今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 4 篇
Effect of fluid scour on stress distribution of film-substrate system
Songhui Luo, Weixu Zhang, Mingda Han, Bin Long, Dingjun Li
doi:10.1016/j.ijsolstr.2024.112999
流体冲刷对膜-基质体系应力分布的影响
Under strong fluid scour in special service environment, the film-substrate system is prone to weaken its mechanical properties due to the additional shear stress by fluid, resulting in film debonding. The present study establishes a mechanical model incorporating the fluid shear stress for a film-substrate system with partial debonding. The debonding length, scour strength and thermal mismatch are considered in the model, respectively. Fluid induces compressive stress on inflow side and tensile stress on outflow side. Potential debonding behavior of film by the additional shear stress is qualitatively analyzed. Results show that the compressive stress by fluid releases part of the tensile stress of thermal mismatch, may mitigate surface cracking of film. The surface scour effect is amplified by the partial debonding, and is further enhanced with the increase of debonding length. The unevenness of stress distribution at the interface is intensified by the debonding and fluid scouring. The fluid scour poses a potential threat to the film-substrate system
在特殊使用环境下,在强流体冲刷作用下,膜-基材体系容易因流体的附加剪切应力而使其力学性能减弱,导致膜脱粘。本研究建立了含流体剪切应力的部分脱粘膜-衬底体系力学模型。模型中分别考虑了脱粘长度、冲刷强度和热失配。流体在流入侧产生压应力,在流出侧产生拉应力。定性分析了附加剪切应力对膜的潜在脱粘行为。结果表明,流体的压应力释放了部分热失配的拉应力,可以缓解膜的表面开裂。局部脱粘放大了表面冲刷效应,并随着脱粘长度的增加而进一步增强。剥离和流体冲刷加剧了界面应力分布的不均匀性。流体冲刷对膜-基质体系构成潜在威胁
Identification, uncertainty quantification and validation of orthotropic material properties for additively manufactured polymers
Jendrik-Alexander Tröger, Christina Steinweller, Stefan Hartmann
doi:10.1016/j.mechmat.2024.105100
增材制造聚合物正交各向异性材料特性的鉴定、不确定度定量和验证
The mechanical behavior of polymeric parts manufactured by fused filament fabrication is often characterized as orthotropic because of the layer-wise extrusion of the material. To perform reliable simulations of the mechanical response of these parts subjected to certain loads, the material parameters have to be known. This leads to the task of material parameter identification from suitable experimental data. In this work, the identification of the material parameters for orthotropic material behavior is studied in detail with a focus on the specific characteristics of additively manufactured parts. This comprises working out the differences that arise compared to the parameter identification for classical orthotropic composite materials. Moreover, the material parameters are identified from tensile and shear test information together with full-field displacement data from digital image correlation measurements. Then, the obtained parameters are compared for analytical and numerical approaches, where a non-linear least-squares method with finite elements is drawn on. The parameters are not only identified, but also an uncertainty analysis is carried out and, subsequently, the different methods are validated. Further, a clear derivation of commonly applied analytical equations is provided with a special focus on the underlying assumptions. It turns out that the analytical parameter identification procedures can not be easily transferred to numerical procedures, especially when using full-field data, because of correlations between the parameters. Moreover, the identified parameters are employed to prove the reasonability of orthotropic material behavior for specimens manufactured by fused filament fabrication. Finally, during validation it turns out that all parameter identification methods provide a good agreement with experimental data, showing only small differences between the results of the different calibration strategies.
