Forces in mechanics最新文献_第5页

Dynamics of nonlocal stress-driven Rayleigh Beam 非局部应力驱动瑞利梁动力学

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2025-02-01 DOI: 10.1016/j.finmec.2024.100299

D. Indronil

This paper presents a novel investigation of the dynamic behavior of Rayleigh nanobeams using a nonlocal stress-driven differential elasticity model, extending the foundational work of Barretta. Unlike previous studies that exclusively employed the Euler-Bernoulli beam theory and neglected rotary inertia, this work is the first to incorporate the rotary inertia term within the stress-driven nonlocal framework, providing a more accurate and comprehensive analysis of nanoscale beam dynamics. The equilibrium equations are derived using a variational approach and solved analytically via the Laplace transform technique, yielding closed-form expressions for the natural frequencies of nanobeams under various boundary conditions, including simply supported, clamped, and cantilevered configurations. The results demonstrate that nonlocal stress effects significantly increase the natural frequencies, particularly in higher vibrational modes, where sensitivity to size-dependent interactions is most pronounced. These findings highlight the inadequacy of classical elasticity models and the necessity of accounting for nonlocal and rotary inertia in dynamic analyses. The proposed model shows excellent agreement with existing literature, validating its robustness and offering valuable insights for designing and optimizing nanoscale devices such as MEMS, NEMS, and nanocomposites. This study sets a new benchmark in nonlocal elasticity by addressing rotary inertia, paving the way for more refined studies of nanoscale dynamics.

本文利用非局部应力驱动的微分弹性模型对瑞利纳米梁的动力行为进行了新的研究，扩展了Barretta的基础工作。与以往只使用欧拉-伯努利梁理论而忽略转动惯量的研究不同，这项工作首次将转动惯量项纳入应力驱动的非局部框架中，为纳米尺度梁动力学提供了更准确和全面的分析。利用变分方法推导了平衡方程，并通过拉普拉斯变换技术进行了解析求解，得到了不同边界条件下纳米梁的固有频率的封闭表达式，包括简支、夹紧和悬臂结构。结果表明，非局部应力效应显著增加了固有频率，特别是在高振动模式下，对尺寸依赖相互作用的敏感性最为明显。这些发现突出了经典弹性模型的不足，以及在动力分析中考虑非局部和旋转惯性的必要性。所提出的模型与现有文献非常吻合，验证了其稳健性，并为MEMS、NEMS和纳米复合材料等纳米级器件的设计和优化提供了有价值的见解。这项研究通过解决旋转惯性，为非局部弹性设定了新的基准，为更精细的纳米尺度动力学研究铺平了道路。

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引用次数: 0

An analytical solution for the evaluation of residual stresses in coiling of metal sheets 金属卷取过程中残余应力评估的解析解

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2025-02-01 DOI: 10.1016/j.finmec.2025.100305

D.P. Yesane , R.S. Hingole , R.V. Bhortake

The coiling process is widely used in the manufacturing industry for the compact storage and transportation of metal sheets. However, this process can induce residual stress in the material, which significantly affects the mechanical properties and performance of the final product. This paper presents a closed-form analytical solution for predicting residual stresses in steel sheets resulting from coiling before cold forming into sections. The study models the coiling process as an elastic-plastic plane-strain pure-bending problem, assuming that the steel obeys the Von Mises yield criterion and the Prandtl-Reuss flow rule. This paper explores the impact of coiling radius and steel yield stress on residual stresses, emphasizing the nonlinear variations in residual stresses across the thickness of steel sheets. The analytical predictions of residual stress were experimentally validated using X-ray diffraction, demonstrating close agreement with the finite element analysis (FEA) results. The impact of coiling radius and yield stress on the final residual stresses was also examined. The developed analytical method provides solutions for developed residual stresses during the coiling of metal sheets with higher accuracy, zero cost, and less time-consuming than current available experimental methods for measuring residual stresses.

