【新文速递】2024年1月31日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 2 篇，Thin-Walled Structures 3 篇

International Journal of Solids and Structures

Persson’s theory of purely normal elastic rough surface contact: A tutorial based on stochastic process theory

Yang Xu, Xiaobao Li, Qi Chen, Yunong Zhou

doi:10.1016/j.ijsolstr.2024.112684

Persson的纯法向弹性粗糙表面接触理论:基于随机过程理论的教程

Persson’s theory of purely normal rough surface contact was developed two decades ago during the study of tire-road interaction, and gradually became one of the dominant approaches to study the solid–solid interaction between rough surfaces. Contrary to its popular applications in various cross-disciplinary fields, the fundamental study of Persson’s theory of contact attracted little attention from the tribology and contact mechanics communities. As far as the authors know, many researchers struggle to understand the derivation of the theory. Few attempts have been made to clarify the oversimplified derivation provided by Persson (2001). The present work provides a detailed tutorial on Persson’s theory, which does not simply follow the commonly adopted derivation initiated by Persson. A new derivation is given based on stochastic process theory, assuming that the variation of the random contact pressure with respect to scale is a Markov process. We revisit the essential assumptions utilized to derive the diffusion equation, boundary conditions, drift and diffusion coefficients, and closed-form results. This tutorial can serve as a self-consistent introduction for solid mechanicians, tribologists, and postgraduate students who are not familiar with Persson’s theory, or who struggle to understand it.

Persson的纯法向粗糙表面接触理论是二十多年前在研究轮胎-路面相互作用的过程中发展起来的，并逐渐成为研究粗糙表面之间固-固相互作用的主要方法之一。与佩尔松接触理论在各个交叉领域的广泛应用相反，佩尔松接触理论的基础研究很少受到摩擦学和接触力学界的重视。据作者所知，许多研究人员都在努力理解这一理论的推导。很少有人试图澄清Persson(2001)提供的过于简化的推导。本文对佩尔松的理论提供了详细的指导，而不是简单地遵循由佩尔松发起的普遍采用的推导。基于随机过程理论，假设随机接触压力随尺度的变化是一个马尔可夫过程，给出了一个新的推导。我们回顾了用于导出扩散方程，边界条件，漂移和扩散系数以及封闭形式结果的基本假设。本教程可以作为固体力学家，摩擦学家和研究生谁不熟悉Persson的理论，或谁努力理解它的自我一致的介绍。

Winding and Unwinding a Pipe with Lüders Bands on a Reel Part II: Effect of Problem Parameters

Weihan Zhang, Stelios Kyriakides

doi:10.1016/j.ijsolstr.2024.112688

在卷轴上用 Lüders 带卷绕和放卷钢管 第二部分：问题参数的影响

The main features of the mechanical behavior of a pipeline with Lüders bands wound/unwound repeatedly on a large diameter reel have been studied in detail in Part I for a particular pipe geometry, material properties, reel radius and back tension. Part II investigates how the complex behavior revealed and its degrading effects are affected by the parameters of the process. The extent of the Lüders strain, the back tension, the reel radius, the material yield stress, and the pipe diameter-to-thickness ratio are varied within practical ranges, and their effects on the mechanical behavior of the pipeline are established. Typically, for a pipe under bending, Lüders banding is in the form of higher strain inclined bands organized in diamond patterns. By contrast, on the reel the bands form clusters separated by elastic zones. This inhomogeneous deformation leads to localized curvature, higher ovality, wrinkling, and the danger of local buckling, all of which are aggravated by higher Lüders strain. The spacing of the clusters on the reel depends on the difference between the Lüders strain and the bending strain induced by the reel, with the banding becoming continuous when the Lüders strain is smaller than the reeling strain. During unwinding, the line straightens free of sharp changes in curvature, the strain in the clusters is reduced, but new localization patterns nucleate in the elastic zones between the initial clusters. In subsequent cycles, the line continues to bend smoothly but the clusters reappear during winding and the secondary patterns during unwinding. The ovality accumulates with every cycle and the wrinkles are permanent. Higher tension reduces the possibility of collapse, but increases the ovality and the net elongation of the line. The reel-induced strain goes as the ratio of the pipe to the reel diameter and decides the cluster spacing and wrinkle amplitude. Ovality increases as the reel radius decreases, while the wrinkle amplitude increases as the reel strains gets closer to the minimum stress on the softening branch. The “strength” of the instability is governed by the ratio of the drop in stress in the softening branch of the stress-strain response and the Lüders stress. Higher value of this ratio increases the degrading effect of the Lüders strain. Increasing the pipe D/t increases the ovality induced by each cycle and makes the pipeline more prone to local collapse.

