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Multi-Mode Guided Waves Based Reference-Free Damage Diagnostic Imaging in Plates 基于多模导波的板材无参考损伤诊断成像
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.05142
Jiaqi Zhang, Kehai Liu, Chang Gao, Zhanjun Wu, Yuebin Zheng, D. Gao
Probability-based diagnostic imaging (PDI) is one of the most well-known damage identification methods using guided waves. It is usually applied to diagnose damage in plates. The previous studies were dependent on the certain damage index (DI) which is always calculated from the guided wave signals. In conventional methods, DI is simply defined by comparing the real-time data with the baseline data as reference. However, the baseline signal is easily affected by varying environmental conditions of structures. In this paper, a reference-free diagnostic imaging method is developed to avoid the influence of environmental factors, such as temperature and load conditions. The DI is defined based on the mode conversion of multi-mode guided waves with realtime signals without baseline signals. To improve the accuracy of diagnosis, two terms are included in the reference-free DI. One is called energy DI, which is defined based on the feature of signal energy. The other is called correlation DI and is defined based on the correlation coefficient. Then the PDI algorithm can be carried out instantaneously according to the reference-free DI. The real-time signals which are used to calculate DI are collected by the piezoelectric lead zirconate titanate (PZT) transducers placed on both sides of a plate. The numerical simulations by the finite element (FE) method on aluminum plates with PZT arrays are performed to validate the effectiveness of the reference-free damage diagnostic imaging. The approach is validated by two different arrays: a circle network and a square network. The results of diagnostic imaging are demonstrated and discussed in this paper. Furthermore, the advantage of reference-free DI is investigated by comparing the accuracy of defined reference-free DI and energy DI.
基于概率的诊断成像(PDI)是一种利用导波进行损伤识别的方法。它通常用于板的损伤诊断。以往的研究都依赖于一定的损伤指数(DI),而损伤指数通常是从导波信号中计算出来的。在传统方法中,DI是通过将实时数据与基线数据进行比较作为参考来定义的。然而,基线信号容易受到结构环境条件变化的影响。本文提出了一种无参考诊断成像方法,以避免温度和负载条件等环境因素的影响。基于无基线信号的多模导波的模式转换,定义了多模导波的模式转换。为了提高诊断的准确性,在无参考DI中加入了两个术语。一种是能量DI,它是根据信号能量的特征来定义的。另一种称为相关DI,是根据相关系数来定义的。然后,PDI算法可以根据无参考的DI进行即时执行。用于计算DI的实时信号由放置在平板两侧的锆钛酸铅(PZT)压电式换能器收集。利用有限元方法对PZT阵列铝板进行了数值模拟,验证了无参考损伤诊断成像的有效性。该方法通过两种不同的数组进行了验证:圆形网络和正方形网络。本文对诊断成像的结果进行了论证和讨论。在此基础上,通过比较自定义无参考点直接检测与能量直接检测的精度,探讨了无参考点直接检测的优越性。
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引用次数: 2
Kinematic Analysis and Rock Mass Classifications for Rock Slope Failure at USAID Highways 美国国际开发署高速公路岩质边坡破坏的运动学分析和岩体分类
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.08192
I. Rusydy, N. Al-Huda, M. Fahmi, Naufal Effendi
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引用次数: 4
Vibration Based Tool Insert Health Monitoring Using Decision Tree and Fuzzy Logic 基于决策树和模糊逻辑的基于振动的刀具插入健康监测
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.00355
Kundur Shantisagar, R. Jegadeeshwaran, G. Sakthivel, T. M. A. Manghai
The productivity and quality in the turning process can be improved by utilizing the predicted performance of the cutting tools. This research incorporates condition monitoring of a non-carbide tool insert using vibration analysis along with machine learning and fuzzy logic approach. A non-carbide tool insert is considered for the process of cutting operation in a semi-automatic lathe, where the condition of tool is monitored using vibration characteristics. The vibration signals for conditions such as heathy, damaged, thermal and flank were acquired with the help of piezoelectric transducer and data acquisition system. The descriptive statistical features were extracted from the acquired vibration signal using the feature extraction techniques. The extracted statistical features were selected using a feature selection process through J48 decision tree algorithm. The selected features were classified using J48 decision tree and fuzzy to develop the fault diagnosis model for the improved predictive analysis. The decision tree model produced the classification accuracy as 94.78% with five selected features. The developed fuzzy model produced the classification accuracy as 94.02% with five membership functions. Hence, the decision tree has been proposed as a suitable fault diagnosis model for predicting the tool insert health condition under different fault conditions.
