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 2 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 10 篇
Manufacturing sensitivity study of tensegrity structures using Monte Carlo simulations
Keyao Song, Fabrizio Scarpa, Mark Schenk
doi:10.1016/j.ijsolstr.2024.112878
用蒙特卡罗模拟研究张拉整体结构的制造灵敏度
The successful construction of a tensegrity structure requires not only design techniques but also a means to account for any manufacturing or assembly errors. As a tensegrity is prestressed and is often stabilised by its prestress, it requires a form-finding technique to determine the balanced configuration in the design phase; this property also makes it challenging for engineers to evaluate the effect of manufacturing imperfections on the self-equilibrated configuration. In this paper we investigate the sensitivity of tensegrity structures to manufacturing imperfections, using a stiffness-matrix-based form-finding technique in combination with the Monte Carlo simulation method to introduce manufacturing length errors. The effects at the structural level are captured, and two general relationships between the variance of the input manufacturing error and the output distribution of the member tensions, between the variance and the mean across all groups, are observed. By identifying the most sensitive member group, this work provides a design and analysis strategy when the natural length errors of members are considered for tensegrity structures.
张拉整体结构的成功建造不仅需要设计技术,还需要一种方法来解释任何制造或装配错误。由于张拉整体是预应力的,并且经常通过其预应力来稳定,因此需要一种寻形技术来确定设计阶段的平衡配置;这种特性也使得工程师很难评估制造缺陷对自平衡结构的影响。在本文中,我们研究了张拉整体结构对制造缺陷的敏感性,使用基于刚度矩阵的寻形技术结合蒙特卡罗模拟方法来引入制造长度误差。捕获了结构层面的影响,并观察了输入制造误差的方差与成员张力的输出分布之间的两种一般关系,以及所有组的方差和平均值之间的关系。通过确定最敏感的构件群,本工作为考虑张拉整体结构构件自然长度误差时的设计和分析提供了一种策略。
Cavitation in elastomers: A review of the evidence against elasticity
Evan Breedlove, Chao Chen, David Lindeman, Oscar Lopez-Pamies
doi:10.1016/j.jmps.2024.105678
弹性体中的空化:反弹性证据的回顾
In spite of the growing body of evidence against it, the elasticity view of the phenomenon of cavitation in elastomers continues to be utilized in numerous studies. In this context, the main objective of this paper is to provide a comprehensive review of the existing evidence that settles that cavitation in elastomers is not a purely elastic phenomenon. To that end, a review is first given of the experimental observations of cavitation in elastomers — gathered since the 1930s until present times — as well as of its theoretical description as an elastic phenomenon — whose development started in the 1950s and was substantially completed by the 2010s. The latter is then confronted to the former to pinpoint the reasons why the elastic behavior of elastomers cannot possibly explain the experimental observations. The last part of the paper includes a brief summary of the current view of cavitation as a fracture phenomenon and an outlook for the field in that direction.
尽管有越来越多的证据反对它,弹性体中空化现象的弹性观点继续在许多研究中使用。在这种情况下,本文的主要目的是提供一个全面的审查现有的证据,解决弹性体中的空化不是一个纯粹的弹性现象。为此,本文首先回顾了弹性体中空化现象的实验观察结果——从20世纪30年代至今——以及它作为一种弹性现象的理论描述——其发展始于20世纪50年代,到2010年代基本完成。后者然后面对前者,以查明弹性体的弹性行为不可能解释实验观察的原因。论文的最后一部分简要总结了目前对空化作为一种裂缝现象的看法,并对该领域的发展方向进行了展望。
On the Interaction of Grain-scale and Hydride-scale Stresses in Hydrogen Enriched Zirconium Alloy Nuclear Cladding via combined Discrete Dislocation Plasticity and Crystal Plasticity Finite Element modelling
Christos Skamniotis, Daniel Long, Liu Yang, Mark Wenman, Daniel S. Balint
doi:10.1016/j.mechmat.2024.105033
基于离散位错塑性和晶体塑性联合有限元模型的富氢锆合金核覆层晶粒尺度和氢化物尺度应力相互作用研究
The interaction of Zircaloy fuel cladding components with coolant water in a nuclear reactor leads to embrittlement and potentially delayed hydride cracking (DHC). We explore rate controlling mechanisms for the detrimental DHC process via Discrete Dislocation Plasticity (DDP) modelling of an intragranular -hydride, informed by Crystal Plasticity Finite Element (CPFE) analysis of a notched Zircaloy-4 (Zr-4) polycrystal. It is believed that nano-hydride plasticity occurs under a background (polycrystalline) stress state that depends on the grain-scale stress re-distribution associated with plastic deformation at a notch. We find that depending on grain size the background stresses can enhance plasticity during hydride growth (cooling), enhancing the residual hydrostatic stresses on hydride dissolution (heating), which encourages local hydrogen accumulation and re-precipitation. This ‘memory effect’ can be enhanced further by obstacles preventing dislocations from gliding backwards and annihilating during dissolution, highlighting that the discrete nature of plasticity can play important role in the DHC process. Our analysis provides a stepping-stone to modelling interacting nano-hydrides and irradiation effects for supporting the design of better nuclear materials.
