今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 3 篇
Hydro-mechanical modeling of cohesive crack propagation of concrete lining in high internal pressure tunnels
Junchao Jin, Laihong Jing, Zhiyu Song, Kai Su, Fengwei Yang, Zhengxiong Bai
doi:10.1016/j.ijsolstr.2024.113108
高内压隧道混凝土衬砌内聚裂缝扩展的水力学模拟
High pressure tunnels with concrete lining have been extensively utilized in project practice. However, due to the characteristic of concrete being susceptible to cracking under tension, the lining inevitably develops cracks under high internal water pressure, posing a serious threat to the operation of tunnels. This study aims at developing a hydro-mechanical numerical model of cohesive crack propagation of concrete lining in high internal pressure tunnels. In this regard, the determination of cohesive element parameters is elucidated, the contact simulation within the software ABAQUS is improved to accurately characterize the interface between lining and surrounding rock, and the numerical calculation process in ABAQUS is realized using indirect coupled method. The simulation results align well with the physical model test and engineering monitoring data, demonstrating that the proposed method can accurately simulate the hydraulic interactions of high pressure tunnel. Additionally, a comparison with calculation models employing tie constraints to simulate the lining-surrounding rock interface is conducted. Finally, comparison with traditional continuum method reveals that while both methods exhibit consistent overall trends. It is recommended to choose the proposed method when describing the discontinuous propagation process of cracks, which cannot be simulated by the continuum analysis method.
高压混凝土衬砌隧道在工程实践中得到了广泛的应用。然而,由于混凝土在受拉作用下易开裂的特性,衬砌在高内水压作用下不可避免地出现裂缝,对隧道的运行构成严重威胁。本研究旨在建立高内压隧道混凝土衬砌内聚裂缝扩展的水力学数值模型。在此基础上,阐述了黏结单元参数的确定,改进了ABAQUS软件中的接触模拟,以准确表征衬砌与围岩界面,并采用间接耦合方法实现了ABAQUS中的数值计算过程。仿真结果与物理模型试验和工程监测数据吻合较好,表明该方法能较准确地模拟高压隧洞的水力相互作用。并与采用约束条件模拟衬砌-围岩界面的计算模型进行了比较。最后,与传统连续统方法的比较表明,两种方法的总体趋势是一致的。在描述裂纹的不连续扩展过程时,建议采用本文提出的方法,连续统分析法无法模拟这一过程。
On the role of the retained porosity on the shock response of additively manufactured high-performance steel: experiments, constitutive model and finite-element predictions
Benoit Revil-Baudard, Peter Sable, Oana Cazacu, Bernard Gaskey, Sujeily Soto-Medina
doi:10.1016/j.jmps.2024.105909
残余孔隙率对增材制造高性能钢冲击响应的影响:实验、本构模型和有限元预测
Experiments have shown that for quasi-static and moderate strain-rates (of the order of 102-103/s) the mechanical response of additively manufactured (AM) and traditionally processed high-strength steels is similar whereas the impact behavior is markedly different. In this paper, we reveal that the main reason for this difference is the retained porosity in the AM material. Fully-implicit finite element calculations are presented in which we simulate both the launching of the impact plate and the impact between the two plates. The constitutive model used is the elastic/plastic model for porous ductile materials with matrix displaying tension-compression asymmetry and Johnson-Cook hardening law that accounts for both strain-rate effects and plastic history. It is shown that even a very small initial porosity changes the wave front, decreases the Hugoniot while increasing the shock rise time, when compared to a void free material. Furthermore, quantitative comparisons between simulation results and plate impact data for both the AM and the wrought AF9628 steel are provided. The good agreement show that the model captures the impact response and illustrates the model capabilities to provide information on field variables that cannot be directly measured.Additive manufacturing (AM) of metals is rapidly advancing as a robust method for production of geometrically complex parts. To enhance understanding of material performance and open up additional application opportunities, dynamic characterization of newly printed alloys is required to validate their effectiveness. In this paper, we present results from plate impact testing of AF9628 steel, a newly developed high-strength low alloy martensitic steel for structural applications which require resistance to high-rate deformation. We put into evidence differences in the shock structure between the AM and the traditionally processed material. To gain understanding, we conduct fully-implicit finite element (FE) calculations in which we model both the launching of the impact plate and the impact between the two plates, respectively. An elastic/plastic damage model that accounts for the effects of the tension-compression asymmetry in plastic deformation and its influence on porosity evolution is used. The FE results reveal that even a very small amount of initial porosity leads to an increase in the shock rise time, explaining the observed trends. Furthermore, quantitative comparisons between simulation results and plate impact data for both the AM and the wrought AF9628 are provided. The good agreement show that the model captures the impact response and illustrates the model capabilities to provide information on field variables that cannot be directly measured.
