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Special Issue: Advanced Modeling and Design for Composite Materials and Structures

Dear Colleagues of the composite community,

Our first Special Issue are already published on Applied Composite Materials as Volume 30, issue 4:

Applied Composite Materials | Volume 30, issue 4 (

Full article list are provided here:


1. Special Issue: Advanced Modeling and Design for Composite Materials and Structures

Editorial Notes by Yucheng Zhong, Tao Wu, Guangyong Sun, Aleksandr Cherniaev, René Alderliesten

2. Strength Prediction of Quasi-Isotropic Scaled Laminates in Open Hole Tension Using Damage Rate Bound Mesomodel

A. Rajaneesh, J. P. Ponthot, M. Bruyneel

Abstract: The open hole tension (OHT) test is one of the standard composite material qualification tests at the coupon level. Predicting OHT strengths using finite element models is essential to minimize the number of tests and associated costs. Present article demonstrates the tensile strength prediction of OHT specimens using Ladevèze (LMT-Cachan) mesomodel in conjunction with damage rate bound (DRB) based delay damage. Intra-laminar ply failure and interface failure are taken into account in the current research. These intraply and interface models are coded as user subroutines in LS-Dyna explicit commercial solver. Matrix in-situ strengths are used to account for ply thickness effects in the finite element simulations. Effect of ply, sub-laminate or in-plane scaling effects on OHT strength are investigated. A calibration procedure for the DRB delay damage constants is proposed. The robustness of the DRB delay damage is evaluated in mitigating mesh size effects by considering two types of mesh topologies. All the test data is taken from the scientific literature. Comparison between tests and present finite element predictions is made in terms of failure stress, failure modes and damage sequence events. Predictions from current finite element models matched well in the matrix or delamination failure mode dominated test cases. A reasonably acceptable agreement was observed in test cases with fiber dominant failure.

3. Residual Compressive Strength of Aluminum Honeycomb Sandwich Structures with CFRP Face Sheets after Low-velocity Impact

Jun Wang, Chen Wang, Ruifang Chen, Chao Zhang

Abstract: Composite sandwich structures are sensitive to low velocity impact (LVI) occasions and the induced damage significantly reduces the residual load-bearing capacity of material structures. In this work, a nonlinear finite element (FE) model is proposed to investigate the buckling and damage behavior of aluminum honeycomb sandwich structures with CFRP face sheets under compression-after-impact (CAI). Johnson-Cook model is applied to identify the damage of aluminum honeycomb core; cohesive elements governed by bilinear traction-separation constitutive model are implemented to describe the inter-laminar delamination induced by LVI and CAI. The numerical results are in good agreement with the available experimental data, which verifies the effectiveness of the proposed FE model. The effects of impact energy and core parameters on the impact performance and residual compressive strength of sandwich structures are analyzed in detail and the energy absorption properties during the corresponding loading are examined. The numerical results show that slight impact damage can also greatly reduce the CAI strength. Besides, the parameters of core have an important influence on the stiffness and CAI strength of sandwich panel.

4. Fully Predictive Micro-mechanical Modelling for Shear Viscosities of Continuous Fiber Reinforced Polymer Composites

Jinhuo Wang, Yang Han, Xiaohong Ge, Zhengbing Qi, Jun Zhao, Rongwen Wang, Huawei Wu, Taiping Han, Shaoxun Sun, Hui Wang, Jia Lin, Yuejun Liu, Xiangsong Kong, Qiming Chen, Xiangxu Zeng

Abstract: Optimisation design of composite structures requires an accurate predictive model for forming behaviour. The simulation process contains a number of model parameters which include transverse and longitudinal viscosities of continuous fibre reinforced viscous composites, fundamental to predicting the shear rheology. Micromechanical interaction between fibre and matrix offers fundamental understanding of deformation mechanisms at the micro-scale level, leading to development of the fully predictive composite viscosity models, so as to eliminate any time-consuming experimental characterisation. The composite viscosity models were developed based on rheological behaviour during movement of fibres, and validation was performed using experimental results collected from the literature, indicating reasonably good agreement with the lower bound of the test data. It is suggested that non-Newtonian effects (rate dependency), viscoelastic effects and fibre rearrangement during shearing should be considered in the models to resolve the underestimation problem.

