Pub Date : 2025-04-04DOI: 10.1016/j.compstruct.2025.119150
Zhongliang Cao , Yang Zhang , Xianfeng Wang , Chen Liu
This study focuses on the layup design of composite blades to enhance the mechanical properties of blades by adjusting the layup angle. The objective is to apply a generalised regression neural network (GRNN) to construct a surrogate model for multi-objective optimisation of composite blades. Four objectives are considered: the maximum displacement of the blade tip (to be minimised) and three metrics measuring the difference between the intrinsic frequency and the excitation frequency, called ‘resonance margin’ (to be maximised). Most of the lay-up angles of the composite blade are fixed and only two directions are considered as variables. Subsequently, the study incorporates the Non-dominated Sequential Genetic Algorithm II (NSGA-II) for multi-objective optimisation. The optimisation scheme achieves a dual enhancement of blade stiffness and resonance margin. After optimisation, the maximum displacement of the blade tip is reduced by about 32% compared with the pre-optimisation. The first three resonance margins are improved, especially the second order resonance margin is increased from 8.15% to 35.18%. The R value of the GRNN model of the blade is greater than 0.95. The high-precision surrogate model achieves accurate prediction of the mechanical properties of the blade. The trade-off of various properties of composite blades was achieved by NSGA-II algorithm.
{"title":"Optimisation of large-Scale composite blade layup using coupled finite element method and machine learning","authors":"Zhongliang Cao , Yang Zhang , Xianfeng Wang , Chen Liu","doi":"10.1016/j.compstruct.2025.119150","DOIUrl":"10.1016/j.compstruct.2025.119150","url":null,"abstract":"<div><div>This study focuses on the layup design of composite blades to enhance the mechanical properties of blades by adjusting the layup angle. The objective is to apply a generalised regression neural network (GRNN) to construct a surrogate model for multi-objective optimisation of composite blades. Four objectives are considered: the maximum displacement of the blade tip (to be minimised) and three metrics measuring the difference between the intrinsic frequency and the excitation frequency, called ‘resonance margin’ (to be maximised). Most of the lay-up angles of the composite blade are fixed and only two directions are considered as variables. Subsequently, the study incorporates the Non-dominated Sequential Genetic Algorithm II (NSGA-II) for multi-objective optimisation. The optimisation scheme achieves a dual enhancement of blade stiffness and resonance margin. After optimisation, the maximum displacement of the blade tip is reduced by about 32% compared with the pre-optimisation. The first three resonance margins are improved, especially the second order resonance margin is increased from 8.15% to 35.18%. The R<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> value of the GRNN model of the blade is greater than 0.95. The high-precision surrogate model achieves accurate prediction of the mechanical properties of the blade. The trade-off of various properties of composite blades was achieved by NSGA-II algorithm.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119150"},"PeriodicalIF":6.3,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-04DOI: 10.1016/j.compstruct.2025.119162
Jaeho Yun , Seungjun Ryu , Jinsol Kim , Yongha Kim , Do-Won Kim
An equivalent model is proposed for the prediction of the mechanical behaviors of a honeycomb core with thick cell walls, including the calculation of failure strength. The method was derived from the homogeneous method used to investigate the mechanical behaviors of composite sandwich structures. We validated the method’s utility through the finite element method and experimentally. A parametric analysis was performed to examine the mechanical properties of a composite sandwich structure with thick cell walls using the proposed method. These results were used to compile information about the mechanical characteristics of the structure for aerospace applications. In conclusion, the method is demonstrated to be well suited for its intended applications due to its relative simplicity and computational efficiency.
