Pub Date : 2025-02-12DOI: 10.1016/j.compstruct.2025.118933
Aman Garg , Weiguang Zheng , Mehmet Avcar , Mohamed-Ouejdi Belarbi , Raj Kiran , Li Li , Roshan Raman
Deployable structures, which can be compacted into small spaces and later deployed into their desired configurations, have gained significant attention due to their versatility. Origami-inspired structures, in particular, leverage the principles of origami to achieve compactness and deploy ability. This study focuses on predicting the free vibration behaviour of Miura-folded laminated composite cylindrical shells, which are modelled using bio-inspired helicoidal schemes. The analysis is conducted through isogeometric analysis (IGA) based on higher-order shear deformation theory (HSDT). A Gaussian Process Regression (GPR) machine learning surrogate is employed to predict the IGA parameters, specifically the knot vectors, which are used to accurately model the geometry of the shells. The performance of the proposed approach is validated by comparing the results with those obtained without the surrogate model. The findings of this study serve as a benchmark for future research on the free vibration behaviour of origami-inspired cylindrical shells and highlight the potential of using machine learning surrogates in structural analysis.
{"title":"Free vibration behaviour of curved Miura-folded bio-inspired helicoidal laminated composite cylindrical shells using HSDT assisted by machine learning-based IGA","authors":"Aman Garg , Weiguang Zheng , Mehmet Avcar , Mohamed-Ouejdi Belarbi , Raj Kiran , Li Li , Roshan Raman","doi":"10.1016/j.compstruct.2025.118933","DOIUrl":"10.1016/j.compstruct.2025.118933","url":null,"abstract":"<div><div>Deployable structures, which can be compacted into small spaces and later deployed into their desired configurations, have gained significant attention due to their versatility. Origami-inspired structures, in particular, leverage the principles of origami to achieve compactness and deploy ability. This study focuses on predicting the free vibration behaviour of Miura-folded laminated composite cylindrical shells, which are modelled using bio-inspired helicoidal schemes. The analysis is conducted through isogeometric analysis (IGA) based on higher-order shear deformation theory (HSDT). A Gaussian Process Regression (GPR) machine learning surrogate is employed to predict the IGA parameters, specifically the knot vectors, which are used to accurately model the geometry of the shells. The performance of the proposed approach is validated by comparing the results with those obtained without the surrogate model. The findings of this study serve as a benchmark for future research on the free vibration behaviour of origami-inspired cylindrical shells and highlight the potential of using machine learning surrogates in structural analysis.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118933"},"PeriodicalIF":6.3,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420927","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 : 2025-02-11DOI: 10.1016/j.compstruct.2025.118960
Heng Cai , Jiale Xi , Yuan Chen , Lin Ye
The fiber surface roughness determines the interface contact between carbon fiber and resin of composites, and its effect is crucial to be investigated. This study develops a micro-mechanical model considering the surface morphology of carbon fibers to examine the impact of microscopic geometric features on the macroscopic mechanical behaviors of composites. The morphological characteristics of the carbon fiber surface were well captured through image processing based on the microscopically scanned images of fiber cross-sections to determine the average depth-to-width ratio of grooves on the fiber surface. Further, based on statistical analysis, the proposed model considering surface roughness of carbon fibers were developed to evaluate the effective mechanical properties of composites. Then, both the experimental and theoretical results demonstrated that the proposed model exhibits a 3 % reduction in the relative error for predicting the transverse modulus when compared to the standard model indicating a minimal effect of surface roughness on the mechanical responses in this case. However, further numerical analyses using an average depth-to-width ratio twice that of the initial proposed model revealed a 4.18 % increase in the transverse elastic modulus. By calculation, the transverse tensile strength was 39.43 MPa when using the proposed model, demonstrating an increment of 5.1 % in strength when compared to that using the standard model.
