Thin-Walled Structures最新文献

{"title":"On the imperfection sensitivity and design of buckling critical wind turbine towers","authors":"H.N.R. Wagner ,&nbsp;C. Hühne","doi":"10.1016/j.tws.2024.112577","DOIUrl":"10.1016/j.tws.2024.112577","url":null,"abstract":"<div><div>Wind turbine towers pose major challenges for design engineers due to their complex geometry, nonlinear material behavior and imperfection sensitivity. In service, these thin-walled shells are burdened by a combination of complex load cases and prone to buckling. In fact, one of the main design drivers of wind turbine towers is stability failure for which often the design recommendation of the EN-1993–1–6 are used.</div><div>Recently an international shell buckling exercise was caried out by the team behind the EN-1993–1–6 design standard. Within this exercise 29 teams from academia and industry were asked to perform a series of linear and non-linear finite element simulations of an 8-MW multi-strake steel wind turbine support tower segment. In general, the linear and nonlinear analyzes posed no challenge for the shell buckling experts from around the world. However, the imperfection sensitivity analysis results scattered significantly among the participants. In addition, there was little consensus as to whether the given tower design is actually safe.</div><div>The authors, whose background is aerospace engineering, participated in this exercise and show in this article how they overcome the challenges of this typical civil engineering problem. Among linear and non-linear analyzes the authors show the results of state-of-the-art shell buckling concepts which were developed for aerospace shells like interstage tanks and adapters but are also applicable to wind turbine towers.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"206 ","pages":"Article 112577"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning based multi-objective optimization on shear behavior of the inter-module connection","authors":"En-Feng Deng ,&nbsp;You-Peng Du ,&nbsp;Xun Zhang ,&nbsp;Jun-Yi Lian ,&nbsp;Zhe Zhang ,&nbsp;Jun-Feng Zhang","doi":"10.1016/j.tws.2024.112596","DOIUrl":"10.1016/j.tws.2024.112596","url":null,"abstract":"<div><div>Prefabricated prefinished volumetric construction (PPVC) has become a research hotspot in recent years. Inter-module connections have a crucial influence on the mechanical behavior of PPVC. However, current studies on shear behavior and optimization design method of the inter-module connection are insufficient. This paper investigated shear behavior and machine learning based optimization method of an innovative fully bolted liftable connection (FBLC) for PPVC. The failure mode, force transferring mechanism, and ultimate load bearing capacity of the FBLC under shear force were revealed by the shear behavior tests. Four specimens were tested and the design parameters included the strength and number of the long stay bolts. Subsequently, a refined finite element model (FEM) of the FBLC was established and validated with the ratios of the shear bearing capacity between the FEA and test results ranging from 0.99 to 1.10. Then, six mainstream machine learning algorithms were utilized to predict shear behavior of the FBLC. The Genetic Algorithm Optimized Neural Network (GANN) provided better prediction accuracy on the shear bearing capacity, with an improvement on <em>R²</em> by 0.1 % – 3 % compared with other algorithms. Similarly, the Support Vector Regression (SVR) showed higher prediction accuracy on the ultimate displacement, improving <em>R²</em> by 0.4 % – 12.9 % compared with other algorithms. A stacking algorithm combing the GANN and SVR was developed as the proxy model between the input variables and optimization metrics. In addition, the NSGA-II algorithm was linked to establish a multi-objective optimization method on shear behavior of the FBLC. The yield load, ultimate load and steel consumption were selected as the optimization objectives and the stacking algorithm was used as the proxy model. The Pareto optimal solution sets on the optimization objectives were explored by the NSGA-II algorithm and the optimization design method of the FBLC was established. Compared with the unoptimized specimen, the yield and ultimate shear bearing capacity of the optimized specimen were increased by 113.5 % and 123.6 %, respectively, with the steel consumption reduced by 26.3 %. Finally, a four-story PPVC was established, and the static analysis was carried out under vertical load and wind load. The shear behavior of the FBLC and inter-story drift ratio of the PPVC before and after optimization were compared to verify the reliability of the optimization method.