5. Fatigue Life Evaluation of Offshore Composite Wind Turbine Blades at Zhoushan Islands of China Using Wind Site Data

P. F. Liu, H. Y. Chen, T. Wu, J. W. Liu, J. X. Leng, C. Z. Wang, L. Jiao

Abstract: As fruitful clean energy, offshore wind turbine power develops rapidly at the coastal area of China that contributes to enabling carbon neutralization. However, the cyclic change of climatic conditions inevitably leads to fatigue issue of wind turbine. This paper makes a survey on the climate condition at Jintang island, Zhoushan islands, China within one year to perform fatigue analysis of in-service composite wind turbine blades. First, the wind velocity rose diagram measured at Jintang island is obtained by investigation, which is used to calculate the wind pressure under some wind velocity and the corresponding direction and frequency, by combining with the modified blade element momentum (BEM) theory. Second, finite element analysis (FEA) of the full-scale composite blade under different wind velocity is performed, where it is almost the first time to introduce the damage model of composites to predict progressive failure properties and stress distributions of composite skin for fatigue analysis. Finally, the fatigue life for blade with three kinds of composite materials for skin is evaluated comparatively by combining with the rainflow counting method, the S–N fatigue curve and the cumulative damage principle. Numerical results show that the fatigue life of blades with three kinds of materials for skin falls within 19–22 years, consistent with the design value of blade in China.

6. Experimental and Finite Element Simulation of Torsional Performance of Skin-core Carbon Fiber-reinforced Composite Rod

Qian Jiang, Heng Chen, Ling Chen, Zhiyan Zhong, Xianyan Wu, Honglei Yi, Liwei Wu

Abstract: For decades, carbon fiber-reinforced composite rods (CFRPRs) have exhibited the advantages of high specific strength, high specific modulus, corrosion resistance and low density, which are widely applied in the aerospace and automotive industries. In this study, a type of skin-core composite rod (SCCR) was manufactured through vacuum-assisted resin infusion technology, and the skin is a two-dimensional (2D) carbon fiber braided tube while the core is unidirectional carbon fiber. Both torsion experiment and full-size mesoscopic numerical simulation were conducted to investigate the special structure effect of SCCR. The results demonstrate that ductile failure mechanism dominates in SCCR, and the extension cracking occurs in the matrix along the direction of braiding yarn while the braiding yarns mainly experience tensile and shear damage. Under the same torsion angle, the damage degree of the resin structure (RS) and braiding structure (BS) is intensified with the braiding angle. With the increase of the braiding angle, the maximum stress of the rods increases, while the BS failure torsion angle decreases. The average stress of the middle section of BS is 234.08, 239.78, and 257.93 MPa corresponding to the braiding angle of 24°, 27°, and 30°, and the critical failure torsion angle is 209°, 199°, and 189°. The path stress of the braiding yarn fluctuates at 5 MPa and the position of the stress fluctuation increases with the braiding angle. This study reveals the unique bearing and damage mechanisms of skin-core composite rod, and provides the theoretical and experimental basis for the design of composite rod.

7. Numerical Study on Damage Behavior of Fiber-Metal Laminates Subjected to High Velocity Fragments Impact

Chao Zhang, Yuefeng Gu, Pibo Ma, Diantang Zhang

Abstract: Fiber metal laminates (FMLs) are widely used in a variety of protective structures due to their excellent impact resistance. In the present work, a nonlinear finite element (FE) model is developed to investigate the damage behavior of carbon fiber reinforced aluminum laminates (CRALLs) under high velocity fragments impact. The strain rate effect of composite ply is involved and the intra-laminar damage is predicted based on 3D Hashin criteria; Johnson-cook model is employed to simulate the high velocity fragments impact response of aluminum layer; cohesive elements are introduced to describe the inter-laminar delamination phenomena. The proposed FE model is verified with the available experimental data in ballistic impact condition and then implemented to predict the fragments impact behavior of FMLs. The dynamic response and damage mechanism of FMLs are analyzed and the effects of explosion distance, explosion mass and impact angle on the impact performance are discussed in detail.