卷取工艺在制造业中广泛应用于金属薄板的紧凑储存和运输。然而，这一过程会在材料中产生残余应力，从而显著影响最终产品的力学性能和性能。本文提出了一种预测钢板冷成形前卷取残余应力的封闭解析解。假设钢服从Von Mises屈服准则和Prandtl-Reuss流动准则，将卷取过程建模为弹塑性平面应变纯弯曲问题。本文探讨了卷取半径和钢材屈服应力对残余应力的影响，强调了残余应力在钢板厚度上的非线性变化。利用x射线衍射实验验证了残余应力的分析预测，证明了与有限元分析（FEA）结果的密切一致性。研究了卷取半径和屈服应力对最终残余应力的影响。与现有的残余应力测量实验方法相比，所开发的分析方法具有更高的精度、零成本和更短的时间，为金属板卷取过程中产生的残余应力提供了解决方案。

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引用次数: 0

Residual stresses in 4D printed structures: A review on causes, effects, measurements, mitigations and its applications 在4D打印结构的残余应力：对原因，影响，测量，缓解及其应用的审查

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2025-02-01 DOI: 10.1016/j.finmec.2024.100304

Chandramohan Abhishek, Nadimpalli Raghukiran

3D printing of stimulus responsive materials or smart materials are referred to as 4D printing. The ability of these materials to change their shape or properties over time is considered the fourth dimension. 4D printed parts possess residual stress just as any other manufactured object. Residual stress is that which remains in an object despite the absence of a load. It may develop during the printing process, or post printing. This paper presents an original review on the causes, adverse effects, measurement techniques, and mitigation of residual stresses in 4D printing. A simple sequence for checking the adverse effects of residual stress on 4D printed parts, and applying mitigation techniques is proposed. Building on the review, discussions on original results from design strategy, experimentation, characterization, and finite element analysis were presented. The applications of residual stress mitigation, and the prospects of this work are also discussed.

刺激响应材料或智能材料的3D打印称为4D打印。这些材料随时间改变其形状或特性的能力被认为是第四个维度。4D打印部件具有残余应力，就像任何其他制造对象。残余应力是物体在没有载荷的情况下仍然存在的应力。它可能在印刷过程中或印刷后形成。本文提出了对原因，不利影响，测量技术，并缓解残余应力在4D打印的原始审查。提出了一种简单的序列，用于检查残余应力对4D打印部件的不利影响，并应用缓解技术。在回顾的基础上，讨论了设计策略、实验、表征和有限元分析的原始结果。最后讨论了残余应力消除技术的应用，并对今后的研究工作进行了展望。

引用次数: 0

Residual stresses in cold-formed steel sections: An overview of influences and measurement techniques 冷弯型钢截面的残余应力：影响和测量技术概述

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2025-02-01 DOI: 10.1016/j.finmec.2025.100306

Ayad Mutafi , J.M. Irwan , Noorfaizal Yidris , Abdullah Faisal Alshalif , Yazid Saif , Hamdi Abdulrahman , Ala Mutaafi , Yasser Yahya Al-Ashmori , Mugahed Amran , Nelson Maureira-Carsalade , Siva Avudaiappan

Cold-formed steel (CFS) members offer significant advantages over hot-rolled sections, primarily due to their high strength-to-weight ratio and versatility in forming various cross-sectional shapes. These attributes make CFS an efficient choice for design and construction. This paper reviews current design methods for CFS, focusing on the impact of initial imperfections. It also examines various techniques for measuring residual stress in CFS sections, including analytical, experimental, and numerical approaches. The study concludes that while analytical methods are effective, they become complex when accounting for material anisotropy. Laboratory techniques provide reliable measurements but are limited in detecting through-thickness residual stresses. Numerical approaches offer comprehensive insights but require further validation across different material and geometric configurations. The paper highlights the need for advanced analytical models, improved laboratory methods, and expanded numerical techniques to address existing knowledge gaps in residual stress assessment for CFS structures.