{"title":"Equivalent modeling for the prediction of mechanical behaviors of composite sandwich structures with thick cell walls","authors":"Jaeho Yun , Seungjun Ryu , Jinsol Kim , Yongha Kim , Do-Won Kim","doi":"10.1016/j.compstruct.2025.119162","DOIUrl":"10.1016/j.compstruct.2025.119162","url":null,"abstract":"<div><div>An equivalent model is proposed for the prediction of the mechanical behaviors of a honeycomb core with thick cell walls, including the calculation of failure strength. The method was derived from the homogeneous method used to investigate the mechanical behaviors of composite sandwich structures. We validated the method’s utility through the finite element method and experimentally. A parametric analysis was performed to examine the mechanical properties of a composite sandwich structure with thick cell walls using the proposed method. These results were used to compile information about the mechanical characteristics of the structure for aerospace applications. In conclusion, the method is demonstrated to be well suited for its intended applications due to its relative simplicity and computational efficiency.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119162"},"PeriodicalIF":6.3,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-03DOI: 10.1016/j.compstruct.2025.119121
Karthik Venkatesan, Boyang Chen
Damage pattern predictions of open-hole laminates under different loading conditions are ubiquitous in the finite element modelling of composite structures. This work investigated the applicability of artificial neural networks for the fast and accurate generation of damage patterns for a composite plate with a cut-out under a variety of loading conditions. The purpose is to explore the neural networks as surrogate models capable of returning damage pattern predictions on par with a finite element model, but requiring less computational effort at run time. Data for training and evaluating these neural networks was generated through nonlinear finite element models. Different neural networks, such as a standard Feedforward Neural Network and a Hybrid Neural Network that combines a Feedforward Neural Network with a convolutional decoder, have been tested for this task. To quantify the resemblance between the predicted and actual outputs in terms of colours and contours, different performance metrics have been explored. The use of the Structural Similarity Index (SSIM), in addition to the standard Mean Square Error (MSE), was explored to improve the visual quality of outputs from the neural network. With an average test MSE of 0.0014, SSIM of 0.9814, and computational speedup factor of 34, the Hybrid Neural Network has been shown to accurately and efficiently predict the damage patterns of the open-hole laminate, thereby constituting a promising candidate for a surrogate model of open-hole composite panels.
{"title":"Hybrid neural network for the prediction of damage patterns in open-hole composites","authors":"Karthik Venkatesan, Boyang Chen","doi":"10.1016/j.compstruct.2025.119121","DOIUrl":"10.1016/j.compstruct.2025.119121","url":null,"abstract":"<div><div>Damage pattern predictions of open-hole laminates under different loading conditions are ubiquitous in the finite element modelling of composite structures. This work investigated the applicability of artificial neural networks for the fast and accurate generation of damage patterns for a composite plate with a cut-out under a variety of loading conditions. The purpose is to explore the neural networks as surrogate models capable of returning damage pattern predictions on par with a finite element model, but requiring less computational effort at run time. Data for training and evaluating these neural networks was generated through nonlinear finite element models. Different neural networks, such as a standard Feedforward Neural Network and a Hybrid Neural Network that combines a Feedforward Neural Network with a convolutional decoder, have been tested for this task. To quantify the resemblance between the predicted and actual outputs in terms of colours and contours, different performance metrics have been explored. The use of the Structural Similarity Index (SSIM), in addition to the standard Mean Square Error (MSE), was explored to improve the visual quality of outputs from the neural network. With an average test MSE of 0.0014, SSIM of 0.9814, and computational speedup factor of 34, the Hybrid Neural Network has been shown to accurately and efficiently predict the damage patterns of the open-hole laminate, thereby constituting a promising candidate for a surrogate model of open-hole composite panels.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119121"},"PeriodicalIF":6.3,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-03DOI: 10.1016/j.compstruct.2025.119167
K. Tian , J. Zhi , V.B.C. Tan , T.E. Tay
This paper presents a comparative study of implicit and explicit finite element methods in simulating open hole compression (OHC) failure in composite laminates, employing the Discrete Crack Method (DCM) with the Floating Node Method (FNM) for enhanced accuracy in matrix crack modeling. The finite element models are built upon experimental OHC tests of carbon fiber/epoxy laminates with both ply-level and sub-laminate scaling. The models are validated through a series of simulations studying the effects of hole sizes on ultimate strength and damage modes. The FNM allows for accurate tracking of crack initiation and propagation. Additionally, parametric analysis further evaluates the impact of factors such as damping, mass scaling, and matrix cracks spacing on the simulation outcomes. The explicit method shows significant savings in computational times. The study demonstrates the effectiveness of the FNM within the explicit FEM framework for predicting OHC failure in composite laminates with precision and efficiency.