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112596"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uncertainty sensitivity analysis for vibration properties of composite doubly-curved shallow shells using Kriging method","authors":"Yaoye Wang ,&nbsp;Rui Zhong ,&nbsp;Qingshan Wang ,&nbsp;Liming Chen ,&nbsp;Bin Qin","doi":"10.1016/j.tws.2024.112600","DOIUrl":"10.1016/j.tws.2024.112600","url":null,"abstract":"<div><div>This paper presents a Kriging based global sensitivity analysis (GSA) method for the frequency response of displacements of composite doubly-curved shallow shells. A unified solution is utilized to develop the dynamic vibration formulation using the First-order Shear Deformation Theory (FSDT) and the Rayleigh–Ritz method. Kriging surrogate model is employed to substitute the frequency response function (FRF) of displacements. Ten parameters including materials and geometrical dimension are considered as input uncertain variables. A variance-based GSA method for dynamic model is employed to quantify the influence of each uncertain parameter. In addition, to avoid the computational burden of Monte Carlo simulation method (MCS), the presented sensitivity indices are computed analytically based on the Kriging mode, which further improves computational efficiency. Based on the convergence studies and comparison with traditional methods, the accuracy and efficiency of the present method are validated. The results shows that the frequency response of displacements exhibits greater sensitivity to changes in width, and thickness is more influential than others in the example from this article. Finally, the presented numerical results demonstrate vibration characteristics of different types of shells and observation points, which can also serve as a reference for further study on uncertainty-propagation analysis.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112600"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thin-layer Ultra-High-Strength Engineered Cementitious Composites (UHS-ECC) reinforced with small-diameter FRP bars for structural strengthening","authors":"Ji-Xiang Zhu ,&nbsp;Ke-Fan Weng ,&nbsp;Wei-He Liu ,&nbsp;Bo-Tao Huang ,&nbsp;Kai-Di Peng ,&nbsp;Ji-Hua Zhu ,&nbsp;Jian-Guo Dai","doi":"10.1016/j.tws.2024.112592","DOIUrl":"10.1016/j.tws.2024.112592","url":null,"abstract":"<div><div>This study proposed a novel strengthening system for reinforced concrete (RC) structures using a thin layer of Ultra-High-Strength Engineered Cementitious Composites (UHS-ECC) reinforced with small-diameter Fiber-Reinforced Polymer (FRP) bars. Experimental investigation, digital image correlation analysis, and numerical simulation were conducted to evaluate the flexural performance and failure mechanism of RC beams strengthened with 20-mm UHS-ECC layers and 3-mm FRP bars. It was found that the 20-mm UHS-ECC layer alone improved the load capacity of RC beams by 8.3 %, though with reduced deflection, whereas incorporating two 3-mm FRP bars increased load capacity by up to 40.4 %, without sacrificing deflection. Failure in all specimens was caused by concrete crushing; however, FRP-reinforced UHS-ECC layers mitigated early crack localization, significantly enhancing both strength and ductility. This study also revealed that cast-in-place FRP-reinforced UHS-ECC layers exhibited higher load capacity and could avoid ECC/concrete interfacial cracks compared to epoxy-bonded prefabricated layers. A three-dimensional finite element model was proposed for the strengthening system, and the flexural behavior was successfully predicted. It is revealed that the FRP-to-UHS-ECC bond had a marginal influence on performance, while the bond at the UHS-ECC-to-concrete interface significantly impacted flexural behavior. Remarkably, the small-diameter FRP bar achieved 75 % of its tensile strength at the ultimate stage. These findings underscore the potential of FRP-reinforced UHS-ECC layers as an effective solution for enhancing the mechanical and durability performance of RC structures.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112592"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RFOR-DQHFEM: Hybrid relaxed first-Order reliability and differential quadrature hierarchical finite element method for multi-physics reliability analysis of conical shells","authors":"M. Furjan ,&nbsp;R. Kolahchi ,&nbsp;M. Yaylacı","doi":"10.1016/j.tws.2024.112583","DOIUrl":"10.1016/j.tws.2024.112583","url":null,"abstract":"<div><div>In this current work, a hybrid reliability analysis and theoretical frequency technique are suggested for the reliability response of conical shells. Two levels of analyses are proposed as the main loop of the reliability method for finding the failure probability and the second level applied in the main loop for giving the performance function of frequency applied in conical shell structures with multi-physics vibration analysis. A dynamical adjusting procedure is proposed for computing the relaxed factor using the enough descent condition inside the reliability method. The superior convergence rate is considered for selecting the relaxed factor of the proposed first-order reliability method named RFORM. An elastic-electro-mechanical model based on the Higher-Order Shear Deformation Theory (HSDT) is extended for frequency analysis of conical shells. The innovative numerical procedure named Differential Quadrature Hierarchical Finite Element Method (DQHFEM) as a robust