由于材料的分层挤压,用熔融长丝制造的聚合物部件的力学行为通常具有正交异性的特征。为了对这些部件在特定载荷下的机械响应进行可靠的模拟,必须知道材料参数。这就导致了从合适的实验数据中识别材料参数的任务。在这项工作中,详细研究了正交异性材料性能的材料参数的识别,重点是增材制造零件的具体特性。这包括计算与经典正交各向异性复合材料参数识别的差异。此外,根据拉伸和剪切试验信息以及数字图像相关测量的全场位移数据识别材料参数。然后,比较了解析法和数值法得到的参数,并采用了非线性最小二乘有限元法。不仅确定了参数,而且进行了不确定度分析,随后对不同的方法进行了验证。此外,对常用解析方程的明确推导提供了对基本假设的特别关注。结果表明,由于参数之间的相关性,解析参数识别过程不容易转化为数值过程,特别是在使用全场数据时。此外,还利用所识别的参数证明了熔丝加工试样正交各向异性材料性能的合理性。最后,在验证过程中,所有参数识别方法与实验数据的一致性都很好,不同校准策略的结果之间只有很小的差异。
Robust ultrasonically welded CF/PEI-CF/epoxy composite joints upon tailoring the thermoplastic resin thickness at the welding interface
Jiaming Liu, Dong Quan, Dongsheng Yue, Jiaying Pan, Xuemin Wang, Zhi Yang, Mengmeng Han, Guoqun Zhao
doi:10.1016/j.tws.2024.112252
通过调整焊接界面热塑性树脂厚度,超声波焊接CF/PEI-CF/环氧复合材料接头
The objective of this study was to develop robust carbon fiber/epoxy (CF/epoxy)-carbon fiber/polyetherimide (CF/PEI) hybrid joint upon an ultrasonic welding process. The co-curing of a PEI coupling layer (CL) on the surface of the CF/epoxy composite makes it “meltable and weldable”. The CF/epoxy was then ultrasonically welded with the CF/PEI using different combinations of energy director (ED) and CL thicknesses. The results showed that high-quality welding line could be obtained by carrying out coupling-optimization to the thicknesses of the EDs and CLs using an optimal welding displacement. For example, a largest lap-shear strength (LSS) of 35.3 MPa was achieved when both of the ED and CL possessed an optimal thickness of 175 μm. In this case, a cohesive failure within either the CF/PEI or the CF/epoxy substrate took place during the single-lap shear test of the hybrid joints. Predictably, this study provides a promising strategy for the production of high-performance hybrid composite joints upon tailoring the thicknesses of the EDs and the CLs for the ultrasonic welding process.
本研究的目的是通过超声波焊接工艺开发坚固的碳纤维/环氧树脂(CF/epoxy)-碳纤维/聚醚酰亚胺(CF/PEI)混合接头。在CF/环氧复合材料表面共固化PEI偶联层(CL),使其“可熔可焊”。然后使用不同的能量导向(ED)和CL厚度组合将CF/环氧树脂与CF/PEI超声焊接。结果表明,采用最优焊接位移对EDs和CLs的厚度进行耦合优化,可获得高质量的焊接线。例如,当ED和CL的最佳厚度为175 μm时,最大的拉剪强度(LSS)为35.3 MPa。在这种情况下,在混合节理的单搭接剪切试验中,CF/PEI或CF/环氧树脂基板内部都发生了内聚破坏。可以预见的是,该研究为生产高性能混合复合材料接头提供了一种有前途的策略,即根据超声波焊接工艺定制EDs和CLs的厚度。
Reconfigurable inverse design of phononic crystal sensor based on a deep learning accelerated evolution strategy
Tong Zhu, Mu Jiang, Yan-Feng Wang, Yue-Sheng Wang
doi:10.1016/j.tws.2024.112255
基于深度学习加速进化策略的声子晶体传感器可重构逆向设计
Phononic crystals offer valuable sensing capabilities due to their high sensitivity to changes in sound velocity of analytes. In this work, a reconfigurable inverse design approach of phononic crystal sensors is achieved using a deep learning accelerated evolution strategy. The training data is acquired through finite element method (FEM). Two multilayer perceptrons (MLP) are constructed and trained to predict the center frequency and bandwidth of a passband in the dispersion relation. Utilizing a two-step training approach enables rapid accuracy enhancements and swift reconstruction of network targets from NaCl to KCl solutions. The trained networks accelerate the optimization process, yielding a phononic crystal with good detection ability. Compared to FEM, invoking the trained networks can reduce optimization time by a factor of 10^5 The optimized and initial structures are both fabricated and experimentally tested. The robust linear relation between the resonant peak and the solution concentration indicates significant sensing value. The experimental results are in good agreement with the FEM simulations. In the detection of NaCl solution, the optimized phononic crystal sensor has a sensitivity increase of 375% and a Q-factor of 999%. Our research demonstrates that the data-driven deep learning network is a very powerful tool for the design and optimization of phononic crystal devices.
