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Plate- and shell-like elements are the main constituent of many engineering structures such as ships and airplanes. This paper develops a frequency domain model updating method using power spectral density function and seeks its viability in damage identification of plates and shells. The derivation of the sensitivity equation is exact and measured natural frequencies of few lower modes are used to overcome the drawbacks of incomplete measurement. The method is numerically examined in several damage cases. The robustness of method against measurement and mass modelling error is numerically assessed using Monte-Carlo analysis and numerically simulated error contaminated data. The method proves to be robust against both kind of errors and performs well, both in cases of plate and shell elements. 相似文献
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Ahmad Beyhaqi 《Inverse Problems in Science & Engineering》2018,26(7):942-965
In this paper, a structural model updating technique is presented using frequency domain representation of incomplete strain data to identify the location and severity of structural damages. The most important challenges of model updating methods such as selection of excitation, measurement locations and interested frequency ranges are addressed. Distribution of strain energy in all structural elements and norms of the derived sensitivity equation are utilized for the selection of measurement and excitation locations. The important effect of different level of noise in measurement data and modelling error on the accuracy and robustness of the proposed method are investigated. A bowstring truss and a two-storey single-bay frame are used to evaluate the numerical ability of proposed method. The results prove the potentials of the proposed method in identifying the location and severity of damage in the presence of different errors. 相似文献
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提出一种改进的柔度灵敏度方法用于工程结构损伤识别.通过在迭代算法中引入一个"加速"公式来迅速获得足够精确的识别结果,避免了多次迭代,可以大大减少计算花费.用两个数值算例对所提方法进行了验证,并把结果和原柔度灵敏度方法的计算结果进行比较.结果表明:采用改进的算法一般只需经过一次计算即可获得很高精度的识别结果,而采用原方法必须经过多次迭代才能获得相同精度的识别结果.改进的方法比原方法大大减少了迭代次数,显著减少了计算花费,显示了改进方法的突出优越性. 相似文献
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An efficient method for the multiple damage detection of truss systems using a flexibility-based damage probability index (FBDPI) and differential evolution algorithm (DEA) is proposed. In the first step, a new FBDPI is introduced to find the potentially damaged elements of truss systems. The proposed FBDPI is based on the changes of elemental strain, due to damage, computed by the flexibility matrix of the structure. The flexibility matrix of the structure is dynamically estimated using modal analysis data. In the second step, the reduced damage problem is transformed into a standard optimization problem having few damage variables. Then, the DEA is employed to solve the optimization problem for determining the actual location and severity of damaged elements. Simulation results considering measurement noise demonstrate the high efficiency of the proposed method for the damage detection of truss structures. 相似文献
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Nizar Faisal Alkayem 《工程优选》2018,50(10):1695-1714
This study presents a methodology which integrates single-objective evolutionary algorithms (EAs) and finite element (FE) model updating for damage inference in three-dimensional (3D) structures. First, original well-known EAs, namely the genetic algorithm, differential evolution (DE) and particle swarm optimization (PSO), are combined with FE model updating for detecting damage in a 3D four-storey modular structure and their performances are compared. Next, to obtain more accurate results, hybrid Lévy flights–DE and hybrid artificial bee colony–PSO are developed for enhancing damage identification. With each method, the objective function composed of modal strain energy and mode shape residuals, taken from the FE model of the intact structure and the simulated damage responses, is initially created. Then, the performance of each algorithm combined with FE model updating for damage detection is assessed in terms of three characteristics: consistency, computational cost and accuracy, and the best performing algorithm is recommended. 相似文献
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This paper develops the point-by-point impact vibration method, a damage diagnosis method for beam structures. The theoretical development and experimental verification were carried out on aluminum beams with single and double cracks in the vertical direction and on pre-stressed concrete beams with local breaks. The processing signals were the time histories of the acceleration responses of the beams and the impact force. The point-by-point impact vibration method is combined with the Dynamic Reciprocal Theorem, the Frequency Domain Decomposition method, and the Damage Index idea, all of which cover the modal curvature change (MCC) and the change of strain energy, as well as other measures. One of the advantages of this method is the ability to use fewer sensors to obtain higher order eigenmodes, which can be applied in the damage index. Experimental results indicate that higher order vibration modes exhibit great potential for damage identification. 相似文献
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基于车激响应和灵敏度分析的桥梁结构损伤识别方法研究 总被引:1,自引:0,他引:1
提出了一种利用桥梁结构在车辆荷载作用下在线响应评估结构性损伤的方法。以单元弯曲刚度的变化量为识别指标,基于车桥动力相互作用理论计算车激桥梁响应以及响应对损伤指数的灵敏度,以结构不同状态下的响应残差为约束条件,利用最小二乘法求解灵敏度方程得到各单元的损伤指数,然后通过有限元更新技术和反复迭代,最终实现对桥梁损伤的定位和定... 相似文献
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摘要:本文提出了一种基于模型修正的钢管焊接结构焊缝损伤识别方法。利用从发射台骨架试验模型获取的模态参数,选择识别结果中精度较好的模态频率作为模型修正的基准频率。通过对待修正参数的灵敏度分析,运用ANSYS和MATLAB软件对有限元模型进行了修正。以实测模态和计算模态之间的误差建立一个带约束边界非线性最小二乘目标函数,将损伤识别问题转化为优化问题,并采用信赖域方法求解该优化问题。以有限元模型焊接结点单元组弹性模量的降低模拟焊缝损伤,并假定了两种损伤工况,通过对发射台骨架模型的数值仿真及试验研究,结果表明本文提出的损伤识别方法识别效果较为理想,为解决这种复杂焊接结构焊缝损伤识别问题提供了新的思路。 相似文献
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An enhanced response sensitivity approach for structural damage identification: convergence and performance 下载免费PDF全文
Zhong‐Rong Lu Li Wang 《International journal for numerical methods in engineering》2017,111(13):1231-1251