在核反应堆中,锆合金燃料包壳组件与冷却水的相互作用会导致脆化和潜在的延迟氢化物开裂(DHC)。我们通过对缺口锆-4 (Zr-4)多晶的晶体塑性有限元(CPFE)分析,通过对颗粒内氢化物的离散位错塑性(DDP)建模,探讨了有害DHC过程的速率控制机制。认为纳米氢化物塑性发生在背景(多晶)应力状态下,这取决于与缺口处塑性变形相关的晶粒级应力重新分布。研究发现,根据晶粒尺寸的不同,背景应力可以增强氢化物生长(冷却)过程中的塑性,增强氢化物溶解(加热)时的残余静水应力,从而促进局部氢的积累和再沉淀。这种“记忆效应”可以通过防止位错在溶解过程中向后滑动和湮灭的障碍进一步增强,强调可塑性的离散性在DHC过程中发挥重要作用。我们的分析为模拟相互作用的纳米氢化物和辐射效应提供了一个跳板,为更好的核材料的设计提供了支持。
Multi-method examination of contact mechanics in orthotropic layers under gravity
Erdal Öner, Ecren Uzun Yaylacı, Murat Yaylacı
doi:10.1016/j.mechmat.2024.105036
重力作用下正交各向异性地层接触力学的多方法检验
Analyzing the behavior of intelligent unconventional materials under diverse contact scenarios, in comparison to conventional materials, is a critical step in the initial design of engineering systems. This paper presents the development of analytical and numerical approaches for analyzing contact mechanics in a system comprising an orthotropic layer resting on a rigid foundation. Parametric analyses include the consideration of cylindrical and flat punch profiles. Analytical formulation utilizes integral transform methods to convert planar elasticity equations into a Cauchy-type singular integral equation of the second kind. A detailed description of the solution technique for the integral equation is provided, encompassing both the analytical formulation and the required discretization for obtaining the solution. Subsequently, a finite element approach (FEA) is employed to approximate contact bodies using a collection of finite elements, while contact boundaries are approximated by utilizing a set of polygons. Alternatively, the problem is addressed using the Multilayer Perceptron approach, a form of artificial neural network frequently applied in diverse machine learning applications, including scenarios involving contact problems. Finally, the resolution to the problem is achieved by employing the multilayer perceptron (MLP) method. The study yields determinations of contact stresses under the punch, the critical separation load resulting in the detachment of the orthotropic layer from the rigid foundation, and the corresponding separation distance. This analysis considers a range of dimensionless parameters and explored the behavior of diverse orthotropic materials. Comparisons between the results of the analytical method and computations from FEA and MLP reveal the exceptional accuracy attained by all three approaches. As the pioneer study employing three distinct approaches to examine continuous contact mechanics within an orthotropic layer under the influence of gravity, this research constitutes a valuable point of reference for upcoming scholars in the field.
