International Journal of Solids and Structures最新文献

Stability discussion and application study of pseudo-corner models 伪角模型的稳定性讨论和应用研究

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-11-13 DOI: 10.1016/j.ijsolstr.2024.113136

Tianyin Zhang , Xianhong Han

Accurate plastic flow modelling under complex working conditions is crucial for metal deformation simulations. Recently, some advanced pseudo-corner models have been developed to describe corner effects and analyze strain localization problems. The present work consists of three parts. The first part discusses the intrinsic stability of the pseudo-corner model class, which forms the premise of application analysis. The second part applies the pseudo-corner models and the associated flow rule (AFR) to buckling onset estimation, plastic post-buckling analysis and shear band analysis. The experimental conditions are strictly reproduced and the optimal model parameters are determined. The results reveal that the pseudo-corner models and AFR are indistinguishable in the buckling onset estimation. AFR overestimates the post-buckling strength of circular tubes under axial compression, and cannot reproduce the shear band development during sheet bending; while the pseudo-corner models have better prediction performance in both scenarios. The results also suggest that the parameter values of pseudo-corner models are apparently inconsistent in the above two types of problems. Then in the third part, two representative influencing factors including strain gradient plasticity and initial imperfections are discussed, and this inconsistency is finally attributed to the shortwave surface defect which however is usually neglected by previous studies.

复杂工作条件下的精确塑性流动建模对于金属变形模拟至关重要。最近，人们开发了一些先进的伪转角模型来描述转角效应和分析应变定位问题。本研究包括三个部分。第一部分讨论了伪转角模型类的内在稳定性，这是应用分析的前提。第二部分将伪角模型和相关流动规则（AFR）应用于屈曲起始估计、屈曲后塑性分析和剪切带分析。严格再现了实验条件，并确定了最佳模型参数。结果表明，伪角模型和 AFR 在屈曲起始估计方面没有区别。AFR 高估了圆管在轴向压缩下的屈曲后强度，并且无法再现板材弯曲过程中的剪切带发展；而伪角模型在这两种情况下都具有更好的预测性能。结果还表明，在上述两类问题中，伪拐角模型的参数值明显不一致。第三部分讨论了两个具有代表性的影响因素，包括应变梯度塑性和初始缺陷，最后将这种不一致性归因于短波表面缺陷，然而之前的研究通常忽略了这一点。

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引用次数: 0

A new porous constitutive model for additively manufactured PLA 聚乳酸添加剂制造的新型多孔结构模型

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-11-12 DOI: 10.1016/j.ijsolstr.2024.113131

P. Areias, N. Silvestre, M.F. Vaz, M. Leite

We introduce a new specific hyperelastic/plastic model and porosity evolution law able to capture the deformation and damage of additively manufactured PLA-N polymers (Fused Filament Fabrication — FFF). Porosity growth is driven by projecting the right Cauchy–Green tensor in the normal to the deposition direction and by solving a local maximization problem. Fracture energy is introduced directly in the resulting law by means of a length scale. A full finite-strain plasticity model is adopted, based on the Hosford yield criterion. Strain softening is regularized with a gradient-enhanced technique, which is solved in tandem with the equilibrium equations. A comprehensive analysis of the hyperelastic transversely isotropic/porous constitutive law is performed, with physical insight on the directional strain softening behavior. A normalized CT test specimen is used to qualitatively assess the effect of deposition direction on the crack path and to investigate the effect of mesh density in the load/displacement curves. We then present a comparison with our experimental results for a cellular PLA-N beam composed of 3 × 13 cells, in terms of crack behavior and load/displacement results. Sequential collapse of the cells and strain localization match the experimental observations.