{"title":"A novel micro-mechanical model for continuous carbon fiber-reinforced composites: Effect of fiber surface roughness on mechanical behaviors","authors":"Heng Cai , Jiale Xi , Yuan Chen , Lin Ye","doi":"10.1016/j.compstruct.2025.118960","DOIUrl":"10.1016/j.compstruct.2025.118960","url":null,"abstract":"<div><div>The fiber surface roughness determines the interface contact between carbon fiber and resin of composites, and its effect is crucial to be investigated. This study develops a micro-mechanical model considering the surface morphology of carbon fibers to examine the impact of microscopic geometric features on the macroscopic mechanical behaviors of composites. The morphological characteristics of the carbon fiber surface were well captured through image processing based on the microscopically scanned images of fiber cross-sections to determine the average depth-to-width ratio of grooves on the fiber surface. Further, based on statistical analysis, the proposed model considering surface roughness of carbon fibers were developed to evaluate the effective mechanical properties of composites. Then, both the experimental and theoretical results demonstrated that the proposed model exhibits a 3 % reduction in the relative error for predicting the transverse modulus when compared to the standard model indicating a minimal effect of surface roughness on the mechanical responses in this case. However, further numerical analyses using an average depth-to-width ratio twice that of the initial proposed model revealed a 4.18 % increase in the transverse elastic modulus. By calculation, the transverse tensile strength was 39.43 MPa when using the proposed model, demonstrating an increment of 5.1 % in strength when compared to that using the standard model.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118960"},"PeriodicalIF":6.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420923","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 : 2025-02-11DOI: 10.1016/j.compstruct.2025.118926
Davide Pellecchia, Francesco Marmo, Luciano Rosati
This paper presents a methodology, based on Heyman’s safe theorem of limit analysis for masonry structures, to allow for the design and analysis of arches both unstrengthened and strengthened with composite materials. More specifically, we propose an extension of the Thrust Line Analysis to account for the expansion or contraction of the geometric domain of the thrust line able to include the effects of the limited compressive strength of masonry as well as the tensile strength and the delamination ruptures of the composite material.
The influence of each one of these issues on the size of the admissible domain, evaluated iteratively as a function of the internal forces, is numerically investigated and discussed.
{"title":"Accounting for material strength in the thrust line analyses of unstrengthened and strengthened arches","authors":"Davide Pellecchia, Francesco Marmo, Luciano Rosati","doi":"10.1016/j.compstruct.2025.118926","DOIUrl":"10.1016/j.compstruct.2025.118926","url":null,"abstract":"<div><div>This paper presents a methodology, based on Heyman’s safe theorem of limit analysis for masonry structures, to allow for the design and analysis of arches both unstrengthened and strengthened with composite materials. More specifically, we propose an extension of the Thrust Line Analysis to account for the expansion or contraction of the geometric domain of the thrust line able to include the effects of the limited compressive strength of masonry as well as the tensile strength and the delamination ruptures of the composite material.</div><div>The influence of each one of these issues on the size of the admissible domain, evaluated iteratively as a function of the internal forces, is numerically investigated and discussed.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"358 ","pages":"Article 118926"},"PeriodicalIF":6.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427551","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}
This investigation explores the non-linear instability phenomena of variable stiffness laminated composite (VSLC) beams subjected to thermo-mechanical loading. A semi-analytical model is developed to determine the post-buckling and post-buckled vibration behavior of VSLC beams based on trigonometric shear deformation theory. Non-linear strain equations are formulated based on von-Karman’s geometric non-linearity assumptions. Constitutive relations are modified for VSLC beam to account for various coupling effects that arise due to varying fiber orientation and Poisson effects that arise due to the development of zero-stress conditions in the width direction of beams. Using Gram-Schmidt orthogonalization process, an orthogonal basis for the displacement field is constructed to enhance accuracy and ease. The model employs a displacement-based Ritz approach to derive the matrix representation of the governing equations. The present model is developed assuming equivalent single-layer theory, and material properties and temperature variations are assumed to be constant across the thickness of the beam. Moreover, arc-length method is employed to obtain the non-linear response curves of VSLC beam. Pre-buckled and post-buckled vibration responses are obtained using a standard eigenvalue approach. A parametric analysis is conducted to investigate the effect of slenderness ratio, boundary conditions, and ply-sequence on post-buckling and post-buckled vibration characteristics of VSLC beam.