与常规材料相比,分析智能非常规材料在不同接触场景下的行为是工程系统初始设计的关键步骤。本文介绍了分析刚性基础上的正交各向异性层系统接触力学的解析和数值方法的发展。参数分析包括圆柱型和平面型冲孔。解析式利用积分变换方法将平面弹性方程转化为第二类柯西型奇异积分方程。详细描述了积分方程的求解技术,包括解析公式和获得解所需的离散化。随后,采用有限元法(FEA)逼近接触体,利用一组有限元逼近接触边界,利用一组多边形逼近接触边界。或者,使用多层感知器方法解决问题,这是一种人工神经网络形式,经常应用于各种机器学习应用,包括涉及接触问题的场景。最后,采用多层感知器(MLP)方法实现了问题的求解。研究得出了冲头作用下的接触应力、导致正交各向异性层脱离刚性基础的临界分离载荷以及相应的分离距离。该分析考虑了一系列无量纲参数,并探讨了不同正交各向异性材料的行为。将分析方法的结果与FEA和MLP的计算结果进行比较,揭示了所有三种方法获得的卓越精度。作为采用三种不同方法研究重力影响下正交各向异性层内连续接触力学的先驱研究,本研究为该领域的新学者提供了有价值的参考点。
Effect of Nb solutes on the Kolbe mechanism for microtwinning in Ni-based superalloys
Valery V. Borovikov, Mikhail I. Mendelev, Nikolai A. Zarkevich, Timothy M. Smith, John W. Lawson
doi:10.1016/j.ijplas.2024.104004
Nb溶质对ni基高温合金微孪晶Kolbe机制的影响
As the operating temperature of jet turbine engines increase, creep becomes the life-limiting property for turbine disks and blades. At intermediate temperatures, between 600-800°C, microtwinning contributes significantly to creep strain in these alloys. Therefore, understanding how microtwins form and grow is critical to improving the creep life of future Ni-base superalloy components. In addition, exploring the effect of different alloying elements, such as Nb and Ta, on the formation of microtwins is critical for future alloy development. Several mechanisms of microtwinning have been proposed among which the Kolbe mechanism, based on thermally activated reordering, is believed to be dominant. In this work we employ atomistic simulation to investigate the effects of Nb solutes on the Kolbe mechanism. The simulation demonstrates that Nb atoms significantly slow down the reordering processes, explaining the experimentally observed improvement in the creep resistance.
随着喷气涡轮发动机工作温度的升高,蠕变成为影响涡轮盘和叶片寿命的主要因素。在600-800℃的中间温度下,微孪晶对合金的蠕变应变有显著影响。因此,了解微孪晶是如何形成和成长的,对于提高未来镍基高温合金部件的蠕变寿命至关重要。此外,探索不同合金元素(如Nb和Ta)对微孪晶形成的影响对未来合金的发展至关重要。人们提出了几种微孪晶的机制,其中基于热激活重排序的Kolbe机制被认为是主要的机制。在这项工作中,我们采用原子模拟来研究Nb溶质对科尔贝机制的影响。模拟结果表明,Nb原子显著减缓了重排序过程,解释了实验观察到的抗蠕变性能的提高。
Experimental and numerical study on the in-plane bending behaviour of FRP-strengthened steel tubular welded T-joints
R. Rashnooie, M. Zeinoddini, E. Ghafoori, M. Sharafi
doi:10.1016/j.tws.2024.112000
frp加固钢管t形接头面内弯曲性能的试验与数值研究
This study reports the first experimental study on the in-plane bending stress concentration factor (SCF) of steel tubular T-joints with fibre-reinforced-polymer (FRP) jacketing. Experimental results showed that the SCF of the FRP-strengthened specimens was reduced by up to 35%, thereby significantly improving the fatigue strength of the joints. A numerical model, validated with experimental data, was used to further investigate the SCF of FRP-strengthened joints with different geometric/mechanical properties. Nonlinear regression analysis was also performed using experimental and numerical data, and parametric formulas were proposed for the in-plane bending SCF of FRP-strengthened tubular steel joints.