在第一部分中，针对特定的管道几何形状、材料特性、卷轴半径和反向张力，详细研究了在大直径卷轴上反复缠绕/放卷 Lüders 带的管道机械性能的主要特征。第二部分研究了所揭示的复杂行为及其退化效应如何受到工艺参数的影响。吕德斯应变、反向拉力、卷轴半径、材料屈服应力和管道直径与厚度比在实际范围内变化，并确定它们对管道机械行为的影响。通常情况下，对于处于弯曲状态的管道，Lüders 带状结构是以菱形图案组织的高应变倾斜带状结构。相反，在卷轴上，应变带形成由弹性区分隔的簇状。这种不均匀变形会导致局部弯曲、椭圆度增大、起皱和局部屈曲的危险，所有这些都会因较高的 Lüders 应变而加剧。卷轴上的线团间距取决于吕德斯应变和卷轴引起的弯曲应变之间的差异，当吕德斯应变小于卷轴应变时，带状线团会变得连续。在放卷过程中，缆线变直，没有急剧的曲率变化，线团中的应变减小，但在最初线团之间的弹性区域会形成新的局部模式。在随后的循环中，线条继续平滑弯曲，但在收卷时会重新出现线团，在放卷时会出现次要图案。椭圆度在每个循环中都会累积，皱纹则是永久性的。张力越大，塌陷的可能性越小，但椭圆度和纱线的净伸长率也会增加。卷轴引起的应变与管材和卷轴直径的比值有关，决定了簇间距和皱纹幅度。卵形度随着卷盘半径的减小而增大，而皱纹幅度则随着卷盘应变越来越接近软化分支上的最小应力而增大。不稳定性的 "强度 "取决于应力-应变响应软化分支的应力下降与吕德斯应力的比值。该比值越大，Lüders 应变的劣化效应就越大。增加管道的 D/t 会增加每个周期引起的椭圆度，使管道更容易发生局部坍塌。

Thin-Walled Structures

On the modelling of distorted thin-walled stiffened panels via a scale reduction approach for a simplified structural stress analysis

Federica Mancini, Heikki Remes, Jani Romanoff

doi:10.1016/j.tws.2024.111637

变形薄壁加筋板的缩比例尺模型化简化结构应力分析

To reduce the weight of cruise ships, the shipbuilding industry is interested in thin-walled superstructures, where the thickness of butt-welded plates in stiffened panels is under 5 mm. Compared to thick plates, thin ones can develop severe welding-induced distortions, which limit the validity of recommended early-design structural stress assessment methods. Therefore, computationally costly 3D non-linear numerical analysis must be used. For a quick and effective early design, this paper investigates on simplified computational models for thin-walled panels under uni-axial tension, considering the distortions measured on 4-mm thick, full-scale ship-deck panels. A 2D simply-supported analytical plate is shown to be sufficiently accurate (i.e., error < 10 % ) at 150MPa for a distortion with maximum slope within 0.02rad and amplitude smaller than the thickness ( t ). Moreover, a 1D beam numerical analysis efficiently predicts local stresses around the butt weld when the maximum distortion amplitude is below 0 . 6 × t mm. The distortion needs to be considered at least up to a length of half of the plate width from the weld location and can represent longitudinal profiles within 60% of the plate width. In conclusion, the early structural stress assessment of thin-walled panels can be significantly simplified, thus helping bridge the gap between complex numerical analysis and simplified analytical solutions.