{"title":"A semi-analytical method for non-linear instability analysis of variable stiffness laminated composite beams under thermo-mechanical loading","authors":"Satyajeet Dash , Tanish Dey , Ayan Haldar , Rajesh Kumar","doi":"10.1016/j.compstruct.2025.118966","DOIUrl":"10.1016/j.compstruct.2025.118966","url":null,"abstract":"<div><div>This investigation explores the non-linear instability phenomena of variable stiffness laminated composite (VSLC) beams subjected to thermo-mechanical loading. A semi-analytical model is developed to determine the post-buckling and post-buckled vibration behavior of VSLC beams based on trigonometric shear deformation theory. Non-linear strain equations are formulated based on von-Karman’s geometric non-linearity assumptions. Constitutive relations are modified for VSLC beam to account for various coupling effects that arise due to varying fiber orientation and Poisson effects that arise due to the development of zero-stress conditions in the width direction of beams. Using Gram-Schmidt orthogonalization process, an orthogonal basis for the displacement field is constructed to enhance accuracy and ease. The model employs a displacement-based Ritz approach to derive the matrix representation of the governing equations. The present model is developed assuming equivalent single-layer theory, and material properties and temperature variations are assumed to be constant across the thickness of the beam. Moreover, arc-length method is employed to obtain the non-linear response curves of VSLC beam. Pre-buckled and post-buckled vibration responses are obtained using a standard eigenvalue approach. A parametric analysis is conducted to investigate the effect of slenderness ratio, boundary conditions, and ply-sequence on post-buckling and post-buckled vibration characteristics of VSLC beam.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118966"},"PeriodicalIF":6.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420925","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 : 2025-02-11DOI: 10.1016/j.compstruct.2025.118965
Seyed Sina Samareh-Mousavi, Xiao Chen
This study develops a novel finite element simulation framework to facilitate thermography-based damage identification in fiber/polymer composite sandwich panels with foam cores under constant amplitude cyclic load. The finite element model predicts surface temperature contours induced by self-heating. The heat generation rate in material points is calculated from viscoelastic energy dissipation in a loading cycle, and the steady-state temperature distribution is predicted by performing a heat transfer analysis. Sandwich panel specimens made of glass/epoxy composite skins and PVC foam core are tested under cyclic load before and after introducing artificial damages with the shape of circular notches. The proposed method identifies the artificially introduced damages as well as fatigue damage initiated in the composite sandwich panels based on temperature contour predictions.
{"title":"A novel finite element-assisted approach for damage detection in composite sandwich panels under cyclic loading using thermography","authors":"Seyed Sina Samareh-Mousavi, Xiao Chen","doi":"10.1016/j.compstruct.2025.118965","DOIUrl":"10.1016/j.compstruct.2025.118965","url":null,"abstract":"<div><div>This study develops a novel finite element simulation framework to facilitate thermography-based damage identification in fiber/polymer composite sandwich panels with foam cores under constant amplitude cyclic load. The finite element model predicts surface temperature contours induced by self-heating. The heat generation rate in material points is calculated from viscoelastic energy dissipation in a loading cycle, and the steady-state temperature distribution is predicted by performing a heat transfer analysis. Sandwich panel specimens made of glass/epoxy composite skins and PVC foam core are tested under cyclic load before and after introducing artificial damages with the shape of circular notches. The proposed method identifies the artificially introduced damages as well as fatigue damage initiated in the composite sandwich panels based on temperature contour predictions.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118965"},"PeriodicalIF":6.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420926","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 : 2025-02-10DOI: 10.1016/j.compstruct.2025.118928
Yilin Wang , Antonio Cibelli , Jan Vorel , Philipp Siedlaczek , Jan Belis , Helga C. Lichtenegger , Roman Wan-Wendner
Adhesive joints are increasingly utilized to address structural challenges by overcoming non-uniform stress transfer and stress concentration common in mechanical joint systems. For hybrid Fiber Reinforced Polymer (FRP)/concrete systems, interfacial bond strength is governed by adhesive joints, which are highly sensitive to environmental factors like moisture and temperature. Moisture ingress, from the surrounding environment and from concrete, can induce hydrolytic degradation, significantly altering the mechanical properties of the adhesive. To address these issues, a nonlinear Finite Element Method (FEM)-based model has been developed, coupling moisture diffusion with a mechanical degradation model for thermoset polymers. This multi-physics framework is able to capture moisture exchange between adhesive, concrete, and the environment, predicting the performance of bulk adhesive under hygrothermal conditions. Calibration and validation were performed using experimental data from bulk adhesive samples. A parametric study on the diffusion model was performed to discuss the influence of the model parameters on the mechanical behavior of bulk adhesive. Furthermore, predictive proof-of concept simulations were conducted, including its application to two representative single-lap shear tests: steel-steel system and FRP-concrete system. This case study aids in evaluating and understanding the fundamental mechanisms of moisture diffusion and mechanical degradation in structural joints.
