共查询到18条相似文献,搜索用时 218 毫秒
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工程结构在使用寿命周期内,各种环境因素会导致结合面出现损伤,从而威胁结构的完整性和功能性,甚至诱发安全事故。研究了一种利用混沌激励与吸引子几何特性进行结合面损伤识别的方法,采用混沌振动信号激励待测结构,对采集到的加速度响应信号进行相空间重构,并构造了一种基于吸引子局部方差计算的特征参量用于损伤识别,同时研究了影响特征参量的主要参数。设计了悬臂梁结合面损伤识别实验,控制固定端螺栓预紧力的下降来模拟结合面损伤,利用上述方法对结合面的损伤状态进行了识别。结果表明:本文方法能够识别结合面的损伤状态,所构造的特征参量随损伤程度改变单调变化,响应测点配置、特征参量计算参数等对损伤识别的效果有影响。 相似文献
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在理论推导梁轴向振动微分方程基础上,提出一种以轴向振动低阶模态振型二阶导数为损伤指标的结构损伤识别方法。在方钢管构件上布置加速度传感器进行轴向振动模态试验,测试时由信号发生器发出正弦波信号,经功率放大器放大后通过电磁激振器对结构进行激励,同时采集各测点的加速度反应信号。在确定结构共振点后,根据共振点处加速度值,编制轴向振动损伤指标的计算程序,分析结果表明该指标对结构损伤的位置和程度均很敏感,既能精确定位损伤,又能标定损伤程度,即在损伤位置将发生相反方向的突变,且突变幅度随损伤程度增大而增大。 相似文献
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桅杆的模态参数和刚度对纤绳平衡张力、激励和环境条件比较敏感,导致目前比较有效的结构损伤识别方法和指标难以直接应用。为此,探索了基于测点振动响应时频分析而不依赖模态信息的桅杆结构损伤识别方法,提出利用结构测点振动响应的Wigner-Ville分布交叉项统计量WCS(WVD Cross-term Statistic),通过比较损伤前后统计量的相对变化量来进行损伤识别。算例分析结果表明,利用测点振动响应的损伤识别指标WCS相对变化量,除能识别杆身单个不同程度的损伤位置以及多个损伤外,还能分辩出纤绳的损伤特征。通过增大激励的幅值和增加测点的数量,可以提高识别的精度和指标的灵敏度;基于测点位移响应与基于测点加速度响应的损伤识别指标相比,具有更好的损伤识别效果。 相似文献
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目前水工结构的动力破坏特性越来越受到关注,其中动力特性是其研究的一个重要方面。通过模型试验的方法研究重力坝模型动力特性的测试方法。重点研究了环境激励法测试结构动力特性的效果,并与传统测力法进行了比较。试验结果表明采用环境激励的方法,可只根据结构的振动响应数据,有效地测试结构的动力特性。并且在不同大小环境激励下结构的振型没有发生变化,频率与阻尼比变化很小。试验结果还表明通过环境激励法与通过传统激励法测试的振型、频率与阻尼比相差很小,可认为采用这两种方法测试的结构动力特性一致。同时还说明环境激励法可有效地测试有损伤结构的动力特性。试验结果为使用环境激励法测试实际在线重力坝结构的动力特性提供了依据。 相似文献
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结合流体动力学和结构动力学分析了空调室外机管路系统由流体引起的振动问题。采用有限元方法建立了管路系统的动力学模型,并通过模态试验验证了模型的准确性。使用流体动力学方法分析了管内流场,获得管道内壁的表面压力,并以压力作为激励,结合实验验证后的管路动力学模型进行了谐响应分析。通过管路ODS(Operational Deflection Shapes)实验,验证了由流体引起的管路振动分析方法的可靠性和有效性。研究表明:管路理论模态分析与实验结果基本吻合,确保建立的动力学模型的准确性,为后续分析的准确度提供了基础;管路振动分析与ODS实验对比结果在低频段理论与实验吻合较好,而在高频段误差较大。分析了误差产生的原因,为后续研究指明了方向。 相似文献
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基于时域振动响应的结构损伤检测方法因其便于实现在线监测受到了越来越多的关注。该文回顾了两种利用时域响应相关函数建立的结构特征向量(即内积向量及互相关函数幅值向量)及其对应的损伤检测方法。为了从时域响应相关函数中提取更多的结构健康信息,通过利用不同的结构响应组合,将上述两种结构特征向量扩展到了多种结构特征向量,并进一步采用数据融合理论,提出了检测精度更高的结构损伤检测方法。针对8层框架结构损伤检测的试验研究结果表明,该文方法可以对框架结构上的微小损伤进行定位。 相似文献
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Maria Cristina Porcu Lukasz Pieczonka Andrea Frau Wieslaw Jerzy Staszewski Francesco Aymerich 《Journal of Nondestructive Evaluation》2017,36(2):33
The scaling subtraction method (SSM) is a non-destructive measurement approach used to extract nonlinear features from the elastic response of a structure. As such it can be used for damage detection purposes by identifying nonlinearities that may result from the presence of micro cracks or inclusions in granular and metallic materials. The effectiveness of such a technique to detect the presence of damage modes typical of laminated composite materials has not been yet assessed. With the purpose of filling this gap, in this paper the SSM is applied to inspect two laminated composite plates with different sizes, impact positions and sensor arrangement. Intact and damaged specimens are tested under harmonic excitations of different amplitude and frequency (the latter selected among the ultrasonic natural frequencies of the two plates). For each excitation case the recorded vibration signals are subtracted from the linearly rescaled reference signals and the SSM nonlinear indicators are calculated. The sensitivity of the method to the presence of damage is assessed in different sensor-receiver scenarios as well as for different excitation frequency and amplitude levels. Finite element numerical investigations are also performed to make comparisons with the experimental results. 相似文献