{"title":"An explicit finite element discrete crack analysis of open hole compression failure in composites","authors":"K. Tian , J. Zhi , V.B.C. Tan , T.E. Tay","doi":"10.1016/j.compstruct.2025.119167","DOIUrl":"10.1016/j.compstruct.2025.119167","url":null,"abstract":"<div><div>This paper presents a comparative study of implicit and explicit finite element methods in simulating open hole compression (OHC) failure in composite laminates, employing the Discrete Crack Method (DCM) with the Floating Node Method (FNM) for enhanced accuracy in matrix crack modeling. The finite element models are built upon experimental OHC tests of carbon fiber/epoxy laminates with both ply-level and sub-laminate scaling. The models are validated through a series of simulations studying the effects of hole sizes on ultimate strength and damage modes. The FNM allows for accurate tracking of crack initiation and propagation. Additionally, parametric analysis further evaluates the impact of factors such as damping, mass scaling, and matrix cracks spacing on the simulation outcomes. The explicit method shows significant savings in computational times. The study demonstrates the effectiveness of the FNM within the explicit FEM framework for predicting OHC failure in composite laminates with precision and efficiency.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119167"},"PeriodicalIF":6.3,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-03DOI: 10.1016/j.compstruct.2025.119161
Heraldo S. Da Costa Mattos, João Laredo dos Reis, Bernardo Santiago Areias, Sérgio Luiz de Souza Junior, Maria Laura Martins-Costa
An alternative method to repair through-wall corrosion defects in pipelines is to use a composite sleeve over the damaged region. Between the metallic surface and the composite surface, it is usually applied an adhesive primer layer. The adhesive is a mixture of a resin (which may not be the same used in the composite) and a curing agent. The bonding efficiency can be significantly impacted by the time it takes to join the adherends with the adhesive after mixing the resin with the hardener. This study investigates the influence of this time interval to join a particular class of composite and metal adherends (which will be called the Initial Time for Application ti) on the failure pressures obtained in hydrostatic blister tests. Blister tests were carried out to verify the failure pressure considering different time intervals ti. It is observed that the failure pressure may increase significantly after a given time interval. An analytical model is proposed to predict the failure pressure as a function of ti. Finally, it is suggested how to adapt these experimental observations to the testing and design of real corroded pipeline repairs with composites using concepts from Linear Elastic Fracture Mechanics.
{"title":"Influence of the application time on the failure pressure of bonded metal/composite layers in presurized blister tests","authors":"Heraldo S. Da Costa Mattos, João Laredo dos Reis, Bernardo Santiago Areias, Sérgio Luiz de Souza Junior, Maria Laura Martins-Costa","doi":"10.1016/j.compstruct.2025.119161","DOIUrl":"10.1016/j.compstruct.2025.119161","url":null,"abstract":"<div><div>An alternative method to repair through-wall corrosion defects in pipelines is to use a composite sleeve over the damaged region. Between the metallic surface and the composite surface, it is usually applied an adhesive primer layer. The adhesive is a mixture of a resin (which may not be the same used in the composite) and a curing agent. The bonding efficiency can be significantly impacted by the time it takes to join the adherends with the adhesive after mixing the resin with the hardener. This study investigates the influence of this time interval to join a particular class of composite and metal adherends (which will be called the <em>Initial Time for Application t<sub>i</sub></em>) on the failure pressures obtained in hydrostatic blister tests. Blister tests were carried out to verify the failure pressure considering different time intervals <em>t<sub>i</sub></em>. It is observed that the failure pressure may increase significantly after a given time interval. An analytical model is proposed to predict the failure pressure as a function of <em>t<sub>i</sub></em>. Finally, it is suggested how to adapt these experimental observations to the testing and design of real corroded pipeline repairs with composites using concepts from Linear Elastic Fracture Mechanics.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119161"},"PeriodicalIF":6.3,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-02DOI: 10.1016/j.compstruct.2025.119166
Yi Zhang , Wei Zhong Jiang , Xiang Yu Zhang , Jun Wen Shi , Yi Chao Qu , Jun Dong , Xin Ren
Auxetic metamaterials have been widely used in sensing, flexible medical devices, and energy absorption, due to their extraordinary physical properties. However, the active tunability of their deformation shapes and mechanical performances remains a significant challenge, which limits the functional applications. Here, we fabricate several auxetic re-entrant honeycombs integrated with thermostat metal strips to achieve arbitrary thermal shape morphing at a wide temperature range. The findings indicate that the maximum positive and negative thermal strains achieved are 45 % and 37 %, respectively. In addition, we introduce a customizable thermal deformation strategy by tessellating the unit cells with different thermo-responsive characteristics, including isotropic or anisotropic thermal expansions. An Ashby plot of thermal strain vs. temperature span among current thermo-responsive metamaterials is concluded to quantitatively compare the capacities that actively tune their thermal morphing configurations. The uniaxial thermal strain range in finite elements is substantially expanded to –47 % to 94 % at a wide working temperature range. Various potential functionalities and applications are illustrated including the tunable bandgap for vibration isolation, multisignal conversion in sensing devices, and thermal actuators.