{"title":"Multi-physics simulation of adhesives for structural joints in hygrothermal environments considering mechanical degradation","authors":"Yilin Wang , Antonio Cibelli , Jan Vorel , Philipp Siedlaczek , Jan Belis , Helga C. Lichtenegger , Roman Wan-Wendner","doi":"10.1016/j.compstruct.2025.118928","DOIUrl":"10.1016/j.compstruct.2025.118928","url":null,"abstract":"<div><div>Adhesive joints are increasingly utilized to address structural challenges by overcoming non-uniform stress transfer and stress concentration common in mechanical joint systems. For hybrid Fiber Reinforced Polymer (FRP)/concrete systems, interfacial bond strength is governed by adhesive joints, which are highly sensitive to environmental factors like moisture and temperature. Moisture ingress, from the surrounding environment and from concrete, can induce hydrolytic degradation, significantly altering the mechanical properties of the adhesive. To address these issues, a nonlinear Finite Element Method (FEM)-based model has been developed, coupling moisture diffusion with a mechanical degradation model for thermoset polymers. This multi-physics framework is able to capture moisture exchange between adhesive, concrete, and the environment, predicting the performance of bulk adhesive under hygrothermal conditions. Calibration and validation were performed using experimental data from bulk adhesive samples. A parametric study on the diffusion model was performed to discuss the influence of the model parameters on the mechanical behavior of bulk adhesive. Furthermore, predictive proof-of concept simulations were conducted, including its application to two representative single-lap shear tests: steel-steel system and FRP-concrete system. This case study aids in evaluating and understanding the fundamental mechanisms of moisture diffusion and mechanical degradation in structural joints.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118928"},"PeriodicalIF":6.3,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421047","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}
2.5D woven composites (2.5DWC) are widely used in aerospace and are often accompanied by complex thermal environments, and many multiscale mechanical models have been proposed to predict the mechanical response and damage behavior in thermal environments. Existing multiscale models make it difficult to consider nonlinear mechanical problems at the yarn level, especially plastic behavior in thermal environments. Herein, a novel multiscale mechanical-thermal elastoplastic progressive damage model for 2.5DWC is proposed to predict the mechanical properties under temperature environment. Different from the traditional hierarchical multiscale approach, this model treats the yarn at mesoscale as a transverse isotropic elastoplastic material, and mechanical-thermal progressive damage models are developed for resin, yarn and carbon fibers, respectively, to characterize the mechanical behaviors of the components at microscale and mesoscale. Subsequently, the effect of temperature on the mechanical properties of 2.5DWC is analyzed based on a homogenization approach, in which the RVE with different volume fractions is used as a bridge to convey the plastic behavior of microscale and mesoscale yarns. Finally, the fracture morphology and stress–strain relationship of the material in a real temperature environment are used to verify the reasonability of the prediction results. This work provides support for advancing the in-depth application of 2.5DWC in aerospace.
{"title":"Investigation on failure behavior of 2.5D woven composites in temperature environments by a novel multiscale mechanical-thermal elastoplastic model","authors":"Wenyu Zhang , Junhua Guo , Huabing Wen , Weidong Wen , Chun Guo , Yifan Zhang , Zhirong Yang , Wantao Guo","doi":"10.1016/j.compstruct.2025.118956","DOIUrl":"10.1016/j.compstruct.2025.118956","url":null,"abstract":"<div><div>2.5D woven composites (2.5DWC) are widely used in aerospace and are often accompanied by complex thermal environments, and many multiscale mechanical models have been proposed to predict the mechanical response and damage behavior in thermal environments. Existing multiscale models make it difficult to consider nonlinear mechanical problems at the yarn level, especially plastic behavior in thermal environments. Herein, a novel multiscale mechanical-thermal elastoplastic progressive damage model for 2.5DWC is proposed to predict the mechanical properties under temperature environment. Different from the traditional hierarchical multiscale approach, this model treats the yarn at mesoscale as a transverse isotropic elastoplastic material, and mechanical-thermal progressive damage models are developed for resin, yarn and carbon fibers, respectively, to characterize the mechanical behaviors of the components at microscale and mesoscale. Subsequently, the effect of temperature on the mechanical properties of 2.5DWC is analyzed based on a homogenization approach, in which the RVE with different volume fractions is used as a bridge to convey the plastic behavior of microscale and mesoscale yarns. Finally, the fracture morphology and stress–strain relationship of the material in a real temperature environment are used to verify the reasonability of the prediction results. This work provides support for advancing the in-depth application of 2.5DWC in aerospace.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118956"},"PeriodicalIF":6.3,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420922","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}
The prime ambition of the current exploration is to signify the consequence of surface elasticity together with the nonlocality on the thermal induced asymmetric nonlinear buckling aspects of reinforced functionally graded (FG) porous arches at nanoscale dominated by dissimilar end conditions. The reinforced FG porous nano-arches are subjected to a concentrated load at different locations in conjunction with a thermal surrounding. In this regard, the Gurtin-Murdoch theory (GMT) besides the nonlocal theory (NT) of continuum elasticity are recruited within the exponential shear bendable curved beam formulations to embrace the consequences of the surface Lame parameters along with the surface residual and nonlocal stresses. In order to track down the unified GMT + NT elastic-based nonlinear equilibrium plots attributed to the asymmetric nonlinear buckling of FG porous nano-arches, the isogeometric type of numerical technique is engaged encompassing the knot insertion together with the knot multiplication peculiarities. It is released that for a nano-arch with smaller thickness, the effect of GMT of elasticity embellishes more appreciable, and the quantities of concentrated mechanical loads allocated to all introduced critical points intensify. However, by taking the unified GMT + NT elastic-based model into account, due to the softening consequence of the nonlocality, the role of GMT of elasticity reduces, even for a very thick nano-arch, an opposite feature is observed. Also, it is extrapolated that increasing the temperature does not affect the number of limit points. However, the influence of size dependencies in the both GMT elastic-based and unified GMT + NT elastic-based concentrated mechanical loads at the introduced critical points seems to become more pronounced after inducing the temperature rise.
