今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 4 篇
International Journal of Solids and Structures
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
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.
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.
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.
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.
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.