我们介绍了一种新的特定超弹性/塑性模型和孔隙率演化规律，能够捕捉到添加式制造的聚乳酸-N 聚合物（熔融长丝制造-FFF）的变形和损坏。通过在沉积方向的法线上投影右 Cauchy-Green 张量，并通过解决局部最大化问题来驱动孔隙率增长。断裂能通过长度标度直接引入所得到的定律中。根据霍斯福屈服准则，采用了完整的有限应变塑性模型。采用梯度增强技术对应变软化进行正则化，并与平衡方程同步求解。对超弹性横向各向同性/多孔组织法进行了全面分析，并对定向应变软化行为提出了物理见解。我们使用归一化 CT 试样来定性评估沉积方向对裂纹路径的影响，并研究网格密度对载荷/位移曲线的影响。然后，我们对由 3 × 13 个单元组成的聚乳酸-N 单元梁的裂纹行为和载荷/位移结果与实验结果进行了比较。单元的顺序塌陷和应变局部化与实验观察结果一致。

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引用次数: 0

Defect dynamics modeling of mesoscale plasticity 中尺度塑性缺陷动力学建模

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-11-07 DOI: 10.1016/j.ijsolstr.2024.113132

Phu Cuong Nguyen , Nicole Aragon , Ill Ryu

The collective motion of defects and their interaction are the basic building blocks for plastic deformation and corresponding mechanical behaviors of crystalline metals. Especially, dislocations among various defects are the “carrier” of plastic deformation in many crystalline materials, particularly ductile materials. To get a fundamental understanding of plastic deformation mechanisms, it calls for an integrated computational platform to simultaneously capture detailed defects characteristics across several length scales together with corresponding macroscopic mechanical response. In this paper, we present a three-dimensional mesoscale defect dynamics model to directly couple the three dimensional discrete dislocation dynamics model with continuum finite element method, aiming at capturing both size dependent plasticity at micron-, and submicron scale and constitutive behaviors at larger scales where such size-dependence disappear. Using non-singular dislocation theories, our model could accurately consider both short- and long-range elastic interactions between multiple dislocation segments with even higher computational efficiency than traditional dislocation dynamics simulations, together with the careful consideration of crystal/material rotation in the coupled framework. In addition, our model could directly model dislocation nucleation from stress concentrators such as a void, crack and indentor tip, which could allow us to investigate various defects’ motion and their mutual interactions, predicting macroscopic mechanical response of complex structures. The developed concurrently coupled model could also consider multiphysical phenomena by solving coupled governing equations in finite element framework, which could shed light on complex defect behaviors under various physical environments.

缺陷的集体运动及其相互作用是结晶金属塑性变形和相应机械行为的基本组成部分。特别是在许多晶体材料，尤其是韧性材料中，各种缺陷之间的位错是塑性变形的 "载体"。为了从根本上了解塑性变形机制，需要一个综合计算平台，以同时捕捉多个长度尺度上的详细缺陷特征和相应的宏观力学响应。在本文中，我们提出了一种三维中尺度缺陷动力学模型，将三维离散位错动力学模型与连续有限元方法直接结合起来，旨在捕捉微米和亚微米尺度上的尺寸依赖性塑性以及尺寸依赖性消失的更大尺度上的构成行为。我们的模型采用非鞘状位错理论，能准确地考虑多个位错段之间的短程和长程弹性相互作用，其计算效率甚至高于传统的位错动力学模拟，同时在耦合框架中仔细考虑了晶体/材料的旋转。此外，我们的模型可直接模拟来自空洞、裂缝和压痕尖端等应力集中点的位错成核，从而研究各种缺陷的运动及其相互影响，预测复杂结构的宏观力学响应。所开发的并行耦合模型还可以通过在有限元框架内求解耦合控制方程来考虑多物理现象，从而揭示各种物理环境下的复杂缺陷行为。

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引用次数: 0

Investigation of dynamic impact behavior of bighorn sheep horn 大角羊角动态冲击行为调查

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-11-06 DOI: 10.1016/j.ijsolstr.2024.113133