利用刀具的预测性能可以提高车削加工的生产率和质量。本研究采用振动分析、机器学习和模糊逻辑方法对非硬质合金刀具刀片进行状态监测。考虑在半自动车床上进行切削操作的非硬质合金刀具刀片,其中刀具的状况是使用振动特性来监测的。利用压电换能器和数据采集系统采集了健康、损伤、热、侧面等工况下的振动信号。利用特征提取技术对采集到的振动信号进行描述性统计特征提取。通过J48决策树算法对提取的统计特征进行特征选择。采用J48决策树和模糊方法对选取的特征进行分类,建立故障诊断模型,进行改进的预测分析。选择5个特征后,决策树模型的分类准确率为94.78%。所建立的模糊模型具有5个隶属函数,分类精度为94.02%。因此,提出了决策树作为预测不同故障条件下刀具健康状况的一种合适的故障诊断模型。
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引用次数: 5
A Fatigue Damage Model for FRP Composite Laminate Systems Based on Stiffness Reduction 基于刚度折减的FRP复合材料层压系统疲劳损伤模型
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/SDHM.2019.04695
Ying Zhao, M. Noori, Wael A. Altabey, Ramin Ghiasi, Zhishen Wu
This paper introduces a stiffness reduction based model developed by the authors to characterize accumulative fatigue damage in unidirectional plies and (0/θ/0) composite laminates in fiber reinforced polymer (FRP) composite laminates. The proposed damage detection model is developed based on a damage evolution mechanism, including crack initiation and crack damage progress in matrix, matrix-fiber interface and fibers. Research result demonstrates that the corresponding stiffness of unidirectional composite laminates is reduced as the number of loading cycles progresses. First, three common models in literatures are presented and compared. Tensile viscosity, Young’s modulus and ultimate tensile stress of composites are incorporated as key factors in this model and are modified in accordance with temperature. Four types of FRP composite property parameters, including Carbon Fiber Reinforced Polymer (CFRP), Aramid Fiber Reinforced Polymer (AFRP), Glass Fiber Reinforced Polymer (GFRP), and Basalt Fiber Reinforced Polymer (BFRP), are considered in this research, and a comparative parameter study of FRP unidirectional composite laminates with different off-angle plies using control variate method are discussed. It is concluded that the relationship between the drop in stiffness and the number of cycles also shows three different regions, following the mechanism of damage of FRP composites and the matrix is the dominant factor determined by temperature, while fiber strength is the dominant factor that determine the reliability of composite.
本文介绍了作者建立的基于刚度折减的模型,用于表征单向层和(0/θ/0)复合材料层合板的累积疲劳损伤。基于损伤演化机制建立了损伤检测模型,包括基体、基体-纤维界面和纤维的裂纹起裂和裂纹损伤过程。研究结果表明,单向复合材料层合板的刚度随加载循环次数的增加而减小。首先,对文献中常用的三种模型进行了比较。该模型将拉伸粘度、杨氏模量和极限拉应力作为关键因素,并根据温度进行修正。本文研究了碳纤维增强聚合物(CFRP)、芳纶纤维增强聚合物(AFRP)、玻璃纤维增强聚合物(GFRP)和玄武岩纤维增强聚合物(BFRP)四种FRP复合材料的性能参数,并采用控制变量法对不同偏角层数的FRP单向复合材料层板进行了参数比较研究。结果表明,刚度下降与循环次数的关系也呈现出三个不同的区域,即FRP复合材料的损伤机理,温度决定基体的主要因素,而纤维强度是决定复合材料可靠性的主要因素。
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引用次数: 20
Monitoring of Real-Time Complex Deformed Shapes of Thin-Walled Channel Beam Structures Subject to the Coupling Between Bi-Axial Bending and Warping Torsion 双轴弯曲与翘曲扭转耦合作用下薄壁沟道梁结构复杂变形形状的实时监测
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.06323
Rui Lu, Zhanjun Wu, Qi Zhou, Hao Xu
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引用次数: 2
Crack Detection and Localization on Wind Turbine Blade Using Machine Learning Algorithms: A Data Mining Approach 基于机器学习算法的风力发电机叶片裂纹检测与定位:一种数据挖掘方法
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/SDHM.2019.00287
Joshuva Arockia Dhanraj, V. Sugumaran
Wind turbine blades are generally manufactured using fiber type material because of their cost effectiveness and light weight property however, blade get damaged due to wind gusts, bad weather conditions, unpredictable aerodynamic forces, lightning strikes and gravitational loads which causes crack on the surface of wind turbine blade. It is very much essential to identify the damage on blade before it crashes catastrophically which might possibly destroy the complete wind turbine. In this paper, a fifteen tree classification based machine learning algorithms were modelled for identifying and detecting the crack on wind turbine blades. The models are built based on computing the vibration response of the blade when it is excited using piezoelectric accelerometer. The statistical, histogram and ARMA methods for each algorithm were compared essentially to suggest a better model for the identification and localization of crack on wind turbine blade.
