Progressive Failure Analysis Research Articles

Compressive failure analysis of composite honeycomb sandwich panels with impact damage and stepped-scarf repairs

Composite honeycomb sandwich panels (CHSPs) have been widely used in the aerospace industry owing to their lightweight and superior mechanical properties. However, these CHSPs are susceptible to impact damage, leading to a significant reduction in compressive strength and potentially jeopardize aircraft safety. It is crucial to investigate repair methods for CHSPs with impact damage. This paper aims to evaluate the repair performance of CHSPs with impact damage through an analysis of their compressive failure behaviors. To accomplish this, both experimental tests and advanced numerical models are employed. The numerical models for the intact, damaged and stepped-scarf repaired CHSPs are established using the progressive failure analysis model, cohesive zone model and sandwich plate theory. A good agreement is observed between the experimental results and numerical predictions of compressive failure behaviors. Moreover, the validated numerical models are successfully utilized for determining optimum repair parameters by parametric analysis of the repaired CHSPs. The establishment of these numerical models offers an accurate and cost-effective evaluation of repair performance for CHSPs with impact damage, highlighting the novelty and main contribution of this paper.

Experimental and numerical studies on compressive failure behaviors of stepped-scarf repaired composite stiffened panels

Composite materials have been widely used in aerospace and other fields due to their superior mechanical properties. The repair of composite structures has received increasing attention in recent decades. In this work, the compressive failure behaviors of intact, defective and stepped-scarf repaired composite stiffened panels are analyzed experimentally and numerically. The evaluation of repair schemes of composite stiffened panels based on finite element (FE) analysis is investigated by comparison with experimental results. The maximum absolute value of error in load-carrying capacity between the numerical and experimental results does not exceed 3.65%. Progressive failure analysis model and cohesive zone model are utilized to reveal the damage evolution of multilayered composites and adhesive film. The failure modes obtained from FE analysis are in good agreement with the experimental observations. Moreover, the influence of the stepped-scarf ratio and repair patch angle deviation on the compressive strength is investigated to determine optimum repair parameters based on the established FE models. On the basis of the conducted studies, the results provide valuable insights into the evaluation and validation of repair schemes for composite stiffened panels with high accuracy and cost-effectiveness.

Progressive failure analysis of z-pin reinforced composite pi joints

A finite element model of a z-pin reinforced composite pi joint has been developed and correlated against experimental results. A smeared cohesive zone modeling approach was implemented to represent the effect of z-pinning in an efficient and scalable manner. In the smeared approach, cohesive properties governing the traction–separation response of the z-pin reinforced areas were defined to account for the effective fracture toughness caused by z-pinning in an averaged sense. The crack band method was used to account for diffuse damage and failure in the weave of the pi preform. The damage in the preform developed due to delamination suppression caused by the z-pinning. The numerical model was calibrated using experimental data from pristine and defective z-pinned pi joints subjected to pull-off and side-bend loading. Comparisons of experimental and numerical results show good agreement in terms of structural response, critical loads, and failure modes.

Progressive Failure Analysis of Carbon Fiber Reinforced Polymer Composite with a Circular Notch by Varying Fiber Orientation

Progressive failure for Carbon Fiber Reinforced Polymer (CFRP) was computationally studied and analyzed using Hashin’s failure criteria. It was an interactive failure criterion having 4 separate modes of failure. 8 layers of plies were oriented at specific stacking sequences to create different laminates with dimensions being specified using the ASTM D5766 standard. A total of 7 types of laminate were modeled and simulated to predict the failure for each type under tensile loading. A circular notch was added in the center for the concentration of stress. The damage to the fiber and matrix propagated and failed the structure. Contour plot analyses showed failure progression of fibers and matrix around the circular notch. Results show that matrix failure most predominant and critical type of failure for most laminates. From the stress vs. strain curves, it was seen that the [0/90]4 cross-ply laminate showed the highest open-hole tensile strength.