冷弯型钢（CFS）成员与热轧型钢相比具有显著的优势，主要是由于其高强度重量比和形成各种截面形状的通用性。这些特性使CFS成为设计和施工的有效选择。本文综述了现有的CFS设计方法，重点讨论了初始缺陷的影响。它还检查了各种技术测量残余应力在CFS部分，包括分析，实验和数值方法。该研究得出结论，虽然分析方法是有效的，但在考虑材料各向异性时，它们变得复杂。实验室技术提供了可靠的测量，但在检测厚度残余应力方面受到限制。数值方法提供了全面的见解，但需要进一步验证不同的材料和几何结构。本文强调需要先进的分析模型、改进的实验室方法和扩展的数值技术来解决现有的CFS结构残余应力评估的知识空白。

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引用次数: 0

Modified CEL method for determination of defect formation mechanism in underwater stationary shoulder FSW based on softened pressure-overclosure contact relationship 基于软化压力-过闭接触关系的水下静肩FSW缺陷形成机理的改进CEL方法

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2024-12-01 DOI: 10.1016/j.finmec.2024.100296

Akbar Hosseini, Alireza Fallahi Arezoudar

The Coupled Eulerian-Lagrangian (CEL) method was employed to simulate underwater friction stir welding with a stationary shoulder tool (USSFSW). The governing equations in the CEL method were formulated for FSW based on the immersed boundary method. A new softened pressure-overclosure model was introduced to define contact pressure within the overclosure zone, and an initial nodal clearance control method was implemented to prevent the penetration of Eulerian elements into the Lagrangian domain. For modeling the mechanical and thermal interactions between surfaces, the VUINTERACTION subroutine was utilized. The study focused on the defect formation mechanisms during USSFSW, highlighting the roles of material flow velocity and nodal forces. Simulation results demonstrated close alignment with experimental data, revealing three flow paths that developed during the process, merging in the empty area behind the pin and generating upward material flow. Notably, the maximum flow velocity at the boundary of the third and fourth quadrants ranged from 0.189 to 0.495 m/s, while the overall maximum material flow velocity varied from 0.193 to 0.502 m/s. The nodal force was found to vary between 180 and 600 N; notably, when this force dropped below 200 N, the driving force for material flow decreased, resulting in the inability to fill the cavity behind the tool. Conversely, increasing the nodal force enhanced both backward flow (BF) and horizontal flow (HF), promoting higher material extrusion into the cavity. Ultimately, when the flow velocity fell below approximately 0.25 mm/s and the nodal force dropped below about 200 N, cavity defects in USSFSW became inevitable.

采用耦合欧拉-拉格朗日（CEL）方法对静肩工具水下搅拌摩擦焊接进行了数值模拟。基于浸入边界法，建立了等效等效等效法的控制方程。引入了一种新的软化压力-过闭模型来定义过闭区内的接触压力，并采用初始节点间隙控制方法来防止欧拉单元渗透到拉格朗日域。为了模拟表面之间的力学和热相互作用，使用了VUINTERACTION子程序。重点研究了USSFSW过程中缺陷的形成机制，强调了材料流速和节点力的作用。模拟结果与实验数据非常接近，揭示了在过程中形成的三条流动路径，在引脚后面的空白区域合并并产生向上的物质流。值得注意的是，第三和第四象限边界处的最大流速范围为0.189 ~ 0.495 m/s，而整体最大物料流速范围为0.193 ~ 0.502 m/s。节点力在180 ~ 600牛之间变化；值得注意的是，当该力低于200 N时，物料流动的驱动力减小，导致无法填充工具后面的空腔。相反，增加节点力会增强回流（BF）和水平流动（HF），促进更高的材料挤压入腔。最终，当流速降至0.25 mm/s左右，节点力降至200 N左右时，USSFSW的空腔缺陷不可避免。

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引用次数: 0

Machine learning approach for predicting early-age thermal cracking potential in concrete bridge piers 预测混凝土桥墩早期热裂潜力的机器学习方法

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2024-12-01 DOI: 10.1016/j.finmec.2024.100297