{"title":"Unified nonlocal surface elastic-based thermal induced asymmetric nonlinear buckling of inhomogeneous nano-arches subjected to dissimilar end conditions","authors":"Saeid Sahmani , Timon Rabczuk , Jeong-Hoon Song , Babak Safaei","doi":"10.1016/j.compstruct.2025.118961","DOIUrl":"10.1016/j.compstruct.2025.118961","url":null,"abstract":"<div><div>The prime ambition of the current exploration is to signify the consequence of surface elasticity together with the nonlocality on the thermal induced asymmetric nonlinear buckling aspects of reinforced functionally graded (FG) porous arches at nanoscale dominated by dissimilar end conditions. The reinforced FG porous nano-arches are subjected to a concentrated load at different locations in conjunction with a thermal surrounding. In this regard, the Gurtin-Murdoch theory (GMT) besides the nonlocal theory (NT) of continuum elasticity are recruited within the exponential shear bendable curved beam formulations to embrace the consequences of the surface Lame parameters along with the surface residual and nonlocal stresses. In order to track down the unified GMT + NT elastic-based nonlinear equilibrium plots attributed to the asymmetric nonlinear buckling of FG porous nano-arches, the isogeometric type of numerical technique is engaged encompassing the knot insertion together with the knot multiplication peculiarities. It is released that for a nano-arch with smaller thickness, the effect of GMT of elasticity embellishes more appreciable, and the quantities of concentrated mechanical loads allocated to all introduced critical points intensify. However, by taking the unified GMT + NT elastic-based model into account, due to the softening consequence of the nonlocality, the role of GMT of elasticity reduces, even for a very thick nano-arch, an opposite feature is observed. Also, it is extrapolated that increasing the temperature does not affect the number of limit points. However, the influence of size dependencies in the both GMT elastic-based and unified GMT + NT elastic-based concentrated mechanical loads at the introduced critical points seems to become more pronounced after inducing the temperature rise.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118961"},"PeriodicalIF":6.3,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420918","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}
This work focused on restrained torsion performance and calculation methods of pultruded GFRP I-section profiles. Material shear properties were tested by V-notched tests, showing significant material nonlinearity. Restrained torsion tests were conducted for six I-section profiles. Three I-section failure modes were found: local buckling failure caused by restrained normal stress at the end, shear failure of the flange-web junction at the midspan and compression failure at the end. Subsequently, finite element analysis was conducted. UMAT based on Puck model was utilized to consider the nonlinearity of shear properties, and simulations and experiments agreed well. Shear property nonlinearity had little influence on the I-section restrained torsion behavior. Vlasov theory was extended to orthotropic materials. The formula of local buckling caused by restrained normal stress was developed based on energy theory. Furthermore, calculation methods to predict restrained torsion failure were proposed and compared; the proposed methods were the most effective.