本文首次对带纤维增强聚合物(FRP)护套的t形钢管接头进行了面内弯曲应力集中系数(SCF)的试验研究。试验结果表明,frp加固试件的SCF降低幅度高达35%,从而显著提高了接头的疲劳强度。采用数值模型,对不同几何/力学性能frp加固节点的SCF进行了进一步研究。利用实验数据和数值数据进行非线性回归分析,提出了frp加固钢管节点面内弯曲SCF的参数公式。
Vibrations and thermoelastic quality factors of hemispherical shells with fillets
Longkai Zheng, Shurui Wen, Guoxing Yi, Fengming Li
doi:10.1016/j.tws.2024.111996
带圆角的半球形壳的振动和热弹性质量因子
In engineering applications, hemispherical shell resonators are typically machined with fillets to reduce stress concentration and enhance structure strength. The fillets will inevitably affect the dynamic properties and the mechanical quality factor of hemispherical shell resonators, which has been seldom investigated before. In this paper, an effective analytical method is developed to explore the free vibration and thermoelastic damping (TED) characteristics of the hemispherical shell with fillets. The fillets are characterized by the variation in the thickness of the hemispherical shell during modelling. The first-order shear deformation theory (FSDT) is used to describe the theoretical formulas of the hemispherical shell with fillets. By employing the unified Jacobi polynomials and Fourier series as the assumed mode shape functions, the equation of motion of the structure is established by Hamilton's principle and the assumed mode method. The analytical model for thermoelastic quality factor (QTED) which is determined by TED is obtained by computing the dissipated energy and the maximum elastic potential energy of the hemispherical shell with fillets. The validity and accuracy of the present method are confirmed by comparing the present solutions with the published results and those obtained from the finite element method (FEM). The influences of fillets on the vibration behaviors and QTED characteristics of the hemispherical shells are analyzed in detail. The present model can be used to optimize the design of the fillets of the hemispherical shell resonators with high quality factors.
在工程应用中,半球形壳体谐振器通常采用圆角加工,以减少应力集中,提高结构强度。圆角不可避免地会影响半球壳谐振器的动态特性和机械品质因数,而这一点以前很少有人研究。本文开发了一种有效的分析方法来探讨带圆角半球壳的自由振动和热弹性阻尼(TED)特性。圆角的特征是半球形壳体在建模过程中的厚度变化。一阶剪切变形理论(FSDT)用于描述带圆角半球壳的理论公式。通过使用统一的雅可比多项式和傅里叶级数作为假定模态形状函数,利用汉密尔顿原理和假定模态法建立了结构的运动方程。通过计算带圆角半球壳体的耗散能量和最大弹性势能,得到了由 TED 确定的热弹性质量因子(QTED)的解析模型。通过将本求解结果与已公布的结果和有限元法(FEM)求解结果进行比较,证实了本方法的有效性和准确性。详细分析了圆角对半球形壳体振动行为和 QTED 特性的影响。本模型可用于优化具有高品质因数的半球壳谐振器的圆角设计。
Fatigue properties of SPS composite-steel panel prepared by ultrasound resistance spot welding
Andrzej Kubit, Hamed Aghajani Derazkola, Koen Faes, Marcin Korzeniowski
doi:10.1016/j.tws.2024.111992
超声电阻点焊SPS复合钢板疲劳性能研究
The aim of this work is to analyze the properties of spot joints of metal-plastic composites (Litecor) with DP 800 steel. The joints were made using ultrasound resistance spot welding technology. A metallographic analysis of the joints was carried out, and the basic areas of the weld structure were determined. The separation and decomposition of the polymer core was also illustrated, with no observed diffusion between the Litecor covers and the polypropylene core. Fatigue tests were the main goal of this work, therefore a fatigue curve was determined and the mechanisms of fatigue failure at various levels of fatigue load were analyzed. The tests were carried out at a frequency of 30 Hz, the cycle asymmetry coefficient was R = 0.1 and the limit number of cycles was 2 × 106 . Fatigue failure mechanisms specific to particular levels of fatigue load were demonstrated, which were: 2.2, 1.9, 1.5, 1.2, and 1 kN. For joints subjected to fatigue shear has been demonstrated that the boundary between low-cycle and high-cycle fatigue is located at a cyclic shear stress level of approximately 132 MPa. however, with the assumed limit number of fatigue cycles, the fatigue shear strength was 70.576 MPa. Macro- and microscopic fractographic analysis was carried out for joints after fatigue tests in order to demonstrate the mechanisms of failure at individual levels of cyclic load.