8. Experiments and Simulations on the Shape Memory Process of Thermally-Induced Shape Memory Polymer Composite Thin-Wall Structure Considering Progressive Damage

Tianyang Yang, Wujun Chen, Guangqiang Fang, Zhengli Cao, Bing Zhao, Xiaozhao Zhang

Abstract: As a deployable mechanism and structural integrated component, the shape memory polymer composites (SMPCs) will inevitably be damaged during folding and storage. However, damage effects on the shape memory behaviour of the SMPCs lack thoroughly investigations. This article aims to research the entire shape memory process of the SMPCs with the consideration of progressive damage. Firstly, uniaxial tensile tests and DMA tests with three-point bending mode are conducted to obtain basic mechanical properties and shape memory capabilities of the SMPCs. A 5 cm-long SMPCs thin-wall tube is subsequently applied in radial flattening and shape recovery experiments. The thin-wall tube’s damage state and shape recovery process are investigated and evaluated in detail. The Von-Mises and 3-D Hashin’s failure criteria are applied on damage evaluation of pure polymer matrix and yarns, respectively. As a result, a homogenized stiffness degradation model was developed through multi-scale analysis method. The homogenized progressive damage model is combined with the shape memory constitutive equation based on phase transition theory to form a simplified algorithm to accurately describe the mechanical behaviour of the SMPCs in the shape memory process. The algorithm is implemented by user subroutine UMAT of finite element analysis packages Abaqus. It is verified that the proposed algorithm could accurately describe the mechanical behaviour for the SMPCs in entire shape memory process.

9. Low-Velocity Impact and Residual Compression Performance of Carbon Fiber Reinforced Composite Stiffened Plates

Jianan Cui, Shi Yan, Yun Zhao, Lili Jiang

Abstract: In this work, compression tests after impact and numerical simulation are combined to study bearing capacity and failure mode of carbon fiber reinforced composite grid plates with reinforcing stiffeners after being impacted at different positions. The mechanism of impact damage formation of composite stiffened plates and the damage propagation and extension process under compressive load are analysed. The results show that when there is no stiffener below the impact position, the main impact failure modes are fibre fracture and internal delamination of the skin, which have little effect on the bearing capacity of the structure; when the impact position is above the stiffener, the primary failure mode is the stiffener’s debonding from the skin, which will lower the remaining bearing capacity of the structure severely.

10. Prediction of Equivalent Elastic Modulus for Metal-Coated Lattice Based on Machine Learning

Yuzhe Liu, Feifan Sun, Min Chen, Jimin Xiao, Ji Li, Bin Wu

Abstract: As additive manufacturing and electroplating technique have progressed, metal-coated lattice material has wide applications due to its lightweight nature and designability. The resin matrix coated with metallic material may enhance mechanical performances while with economic cost and additional conductivity. However, a quick evaluation of equivalent material properties of metal-coated lattices is a challenging task due to the various geometric designs and coating parameters. In this paper, a numerical prediction approach is proposed with the combination of data acquisition from Finite Element Analysis (FEA) and the Machine Learning (ML) models. Firstly, a finite element model with hybrid solid and membrane elements was adopted to simulate the metal-coated lattice structure. Based on the homogenization theory, appropriate boundary conditions were defined for the Representative Volume Element (RVE) to evaluate the effective elastic modulus. With the limited numerical results, data amplification was implemented by using Polynomial Regression (PR). Finally, different ML algorithms were investigated. Artificial Neural Network (ANN) was verified as an efficient one with better prediction accuracy 99.97% for 4 variables. The proposed approach could give a reasonable property evaluation of metal-coated lattices avoiding repetitive tests and provide a feasible reference for the lattice design.

11. An Artificial Neural Network-based Approach to Predict the R-curve of Composite DCB Multidirectional Laminates

Dingli Tian, Yu Gong, Luohuan Zou, Libin Zhao, Jianyu Zhang, Ning Hu

Abstract: An artificial neural network-based approach is used to determine the R-curve of multidirectional laminates. The main idea of the approach is to extract the hidden information of the R-curve from the load-displacement curve of mode I delamination test while without measuring the delamination growth length. In order to obtain the training data set, R-curve is randomly generated, and then the corresponding load-displacement curve is obtained through finite element simulation. A bilinear cohesive constitutive law taking into account the R-curve is used, which has been shown to reproduce well the experiments. After training the neural network with simulated data, the load-displacement data are then taken as the input of the artificial neural network, and the description parameters of R-curve are the output. The predicted R-curves from the trained neural network are consistent with experimental results of composite laminates with different material systems and interfaces. The bridging stress and load-displacement response also agree well with experimental results. All these demonstrate applicability of the proposed approach.