Tu Anh Do, Ba-Anh Le

In concrete construction, early-age thermal cracks in foundations, abutments, piers, and slabs can arise from non-uniform temperature distribution due to heat from cement hydration. These cracks negatively impact the integrity, load-bearing capacity, and service life of the concrete structures. This paper investigates the application of machine learning (ML) models to predict early-age thermal cracking in concrete bridge piers. The study aims to develop models to forecast thermal cracking potential (η_max) and estimate the timing of potential cracking (t) based on a dataset of various cross-sectional bridge piers and typical tropical temperatures. Four ML models—Support Vector Machine (SVM), Extreme Gradient Boosting (XGB), Artificial Neural Network (ANN), and Genetic Programming (GP)—were trained on 759 samples. The dataset, prepared using the EACTSA program, included parameters like cross-sectional dimensions, ambient temperature, and initial concrete temperature, with η_max and t as outputs. Results show that all the ML models achieved high prediction accuracy with R² scores over 0.96. The GP symbolic equations offer transparency and practical implementation. Compared to conventional methods, ML models provide a rapid, effective tool to optimize concrete member dimensions, formwork removal timing, and control concrete temperature, mitigating early-age thermal cracking risk.

在混凝土施工中，由于水泥水化产生的热量导致温度分布不均匀，地基、桥台、桥墩和楼板中的早期热裂缝可能会产生。这些裂缝对混凝土结构的完整性、承载能力和使用寿命产生负面影响。本文研究了机器学习（ML）模型在混凝土桥墩早期热裂预测中的应用。基于不同截面桥墩和典型热带温度的数据集，建立了预测热裂潜力（ηmax）和估计潜在裂缝时间(t)的模型。在759个样本上训练了支持向量机（SVM）、极端梯度增强（XGB）、人工神经网络（ANN）和遗传规划（GP）四种ML模型。使用EACTSA程序编制的数据集包括截面尺寸、环境温度和初始混凝土温度等参数，输出ηmax和t。结果表明，所有ML模型均具有较高的预测精度，R²分数均在0.96以上。GP符号方程提供了透明性和实用性。与传统方法相比，ML模型提供了一种快速有效的工具，可以优化混凝土构件尺寸，拆除模板的时间，控制混凝土温度，降低早期热裂的风险。

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引用次数: 0

Theoretical and numerical stress analysis in the cam of a medium voltage switchgear vacuum circuit breaker supported by image processing of deformation 通过变形图像处理对中压开关真空断路器凸轮进行理论和数值应力分析

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2024-11-22 DOI: 10.1016/j.finmec.2024.100298

Mahmood Matin , Erfan Fatahi , Hossein Darijani , Aram Arjmand

Vacuum circuit breakers (VCBs) are widely used in the switchgear industry. Over the past decades, leading companies have conducted extensive research and development to optimize the mechanical mechanisms and understand the kinematics and dynamics behavior of VCBs. The mechanical life of these devices is crucial for safety and reliability. This paper investigates an essential component of the VCB mechanism by evaluating the stress in the cam using theoretical and numerical methods. Furthermore, the calculations are supported by examining a deformed cam in a VCB after 2500 cycles. To this end, contact stress equations for the cylindrical part of the cam and its follower were developed. The ABAQUS finite element software was employed with specified contact properties. Additionally, an image of a cam in a VCB after 2500 cycles was processed and compared to other methods. The results demonstrate that the cam exhibited alternating stress values at different local locations at the end of its profile. However, in general, the Von Mises stress increased as the location on the cam progressed from 0° to 240°.

真空断路器（VCB）广泛应用于开关设备行业。在过去的几十年中，领先的公司进行了广泛的研究和开发，以优化真空断路器的机械结构并了解其运动学和动力学行为。这些设备的机械寿命对安全性和可靠性至关重要。本文通过使用理论和数值方法评估凸轮中的应力，研究了气动阻尼器机构的一个重要组成部分。此外，还通过研究 2500 次循环后 VCB 中变形的凸轮来支持计算。为此，开发了凸轮圆柱形部分及其从动件的接触应力方程。使用的 ABAQUS 有限元软件具有指定的接触属性。此外，还处理了 2500 次循环后 VCB 中凸轮的图像，并与其他方法进行了比较。结果表明，凸轮在其轮廓末端的不同局部位置表现出交替的应力值。不过，一般来说，随着凸轮上的位置从 0° 转到 240°，Von Mises 应力会增加。