实验表明,在准静态和中等应变速率(102 ~ 103/s量级)下,增材制造和传统加工的高强钢的力学响应相似,但冲击行为有明显不同。在本文中,我们揭示了这种差异的主要原因是AM材料中保留的孔隙率。在全隐式有限元计算中,我们模拟了冲击板的发射和两板之间的碰撞。采用的本构模型为多孔延性材料的弹塑性模型,基体呈现拉压不对称,Johnson-Cook硬化规律兼顾应变率效应和塑性历史。结果表明,与无孔隙材料相比,即使初始孔隙率很小,也会改变波前,降低Hugoniot,同时增加激波上升时间。此外,还提供了模拟结果与AM和变形后的AF9628钢的板冲击数据的定量比较。良好的一致性表明,该模型捕获了冲击响应,并说明了该模型能够提供无法直接测量的现场变量的信息。金属增材制造(AM)作为一种生产几何复杂零件的强大方法 正在迅速发展。为了加强对材料性能的理解并开辟更多的应用机会,需要对新打印的合金进行动态表征以验证其有效性。本文介绍了AF9628钢板冲击试验的结果,AF9628是一种新开发的高强度低合金马氏体钢,用于要求抗高速变形的结构应用。我们证明了AM和传统加工材料在冲击结构上的差异。为了获得理解,我们进行了全隐式有限元(FE)计算,其中我们分别模拟了撞击板的发射和两个板之间的撞击。采用了考虑塑性变形中拉压不对称性及其对孔隙度演化影响的弹塑性损伤模型。有限元结果表明,即使是非常小的初始孔隙率也会导致冲击上升时间的增加,这解释了观察到的趋势。此外,还对AM和变形后的AF9628的模拟结果与板冲击数据进行了定量比较。良好的一致性表明,该模型捕获了冲击响应,并说明了该模型能够提供无法直接测量的现场变量的信息。
Low-dose neutron irradiation effects on the elastoplastic deformation mechanisms of aluminum-doped gallium nitride under contact loading
Tiankun Li, Pengfei Zhao, Fulin Shang
doi:10.1016/j.mechmat.2024.105180
低剂量中子辐照对接触载荷下掺铝氮化镓弹塑性变形机制的影响
The elastoplastic deformation mechanisms of irradiated aluminum (Al)-doped gallium nitride (GaN) under contact loading are investigated in this work using the nanoindentation simulations, which is of great significance for understanding the mechanical properties of the Al-doped GaN and guiding the design of durable and high-performance GaN-based devices. The mechanical behaviors of the Al-doped GaN with different doping concentrations are analyzed, including the indentation hardness, Young's modulus, elastic recovery rates, phase transformations, and stress distribution. It is found that Al doping increases their hardness, Young's modulus, and elastic recovery rates, and leads to an enlargement of the phase transformation regions, which is dominated by the high coordination number (CN) phase transformations. Furthermore, the effects of low-dose neutron irradiation on their elastoplastic deformation mechanisms are studied by triggering cascade collisions within the structure. When subjected to such irradiation, structural changes occur in the Al-doped GaN, their indentation hardness, Young's modulus, and elastic recovery rates increase remarkably, and its phase transformation mechanism is changed remarkably. The dislocation behaviors of the doped and undoped GaN are different under neutron irradiation. This study is important for capturing the mechanical stability and integrity of Al-doped GaN in an irradiation environment, as well as developing GaN-based devices with superior irradiation resistance.
本文采用纳米压痕模拟方法研究了辐照铝掺杂氮化镓(GaN)在接触载荷作用下的弹塑性变形机理,这对于理解掺铝氮化镓的力学性能,指导设计耐用、高性能的氮化镓器件具有重要意义。分析了不同掺杂浓度al掺杂GaN的力学行为,包括压痕硬度、杨氏模量、弹性回复率、相变和应力分布。结果表明,Al的掺入增加了合金的硬度、杨氏模量和弹性回复率,并导致相变区域的扩大,其中以高配位数(CN)相变为主。此外,通过触发结构内部的级联碰撞,研究了低剂量中子辐照对其弹塑性变形机制的影响。在这种辐照下,掺al GaN的结构发生了变化,压痕硬度、杨氏模量和弹性回复率显著提高,相变机理发生了显著变化。在中子辐照下,掺杂氮化镓和未掺杂氮化镓的位错行为不同。该研究对于捕获al掺杂GaN在辐照环境中的机械稳定性和完整性,以及开发具有优异耐辐照性的GaN基器件具有重要意义。
Intelligent design of multi-layered variable stiffness composite structure based on transfer learning
Kunpeng zhang, Hongjiang Liu, Shaojun Feng, Long Li, Dachuan Liu, Peng Hao, Zekai Huo, Jing Li
doi:10.1016/j.tws.2024.112588
基于迁移学习的多层变刚度复合材料结构智能设计
Variable stiffness composite structures offer more flexible design space than thin-walled metal structures and have greater potential for vibration-resistant design. When faced with multiple new types of design problems, the complex modelling and analysis procedures frequently prove to be both time-consuming and costly in terms of optimization. In this study, an innovative multi-layered variable stiffness (MVS) composite structure with high design flexibility is proposed, with images representation for curvilinearly stiffened paths, non-uniform layouts, and fiber and layup angles. Moreover, an intelligent optimization method based on transfer learning is proposed for addressing a variety of factors affecting dynamic design, including boundary types, structural features, and dynamic responses. The objective of the transfer learning model is to facilitate the inheritance and sharing of variable stiffness features, thereby enabling the efficient design of new problems with limited datasets. The validation of different examples shows that the transfer learning can effectively acquire the structural features from the existing source domain datasets, thereby significantly reducing the data for some new target domains by approximately 50%. In comparison to the initial constant stiffness (CS) structures, the different optimized configurations indicate that the MVS composite structures are capable of effectively enhancing the dynamic responses by 10%∼146% for natural frequency and dynamic compliance. Furthermore, the MVS optimized configuration displays superior dynamic responses in some problems, when compared to the CS optimized configuration.