This paper develops an enhanced response sensitivity approach for structural damage identification. The whole work is mainly two‐fold. Firstly, the general response sensitivity approach has been shown to perform well for small damage, but may not work for moderate or large damage. Therefore, to overcome this drawback, the trust‐region restriction is additionally enforced to enhance the general response sensitivity approach. In doing so, the Tikhonov regularization is invoked which is simple for practical manipulation and is shown equivalent to trust‐region considerations. Secondly, concrete convergence analysis is presented to guarantee the performance of the enhanced response sensitivity approach. Numerical examples are studied to verify the proposed approach. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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A directly analytical method of structural identification is derived by sensitivity theory and iteration theory. The application.of the directly analytical method of damage identification for frame structures is discussed in this paper. To increase the calculation accuracy and the construction convenience, the author improved the modal truncation error on the basis of the generally direct analytical method, and thus the required modal number could be reduced. The least modal number for damage identification drops from 23 to 16 by improving the method. The damage identification is made by the numerical simulation analysis of a five-storey-and-two-span RC frame structure, using improved and unimproved direct analytical method respectively; and the fundamental equations was solved by the minimal least square method (viz. general inverse method). It demonstrates that the feasibility and the accuracy of the present approach was impoved significantly, compared with the result of unimproved damage identification. 相似文献
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复合材料结构在服役过程中遇到的损伤主要来自于意外冲击,会产生永久性的凹坑.为了得到凹坑的检出概率,采用最大似然估算法对一般目视检测(GVI)和详细目视检测(DET)的两种损伤检出概率模型(POD评估模型,即累积对数正态模型和对数奇函数模型)中的参数进行评估;开展详细目视检测的试验研究,并根据检测数据对POD模型进行了验证.结果表明:凹坑深度的检出概率曲线更符合累积对数正态模型.绿色板的凹坑比黑色板更容易被检出,且检测角越大越容易被检出.目视勉强可见损伤(BVID)的门槛值在0.35~0.8mm之间. 相似文献
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A Jaya algorithm was recently proposed for solving effectively both constrained and unconstrained optimization problems. In this article, the Jaya algorithm is further extended for solving the optimization-based damage identification problem. In the current optimization problem, the vector of design variables represents the damage extent of elements discretized by the finite element model, and a hybrid objective function is proposed by combining two different objective functions to determine the sites and extent of damage. The first one is based on the multiple damage location assurance criterion and the second one is based on modal flexibility change. The robustness and efficiency of the proposed damage detection method are verified through three specific structures. The obtained results indicate that even under relatively high noise level, the proposed method not only successfully detects and quantifies damage in engineering structures, but also shows better efficiency in terms of computational cost. 相似文献
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X. G. Hua Y. Q. Ni Z. Q. Chen J. M. Ko 《International journal for numerical methods in engineering》2008,73(13):1845-1864
In this paper, an improved perturbation method is developed for the statistical identification of structural parameters by using the measured modal parameters with randomness. On the basis of the first‐order perturbation method and sensitivity‐based finite element (FE) model updating, two recursive systems of equations are derived for estimating the first two moments of random structural parameters from the statistics of the measured modal parameters. Regularization technique is introduced to alleviate the ill‐conditioning in solving the equations. The numerical studies of stochastic FE model updating of a truss bridge are presented to verify the improved perturbation method under three different types of uncertainties, namely natural randomness, measurement noise, and the combination of the two. The results obtained using the perturbation method are in good agreement with, although less accurate than, those obtained using the Monte Carlo simulation (MCS) method. It is also revealed that neglecting the correlation of the measured modal parameters may result in an unreliable estimation of the covariance matrix of updating parameters. The statistically updated FE model enables structural design and analysis, damage detection, condition assessment, and evaluation in the framework of probability and statistics. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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A combined elastoplastic damage model for progressive failure analysis of composite materials and structures 总被引:1,自引:0,他引:1
The paper is concerned with the development and verification of a combined elastoplastic damage model for the progressive failure analysis of composite materials and structures. The model accounts for the irreversible strains caused by plasticity effects and material properties degradation due to the damage initiation and development. The strain-driven implicit integration procedure is developed using equations of continuum damage mechanics, plasticity theory and includes the return mapping algorithm. A tangent operator consistent with the integration procedure is derived to ensure a computational efficiency of the Newton–Raphson method in the finite element analysis. The algorithm is implemented in Abaqus as a user-defined subroutine. The efficiency of the constitutive model and computational procedure is demonstrated using the analysis of the progressive failure of composite laminates containing through holes and subjected to in-plane uniaxial tensile loading. It has been shown that the predicted results agree well with the experimental data reported in the literature. 相似文献
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Sang-Youl Lee 《Inverse Problems in Science & Engineering》2019,27(8):1038-1056
This study deals with an identification of stiffness reduction and response predictions occurred by the delamination damage in laminated composite plates under impact loads. Combined bivariate Gamma function and microgenetic algorithms are developed to determine the crack region due to the delamination and predict future responses. The validity of the proposed method was verified using impact-induced data obtained from a two-dimensional delamination finite element model. Examples indicated that the proposed approach is a feasible and advantageous method through which future dynamic responses can be predicted and the distribution of the degraded stiffness of laminated composite structures can be inspected for different measuring locations and fibre angles. 相似文献