Emre Palta , Howie Fang , Qian Wang , Zheng Li

The horn of the bighorn sheep is composed of keratin-based biological material that has a tubule-lamella structure, which gives it anisotropic hardening properties under impact loading. This paper aims to investigate the energy dissipation mechanisms inherent in bighorn sheep horns by developing a numerical material model that accounts for the horn’s anisotropic features and strain-rate effects. To this end, a transversely isotropic constitutive model, which includes both anisotropic hardening and strain-rate effects, was formulated to accurately predict the mechanical behavior of bighorn sheep horns. Material characterization was conducted through uniaxial compression tests that were conducted under quasi-static and dynamic conditions. The developed constitutive model was implemented into LS-Dyna via a user-defined material subroutine and was validated against empirical data. The validated numerical model was used to investigate the horn’s mechanical responses under dynamic loading conditions. The paper focused on impact energy dissipation mechanisms, including energy absorption and transition, stress distribution, and displacement wave propagation. The insights gained from this paper are expected to significantly contribute to the development of novel artificial materials with enhanced energy absorption and impact mitigation properties.

大角羊的角由角蛋白生物材料组成，具有小管-拉梅拉结构，这使其在冲击载荷下具有各向异性的硬化特性。本文旨在通过建立一个考虑到羊角各向异性特征和应变率效应的数值材料模型，研究大角羊角固有的能量耗散机制。为此，本文建立了一个横向各向同性构成模型，其中包括各向异性硬化和应变速率效应，以准确预测大角羊角的机械行为。通过在准静态和动态条件下进行的单轴压缩试验对材料特性进行了分析。通过用户定义的材料子程序将所开发的构成模型应用于 LS-Dyna，并根据经验数据进行了验证。经过验证的数值模型用于研究动态加载条件下喇叭的机械响应。论文的重点是冲击能量耗散机制，包括能量吸收和转换、应力分布和位移波传播。从本文中获得的见解有望为开发具有更强能量吸收和冲击缓解性能的新型人工材料做出重大贡献。

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引用次数: 0

Influence of agglomeration and waviness phenomena on torsional oscillation of MWCNTs-reinforced composite rods 团聚和波状现象对 MWCNT 增强复合材料棒扭转振荡的影响

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-11-02 DOI: 10.1016/j.ijsolstr.2024.113127

Wenyuan Zhou , Yong Huang , Zhixin Wu , Mostafa Habibi , Mohamad Habibi , Riadh Marzouki

There are some inevitable challenges during the manufacturing of reinforced composite structures. Agglomeration of reinforcement and wavy reinforcement are in this category. These phenomena possess remarkable effects on the mechanical behavior of reinforced composite structures. In the current research, the effect of agglomeration and waviness of reinforcements on torsional dynamic characteristics of multi-walled carbon nanotubes (MWCNTs) reinforced composite rods subjected to two various boundary conditions have been evaluated. Three dissimilar cross-section shapes have been considered to understand the effect of cross-section shapes on torsional behavior of MWCNTs-reinforced composite rods. A new form of Halpin-Tsai homogenization model has been exerted to estimate the material properties of composite structures. Additionally, Timoshenko-Gere theory in conjunction with the Hamilton’s principle has been employed to derive the partial differential governing equation of MWCNTs-reinforced composite rods. Afterward, the obtained equation was solved using an analytical approach. The precision of the methodology utilized has been evaluated against the results of previous studies documented in the literature. Ultimately, the effects of various significant parameters on the changes in natural torsional frequency have been analyzed and presented in a series of tables and figures. Based on the obtained results, the rectangular rod has the highest torsional frequency and also the effect of MWCNTs’ volume fraction depends on the consideration of waviness and agglomeration factors. At a greater volume fraction of MWCNTs, the agglomeration factor is more effective than the waviness factor and vice versa.

在制造增强复合材料结构的过程中，不可避免地会遇到一些挑战。钢筋聚集和波浪形钢筋就是其中之一。这些现象对增强复合材料结构的力学行为有着显著的影响。在当前的研究中，我们评估了多壁碳纳米管（MWCNTs）增强复合材料棒在两种不同的边界条件下，增强体的聚集和波浪状对其扭转动态特性的影响。为了了解横截面形状对 MWCNTs 增强复合材料杆扭转行为的影响，我们考虑了三种不同的横截面形状。采用了一种新形式的 Halpin-Tsai 均质化模型来估算复合材料结构的材料特性。此外，Timoshenko-Gere 理论与汉密尔顿原理相结合，推导出了 MWCNTs 增强复合材料杆的偏微分控制方程。随后，利用分析方法求解了所得方程。所使用方法的精确度已根据文献中记录的先前研究结果进行了评估。最后，分析了各种重要参数对自然扭转频率变化的影响，并通过一系列表格和图表进行了展示。根据所获得的结果，矩形杆的扭转频率最高，同时，MWCNTs 体积分数的影响取决于对波浪度和聚结因素的考虑。当 MWCNT 的体积分数越大时，聚结因子比波状因子更有效，反之亦然。