framework for giving the vibration behavior of studied mechanical structures is applied for solving motion equations. The developing DQHFEM and RFORM are applied for the laminated, nanocomposite, and piezoelectric conical shell structures with multi-source uncertainties. Increasing the volume percentage of nanoparticles from 0% to 10% significantly enhances the reliability index, with carbon nanoparticles showing a 132% increase, silica nanoparticles showing a 97% increase, and other nanoparticles showing an approximate 40% increase. Also, as moisture content increases from 0% to 30%, the reliability index for a thickness-to-large-radius ratio of 0.2 drops by about five times. Excessive moisture levels (above 20%) result in a negative reliability index, indicating a hazardous condition.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112583"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Propagation of leaky surface acoustic waves in a layered piezoelectric semiconductor structure","authors":"Yuyang Zou,&nbsp;Qingguo Xia,&nbsp;Menghui Xu,&nbsp;Jia Lou,&nbsp;Minghua Zhang,&nbsp;Jianke Du","doi":"10.1016/j.tws.2024.112601","DOIUrl":"10.1016/j.tws.2024.112601","url":null,"abstract":"<div><div>Some piezoelectric materials, such as ZnO and AlN, have not only piezoelectric properties but also semiconductor property. In this paper, an analytical solution of the leaky surface acoustic waves (LSAW) is developed for the structure composed of piezoelectric substrate boned with piezoelectric semiconductor (PSC) film using the partial wave method. Furthermore, the dispersion, loss, and attenuation curves of the LSAW in the composite structure have been obtained by combining the boundary conditions at the top of the film and the continuity conditions on the interface between the film and the substrate. Numerical examples illustrate the effects of PSC film thickness-to-wavelength ratio, steady-state carrier concentration, and biasing electric field on the dispersion, loss, and attenuation curves of LSAW in AlN film/LiNbO₃ substrate. In addition, we conducted simulation by means of the PDE module in COMSOL. The theoretical results are consistent with the simulations, which could be helpful for the design of surface acoustic wave devices based on PSC materials.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112601"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Progressive collapse of beam-to-upright subassemblies of steel storage racks under a column removal scenario","authors":"Liusi Dai ,&nbsp;Hao Yao ,&nbsp;Shen Yan ,&nbsp;Chong Ren","doi":"10.1016/j.tws.2024.112575","DOIUrl":"10.1016/j.tws.2024.112575","url":null,"abstract":"<div><div>This paper presents an experimental investigation into progressive collapse behaviour of steel storage pallet racks under a column removal scenario. The double-half-span substructure is applied in experimental tests. A total of eight substructures are tested, considering two types of beam-to-upright connections, i.e., boltless and bolted connections, commonly used in pallet racks. Different upright profiles and thicknesses, varied beam heights, and the number of tabs are carefully considered in the tests, and their effects on progressive collapse behaviour of pallet racks are thus evaluated. In particular, the influence of pallet loads is carefully evaluated in this paper. Detailed experimental results of all specimens are provided, including the full-range force-displacement curves and the failure modes. The dominated failure modes observed in the tests are the combination of tab crack and bolt bearing failure leading to tearing of beam-end-connector (T+B), the combination of tab crack and bolt bearing failure leading to tearing of upright wall (T+C), and tab crack (T). The test results revealed that the presence of pallet loads greatly influences structural progressive collapse behaviour and thus should be considered in further studies. Moreover, in bolted connections, smaller beam heights and thinner column thicknesses exhibit better resistance against progressive collapse. Whereas in boltless connections, increasing the number of tabs enhances the resistance against progressive collapse. Generally, the bolted connections are proven to have better resistance against progressive collapse than boltless connections and can be used in storage racks to improve structural robustness.