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引用次数: 0

Quasi-static puncture shear loading characteristics of GLARE/nanoclay laminates with various indenters 带有不同压头的 GLARE/nanoclay 层压板的准静态穿刺剪切加载特性

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2024-11-22 DOI: 10.1016/j.finmec.2024.100295

Thiyagu Murgaiyan , Vasudevan Alagumalai , Yoganandam Krishnamoorthy , Prem kumar , Arumugaprabu Veerasimman , Sundarakannan Rajendran , Megavannan Mani , Senthilkumar Jadamuni , Vigneshwaran Shanmugam , Oisik Das

The potential challenge of delamination in fibre–metal laminates highlight the importance of improving interfacial bonding within the laminate. Developing a comprehensive understanding of the nature of this failure is essential for implementing effective mitigation strategies. This study explores fibre metal laminates comprising aluminium sheets and glass/epoxy, with and without the addition of nanoclay at varying weight percentages (0.5, 1, 1.5, and 2 wt.%). Fabrication involved the hand layup method followed by compression moulding, and the laminates were subjected to flexural, inter-laminar shear strength, and quasi-static punch shear tests (QS-PS). Two different indenters, flat and hemispheric, were employed in the QS-PS. Observations from flexural and interlaminar shear strength tests indicated that fibre metal laminate (FML) composites lacking nanoclay exhibit weakened interfacial bonding between aluminium and fibre layers. Notably, at 1.5 wt.% nanoclay, a substantial improvement in interfacial bonding between the fibre and aluminium layers improved the flexural strength (ca. 337 MPa), interfacial shear strength (ca. 16 MPa) and puncture resistance. The puncture failure modes exhibited variability based on the type of the indenter used, whether flat or hemispherical. For FML composites containing 2 wt.% nanoclay, the puncture shear strength differed significantly between the two indenters, measuring approximately 81 MPa under the flat indenter and about 49 MPa under the hemispherical indenter. Additionally, the corresponding energy absorption values were 880 KJ/g and 919 KJ/g for the flat and hemispherical indenters, respectively.

纤维-金属层压板分层的潜在挑战凸显了改善层压板内部界面粘合的重要性。全面了解这种故障的性质对于实施有效的缓解策略至关重要。本研究探讨了由铝板和玻璃/环氧树脂组成的纤维金属层压板，其中是否添加了不同重量百分比（0.5、1、1.5 和 2 wt.%）的纳米粘土。层压板的制造采用手糊法，然后进行压缩成型，并进行弯曲、层间剪切强度和准静态冲压剪切试验（QS-PS）。在 QS-PS 试验中使用了两种不同的压头，即平面压头和半球形压头。挠曲和层间剪切强度试验的观察结果表明，缺乏纳米黏土的纤维金属层压板（FML）复合材料表现出铝层和纤维层之间的界面粘合力减弱。值得注意的是，当纳米黏土的重量百分比为 1.5 时，纤维层和铝层之间的界面粘合力大幅提高，从而改善了抗弯强度（约 337 兆帕）、界面剪切强度（约 16 兆帕）和抗穿刺性。穿刺失效模式因所使用的压头类型（扁平或半球形）而有所不同。对于含有 2 wt.% 纳米黏土的 FML 复合材料，两种压头的穿刺剪切强度差别很大，扁平压头下约为 81 兆帕，半球形压头下约为 49 兆帕。此外，平面压头和半球形压头的相应能量吸收值分别为 880 KJ/g 和 919 KJ/g。

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引用次数: 0

Free vibration analysis of a functionally graded porous nanoplate in a hygrothermal environment resting on an elastic foundation 湿热环境中位于弹性地基上的功能分级多孔纳米板的自由振动分析

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2024-11-14 DOI: 10.1016/j.finmec.2024.100294

Ali Mottaghi , Ali Mokhtarian , Mohammad Hashemian , Mostafa Pirmoradian , Soheil Salahshour