本工作的目的是分析金属-塑料复合材料(Litecor)与DP 800钢的点焊接头的性能。接头采用超声电阻点焊技术。对接头进行了金相分析,确定了焊缝组织的基本区域。还说明了聚合物芯的分离和分解,没有观察到Litecor覆盖层和聚丙烯芯之间的扩散。疲劳试验是这项工作的主要目的,因此确定了疲劳曲线,并分析了不同疲劳载荷下的疲劳破坏机制。试验频率为30 Hz,循环不对称系数R = 0.1,极限循环次数为2 × 106。特定水平的疲劳载荷的疲劳失效机制被证明,这是:2.2,1.9,1.5,1.2和1 kN。对于受疲劳剪切作用的节理,低周疲劳和高周疲劳的边界位于约132 MPa的循环剪切应力水平。在假定极限疲劳循环次数下,疲劳抗剪强度为70.576 MPa。对疲劳试验后的接头进行了宏观和微观断口分析,以证明在各个循环荷载水平下的破坏机制。
Calculation of natural frequencies of doubly curved laminated shells using a modified higher order zigzag theory
Md. Irquam Alam, Mihir Kumar Pandit, Arun Kumar Pradhan
doi:10.1016/j.tws.2024.112007
用改进的高阶之字形理论计算双弯曲层合壳的固有频率
In this study, the analysis of free vibrations for doubly curved laminated shells has been performed with modified higher order zigzag theory (MHOZT). This approach incorporates higher order displacement kinematics and considers both transverse normal and shear strains. The model assumes that the displacement fields within the plane are a combination of a global cubicly varying field and a locally zigzag linearly varying field. On the other hand, the out-of-plane displacement field varies quadratically with shell thickness coordinates. This formulation considers extended thickness criteria, ensuring the inclusion of the ratio of thickness to the radius of curvature (z/R) in strain displacement relations. Additionally, this model guarantees that there is no transverse shear stress at the extreme surfaces of the shell and that inter-laminar shear stress at interfaces is continuous. To implement this formulation effectively, a C° finite element is used. The outcomes are compared against a three-dimensional (3D) elasticity solution, as well as other pertinent results available in the literature. The suggested model accurately predicts the vibration characteristics of laminated shells, showing good agreement with the 3D elasticity solutions.
本研究采用修正的高阶之字形理论(MHOZT)对双曲面层叠壳体的自由振动进行了分析。这种方法采用了高阶位移运动学,并考虑了横向法向应变和剪切应变。该模型假定平面内的位移场是全局立方变化场和局部人字形线性变化场的组合。另一方面,平面外位移场随壳厚度坐标二次变化。该模型考虑了扩展的厚度标准,确保在应变位移关系中包含厚度与曲率半径之比 (z/R)。此外,该模型还确保在壳体的极端表面不存在横向剪应力,并且界面上的层间剪应力是连续的。为了有效地实现这一公式,我们使用了 C° 有限元。研究结果与三维(3D)弹性解决方案以及文献中的其他相关结果进行了比较。建议的模型准确预测了层叠壳体的振动特性,与三维弹性解法显示出良好的一致性。
Blast resistance performance and failure modes of prestressed thin-walled aqueducts subjected to underwater contact explosion
Tao Peng, Gaohui Wang, Wenbo Lu, Zheng Gao, Xinhao Pan, Yizhan Shu
doi:10.1016/j.tws.2024.111993
水下接触爆炸作用下预应力薄壁渡槽的抗爆性能及破坏模式
To solve the problem of regional water resource shortage, water diversion projects have been built around the world. As an essential lifeline project, the prestressed aqueduct is commonly used in cross-regional water transfer and diversion projects. However, the prestressed aqueduct is inclined to damage and collapse under explosion loading due to its thin structure. The main purpose of this paper is to investigate the nonlinear dynamic performance and failure modes of the large prestressed U-shaped thin shell aqueduct to underwater contact explosion. The prestress application approach is validated by theoretical calculations. The reliability of the analysis method of underwater contact explosion for reinforced concrete structures is verified by the underwater contact explosion test. Damage cracking process and nonlinear dynamic response characteristics of prestressed aqueducts to the underwater contact explosion with different explosive weights are performed. Blast resistance performances of prestressed aqueducts are discussed in terms of the crack length, residual displacement, and prestressing force loss. The influence of prestress level on the damage modes of the prestressed aqueduct under the blast loading is discussed. The results indicate that thin-walled U-shaped structures are extremely vulnerable to localized damage from underwater contact explosions. The blast-resistance performance of the U-shaped thin shell aqueduct can be significantly improved by applying prestress.