风力涡轮机叶片通常使用纤维型材料制造,因为它们具有成本效益和重量轻的特性,但是由于阵风,恶劣天气条件,不可预测的空气动力,雷击和重力载荷导致叶片表面裂纹,叶片会受到损坏。在风力机叶片发生灾难性坠毁前识别其损伤是非常必要的,否则叶片可能会破坏整个风力机。本文建立了一种基于15树分类的机器学习算法,用于风力发电机叶片裂纹的识别和检测。利用压电加速度计计算叶片受激励时的振动响应,建立了叶片振动响应模型。对每种算法的统计、直方图和ARMA方法进行了本质比较,为风电叶片裂纹的识别和定位提供了更好的模型。
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引用次数: 16
Flexural Property of String Beam of Pre-Stressed Glulam Based on Influence of Regulation and Control 基于调控影响的预应力胶合木弦梁抗弯性能研究
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.04640
N. Guo, Wenbo Wang, H. Zuo
Applying pre-stress in glulam beam can reduce its deformation and make full use of the compressive strength of wood. However, when the glulam with low strength and the pre-stressed steel with high strength form combined members, materials of high strength can’t be fully utilized. Therefore, this study puts forward the idea of regulating and controlling string beam of pre-stressed glulam. By regulating and controlling the pre-stress, a part of the load borne by the wood is allocated to the pre-stressed tendon, which is equivalent to completing a redistribution of internal force, thus realizing the repeated utilization of the wood strength and the full utilization of the strength of the high-strength pre-stressed tendon. The bending experiments of 10 beams under 5 working conditions are carried out. The failure mode, bearing capacity and deformation of the beams are analyzed. The results show that 90% of beams are deformed under compression. The ultimate load of the regulated and controlled beam is obviously larger than that of the unregulated beam, and the ultimate load of the beam increases with the increase of the degree of regulation and control. Compared with that of the unregulated beams, the ultimate load of beams regulated by 7.5%-30% increases by 25.42%-65.08%, and the regulated and controlled effect is obvious. With the increase of the regulation and control amplitude of pre-stress, the stiffness of string beam of pre-stressed glulam increases. In addition, with the increase of the regulation and control amplitude, the compression height of the beam increases before the failure, and it reaches the state of full-section compression at the time of failure, giving full play to the compressive property of the glulam. At the end of the experiment, the constitutive relation which can reflect the anisotropy of the wood is established combined with the experimental data. The finite element analysis of the beam under 7 working conditions is carried out by using ABAQUS finite element program, and the influence of the regulation and control amplitude on the stress distribution and ultimate bearing capacity of the beam is discussed.
在胶合木梁中施加预应力可以减小其变形,充分利用木材的抗压强度。然而,当低强度胶合木与高强度预应力钢组成组合构件时,高强度材料不能得到充分利用。因此,本研究提出了预应力胶合木弦梁的调控思路。通过对预应力的调节和控制,将木材所承受的一部分荷载分配给预应力筋,相当于完成了一次内力的重新分配,从而实现了木材强度的重复利用和高强预应力筋强度的充分利用。进行了10根梁在5种工况下的弯曲试验。对梁的破坏模式、承载力和变形进行了分析。结果表明,90%的梁在压缩作用下发生变形。调节和控制梁的极限荷载明显大于不调节梁的极限荷载,且随着调节和控制程度的增加,梁的极限荷载增大。与未调节梁相比,7.5% ~ 30%调节梁的极限荷载提高了25.42% ~ 65.08%,调节控制效果明显。随着预应力调节控制幅值的增大,预应力胶合层串梁的刚度增大。此外,随着调节控制幅度的增大,梁在破坏前压缩高度增大,破坏时达到全截面压缩状态,充分发挥了胶合木的抗压性能。实验结束时,结合实验数据建立了反映木材各向异性的本构关系。利用ABAQUS有限元程序对该梁进行了7种工况下的有限元分析,讨论了调节和控制幅值对梁的应力分布和极限承载力的影响。
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引用次数: 5
Seismic Reliability Assessment of Inelastic SDOF Systems Subjected to Near-Fault Ground Motions Considering Pulse Occurrence 考虑脉冲发生的近断层地震动作用下非弹性SDOF系统的地震可靠性评估
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.05171
Jilei Zhou, Chuansong Sun, X. Dai, Guohai Chen
The ground motions in the orientation corresponding to the strongest pulse energy impose more serious demand on structures than that of ordinary ground motions. Moreover, not all near-fault ground motion records present distinct pulses in the velocity time histories. In this paper, the parameterized stochastic model of near-fault ground motion with the strongest energy and pulse occurrence probability is suggested, and the Monte Carlo simulation (MSC) and subset simulation are utilized to calculate the first excursion probability of inelastic single-degree-of-freedom (SDOF) systems subjected to these types of near-fault ground motion models, respectively. Firstly, the influences of variation of stochastic pulse model parameters on structural dynamic reliability with different fundamental periods are explored. It is demonstrated that the variation of pulse period, peak ground velocity and pulse waveform number have significant effects on structural reliability and should not be ignored in reliability analysis. Then, subset simulation is verified to be unbiased and more efficient for computing small reliable probabilities of structures compared to MCS. Finally, the reliable probabilities of the SDOF systems with different fundamental periods subjected to impulsive, non-pulse ground motions and the ground motions with pulse occurrence probability are performed, separately. It is indicated that the ground motion model with the pulse occurrence probability can give a rational estimate on structural reliability. The impulsive and ordinary ground motion models may overestimate and underestimate the reliability of structures with fundamental period much less than the mean pulse period of earthquake ground motions.