Assessing elevated home slab retrofitting method for residential coastal buildings under hurricane loads

With an increase in the frequency and intensity of hurricanes in the United States, effective mitigation solutions should be considered by individuals and governments. This paper investigates the slab elevation retrofit method as a mitigation strategy for residential timber buildings to reduce structural damage and associated economic losses due to hurricane loads. More specifically, a holistic assessment was performed to compare the structural response for typical coastal residential buildings with and without slab elevation incorporated and assess the impact of this retrofitting scheme on the overall building performance. A detailed finite element model was generated for a typical archetype and was used to conduct dynamic analyses for various wind and flood load conditions. The results of the progressive failure analyses were then used to perform loss assessments based on the methodology of the HAZUS hurricane manual. Based on the results of this study, when implementing the slab elevation retrofit method, the damage and associated economic losses due to hurricane-induced loads were reduced. It was observed for all analysis cases that damage due to flood loading dominated the response and economic losses. A noticeable reduction in the recovery time (in days) was also obtained for the considered elevated structures.

Damage failure analysis of flexible-oriented three-dimensional woven composites with void defects: An experimental and numerical study

Three-dimensional woven structures have garnered significant interest due to their enhanced mechanical properties and structural integrity. This study delves into a detailed analysis of progressive damage failure in multi-structured, flexible-oriented three-dimensional woven composites (FO3DWC), with a specific focus on the effects of voids. Employing the flexible-oriented three-dimensional woven process (FO3DWP), four distinct structures were fabricated and subjected to uniaxial tensile tests. The study integrates an progressive damage failure model coupled with a random element selection method to investigate the effects of void defects on mechanical properties. The results show that significant variations occur in the strength of the L45135 structure due to the void defects, with a maximum decrease of up to 4.37% when the porosity is 5%. This research provides a quantitative understanding of how voids impact the mechanical performance of FO3DWC, offering valuable guidance for material design and application in various engineering fields.

A low-cost multiscale model with fiber/matrix interface for cryogenic composite storage tanks considering temperature effects based on self-consistent clustering analysis

Matrix (including interface) failure is a typical form of failure in the composite laminates for cryogenic storage tanks causing functionally useless of the structure. In this work, a low-cost multiscale model based on the Self-consistent Clustering Analysis (SCA) method is developed to predict the matrix failure process of the composite storage tanks. First, a reduced order model modeling method with fiber/matrix interfaces is proposed. Then, in conjunction with Progressive Failure Analysis (PFA), a reduced-order model is used to predict matrix failure and interface failure of the composites, mesh sensitivity analyses were carried out, and strength damage envelopes were obtained for unidirectional composites subjected to a combination of transverse stresses and in-plane shear. Compared with the prediction results of the Puck criterion, the errors in predicting damage strength for compressive-shear load and tensile-shear load do not exceed 10% and 30%, respectively. And finally, the thermal-mechanical load analysis of the composite storage tanks is carried out and the effect of homogenous temperature field and heterogenous temperature field on the load-bearing performance of the composite structure is analyzed. The method is proved to have good accuracy and to be very efficient. Its main feature is the ability to rapidly predict the stiffness and strength properties of composite structures under different environmental conditions, in agreement with experimental results, showing the potential to reduce the time and cost required for structural design.

Progressive failure analysis of perforated composite laminates considering nonlinear shear effect

Composites are widely used in high performance structures such as aerospace structures due to their excellent properties. The analysis of failure evolution of composite perforated structures by finite element simulation is of great significance for practical work as engineering composite structures often contain notches and voids. In this paper, the numerical simulation of failure evolution and failure modes of carbon fiber reinforced resin composite laminates with large openings was carried out. A UMAT subroutine was written based on the 3D Hashin-Ye failure criterion and progressive damage model theory. The characteristic length and viscosity coefficient were introduced into the model to reduce mesh dependency and improve computational convergence. The nonlinear shear constitutive relationship defined by the Ramberg–Osgood equation was introduced into the continuous damage degradation model. The effect of nonlinear shear on the failure evolution of laminates with different stacking sequence was studied.