为了解决区域水资源短缺的问题,世界各地纷纷修建调水工程。预应力渡槽是跨区域调水引水工程中常用的一种重要的生命线工程。然而,预应力渡槽由于结构较薄,在爆炸荷载作用下容易发生破坏和倒塌。本文的主要目的是研究大型预应力u型薄壳渡槽在水下接触爆炸作用下的非线性动力性能和破坏模式。理论计算验证了预应力方法的有效性。通过水下接触爆炸试验,验证了钢筋混凝土结构水下接触爆炸分析方法的可靠性。研究了预应力渡槽在不同炸药重量水下接触爆炸作用下的损伤开裂过程和非线性动力响应特性。从裂缝长度、残余位移和预应力损失等方面讨论了预应力渡槽的抗爆性能。讨论了在爆炸荷载作用下,预应力水平对预应力渡槽损伤模式的影响。结果表明,薄壁u型结构极易受到水下接触爆炸的局部损伤。u型薄壳渡槽通过施加预应力可显著提高其抗爆性能。
Non-linear buckling analysis of thin-walled beams modelled with 7-parameter shell elements
Anh-Khoa Chau, Michael Brun, Pascal Ventura, Hamid Zahrouni, Michel Potier-Ferry
doi:10.1016/j.tws.2024.111994
7参数壳单元薄壁梁非线性屈曲分析
The non-linear quasi-static buckling of thin-walled beams with arbitrary cross-sections is studied by developing coupling strategies between the composing plates (web, flanges). The element adopted for modeling the plates is a 7-parameter shell element using the Enhanced Assumed Strain concept (Bütcher et al., 1994). Different nodal shell directors exist at the interface between plates for thin-walled beams with arbitrary cross-sections, requiring appropriate strategies. The coupling between plates first considers Lagrange multipliers at the interface, following the mortar method on the surface between the plates. Second a simplified pre-processing method is proposed by modifying the shell directors of the nodes close to the interface. In the case of the quasi-static buckling of thin-walled beams with L-shaped and I-shaped cross-sections, the two coupling strategies are thoroughly assessed by using three different solution procedures: Newton–Raphson, Newton-Riks and Asymptotic Numerical Method (ANM). The pre-processing method is simple and turns out to be robust and efficient.
研究了任意截面薄壁梁的非线性准静力屈曲问题,提出了组合板(腹板、翼缘)之间的耦合策略。钢板建模采用的单元是采用增强假设应变概念的7参数壳单元(b<s:1> tcher et al., 1994)。任意截面薄壁梁在板间界面处存在不同的节点壳方向,需要适当的策略。板间耦合首先考虑界面处的拉格朗日乘子,遵循板间表面的砂浆方法。其次,提出了一种简化的预处理方法,即修改靠近接口的节点的shell指示符。以l形和i形截面薄壁梁的准静力屈曲为例,采用牛顿-拉夫森、牛顿-瑞克和渐近数值方法(ANM)三种不同的求解方法,对两种耦合策略进行了全面的评估。该预处理方法简单,鲁棒性好,效率高。
Hygrothermal vibro-buckling of FG ceramic-steel porous consolidated conical-conical shells
Ali Heidari-Soureshjani, Mohammad Rajabi, Roohollah Talebitooti, Mostafa Talebitooti
doi:10.1016/j.tws.2024.112002
FG陶瓷-钢多孔固结锥形-锥形壳的湿热振动屈曲
The present research deals with buckling and vibration analysis of joined functionally graded porous (FGP) conical-conical shells under hygro-thermal environments for the first time. Three different types of porosity distributions are considered across the thickness of temperature-dependent ceramic-steel functional material. Obtaining initial hygro-thermal stress resultant through the static step based on the FSDT and benefitting it in the dynamic one makes this research distinguished from other researches in dealing with hygro-thermal conditions. After consolidating two conical segments by following continuity rules, GDQ approach is implemented to the complete set of motion, marginal and continuity equations. Firstly, the accuracy of the results is checked via some comparisons with prior researches. Additionally, the paper provides novel results in the favor of temperature and moisture rises, porosity models and coefficients on the frequency trends from room conditions to hygro-thermal buckling states.