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112575"},"PeriodicalIF":5.7,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling anisotropic mechanical behaviors of lithium-ion battery separators: Microstructure insights","authors":"Zhiwei Hao ,&nbsp;You Gao ,&nbsp;Ji Lin ,&nbsp;Lubing Wang","doi":"10.1016/j.tws.2024.112593","DOIUrl":"10.1016/j.tws.2024.112593","url":null,"abstract":"<div><div>The mechanical properties of separators significantly affect the electrochemical stability and potential short circuit risks in lithium-ion batteries. An important aspect of their mechanical behavior is their anisotropy, which is predominantly influenced by the microstructures formed during manufacturing process. This study aims to bridge the gap between the anisotropic mechanical features of the separators and their microstructures caused by the manufacturing methods. Initially, we delve into the characterization of separators, featuring their heterogeneous components and orientated arrangement of fibers. Then, we conduct uniaxial tensile tests to measure the stress-strain relationships of separators along the machine direction (MD), diagonal direction (DD), and transverse direction (TD), revealing pronounced anisotropy in both strength and rate sensitivity. Subsequently, image processing techniques is adopted to obtain a representative configuration of separators, which is further divided into fibers and lamellae. According to the manufacturing process of separators, a viscoplastic model is used to describe the mechanical behavior of lamellae while a strengthened viscoplastic model is utilized to mimic the mechanical response of fibers. The finite element analyses underscore the dominant role of orientated fibers in determining anisotropic mechanical properties. Furthermore, we explore the effects of manufacturing and geometry parameters on the separator's anisotropic mechanical behavior. This research provides valuable insights for optimizing manufacturing parameters and enhancing safety measures for lithium-ion batteries.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112593"},"PeriodicalIF":5.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Creep relaxation to relieve residual stress in girth-butt welded X80 pipelines: Simulation and experiment","authors":"Xiaoguang Huang ,&nbsp;Hehe Liu ,&nbsp;Chang Huang ,&nbsp;Jiren Cui ,&nbsp;Zhenxiong Xiao ,&nbsp;Xiuxing Zhu","doi":"10.1016/j.tws.2024.112597","DOIUrl":"10.1016/j.tws.2024.112597","url":null,"abstract":"<div><div>The residual stress in girth-butt weld presents safety risks for large-diameter oil-gas pipelines, necessitating an in-depth investigation into the welding residual stress and the development of effective methods to mitigate these stresses, thereby enhancing structural integrity. In this work, a finite element girth-butt welding model was developed to predict the residual stress of X80 pipelines. The residual stress relief resulting from local post-weld heat treatment (PWHT) was simulated based on the Norton creep model applicable to X80 steel. The simulation results, encompassing the residual stress both before and after PWHT, were validated through blind-hole drilling measurements. The results demonstrate that the welding residual stresses across all orientations were significantly reduced following PWHT, with a maximum stress reduction of approximately 360 MPa. The primary mechanical mechanism for residual stress relief was identified as high-temperature creep, and it was concluded that the PWHT alleviated welding residual stress effectively when the heating temperature exceeded the creep activation temperature. The consistency between the finite element analysis results and the experimentally measured residual stresses affirms the validity and feasibility of the finite-element-based approach for predicting welding residual stresses.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112597"},"PeriodicalIF":5.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Damage behavior of composite honeycomb sandwich structure subject to low-velocity impact and compression-after-impact using experimental and numerical methods","authors":"Wanhui Ma,&nbsp;Hongliang Tuo,&nbsp;Qingtian Deng,&nbsp;Xinbo Li","doi":"10.1016/j.tws.2024.112594","DOIUrl":"10.1016/j.tws.2024.112594","url":null,"abstract":"<div><div>The paper studies the damage initiation and evolution of composite honeycomb sandwich structure subject to low-velocity impact and CAI (compression after impact) loadings by a combination of experimental and numerical methods. The impact responses including impact force and energy absorption were obtained through impact tests, and detailed damage analysis was conducted using various testing methods including ultrasonic C-scan, DIC (digital image correlation), infrared thermography and SEM (scanning electron microscope). A damage model based on MMF (micro-mechanics of failure) and cohesive behavior were used to predict the mechanical behavior of composite facesheets, and an elastoplastic constitutive model with ductile damage was used to model the honeycomb core. The experimental and numerical results show good agreements and reveal that the matrix damage, delamination, core crushing and fiber damage will be induced in the composite honeycomb sandwich structure depending on the impact energy levels. During the CAI process, the strain concentration in the impact region will lead to local buckling of the sandwich structure, and the damage expands from the impact region to the free edges along the transverse direction until the final collapse, which will cause an obvious temperature increase in the damage area.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112594"},"PeriodicalIF":5.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}