12. Fatigue Life Prediction Method of Ceramic Matrix Composites Based on Artificial Neural Network

Hui Qian, Jincheng Zheng, Yusheng Wang, Dong Jiang

Abstract: Ceramic matrix composites have been widely applied in the aerospace field due to the excellent mechanical properties. However, the complex microstructure and failure mechanism bring great difficulties to the fatigue life analysis. Aiming at the problems that mesoscopic mechanical model and macroscopic phenomenological model requires a large amount of experimental data and the model parameters are difficult to obtain, a fatigue life analysis method for composites materials based on Artificial Neural Network (ANN) is proposed. In the neural network, material parameters and loading parameters are used as inputs, and fatigue life is used as output to build a model of the relationship between input parameters and fatigue life. Comparative investigation of different neural networks in the fatigue life prediction of two-dimensional braided ceramic matrix composites under the condition of small samples are investigated. Results show that Elman Network (ENN) and Convolutional Neural Network (CNN) can obtain high-precision prediction results under different training data volumes when using simulation data sets. The prediction accuracy decreases with the reduction of data volume, while the prediction accuracy of Generalized Regression Neural Network (GRNN) is difficult to meet the requirements. Taking the experimental data from literature as the data set, ENN and CNN are used for training, and good prediction are obtained under the condition of using only 4 S-N curves as the training set.

13. Numerical Simulation of Composite Material Light-Curing Process Based on the Finite Element Analysis Method

Jiazhong Xu, Yue Jiang, Meijun Liu, Xiaobing Zhang, Hao Zhang

Abstract: Compared to the traditional thermal curing method, ultraviolet light-curing can effectively avoid the problems of long curing time and complicated curing equipment. In this paper, a geometric and physical model of the light-curing process of the glass fiber reinforced composite multilayer laminate is established based on the theory of optics and curing kinetics, considering the propagation of ultraviolet light in the laminate is affected by the interlayer during the light-curing process. The meta-analysis method is adopted to calculate and predict the changes in the curing degree, temperature, and stress fields during the light-curing process of glass fiber composites, which also analyzes and summarizes the multi-field distribution and its variation law during the process. By comparing the experimental data with the predicted results, the model's accuracy is verified, and the causes of errors are analyzed, providing an efficient analysis method to investigate the composite light-curing.

14. A Computational Study of Stentering Process of 3D Mesh Fabric

Fei Zheng, Xia Liu, Jing Huang, Yanping Liu

Abstract: Three-dimensional (3D) mesh fabric has a one-piece sandwich structure, consisting of two separate outer layers linked together with a layer of spacer monofilaments. Its intermeshed monofilament architecture provides excellent cushioning and ventilation properties, making the 3D mesh fabric ideal for ventilated car seats. This paper presents a computational study to examine how stentering affects the mesh and monofilament structure of a typical 3D mesh fabric. Experimentally validated finite element (FE) models of the fabric stentering process and its compression following stentering were developed. The structural changes of the fabric in the stentering process were quantitatively analysed in terms of global fabric deformation, mesh deformation, and spacer monofilament deformation. The numerical and experimental results indicate that stentering opens up the meshes differently across the width, with the intermediate mesh being more open and uniform than the two selvage meshes. Stentering sufficiently is essential for obtaining a 3D mesh fabric with uniform meshes. Two adjacent wales of spacer monofilaments are inclined and twisted symmetrically in the stentering process. After stentering, the 3D mesh fabric has more inclined, twisted, and sparse spacer monofilaments, which reduces its compression resistance. By utilising different stentering ratios, 3D mesh fabrics can be engineered to form various monofilament architectures to suit a variety of different applications.

15. The Effects of Curing Process on the Damage Behavior of Additively Manufactured Fiber-Reinforced Thermosetting Composites

Sina Niazi, Aimane Najmeddine, Maryam Shakiba

Abstract: This work investigates the effects of high-temperature curing processes on the stress–strain and failure responses of additively manufactured aligned discontinuous fiber-reinforced composites (DFRCs). A micromechanical framework is used for finite element simulation of damage and failure in the three-dimensional (3-D) representation of DFRCs under mechanical and thermal loadings. Accurate constitutive equations are utilized to explicitly consider the fibers, matrix, and fiber/matrix interfaces within the composite’s microstructure. The coupled thermo-mechanical analysis available on the commercial nonlinear finite element software ABAQUS is used to accurately simulate the response of the studied DFRC when exposed to different curing temperatures and mechanical loading. All material and geometrical parameters of the microstructural representation are defined based on a recently developed 3-D printed aligned discontinuous fiber-reinforced thermosetting polymer. The curing-induced thermal residual stresses and damage are then simulated and validated against the experimental data. The effects of different curing processes on the initiation and propagation of different damage types and on the stress–strain response up to and including final failure are predicted. Also, the impact of the perfect versus cohesive interfacial bonding on the DFRC’s performance is examined. This work reveals that the DFRCs’ responses are significantly affected when residual thermal stresses due to curing are considered, providing guidance for better design, manufacturing, and analysis of such composites.