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引用次数: 0

OXFORD-UMAT: An efficient and versatile crystal plasticity framework OXFORD-UMAT：高效多用途晶体塑性框架

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-11-01 DOI: 10.1016/j.ijsolstr.2024.113110

Eralp Demir , Alvaro Martinez-Pechero , Chris Hardie , Edmund Tarleton

The crystal plasticity-based finite element method is widely used, as it allows complex microstructures to be simulated and allows direct comparison with experiments. This paper presents the OXFORD-UMAT for Abaqus®, a novel crystal plasticity code that is publicly available online for researchers interested in using crystal plasticity. The model is able to simulate a wide range of materials and incorporates two different solvers based on the solution of slip increments and Cauchy stress, with variants of state update procedures including explicit, semi-implicit, and fully-implicit for computational efficiency that can be set by the user. Constitutive laws are available for a range of materials with single or multiple phases for slip, creep, strain hardening, and back stress. The model includes geometrically necessary dislocations that can be computed using finite element interpolation functions by four alternative methods, including the total form with and without a correction for the dislocation flux, a widely used rate form, and a slip-gradient formulation. In addition, the initial strengthening and subsequent softening seen in irradiated materials can also be simulated with the model. The analysis is available in 2D (plane stress and plane strain) and 3D, including linear and quadratic elements. Here we include full derivations of the key equations used in the code and then demonstrate the capability of the code by modeling single-crystal and large-scale polycrystal cases. Comparison of OXFORD-UMAT with other available crystal plasticity codes for Abaqus® reveals the efficiency of the proposed approach, with the backup solver offering greater versatility for handling convergence issues commonly found in practical applications.

基于晶体塑性的有限元方法可以模拟复杂的微结构，并能与实验进行直接比较，因此被广泛使用。本文介绍了适用于 Abaqus® 的 OXFORD-UMAT 模型，这是一种新型晶体塑性代码，可在线公开，供有兴趣使用晶体塑性的研究人员使用。该模型能够模拟多种材料，并结合了基于滑移增量和考奇应力求解的两种不同求解器，其状态更新程序包括显式、半隐式和全隐式，计算效率可由用户设置。对于滑移、蠕变、应变硬化和背应力的单相或多相材料，可提供各种构造定律。该模型包括几何上必要的位错，可通过四种方法使用有限元插值函数进行计算，包括有位错通量校正和无位错通量校正的总形式、广泛使用的速率形式和滑移梯度形式。此外，该模型还能模拟辐照材料的初始强化和随后的软化。该分析可用于二维（平面应力和平面应变）和三维，包括线性和二次元元素。在此，我们将对代码中使用的关键方程进行全面推导，然后通过对单晶和大规模多晶体进行建模来展示代码的能力。将 OXFORD-UMAT 与其他可用的 Abaqus® 晶体塑性代码进行比较后，我们发现所提议的方法非常高效，其备份求解器在处理实际应用中常见的收敛问题方面具有更高的通用性。

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引用次数: 0

Microvoiding and constitutive damage modeling with artificial neural networks 利用人工神经网络建立微空洞和构成性损伤模型

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-10-30 DOI: 10.1016/j.ijsolstr.2024.113125