Progressive failure analysis on composite structures using a wave based method

This research examines a Progressive Damage Model for laminated composites using a wave-based technique. Using conventional numerical methodologies, such studies may require a significant amount of CPU time. Compared to standard techniques, the approach proposed can provide a quick and cost-effective evaluation. This work presents a numerical approach for dealing with periodic media subjected to an impact load that can provide damage initiate and evolution. The proposed model is based on a hybrid formulation for the wave-damage interaction that describes wave scatterings, as well as a stress analysis of a composite structure subjected to an impact force. The failure analysis is carried out by identifying the damage location and then describing the modification of the material properties of the damaged elements using Hashin’s failure criteria and material property degradation rules. A comparison of stress distribution with results from the conventional finite element approach was performed in order to confirm the hybrid WFE/FE method, and good agreement was noted. Finally, an impact on a composite beam was studied. The evolution of the structural failure is presented. This article takes into consideration material degradation over time.

Piecewise damage model for SiC/SiC composites with multilevel experimental validation

Using multiscale and multidimensional data from experiments and advanced microscopic characterisation, a piecewise damage model for SiC/SiC composite structures has been proposed. First, the geometric information of the microstructure was acquired using scanning electron microscopy (SEM) and X-ray computed tomography (X-CT). High-precision and total-factor finite element models were established, and a piecewise damage model was introduced to simulate in detailing the initiation and propagation of damage. Subsequently, in-situ experiments using the digital image correlation method were conducted to capture the strain fields. After failure, the failure modes were observed and analysed by SEM and X-CT. In the piecewise damage model, observed failure modes were associated within the progressive failure analysis concretely. Combining the multisource data during and after loading, the validity and reliability of this damage model based on failure mechanisms are demonstrated in the accurate prediction of the properties, deformation and stress fields in multilevel structures of SiC/SiC composites.

Thermal-fluid-structure coupling progressive failure analysis for the type III composite cylinder under localized fire

Predicting the failure characteristics of composite cylinders under fire is the key to improve the fire resistance and safety of cylinders. However, the current thermal-mechanical coupled failure analysis methods for composite cylinders under fire have several limitations such as oversimplification of the cylinder dome's geometric model and the fire source. To solve these problems, a comprehensive three-dimensional thermal-fluid-structure coupling progressive failure analysis method is developed. This method encompasses a fully coupled conjugate heat transfer model, a FLUENT-ABAQUS data transfer method, and a progressive failure analysis model integrates the Hashin failure criterion and nonlinear damage evolution for fiber reinforced composites. The method is adopted to analyze the fire-resistant performance of a type Ⅲ cylinder to obtain the fire-resistant time, failure pressure and burst location of the cylinder, finding that the pattern of failure pressure depreciation correlates with the burst location of cylinder under localized fire. Besides, the influence of the glass-fiber/epoxy layer on the fire-resistant performance of the cylinder is discussed, demonstrating that even a thin layer of glass-fiber epoxy can significantly increase the fire resistance time of the cylinder.

1D higher-order theories for quasi-static progressive failure analysis of composites based on a full 3D Hashin orthotropic damage model

This work investigates the crack propagation in composites by adopting a novel full three-dimensional (3D) Hashin-based orthotropic damage model combined with higher-order one-dimensional (1D) finite elements based on the Carrera Unified Formulation (CUF). Previous literature has proven that CUF provides structural formulations with great accuracy and improved computational efficiency. Moreover, a Layer-Wise (LW) formulation can be implemented within the CUF framework, allowing an accurate description of the 3D stress state in composite laminate, representing crucial information for progressive failure analysis. A Newton–Raphson predictor–corrector algorithm is used for the numerical solution of classical case tests, i.e., compact tension and three-point bending tests. The obtained results are compared with experimental outcomes and with solutions from well-established 2D damage models and a 3D Abaqus numerical model, demonstrating the capability of the proposed method to efficiently capture both the failure load and shape of the crack pattern.