16. Design and Assessments of Gradient Chamfer Trigger for Enhancing Energy-Absorption of CFRP Square Tube

Tao Ran, Yiru Ren, Hongyong Jiang

Abstract: It is proposed to use the gradient chamfer trigger method to explore the axial crush response phenomenon of Carbon fiber reinforced plastic (CFRP) composite materials square tube. A reliable non-linear progressive damage failure model based on numerical simulation method is established for verification and parameter evaluation. The discrepancy in the crush response between the tube of gradient trigger (GT) and uniform thickness (UT) reveals the exceptional amelioration effect of GT design on the crush behavior of the composite tube. Through the parameters analysis of the trigger chamfer of each layer, the gradient distance and the layer number of GT, the improvement mechanism of the GT design is extensively revealed. Numerical results show that the gradient chamfer-triggered interlayer distance has the most significant improvement in energy absorption when the structural collapse process exhibits stable progressive failure behavior. And the specific energy absorption of GT structure also showed an upward trend when the number of layers triggered by gradient chamfering increased. When the chamfer angle of the inner layer of the GT structure is smaller than that of the outer layer, it is most beneficial to improve the specific energy absorption.

17. Tolerance Optimization of Patch Parameters for Locally Reinforced Composite Structures

Michael Franz, Sandro Wartzack

Abstract: A rising number of applications and increasing volume of composite structures production lead to a high relevance of variation management during their design. Structural optimization for lightweight purposes often results in designs consisting of a base laminate with local reinforcement patches. Nominally, these optimized designs offer a thorough exploitation of lightweight potential. Yet, they suffer from variations of the reinforcements resulting in a worsened manufacturing behavior and reduced structural performance. To ensure the quality, tolerances should be allocated for the parameters of the local reinforcement patches. Therefore, in the current contribution a tolerance optimization method is presented identifying optimal tolerance values for the design parameters of the reinforcements with respect to the structural behavior. This includes the discussion of challenges regarding the suitable parametrization and modeling of local reinforcement patches for variation simulation based on Finite Element Analysis (FEA), the usage of surrogate modeling to reduce the computational effort of structural analyses, as well as an approach to penalize tight tolerances of different parameter types. The proposed tolerance optimization is applied to a use case. Tolerances for the patch parameters are optimized, meeting the structural quality constraints of the composite structure.

18. A New Composite Leaf Spring for In-Board Bogie of New Generation High-Speed Trains

Xutong Zhang, Junfeng Hu, Yifan Wang, Dingding Chen, Siqi Zhang, Rui Qian, Yinyuan Huang, Felix Thompson, Jingxuan Ma, Wenlong Lu, Qingji Cui

Abstract: The in-board bogie is designed to be applied in next-generation China railway high-speed trains to further achieve lightweight and higher speed (400 km/h). Traditional steel coil springs could not be used in the in-board bogie due to strict lightweight requirements and narrow installation space. This research aims to propose a buckle-type composite leaf spring assembly to replace the traditional steel coil springs. Meanwhile, the buckle-type leaf spring assembly is needed to meet specific size (length and width less than 720 mm and 120 mm) and performance requirements (ultimate load over 100 kN, vertical stiffness around 1300 N/mm) for the primary suspension. Static and dynamic flexural experiments, as well as relevant finite element method (FEM) analysis were carried out to explore the mechanical properties of the composite leaf springs assembly. Simulation results show that the maximum stress of the leaf spring body under the rated load and ultimate load is 314.6 MPa and 488.1 MPa, respectively. The vertical stiffness of the composite leaf spring assembly from numerical simulation is 1362.3 N/mm, which is consistent with that from the static flexural test (1350.4 N/mm). Experimental results revealed that the vertical stiffness of the composite leaf spring was decreased by 1.06% and 1.32% compared to its initial stiffness after one and two million cycles of cyclic flexural load, respectively, and a slight matrix damage was observed in the leaf spring body. Therefore, this buckle-type composite leaf spring assembly meets the design requirements, and can ensure a safe and smooth operation of high-speed trains.



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