Ning Li, Huck Beng Chew

Continuum models of porous media have revolutionized computational fracture mechanics for traditional ductile materials, but the inherent assumptions have limited generalizability to other target materials or loading conditions. Here, we adopt a series of artificial neural networks (ANNs) to predict both the microscopic voiding characteristics (void shape, porosity) and macroscopic stress–strain constitutive response of porous elasto-plastic materials under various deformation states. We train the ANNs on a dataset generated from finite element models of 3D representative volume elements (RVEs), each containing a discrete spherical void, subjected to combinations of loading states. Results show that the data-driven model is capable of interpolative predictions as well as some levels of extrapolative predictions across a wide range of initial porosities (0–20%) and loading states outside of the training dataset, even at high deformation strains which induce extensive material softening and void growth. Through transfer learning, we further demonstrate that the ANNs, originally trained on a specific porous material dataset, can be readily adapted to other porous materials with substantially different properties through a significantly reduced training dataset. We discuss the implications of this machine learning approach vis-à-vis the extensively-developed Gurson model for porous material damage and failure predictions.

多孔介质的连续介质模型彻底改变了传统韧性材料的计算断裂力学，但其固有假设对其他目标材料或加载条件的通用性有限。在此，我们采用一系列人工神经网络（ANN）来预测多孔弹塑性材料在各种变形状态下的微观空隙特征（空隙形状、孔隙率）和宏观应力应变构成响应。我们在三维代表性体积元素（RVE）的有限元模型生成的数据集上训练 ANNs，每个模型都包含一个离散的球形空隙，并受到加载状态组合的影响。结果表明，数据驱动模型能够对训练数据集之外的各种初始孔隙率（0-20%）和加载状态进行内推预测和一定程度的外推预测，即使在高变形应变导致材料软化和空隙增长的情况下也是如此。通过迁移学习，我们进一步证明，最初在特定多孔材料数据集上训练的方差网络，可以通过大幅减少训练数据集，很容易地适用于性质大相径庭的其他多孔材料。我们讨论了这种机器学习方法与广泛开发的 Gurson 模型相比对多孔材料损伤和失效预测的影响。

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引用次数: 0

Analyzing creep-recovery behavior of tropical Entandrophragma cylindricum wood: Traditional and fractional modeling methods 分析热带 Entandrophragma cylindricum 木材的蠕变恢复行为：传统和分数建模方法

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-10-30 DOI: 10.1016/j.ijsolstr.2024.113122

L.C. Nguedjio , J.S. Mabekou Takam , R. Moutou Pitti , B. Blaysat , N. Sauvat , J. Gril , F. Zemtchou , P.K. Talla

Nowadays, wood stands as one of the foremost used construction materials, owing largely to its exceptional physical and mechanical properties. Ensuring the safety of timber structures necessitates thorough investigations into the influential phenomena that significantly affect their strength and longevity. The aim of this paper is to study the coupled creep-recovery behavior of tropical wood from the Entandrophragma cylindricum species by evaluating the influence of stress levels on the performance of rheological models. Hence, the Burger and Weibull classic models were introduced to elucidate these phenomena. These models have been compared with the fractional Maxwell and Zener models. Following the simulations, the Burger classic model effectively characterized creep and recovery, comprising elastic, viscoelastic, and viscous elements arranged in series, as well as the classic Weibull model. During the recovery phase, the four-parameter Weibull model demonstrated a satisfying description, achieving 99% accuracy compared to 97% for the four-parameter Burger classic model. Three-parameter fractional Maxwell model fit all phases of the process for all deformations with an average accuracy of 98% for creep and 95% for recovery. These results provide valuable information on the material’s ability to recover from deformation and offer essential insights for materials characterization, engineering design, and quality assurance processes in materials engineering.