Embedding deep neural network in enhanced Schapery theory for progressive failure analysis of fiber reinforced laminates

Abstract Computational progressive failure analysis of carbon fiber reinforced polymer composite is of vital importance in the verification and validation process of the structural integrity and damage tolerance of modern lightweight aeronautical structures. Enhanced Schapery theory (EST) has been developed and applied to predict the damage pattern and load-bearing capacity of various composite structures. In this paper, EST is enhanced by a deep neural network (DNN) model, which enables fast and accurate predictions of matrix cracking angles under arbitrary stress states of any composite laminate. The DNN model is trained by TensorFlow based on data generated by a damage initiation criterion, which originates from the Mohr–Coulomb failure theory. The EST-DNN model is applied to open-hole tension/compression problems. The results from the EST-DNN model are obtained with no loss in accuracy. The results presented combine the efficient and accurate predicting capabilities brought by machine learning tools and the robustness and user-friendliness of the EST finite element model.

A Multi-Scenario analysis method for collapse risks due to initial local failure of building structures

Traditional progressive failure analysis is usually computationally expensive and can only be used to analyze a limited number of cases. The resulting mechanical data on structural components are not suitable for displaying collapses or providing an intuitive reference for emergency management. In addition, numerical models do not incorporate uncertain factors in failure development, which makes it difficult to deduce multiple scenarios of future. This paper proposes a multi-scenario progressive failure analysis method based on a sub-region model for emergency management. Firstly, the material model is augmented with a possibility factor to evaluate the failure of components based on internal forces, and thereby deduce different progressive collapse scenarios. Secondly, the building structure is divided into several sub-regions based on the damage correlation of components, so that the degree of regional collapse can be demonstrated at a more macroscopic scale, which is more suitable for emergency management. By analyzing typical failure scenarios, the collapse evolution rules at the sub-region level can be summarized, which can be used for deducing the results of multiple collapse scenarios rapidly. The proposed method can identify the weak positions of buildings, deduce highly probable progressive damage scenarios, and exhibit macro collapse processes. The multi-scenario analysis results can serve as a reference for collapse safety management in risk pre-assessment and help to reconstruct the collapse process in post-disaster analysis.

Multi-scale progressive failure analysis of shear deformed woven fabric composites considering its pre-forming process

Multi-scale progressive failure analysis of shear deformed woven fabric composites considering its pre-forming process

Progressive failure analysis of soil slopes considering the influences of humidity and loading

To analyze the progressive failure of structural loess slopes due to changes in humidity and loading, this study analyzes the degrees of influence of these changes on slope failure and their relationships with various structural parameters. According to the analysis, the shear failure of the soil gradually develops with the change of the water content. When the water content reaches a 17%, with the development of shear deformation, the shear zone is formed and finally penetrates the soil body. With the increase of the water content, the total displacement of the slope body gradually develops. When the water content reaches 17%, the total displacement of the slope body changes suddenly. This mutation is consistent with the formation of the shear zone. The sudden change of displacement indicates the penetration of the shear zone and the damage and slippage of the slope. With the increase of the soil moisture of the slope, the strain localization phenomenon occurs, the development of strain localization and shear bands increases, the structural damage increases, and the quantitative structural parameters decrease. The quantitative parameters can therefore be used to evaluate the feasibility and rationality of the progressive failure process of homogeneous structural loess slopes.