{"title":"Behavior of pultruded I-section GFRP profiles under restrained torsion","authors":"Peng Feng , Juntian Tang , Shuxin Liao , Yuwei Wu , Yu Bai","doi":"10.1016/j.compstruct.2025.118959","DOIUrl":"10.1016/j.compstruct.2025.118959","url":null,"abstract":"<div><div>This work focused on restrained torsion performance and calculation methods of pultruded GFRP I-section profiles. Material shear properties were tested by V-notched tests, showing significant material nonlinearity. Restrained torsion tests were conducted for six I-section profiles. Three I-section failure modes were found: local buckling failure caused by restrained normal stress at the end, shear failure of the flange-web junction at the midspan and compression failure at the end. Subsequently, finite element analysis was conducted. UMAT based on Puck model was utilized to consider the nonlinearity of shear properties, and simulations and experiments agreed well. Shear property nonlinearity had little influence on the I-section restrained torsion behavior. Vlasov theory was extended to orthotropic materials. The formula of local buckling caused by restrained normal stress was developed based on energy theory. Furthermore, calculation methods to predict restrained torsion failure were proposed and compared; the proposed methods were the most effective.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118959"},"PeriodicalIF":6.3,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421121","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 : 2025-02-10DOI: 10.1016/j.compstruct.2025.118955
Xiao Zhang , Mi Xiao , Wei Luo , Liang Gao , Jie Gao
The parametric designs for the Triply Periodic Minimal Surfaces (TPMS) have been widely discussed due to flexible adjustments of structural performance using mathematical equations. However, the only change of structural shape and thickness in TPMS using few parameters extensively poses more challenges on the improvement of concerned performance. In the current work, the main intention is to propose an innovative design method for TPMS unit cells with the reinforced performance using a combination of the T-splines-oriented Isogeometric Topology Optimization (T-ITO) method and the double offset strategy. Firstly, the T-splines with powerful capability and superior flexibility are applied to model structural geometries of TPMS unit cells accurately, which can effectively remove the limitations of previous B-splines. Secondly, the IGA (IsoGeometric Analysis) with T-splines, which can effectively ensure the consistency of structural geometry and numerical analysis, is adopted to implement the shell analysis of TPMS unit cells to maintain the high-precision, even if complex geometries are considered. Thirdly, the T-ITO formulation is developed to improve the loading-capability of TPMS unit cells, in which materials can be reasonably distributed within the design domain of unit cells. Fourthly, the double offset strategy is employed to construct a series of reinforced TPMS unit cells enhance structural performance as much as possible, where the curvy stiffeners can be rationally generated based on T-ITO method in the reinforcement layer of unit cells. Finally, several numerical examples are addressed to demonstrate the effectiveness of the proposed innovative design method for TPMS, which clearly show the reinforced TPMS unit cells with shell-plate-beam combined designs have preferable stiffness, yield strength and energy absorption characteristics.
{"title":"Isogeometric topology optimization for innovative designs of the reinforced TPMS unit cells with curvy stiffeners using T-splines","authors":"Xiao Zhang , Mi Xiao , Wei Luo , Liang Gao , Jie Gao","doi":"10.1016/j.compstruct.2025.118955","DOIUrl":"10.1016/j.compstruct.2025.118955","url":null,"abstract":"<div><div>The parametric designs for the Triply Periodic Minimal Surfaces (TPMS) have been widely discussed due to flexible adjustments of structural performance using mathematical equations. However, the only change of structural shape and thickness in TPMS using few parameters extensively poses more challenges on the improvement of concerned performance. In the current work, the main intention is to propose an innovative design method for TPMS unit cells with the reinforced performance using a combination of the T-splines-oriented Isogeometric Topology Optimization (T-ITO) method and the double offset strategy. Firstly, the T-splines with powerful capability and superior flexibility are applied to model structural geometries of TPMS unit cells accurately, which can effectively remove the limitations of previous B-splines. Secondly, the IGA (IsoGeometric Analysis) with T-splines, which can effectively ensure the consistency of structural geometry and numerical analysis, is adopted to implement the shell analysis of TPMS unit cells to maintain the high-precision, even if complex geometries are considered. Thirdly, the T-ITO formulation is developed to improve the loading-capability of TPMS unit cells, in which materials can be reasonably distributed within the design domain of unit cells. Fourthly, the double offset strategy is employed to construct a series of reinforced TPMS unit cells enhance structural performance as much as possible, where the curvy stiffeners can be rationally generated based on T-ITO method in the reinforcement layer of unit cells. Finally, several numerical examples are addressed to demonstrate the effectiveness of the proposed innovative design method for TPMS, which clearly show the reinforced TPMS unit cells with shell-plate-beam combined designs have preferable stiffness, yield strength and energy absorption characteristics.</div></div>","PeriodicalId":281,"journal":{"name":"Composite Structures","volume":"357 ","pages":"Article 118955"},"PeriodicalIF":6.3,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395393","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}
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