{"title":"Re-entrant thermal-responsive metamaterials with widely tunable thermal expansion","authors":"Yi Zhang , Wei Zhong Jiang , Xiang Yu Zhang , Jun Wen Shi , Yi Chao Qu , Jun Dong , Xin Ren","doi":"10.1016/j.compstruct.2025.119166","DOIUrl":"10.1016/j.compstruct.2025.119166","url":null,"abstract":"<div><div>Auxetic metamaterials have been widely used in sensing, flexible medical devices, and energy absorption, due to their extraordinary physical properties. However, the active tunability of their deformation shapes and mechanical performances remains a significant challenge, which limits the functional applications. Here, we fabricate several auxetic re-entrant honeycombs integrated with thermostat metal strips to achieve arbitrary thermal shape morphing at a wide temperature range. The findings indicate that the maximum positive and negative thermal strains achieved are 45 % and 37 %, respectively. In addition, we introduce a customizable thermal deformation strategy by tessellating the unit cells with different thermo-responsive characteristics, including isotropic or anisotropic thermal expansions. An Ashby plot of thermal strain vs. temperature span among current thermo-responsive metamaterials is concluded to quantitatively compare the capacities that actively tune their thermal morphing configurations. The uniaxial thermal strain range in finite elements is substantially expanded to –47 % to 94 % at a wide working temperature range. Various potential functionalities and applications are illustrated including the tunable bandgap for vibration isolation, multisignal conversion in sensing devices, and thermal actuators.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119166"},"PeriodicalIF":6.3,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-02DOI: 10.1016/j.compstruct.2025.119158
Meirong Hao , Lai Liang , Jialin Wang , Lanlan Jiang , Zaoyang Guo , Jun Liang
This paper reports the investigation of the elastic properties of 3D-printed carbon fiber-reinforced nylon-based composites (CFRNCs) using experiments and multi-scale numerical modeling. Short-cut carbon fiber-reinforced nylon-based composites (sCFRNCs) and continuous carbon fiber-reinforced nylon-based composites (cCFRNCs) laminates were printed, and a comprehensive set of experimental data for their elastic properties was obtained. Some data were used to calibrate the material parameters of the printed filaments, and the rest were employed to assess the predictive capability of the multi-scale numerical model at determining the elastic parameters of macroscale 3D-printed laminates. Also, the elastic parameters of microscale printed filaments and mesoscale unidirectional laminas were determined. Unlike conventional models, this model considered the structural characteristics of the 3D-printed laminates, where each layer of the laminates was divided into a wall zone, edge zone, and unidirectional laminate zone at the macroscale. The results showed that the reinforcement in both the carbon fiber (CF) filaments and Onyx filaments was T300 CF monofilaments, while the matrix was different types of nylon materials. The predicted tensile modulus of CF filaments closely matched the experimental values reported in the literature, with an error of −0.95 %. Similarly, the predicted elastic properties of 3D-printed laminates agreed well with the experimental results, while the multi-scale model performed better for the 0° cCFRNCs laminates than the multi-directional cCFRNCs laminates. For the 0° laminates, the absolute error was less than 5.5 %, but for the multi-directional laminates, the absolute error was less than 9 %, with a few exceptions. In addition, a linear relationship was found between the tensile modulus and the mesoscale fiber volume fraction in 0° laminates, similar to the rule of mixtures (ROM) model. The results revealed that the ROM model served as a simplified model to replace the multi-scale numerical model for 0° cCFRNCs laminates when the influence of the edge zone was appropriately considered. An attempt was also made to employ a coordinate transformation (CT) method to simplify the multi-scale numerical model for off-axis multi-directional laminates. The results indicated that this method was ineffective when the edge zone was not considered.