Low-velocity impact behaviours of sandwiches manufactured from fully carbon fiber composite for different cell types and compression behaviours for different core types

Abstract This study aims to manufacture sandwich composite structures consisting of fully fiber-reinforced composites and then to investigate experimentally and numerically the impact and compressive strength and damage mechanisms of these structures for different cell and core types. To achieve this, firstly, composite sandwich plates with triangular, square and rectangular cell structures were manufactured. Low-velocity impact tests were run on sandwich structures with these three different cell geometries and the effect of cell shape on impact strength was determined. Although the maximum contact force of the square structure under impact load was smaller than the maximum contact force of the triangular and rectangular specimens, the specific contact force was 15.52 % greater than the triangular specimen and 16.29 % greater than the rectangular specimen. Then, the specimens with square, egg box and lattice core types were manufactured and compression tests were performed. The specific peak load value for square specimens was 33.2 % greater than that of egg box specimens and 78.1 % greater than that of lattice specimens. In the numerical study, the experimental results were confirmed by applying the progressive failure analysis with the LS-DYNA finite element program.

Progressive Failure Analysis of Composite Overwrapped Pressure Vessel

Stress and progressive failure analysis (First Ply Failure to Last Ply Failure) of a composite overwrapped pressure vessel (COPV) with an aluminum liner using the finite element method (FEM) in general and commercial finite element analysis (FEA) software ANSYS in particular is presented in this paper. Ply failure prediction is based on failure criteria implemented in ANSYS software. The first-ply failure (FPF) does not necessarily imply the total failure of a laminate. After FPF, the laminate stiffness is reduced consistent with identified ply failure mode. The strength of the composite laminate is evaluated again to see if it could carry additional load. This ply-by-ply analysis progresses, until the ultimate strength is reached. In the present study the methodology is validated using benchmarks and applied to a filament wound fibre reinforced plastic composite pressure vessel with an aluminum liner. Significant results are presented and critically assessed. Directions for further work in this field are identified.

Strength Prediction and Damage Assessment of Laminated Composite Plates With Rectangular/Square Cutout Using Finite Element Method

The progressive failure analysis of symmetrically laminated rectangular composite plate [0/+45/-45/90]2s with square/rectangular cutout under uniform uniaxial compression loading is carried out using finite element method. Hashins failure criterion is used to predict the failure of lamina. A parametric study has been carried out to study the influence of square/rectangular cutout size, cutout orientation and plate thickness on the ultimate failure load of laminated composite plate under uni-axial compression loading. Ultimate failure loads were computed for six different laminate configurations [0/+45/-45/90]2s, [75/-60/30/-15]2s, [0/90]4s, [-45/45]4s, [15/-75]4s, [30/-60]4s. It is observed that the laminate stacking sequence, plate thickness , cutout size and cutout orientation has substantial influence on the ultimate failure load of notched composite plates.

Experimental and numerical study on the dry/wet burst failure of reinforced thermoplastic pipes

AbstractThis paper investigates the burst failure of reinforced thermoplastic pipes (RTPs) via combined experimental and numerical research. Two completely different burst forms appeared during the experiments. The dry burst form occurs with matrix cracks, fiber breakage and crack of liner and coating, which is a common burst morphology. A new burst morphology, which is never reported in open literature, is observed in the experiments. This burst morphology, defined as wet burst form, presents a long dent in the coating and invisible composite damage. In order to simulate the burst failure of RTPs, a numerical model was proposed, in which element removal criteria and the nonlinear stiffness degradation model based on Hashin‐Yeh failure criterion were employed to conduct progressive failure analysis on 3D composites. It was found that the wet burst form has lower burst pressure and causes larger damaged area, which is more dangerous in engineering. For the damage propagation, progressive failure occurs on middle composites and induces the final burst when the dry burst form occurs. As for the wet burst form, water flows into the middle of RTPs, which causes the delamination, matrix crack and bulge of coating. During the process, fibers play few roles in bearing loads.Highlights The wet burst form of reinforced thermoplastic pipes is firstly observed. Element removal criteria and nonlinear stiffness degradation model were used to simulate the burst failure. The numerical model has a good performance on predicting the burst pressure and damage propagation of composites. The wet burst form has lower burst pressure compared with the dry burst form. Fiber and matrix tensile failure mode are dominant.