变刚度复合材料结构提供了比薄壁金属结构更灵活的设计空间,具有更大的抗振动设计潜力。当面临多种新型设计问题时,复杂的建模和分析过程往往证明在优化方面既耗时又昂贵。本研究提出了一种具有高设计灵活性的创新型多层变刚度(MVS)复合材料结构,该结构具有曲线加筋路径、非均匀布局、纤维和铺层角度的图像表示。此外,针对边界类型、结构特征和动态响应等影响动态设计的多种因素,提出了一种基于迁移学习的智能优化方法。迁移学习模型的目标是促进变刚度特征的继承和共享,从而在有限的数据集上有效地设计新问题。不同示例的验证表明,迁移学习可以有效地从现有的源域数据集中获取结构特征,从而显著减少一些新目标域的数据量,减少了约50%。与初始恒刚度(CS)结构相比,不同的优化配置表明,MVS复合结构的固有频率和动态柔度能够有效地提高10% ~ 146%的动态响应。此外,与CS优化构型相比,MVS优化构型在某些问题上表现出更好的动态响应。
Digital Image Correlation in Extreme Conditions
Bo Liu, Shuzhao Lan, Jiaqiang Li, Qihong Fang, Yiru Ren, Wei He, Huimin Xie
doi:10.1016/j.tws.2024.112589
极端条件下的数字图像相关
Digital Image Correlation (DIC) has emerged as a pivotal non-contact, full-field deformation measurement method over the past four decades, witnessing a remarkable expansion in its applications across diverse fields. With the rapid progression of cutting-edge science and technologies, the manufacturing and service environments, as well as the scale and characteristics of critical components are advancing toward extremes. There is an urgent necessity to enhance the DIC method to enable the precise capture of mechanical behaviors and principles under extreme conditions. The difficulties, solutions, and applications of DIC in extreme conditions are herein reviewed, together with a discussion of current limitations and future opportunities.
在过去的四十年里,数字图像相关(DIC)已经成为一种关键的非接触、全场变形测量方法,在各个领域的应用都得到了显著的扩展。随着尖端科学技术的快速发展,制造和服务环境以及关键部件的规模和特性正在向极端发展。迫切需要对DIC方法进行改进,以精确捕获极端条件下的力学行为和原理。本文回顾了DIC在极端条件下的困难、解决方案和应用,并讨论了当前的局限性和未来的机会。
Cross-sectional zero-dimension temperature model for thin-walled circular tubes in space environment
Zhe Ma, Zhenxing Shen
doi:10.1016/j.tws.2024.112591
空间环境下薄壁圆管截面零维温度模型
A sufficiently accurate, yet computationally efficient prediction of temperature field is essential for design of spacecraft structures. This paper presents a model dimension reduction method for thermal analysis of thin-walled circular tubes in space environment, which takes into account radiation heat transfer among the internal surfaces besides heat conduction along the circumferential direction and radiative emission from the external surface. Temperature distribution on the tube cross section is approximated by a series of harmonic functions, so that a one-dimensional problem is reduced to that of zero dimension. The relation between average and perturbation temperatures that depend only on time is broadened to fully coupled one. By comparison to the previous model and the plane finite element model, the accuracy and economy of the new model are illustrated. The results show that internal radiation exchange plays an important role in thermal analysis of thin-walled circular tubes used extensively in spacecraft appendages. Furthermore, differences between present and previous models are analyzed and a two-way analysis of variance is performed to determine the effect of various physical and geometric parameters on the temperature distribution and response of the tubes. The work can be further developed to analyze thermally induced deformation and vibration of spacecraft structures.
一个足够精确且计算效率高的温度场预测对于航天器结构设计至关重要。本文提出了空间环境下薄壁圆管热分析的模型降维方法,该方法考虑了薄壁圆管除周向热传导和外表面辐射发射外,内表面之间的辐射换热。用一系列的调和函数来近似管道截面上的温度分布,从而将一维问题简化为零维问题。仅依赖于时间的平均温度和扰动温度之间的关系被扩展为完全耦合的关系。通过与原模型和平面有限元模型的比较,说明了新模型的准确性和经济性。结果表明,内辐射交换在航天器附件中广泛使用的薄壁圆管的热分析中起着重要作用。此外,分析了现有模型与以往模型之间的差异,并进行了双向方差分析,以确定各种物理和几何参数对管道温度分布和响应的影响。这项工作可以进一步发展到分析航天器结构的热致变形和振动。