本文首次对连接功能梯度多孔(FGP)锥形-锥形壳在湿热环境下的屈曲和振动进行了研究。考虑了三种不同类型的孔隙率分布在温度相关的陶瓷-钢功能材料的厚度。基于FSDT的静态步长得到初始湿热应力,并在动态步长中受益,这使得本研究区别于其他处理湿热条件的研究。在遵循连续性规则合并两个圆锥段后,对运动、边缘和连续性方程的完整集 合实施GDQ方法。首先,通过与已有研究的比较,验证了所得结果的准确性。此外,本文还提供了有利于温度和湿度上升的新结果,孔隙率模型和从室温到湿热屈曲状态的频率趋势系数。
Experimental study on interfacial bond-slip behavior of weathering steel and seawater sea-sand concrete in corrosive marine environments
Xuetong Li, Yuhan Lin, Canlin Zhang, Yu Chen, Wei Chen, Li Geng
doi:10.1016/j.tws.2024.112003
海洋腐蚀环境下耐候钢与海水海砂混凝土界面粘结滑移特性试验研究
To improve the durability of marine renewable energy infrastructures, this paper proposed a weathering steel reinforced seawater sea-sand concrete (WSRSSC) structure and investigated its interfacial bond-slip behavior. Forty specimens were designed and underwent simulated marine corrosion tests and push-out tests to explore the effect of various factors, including the corrosion time, shaped steel type, steel section form, seawater sea-sand concrete (SSC) strength, and stirrup spacing. The findings indicated that the ultimate bond stress and residual bond stress increase with higher SSC strength but decrease with greater stirrup spacing. The steel section form significantly affected the ultimate bond stress. With the increase in corrosion time, the ultimate bond stress of WSRSSC specimens first increased and then slowly decreased in the later stages. Weathering steel specimens demonstrated superior corrosion resistance and long-term performance compared to carbon steel specimens. Considering the bond formation mechanism and corrosion damage, the calculation model for the ultimate bond stress and residual bond stress of WSRSSC specimens was proposed. Furthermore, the four-stage bond-slip constitutive model between weathering steel and seawater sea-sand concrete was established, aligning with the bond characteristics of different corrosion degrees and contributing to the numerical simulation of WSRSSC structures in corrosive marine environments.
为了提高海洋可再生能源基础设施的耐久性,提出了一种耐候钢增强海水海砂混凝土(WSRSSC)结构,并对其界面粘结滑移行为进行了研究。设计了40个试件,进行了模拟海蚀试验和推出试验,探讨了腐蚀时间、型钢类型、型钢截面形式、海水海砂混凝土(SSC)强度、箍筋间距等因素对试件的影响。结果表明:粘结极限应力和残余应力随SSC强度的增大而增大,随箍筋间距的增大而减小;型钢截面形式对极限粘结应力有显著影响。随着腐蚀时间的延长,WSRSSC试样的极限粘结应力先增大后缓慢减小。与碳钢试样相比,耐候钢试样表现出优越的耐腐蚀性和长期性能。考虑粘结机制和腐蚀损伤,建立了WSRSSC试件的极限粘结应力和残余粘结应力计算模型。建立了耐候钢与海水海砂混凝土的四阶段粘结-滑移本构模型,符合不同腐蚀程度下的粘结特性,为海洋腐蚀环境下WSRSSC结构的数值模拟提供了依据。
Experimental investigation on the low-velocity impact responses of fibre metal laminates with various internal and external factors
Zheng-Qiang Cheng, Yi-Zhi Zhong, Wei Tan, Zhi-Wu Zhu, Jun-Jiang Xiong, Hu Liu
doi:10.1016/j.tws.2024.112004
不同内外因素下金属纤维层合板低速冲击响应的实验研究