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使用结构加速度响应协方差和应变响应协方差参数以及基于贝叶斯估计的数据融合理论进行结构损伤判定和损伤位置识别,理论推导证明响应协方差参数是结构模态参数的函数,结构损伤会导致响应协方差参数的改变,当只使用结构损伤前后的响应协方差参数,不使用结构分析模型进行结构损伤识别时,损伤向量会受到激励位置、测试噪声和误差等的影响,所以使用贝叶斯数据融合理论,对来自多种传感器和多种测试环境下得到的多组损伤向量进行数据融合,以提高损伤识别的精度;利用一个七层框架结构进行包括单损伤和多损伤的多种损伤工况的数值模拟,研究所提方法的适用性和有效性,最后对简支钢梁进行实验验证,损伤位置附近的传感器所得到的损伤指标具有最大的损伤概率。 相似文献
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This paper experimentally investigates a notch-type damage identification methodology for beams by using a continuously scanning laser Doppler vibrometer (CSLDV) system. Velocity response of a beam along a scan line under sinusoidal excitation is measured by the CSLDV system and an operating deflection shape (ODS) of the beam is obtained by the demodulation method from velocity response. The ODS of an associated undamaged beam is obtained by using a polynomial with a proper order to fit the ODS from the demodulation method. The curvature of an ODS (CODS) can be calculated with a high quality due to a dense measurement grid of the ODS. A curvature damage index (CDI) is proposed to identify a notch with a length of 1 mm along a beam and a depth of 0.9 mm under different excitation frequencies. The CDI uses differences between CODSs associated with ODSs that are obtained by the demodulation method and the polynomial fit; an auxiliary CDI obtained by averaging CDIs at different excitation frequencies is defined to further assist identification of damage. An averaging technique is applied to velocity response of the beam to reduce measurement noise. Effects of the number of averages on ODSs, CODSs, and CDIs are investigated. Four scan lines with an equal length of 151 mm and different locations with respect to the notch are used to investigate reliability of the proposed methodology. Finally, a whole scan line with a length of 555 mm along the beam is applied and the notch is successfully identified near regions with consistently high values of CDIs at different excitation frequencies; it can also be identified with the auxiliary CDI by a prominent peak at the location of the notch. 相似文献
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针对如何从结构响应信息中提取结构损伤指标的问题,提出了一种基于时间序列分析的结构损伤识别方法。对结构响应数据进行预处理,利用完好工况下的结构响应数据作为参考数据,建立自回归(Auto regression-AR)预测参考模型。利用已建立的AR预测参考模型计算待识别工况的残差,将待识别工况的残差与AR预测参考模型的残差的方差之比作为损伤指标,对结构损伤进行识别;通过算例表明:该损伤指标不仅可以判断结构是否发生损伤,而且可以识别结构的损伤位置。 相似文献
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Integrated FEM/BEM approach to the dynamic and acoustic analysis of plate structures 总被引:1,自引:0,他引:1
?adi Kopuz Y. Samim Ünlüsoy Mehmet Çali?kan 《Engineering Analysis with Boundary Elements》1996,17(4):269-277
An integrated finite element/boundary element method approach to the prediction of the interior acoustic radiation of open ended box structures is presented. Dynamic response of the structure is predicted in terms of the nodal displacements under sinusoidal point force excitation using the finite element method. Theoretical results obtained in terms of frequency response functions are verified using the results from tests performed on a box structure. The interior acoustic field is then examined by the boundary element method using the boundary conditions obtained from the finite element analysis. Sound pressure levels produced inside the structure are calculated and the results are compared with the experimental measurements. 相似文献