声波晶体对分析物的声速变化具有高灵敏度,因此具有宝贵的传感能力。在这项工作中,利用深度学习加速进化策略实现了声波晶体传感器的可重构逆向设计方法。训练数据通过有限元法(FEM)获取。构建并训练了两个多层感知器(MLP),用于预测频散关系中通带的中心频率和带宽。利用两步训练法可以快速提高准确度,并迅速重建从 NaCl 到 KCl 溶液的网络目标。经过训练的网络加速了优化过程,产生了具有良好探测能力的声子晶体。与有限元法相比,使用训练有素的网络可以将优化时间缩短 10^5 倍。共振峰与溶液浓度之间的稳健线性关系表明,该结构具有重要的传感价值。实验结果与有限元模拟结果十分吻合。在检测 NaCl 溶液时,优化的声波晶体传感器的灵敏度提高了 375%,Q 因子达到了 999%。我们的研究表明,数据驱动的深度学习网络是设计和优化声子晶体器件的一个非常强大的工具。
A Shell Theory Approach for the Analysis of Metal-FRP Hybrid Toroidal Pressure Vessels
Mohan Krishna Paleti, S Suriya Prakash, V. Narayanamurthy
doi:10.1016/j.tws.2024.112266
金属- frp复合压力容器壳体理论分析
This study focuses on the analysis of metal-FRP hybrid toroidal pressure vessels (TPV) using shell theory. The analytical approaches for the design of metal-FRP TPVs considering bending effects are currently not available. Invariably the designs are done based on the most simplified approach like linear membrane theory. In this work, a potential energy functional for the metal-FRP TPV considering the membrane and bending deformations is developed using Love's shell theory. The classical laminate theory is employed to determine the stresses/strains throughout the thickness of the FRP laminate. The Rayleigh-Ritz method is adopted to solve the proposed potential energy functional. A finite element analysis (FEA) is conducted using ABAQUS to validate the proposed analytical solution. In addition, a parametric analysis is carried out to understand the influence of various parameters viz. thickness of base metal, thickness of FRP, and ratio between radii of toroid and cross-section on bending deformations in the hybrid TPV. The results from the proposed solution are in good agreement with that from FEA. Therefore, the proposed solution can be used in the analysis and design of the metal-FRP TPV irrespective of any variations in the geometric parameters. It is found that the inclusion of bending deformations can improve the accuracy of solution and the bending deformations in the base metal decreases or become negligibly small with the increase in R/r ratio and thickness of FRP. The orientation of fibers can change the direction of failure in the base metal. The important design parameters that influence the yield pressure are thickness of base metal and FRP, orientation of fibers and R/r ratio.
本研究的重点是利用壳理论分析金属-FRP 混合环形压力容器(TPV)。目前还没有考虑到弯曲效应的金属-FRP TPV 设计分析方法。设计总是基于最简化的方法,如线性膜理论。在这项工作中,使用 Love 壳理论开发了考虑膜和弯曲变形的金属-玻璃纤维热塑性硫化弹性体势能函数。经典层压板理论用于确定玻璃钢层压板整个厚度上的应力/应变。采用 Rayleigh-Ritz 方法求解所提出的势能函数。使用 ABAQUS 进行了有限元分析 (FEA),以验证所提出的分析解决方案。此外,还进行了参数分析,以了解各种参数(即基体金属厚度、玻璃钢厚度以及环形半径和横截面之间的比率)对混合热塑性硫化弹性体弯曲变形的影响。所提出解决方案的结果与有限元分析的结果十分吻合。因此,无论几何参数如何变化,所提出的解决方案都可用于金属-FRP 热塑性硫化弹性体的分析和设计。研究发现,加入弯曲变形可以提高求解的准确性,并且随着 R/r 比和 FRP 厚度的增加,基体金属的弯曲变形会减小或变得很小,可以忽略不计。纤维的取向会改变基体金属的破坏方向。影响屈服压力的重要设计参数包括基体金属和玻璃钢的厚度、纤维的取向以及 R/r 比。
Numerical and Experimental Verification of Column Web in Transverse Compression
Ivan Balázs, Ondřej Pešek, Martin Horáček, Martin Vild
doi:10.1016/j.tws.2024.112267
横向压缩柱腹板的数值与实验验证
This paper focuses on the problem of steel members of open double symmetrical cross-sections in transverse compression. First, the problem is introduced with examples of its application in steel structures of buildings and followed by the overview of selected substantial literature resources and current design codes provisions. The essential part of the paper is a presentation of results of experimental tests and advanced numerical analysis of members subjected to selected cases of transverse compression. Where possible, the results are compared with resistances obtained using provisions in currently valid design codes for steel structures. The influence of selected parameters on the resistance in transverse compression is quantified within the evaluation with specific attention paid to plate buckling of the web. Based on data obtained from the experimental and numerical investigations, the most notable findings are summarized.
本文主要研究开双对称截面钢构件的横向受压问题。首先介绍了该问题及其在建筑钢结构中的应用实例,然后概述了选定的大量文献资源和现行设计规范规定。本文的主要部分是介绍了在选定的横向压缩情况下构件的试验测试结果和先进的数值分析。在可能的情况下,将结果与当前有效的钢结构设计规范中规定的阻力进行比较。在评价中量化了所选参数对横向压缩阻力的影响,特别关注了腹板的板屈曲。根据实验和数值研究的数据,总结了最显著的发现。