为了减轻游轮的重量，造船业对薄壁上层建筑很感兴趣，在那里，加筋板的对接焊接板的厚度在5毫米以下。与厚板相比，薄板会产生严重的焊接变形，这限制了推荐的早期设计结构应力评估方法的有效性。因此，必须使用计算代价高昂的三维非线性数值分析。为了快速有效地进行早期设计，本文研究了薄壁板在单轴拉伸作用下的简化计算模型，考虑了在4毫米厚的全尺寸船舶甲板板上测量的变形。二维简支解析板在150MPa下，对于最大斜率小于0.02rad且振幅小于厚度(t)的畸变，显示出足够的精度(即误差< 10%)。此外，一维梁数值分析有效地预测了最大变形幅度小于0时对接焊缝周围的局部应力。6 × t mm。从焊缝位置至少考虑到板宽的一半长度的变形，并且可以代表板宽60%以内的纵向轮廓。综上所述，薄壁板的早期结构应力评估可以大大简化，从而有助于弥合复杂数值分析与简化解析解之间的差距。

Reversible shape transition of nanostructure-induced bistable shells based on pneumatic actuations

Shenghui Yi, Shasha Qi, Yixin Yu, Mingde Yang, Honglu Wang, Qinghua Qin, Xiaoqiao He, Ligang Sun, Jian Lu

doi:10.1016/j.tws.2024.111632

基于气动驱动的纳米结构诱导双稳壳的可逆形状转变

Shape reconfiguration is a crucial feature in aerodynamic applications of bistable shells, especially for nanostructure-induced bistable shells, which offer good load-bearing capacities. Traditional actuation methods using smart materials are not powerful enough to trigger the transition of the nanostructured bistable shells. This study proposes a pneumatic actuation approach based on analytical and numerical investigations on their transition characteristics. Two distinct transition paths are theoretically identified, dependent on the nanostructured region ratio and pneumatic region ratio. With the guidance from the theoretical models, custom-made pneumatic suction cups are employed to achieve wireless and automatic reconfigurations of the nanostructured bistable shells. This pneumatic shape morphing provides a valuable approach for creating adaptive surfaces in aerodynamic applications.

形状重构是双稳壳气动应用的关键特征，尤其是纳米结构诱导的双稳壳具有良好的承载能力。使用智能材料的传统驱动方法不足以触发纳米结构双稳壳的转变。本文在对其过渡特性进行分析和数值研究的基础上，提出了一种气动驱动方法。理论上确定了两种不同的过渡路径，依赖于纳米结构区域比和气动区域比。在理论模型的指导下，采用定制的气动吸盘实现了纳米结构双稳壳的无线和自动重构。这种气动形状变形为在气动应用中创建自适应表面提供了一种有价值的方法。

An efficient compound strip method for buckling analysis of stiffened cylinders

Hao Yu, Pizhong Qiao

doi:10.1016/j.tws.2024.111646

一种有效的加筋圆柱屈曲分析复合条法

Buckling behavior is of utmost importance in design analysis of thin-walled structures. This paper proposes an efficient compound strip method for buckling analysis of stiffened cylinders. The novel method overcomes the modeling complexity and additional degrees brought by stiffeners, and it significantly improves computational efficiency at the same level of computational accuracy. The stiffened cylinders, discretized into a series of plate strips attached with stiffeners, are treated as assemblies of skin and stiffeners. The displacements of the stiffeners are expressed compatibly by the fundamental displacement parameters of the base plate, while the reinforcement of stiffeners is naturally incorporated by adding the beam stiffness matrix to the corresponding strips. Therefore, the discrete model is constructed only by the base plate strips formulated using the first-order shear deformation plate theory. With excellent computational convergence, accuracy and efficiency, the present method investigates the reinforcement of different types of stiffeners and the buckling behavior of stiffened cylinders surrounded by elastic foundation. The impact of the number and height of stiffeners as well as the foundation type is investigated through a parametric study. A concise and efficient buckling analysis of stringer-, ring-, or orthogonally-stiffened cylinders can be achieved by the proposed method.

屈曲行为是薄壁结构设计分析的重要内容。本文提出了一种有效的加筋圆柱屈曲分析复合条法。该方法克服了加筋带来的建模复杂性和附加度，在相同的计算精度下显著提高了计算效率。将加劲圆柱离散成一系列附加加劲筋的板条，作为蒙皮和加劲筋的组合。加劲筋的位移由基础板的基本位移参数协调表示，而加劲筋的配筋则通过在相应的筋条上加入梁刚度矩阵而自然结合。因此，离散模型仅由采用一阶剪切变形板理论表述的底板条构成。该方法具有良好的计算收敛性、精度和效率，研究了不同类型加劲筋的配筋和弹性基础包围下加劲圆柱的屈曲行为。通过参数化分析，探讨了加劲筋数目、加劲筋高度以及基础类型对结构的影响。采用本文提出的方法，可以对柱状、环形或正交加筋圆柱体进行简洁有效的屈曲分析。