This research investigates the free vibrational behavior of a functionally graded porous (FGP) nanoplate resting on an elastic Pasternak foundation in a hygrothermal environment. The nanoplate is modeled based on the nonlocal strain gradient theory (NSGT) and considering several plate theories including the CPT (classical plate theory), the FSDT (first-order shear deformation theory), and the TSDT (third-order shear deformation theory). Several patterns are investigated for the dispersion of pores, and the surface effects are incorporated to enhance the precision of the model. The governing equations and boundary conditions are derived via Hamilton's principle and an exact solution is provided via the Navier method. The impacts of several parameters on the natural frequencies are inspected such as length scale and nonlocal parameters, surface effects, porosity parameter, hygrothermal environment, and coefficients of the foundation. The results show that the impact of the porosity parameter on the natural frequencies of nanoplates is significantly dependent on the porosity distribution pattern. It is discovered that by increasing the porosity parameter from 0 to 0.6, the relative changes of natural frequencies vary from a decrease of 30 % to an increase of 6 %.

本研究探讨了在湿热环境中，位于弹性帕斯捷尔纳克地基上的功能分层多孔（FGP）纳米板的自由振动行为。纳米板的建模基于非局部应变梯度理论（NSGT），并考虑了多种板理论，包括经典板理论（CPT）、一阶剪切变形理论（FSDT）和三阶剪切变形理论（TSDT）。研究了孔隙分散的几种模式，并纳入了表面效应以提高模型的精度。通过汉密尔顿原理推导出了治理方程和边界条件，并通过纳维叶方法提供了精确解。研究了多个参数对固有频率的影响，如长度尺度和非局部参数、表面效应、孔隙度参数、湿热环境和地基系数。结果表明，孔隙率参数对纳米板固有频率的影响很大程度上取决于孔隙率分布模式。研究发现，将孔隙率参数从 0 增加到 0.6，自然频率的相对变化从降低 30% 到增加 6% 不等。

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引用次数: 0

Enhanced meshfree method with nodal integration for analysis of functionally graded material sandwich curved shells 用于分析功能梯度材料夹层曲面壳的节点积分增强型无网格方法

IF 3.2 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Forces in mechanics

Pub Date : 2024-10-23 DOI: 10.1016/j.finmec.2024.100292

Thien Tich Truong, Binh Khanh Ngo, Nha Thanh Nguyen, Vay Siu Lo

This paper presents a nodal integration technique, the sub-domain stabilized conforming integration (SSCI), for the meshfree radial point interpolation method (RPIM) applied to the static and modal analysis of functionally graded material (FGM) sandwich curved shells. FGM sandwich shells with different kinds of core and face sheets are considered in this work while the interested curved shell is formulated by the first-order shear deformation theory. The numerical integration technique to compute the stiffness and mass matrices in the equilibrium equation is the SSCI, which is a stabilized nodal integration with strain smoothing to preserve the accuracy and stability of the numerical results. The RPIM shape functions are utilized in this study for interpolating both the field variables and the geometry of the curved shell due to their ability to satisfy the Kronecker delta property, a rare advantage among meshfree methods. The static and modal analysis of different geometry curved shells with various sandwich FGMs are conducted. Through several numerical examples, the accuracy and efficiency of the SSCI technique in the meshfree RPIM are demonstrated and discussed.

本文针对无网格径向点插值法（RPIM）提出了一种节点积分技术--子域稳定保形积分（SSCI），并将其应用于功能梯度材料（FGM）夹层曲面壳的静态和模态分析。本研究考虑了具有不同芯材和面片的 FGM 夹层曲面壳体，而感兴趣的曲面壳体则采用一阶剪切变形理论。计算平衡方程中刚度矩阵和质量矩阵的数值积分技术是 SSCI，它是一种带有应变平滑的稳定节点积分，以保持数值结果的精度和稳定性。由于 RPIM 形状函数能够满足 Kronecker delta 特性，因此本研究采用 RPIM 形状函数对场变量和曲面壳的几何形状进行插值，这在无网格方法中是一个罕见的优点。本研究对带有各种夹层 FGM 的不同几何形状的曲面壳进行了静态和模态分析。通过几个数值示例，展示并讨论了无网格 RPIM 中 SSCI 技术的精度和效率。

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引用次数: 0