique for 0.65% and 7.90%, respectively. However, the difference is still low, i.e. less than 10%. The results confirmed that the use of the combined technique is almost similar to the conventional drilling alone in terms of bearing strength, failure mode, and surface roughness.

Deformation and failure behavior of hybrid composite laminates made of Glass Epoxy and woven Kevlar Epoxy

Due to the demand of reducing costs for high strength materials, hybridizing composite laminates could offer the alternative in producing materials with superior properties at reduced costs. Moreover, preparing samples and conducting experiments for these materials are very costly and tedious. Therefore, in order to establish the complex failure behavior of hybrid composite laminates, finite element analysis and simulation has been the choice for failure prediction. Accepting, this challenge, this paper investigates the deformation and failure behavior of composite plates made of woven Kevlar Epoxy (KE), unidirectional Glass Epoxy (GE), and their hybrids (KE/GE) under uniaxial tension. Solid plates and plates with circular hole were modeled using commercial finite element software, ANSYS APDL. In general, all laminates having the layup of [θ4/04/-θ4]s but the hybrid laminate arrangement varies between the number of GE and woven KE laminates. Using the built-in failure criteria function provided by ANSYS APDL, the first ply failure (FPF) and last ply failure (LPF) loads for several configuration of hybrid laminates were determined. In addition, the angle of fiber orientation, θ, was varied from 0° to 90° to generate the trend of failure curves. The results show that the FPF and LPF curves for the plates with hole are lower compared to the solid plate. Nevertheless, the patterns of the failure curves are very much influenced by the angle of fiber orientation. This indicates that the fiber angles have a significant effect on the strength of hybrid composite laminates. Compared to GE and woven KE composite laminates, the hybridization between unidirectional lamina and woven lamina could also influence the pattern of the failure curves. It could be concluded that the current study is useful; and has provided knowledge about the failure and deformation behavior of hybrid composite laminates by combining unidirectional (GE) and woven (KE) laminates.

Postbuckling response of functionally graded hybrid plates with cutouts under in-plane shear load

The present study deals with the investigation of buckling and postbuckling responses of functionally graded hybrid square plates which are symmetric about its mid plane. The cutouts of various sizes and shapes located at the center of the plate are considered. The plate is subjected to positive and negative in-plane shear loads. The boundary conditions used are simply supported on all the four edges of the plate. Three stacking sequences are considered to investigate the optimum stacking sequence at which the critical buckling and first failure loads are highest. Functionally graded hybrid plates (FH) subjected to negative in-plane shear load is more effective compared to plates subjected to positive in-plane shear load. Diamond shaped cutout with small sized perforation has the highest critical buckling and first ply failure loads amongst the FH plates with cutouts. It is observed that the direction of applied in-plane shear load, fiber stacking sequence; cutout shape and size substantially influence the strength and failure characteristics of functionally graded hybrid composite plates.

First Ply Failure Analysis of Laminated Composite Beam for Different Boundary Conditions Under Thermo Mechanical Loading

Failure analysis of a laminated composite beam subjected to uniformly distributed load and thermal load is studied for different boundary conditions and fiber orientation angles, based on first ply failure load. Three different boundary conditions are studied: simply supported, fixed-fixed and fixed-free. The strength ratio is computed and compared for different failure theories. The effect of fiber orientation angle and aspect ratio on the strength ratio based on first ply failure load is presented in the paper. The strength ratio and transverse deflection are determined for Graphite/Epoxy and Glass/Epoxy composite and their hybrid combinations to find out the optimum hybrid composite beam with minimum weight, deflection and cost. The problem is solved in MATLAB platform. The mode of failure of the composite beam is determined by using maximum stress theory.