{"title":"Multiscale analysis of elastic properties of 3D-printed carbon fiber-reinforced nylon-based composites: Numerical approach","authors":"Meirong Hao , Lai Liang , Jialin Wang , Lanlan Jiang , Zaoyang Guo , Jun Liang","doi":"10.1016/j.compstruct.2025.119158","DOIUrl":"10.1016/j.compstruct.2025.119158","url":null,"abstract":"<div><div>This paper reports the investigation of the elastic properties of 3D-printed carbon fiber-reinforced nylon-based composites (CFRNCs) using experiments and multi-scale numerical modeling. Short-cut carbon fiber-reinforced nylon-based composites (sCFRNCs) and continuous carbon fiber-reinforced nylon-based composites (cCFRNCs) laminates were printed, and a comprehensive set of experimental data for their elastic properties was obtained. Some data were used to calibrate the material parameters of the printed filaments, and the rest were employed to assess the predictive capability of the multi-scale numerical model at determining the elastic parameters of macroscale 3D-printed laminates. Also, the elastic parameters of microscale printed filaments and mesoscale unidirectional laminas were determined. Unlike conventional models, this model considered the structural characteristics of the 3D-printed laminates, where each layer of the laminates was divided into a wall zone, edge zone, and unidirectional laminate zone at the macroscale. The results showed that the reinforcement in both the carbon fiber (CF) filaments and Onyx filaments was T300 CF monofilaments, while the matrix was different types of nylon materials. The predicted tensile modulus of CF filaments closely matched the experimental values reported in the literature, with an error of −0.95 %. Similarly, the predicted elastic properties of 3D-printed laminates agreed well with the experimental results, while the multi-scale model performed better for the 0° cCFRNCs laminates than the multi-directional cCFRNCs laminates. For the 0° laminates, the absolute error was less than 5.5 %, but for the multi-directional laminates, the absolute error was less than 9 %, with a few exceptions. In addition, a linear relationship was found between the tensile modulus and the mesoscale fiber volume fraction in 0° laminates, similar to the rule of mixtures (ROM) model. The results revealed that the ROM model served as a simplified model to replace the multi-scale numerical model for 0° cCFRNCs laminates when the influence of the edge zone was appropriately considered. An attempt was also made to employ a coordinate transformation (CT) method to simplify the multi-scale numerical model for off-axis multi-directional laminates. The results indicated that this method was ineffective when the edge zone was not considered.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119158"},"PeriodicalIF":6.3,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.compstruct.2025.119053
Maryam Niazi , Federico Danzi , Denis Dalli , Pedro P. Camanho
In the development of structural batteries, achieving optimal performance relies on the effective integration of different materials. Glass fiber Reinforced Polymer (GFRP) can be used as an insulator and structural shell in various types of structural batteries. However, the elastic mismatch with metallic current collectors can lead to interface cracks, compromising the mechanical and electrochemical functionality of the system. In this study, the modified transverse crack tension test is used to measure the mode II interlaminar fracture toughness of GFRP/current collector interfaces, with the current collectors being aluminum and copper. The dominance of mode II loading, using the modified transverse crack tension specimens is verified using the virtual crack closure technique. For the designed configurations, an analytical, closed-form solution to obtain the mode II interlaminar fracture toughness equation is derived, and verified numerically, considering residual thermal stresses and elastic mismatch. The effects of metal surface treatment and transverse pressure on mode II fracture toughness are assessed and compared with untreated samples and an All-GFRP configuration. Digital image correlation technique is employed to accurately identify the onset of crack propagation of each specimen. Additionally, scanning electron microscopy images of the surfaces of the current collectors are taken after debonding to analyze the failure mechanisms. The findings indicate that both compressive transverse stress and Sol–Gel surface treatment are effective techniques for enhancing the mode II interlaminar fracture toughness of hybrid joints in structural batteries.