This paper aims to investigate the low-velocity impact (LVI) failure mechanism of fibre metal laminates (FMLs), and systematically explore the effects of internal factors (layup sequence and laminate configuration) and external factors (impact energy and environmental temperature) on the LVI responses. The drop-weight impact tester was utilised to conduct LVI tests at -30 ℃, 25 ℃, and 80 ℃ on FML-2/1 and FML-3/2 laminates. These laminates were made of S-class high-strength glass fibre and 2024 aluminium-alloy sheet with unidirectional, angle-ply, cross-ply and quasi-isotropic layup sequences. The characteristic curves including contact force-time, contact force-deflection, absorbed energy-time, and strain-time near the dent on the impacted and non-impacted specimen surfaces were obtained respectively. Furthermore, the dent depth of the impacted surface of the FMLs was measured. FML's damage was detected by ultrasonic C-scan, and its longitudinal and transverse sections were scanned by X-ray computed tomography (CT). The findings suggest that the layup sequence has a significant effect on the LVI response of FML-2/1, but has no obvious influence on FML-3/2. Moreover, FML-3/2 exhibits greater impact resistance compared to FML-2/1. The severity of LVI damage increases with the increase of impact energy. Notably, compared to the cases at 25 ℃, the LVI failure mechanisms of FMLs undergo significant changes at -30 ℃. The elevated temperature of 80 ℃ significantly affects the LVI damage of FML-2/1, while it has no significant effect on FML-3/2.
本文旨在研究金属纤维层压板(FMLs)的低速冲击(LVI)破坏机理,系统探讨内部因素(铺层顺序和层压板构型)和外部因素(冲击能量和环境温度)对LVI响应的影响。采用落锤冲击试验机对FML-2/1和FML-3/2层压板在-30℃、25℃和80℃下进行LVI试验。这些层压板由s级高强玻璃纤维和2024铝合金板制成,具有单向、角铺层、交叉铺层和准各向同性铺层顺序。得到了冲击和非冲击试样表面凹痕附近的接触力-时间、接触力-挠度、吸收能量时间和应变时间特征曲线。此外,还测量了FMLs撞击表面的凹痕深度。超声c扫描检测FML损伤,x线CT扫描FML纵、横切面。结果表明,铺层顺序对FML-2/1的LVI反应有显著影响,但对FML-3/2无明显影响。此外,与FML-2/1相比,FML-3/2具有更强的抗冲击性。LVI损伤程度随冲击能量的增加而增加。值得注意的是,与25℃时相比,-30℃时FMLs的LVI破坏机制发生了显著变化。80℃的高温对FML-2/1的LVI损伤有显著影响,而对FML-3/2无显著影响。
Modeling Frequency Shifts in Small-Scale Beams with Multiple Eccentric Masses
Hossein Darban, Raimondo Luciano, Michał Basista
doi:10.1016/j.tws.2024.112005
具有多个偏心质量的小尺度梁的频移建模
Studying the dynamics of small-scale beams with attached particles is crucial for sensing applications in various fields, such as bioscience, material science, energy storage devices, and environmental monitoring. Here, a stress-driven nonlocal model is presented for the free transverse vibration of small-scale beams carrying multiple masses taking into account the eccentricity of the masses relative to the beam axis. The results show excellent agreement with the experimental and numerical data in the literature. New insights into the frequency shifts and mode shapes of the first four vibrational modes of stress-driven nonlocal beams with up to three attached particles are presented. The study investigates the inverse problem of detecting the location and mass of an attached particle based on natural frequency shifts. The knowledge acquired from the present study provides valuable guidance for the design and analysis of ultrasensitive mechanical mass sensors.
研究带有附着粒子的小尺度光束的动力学对于生物科学、材料科学、储能装置和环境监测等各个领域的传感应用至关重要。本文建立了考虑质量相对于梁轴偏心率的多质量小梁横向自由振动的应力驱动非局部模型。计算结果与文献中的实验和数值数据吻合良好。提出了应力驱动的非局部梁的前四个振动模态的频移和模态振型的新见解。研究了基于固有频移的附着粒子位置和质量检测的反问题。本研究为超灵敏机械质量传感器的设计和分析提供了有价值的指导。