如今，木材已成为最常用的建筑材料之一，这主要归功于其卓越的物理和机械性能。要确保木材结构的安全性，就必须对严重影响其强度和寿命的影响现象进行深入研究。本文旨在通过评估应力水平对流变模型性能的影响，研究热带木材 Entandrophragma cylindricum 品种的蠕变-恢复耦合行为。因此，引入了 Burger 和 Weibull 经典模型来阐明这些现象。这些模型与分数麦克斯韦模型和齐纳模型进行了比较。经过模拟，Burger 经典模型和 Weibull 经典模型有效地描述了蠕变和恢复的特征，Burger 经典模型由串联排列的弹性、粘弹性和粘性元素组成。在恢复阶段，四参数 Weibull 模型的描述令人满意，准确率达到 99%，而四参数 Burger 经典模型的准确率为 97%。三参数分数麦克斯韦模型适合所有变形过程的所有阶段，蠕变的平均准确率为 98%，恢复的平均准确率为 95%。这些结果为材料的变形恢复能力提供了宝贵的信息，并为材料工程中的材料表征、工程设计和质量保证过程提供了重要的启示。

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引用次数: 0

Advanced finite element modeling methods for tensile and bending analysis of arresting gear cables 用于拦阻索拉伸和弯曲分析的先进有限元建模方法

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-10-29 DOI: 10.1016/j.ijsolstr.2024.113126

Long Li , Yiming Peng , Yifeng Wang , Xiaohui Wei , Hong Nie

This study addresses the gap in understanding the dynamic bending behavior of multi-layer twisted steel cable, pivotal in various industrial applications such as naval aircraft arresting systems. Utilizing advanced finite element modeling, the research explores the mechanical responses of these cables under macroscopic bending scenarios. By integrating beam elements and connectors within the finite element framework, the study simulates complex inter-strand interactions under various loading conditions. Results indicate that this method significantly enhances the prediction accuracy of the cables’ mechanical properties, thus offering substantial improvements in design and performance analysis of arresting gear systems. This study’s value lies in its potential to refine mechanical modeling of complex cable systems, thereby optimizing operational efficiency and safety in engineering applications.

这项研究填补了对多层扭转钢缆动态弯曲行为理解方面的空白，多层扭转钢缆在各种工业应用（如舰载机拦阻系统）中具有举足轻重的地位。研究利用先进的有限元建模，探讨了这些钢缆在宏观弯曲情况下的机械响应。通过在有限元框架内集成梁元素和连接器，该研究模拟了各种加载条件下复杂的链间相互作用。结果表明，这种方法大大提高了缆索机械性能的预测精度，从而极大地改进了捕捉装置系统的设计和性能分析。这项研究的价值在于它有可能完善复杂缆索系统的机械建模，从而优化工程应用中的运行效率和安全性。

引用次数: 0

Free vibration of electroelastic thin-walled structures under static load 静载荷下电弹性薄壁结构的自由振动

IF 3.4 3区工程技术 Q1 MECHANICS

International Journal of Solids and Structures

Pub Date : 2024-10-29 DOI: 10.1016/j.ijsolstr.2024.113123

A.O. Kamenskikh, S.V. Lekomtsev, A.N. Senin, V.P. Matveenko

The mathematical formulation and finite element algorithm for solving the problem of free vibration of electroelastic plates and shells under static load are considered. In modeling, the curvilinear surface of a thin-walled structure is represented as a set of flat segments. In each of them, the physical relations of the classical laminated plate theory and the theory of electroelasticity, written for a plane stress state, are fulfilled. The strains are determined using nonlinear equations, which are linearized with respect to the state with a small deviation from the initial equilibrium position caused by static forces. As an examples, we consider a rectangular plate and a circular cylindrical shell with a piezoelectric element under the action of the uniform pressure. The validity of the solution is confirmed by comparing the normal displacement and natural frequencies of vibration with experimental data and results obtained with the use of commercial finite element software.

研究了解决静载荷下电弹性板和壳自由振动问题的数学公式和有限元算法。在建模过程中，薄壁结构的曲线表面表示为一组平面段。在每个片段中，经典层压板理论和电弹性理论的物理关系都是针对平面应力状态编写的。应变是通过非线性方程确定的，而非线性方程是针对静力导致的与初始平衡位置有微小偏差的状态线性化的。作为示例，我们考虑了在均匀压力作用下带有压电元件的矩形板和圆形圆柱壳。通过将法向位移和振动的自然频率与实验数据和使用商业有限元软件获得的结果进行比较，证实了该解决方案的有效性。

引用次数: 0