{"title":"The effect of compressive transverse stress on the mode II fracture toughness of composite joints used in structural batteries","authors":"Maryam Niazi , Federico Danzi , Denis Dalli , Pedro P. Camanho","doi":"10.1016/j.compstruct.2025.119053","DOIUrl":"10.1016/j.compstruct.2025.119053","url":null,"abstract":"<div><div>In the development of structural batteries, achieving optimal performance relies on the effective integration of different materials. Glass fiber Reinforced Polymer (GFRP) can be used as an insulator and structural shell in various types of structural batteries. However, the elastic mismatch with metallic current collectors can lead to interface cracks, compromising the mechanical and electrochemical functionality of the system. In this study, the modified transverse crack tension test is used to measure the mode II interlaminar fracture toughness of GFRP/current collector interfaces, with the current collectors being aluminum and copper. The dominance of mode II loading, using the modified transverse crack tension specimens is verified using the virtual crack closure technique. For the designed configurations, an analytical, closed-form solution to obtain the mode II interlaminar fracture toughness equation is derived, and verified numerically, considering residual thermal stresses and elastic mismatch. The effects of metal surface treatment and transverse pressure on mode II fracture toughness are assessed and compared with untreated samples and an All-GFRP configuration. Digital image correlation technique is employed to accurately identify the onset of crack propagation of each specimen. Additionally, scanning electron microscopy images of the surfaces of the current collectors are taken after debonding to analyze the failure mechanisms. The findings indicate that both compressive transverse stress and Sol–Gel surface treatment are effective techniques for enhancing the mode II interlaminar fracture toughness of hybrid joints in structural batteries.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119053"},"PeriodicalIF":6.3,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.compstruct.2025.119119
John Susainathan , Enrique Barbero , Sonia Sanchez , Arthur Cantarel , Florent Eyma
The dynamic flexural behaviour of sandwich beams made of a composite eco-structure (plywood and flax/epoxy composite skin) is studied using an explicit 3D numerical model. The model includes a constitutive elastic–plastic behaviour with a plastic potential and its consistency multiplier-based yield stress criteria, a modified 3D-Hashin damage initiation and a strain threshold-based exponential damage evolution model. Experimental tests at different impact energies were carried out to validate the proposed model. The variation of force with time and displacement as well as the velocity–time profile are accurately predicted. The model is able to capture the stiffness degradation, post-peak softening, de-kinking and unloading phase that appear in the force–displacement curve. The validated model is employed to investigate the evolution of inter- and intralaminar damage for different impact energies. The most relevant damage modes are delamination and compressive damage modes (transverse and normal) for the impact energies studied.
{"title":"Modelling of dynamic flexural response of composite eco-structure beams using a 3D elastic–plastic damage model","authors":"John Susainathan , Enrique Barbero , Sonia Sanchez , Arthur Cantarel , Florent Eyma","doi":"10.1016/j.compstruct.2025.119119","DOIUrl":"10.1016/j.compstruct.2025.119119","url":null,"abstract":"<div><div>The dynamic flexural behaviour of sandwich beams made of a composite eco-structure (plywood and flax/epoxy composite skin) is studied using an explicit 3D numerical model. The model includes a constitutive elastic–plastic behaviour with a plastic potential and its consistency multiplier-based yield stress criteria, a modified 3D-Hashin damage initiation and a strain threshold-based exponential damage evolution model. Experimental tests at different impact energies were carried out to validate the proposed model. The variation of force with time and displacement as well as the velocity–time profile are accurately predicted. The model is able to capture the stiffness degradation, post-peak softening, de-kinking and unloading phase that appear in the force–displacement curve. The validated model is employed to investigate the evolution of inter- and intralaminar damage for different impact energies. The most relevant damage modes are delamination and compressive damage modes (transverse and normal) for the impact energies studied.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"364 ","pages":"Article 119119"},"PeriodicalIF":6.3,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-30DOI: 10.1016/j.compstruct.2025.119159
Shengjie Wang , Wenhao Zhao , Binghao Lang , Yana Wang , Yifeng Dong , Qiqige Wuyun , Hongshuai Lei , Xuefeng Yao , Heng Yang
Carbon fiber-reinforced polymer (CFRP) composites are widely used in aerospace and automotive industries for their superior mechanical properties and lightweight characteristics. However, their complex behavior challenges structural safety, requiring effective online monitoring. Existing sensors lack sufficient sensitivity to detect minor damage, while embedded sensors may compromise the mechanical properties of CFRP, impairing long-term strain monitoring. This study proposes a reduced graphene oxide (rGO)/epoxy strain sensor based on a pre-strain strategy, which achieves anisotropic regulation through the directional alignment of microstructures and effectively preserves both the pre-strained configuration and aligned microstructure using transfer printing technology. The sensor demonstrates a gauge factor of 80.07 under 25 % pre-strain, representing a 9.43-fold enhancement compared to sensors without pre-strain. The underlying mechanism of sensitivity enhancement was revealed using a tunneling theory model. During cyclic tensile testing, the sensor demonstrated excellent stability and repeatability, underscoring its potential for real-time structural health monitoring of CFRP composites. The simulation results demonstrate that when the thickness of the embedded sensor is 20 μm, the maximum relative strain error induced is only 1.220 %, indicating that reducing the sensor thickness is a critical approach to minimizing interference with the strain field of the composite material and preserving its mechanical properties.
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