脉冲能量最强方向的地震动比普通地震动对结构的要求更大。此外,并非所有近断层地震动记录在速度时程中都有明显的脉冲。本文提出了具有最强能量和脉冲发生概率的近断层地震动参数化随机模型,并利用蒙特卡罗模拟(MSC)和子集模拟(子集模拟)分别计算了这两种近断层地震动模型作用下非弹性单自由度系统的首次偏移概率。首先,探讨了随机脉冲模型参数变化对不同基本周期结构动力可靠度的影响。结果表明,脉冲周期、峰值地速度和脉冲波形数的变化对结构的可靠性有显著影响,在可靠性分析中不可忽视。然后,验证了子集仿真与MCS相比具有无偏性和更有效的计算结构小可靠概率的能力。最后,分别计算了具有不同基本周期的SDOF系统在脉冲、非脉冲地震动和具有脉冲发生概率地震动作用下的可靠概率。结果表明,考虑脉冲发生概率的地震动模型可以合理地估计结构的可靠度。脉冲地震动模型和普通地震动模型可能会高估和低估结构的可靠度,其基本周期远小于地震地震动的平均脉冲周期。
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引用次数: 2
System Identification of Heritage Structures through AVT and OMA: A Review 基于AVT和OMA的遗产结构系统识别综述
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.05951
Vinay Shimpi, M. Sivasubramanian, S. B. Singh
In this review article, the past investigations carried out on heritage structures using Ambient Vibration Test (AVT) and Operational Modal Analysis (OMA) for system identification (determination of dynamic properties like frequency, mode shape and damping ratios) and associated applications are summarized. A total of 68 major research studies on heritage structures around the world that are available in literature are surveyed for this purpose. At first, field investigations carried out on heritage structures prior to conducting AVT are explained in detail. Next, specifications of accelerometers, location of accelerometers and optimization of accelerometer networks have been elaborated with respect to the geometry of the heritage structures. In addition to this, ambient vibration loads and data acquisition procedures are also discussed. Further, the state of art of performing OMA techniques for heritage structures is explained briefly. Furthermore, various applications of system identification for heritage structures are documented. Finally, conclusions are made towards errorless system identification of heritage structures through AVT and OMA.
本文综述了利用环境振动试验(AVT)和运行模态分析(OMA)进行系统识别(确定频率、模态振型和阻尼比等动态特性)和相关应用对传统结构进行的研究。为此,我们对世界上现存文献中关于遗产建筑的68项主要研究进行了调查。首先,详细介绍了在进行AVT之前对遗产结构进行的实地调查。其次,针对遗产结构的几何形态,阐述了加速度计的规格、加速度计的位置和加速度计网络的优化。此外,还讨论了环境振动载荷和数据采集程序。此外,简要说明了对遗产建筑进行OMA技术的技术现状。此外,还介绍了遗产建筑系统识别的各种应用。最后,通过AVT和OMA对遗产建筑进行无差错系统识别。
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引用次数: 10
Seismic Vulnerability Analysis of Single-Story Reinforced Concrete Industrial Buildings with Seismic Fortification 带抗震设防的单层钢筋混凝土工业建筑地震易损性分析
Q2 Engineering Pub Date : 2019-01-01 DOI: 10.32604/sdhm.2019.04486
Jieping Liu, Lingxin Zhang, Haohao Zhang, Tao Liu
As there is a lack of earthquake damage data for factory buildings with seismic fortifications in China, seismic vulnerability analysis was performed by numerical simulation in this paper. The earthquake-structure analysis model was developed with considering the influence of uncertainties of the ground motion and structural model parameters. The small-size sampling was conducted based on the Latin hypercube sampling and orthogonal design methods. Using nonlinear analysis, the seismic vulnerability curves and damage probability matrix with various seismic fortification intensities (SFI) were obtained. The seismic capacity of the factory building was then evaluated. The results showed that, with different designs at different SFIs, the factory building could consistently achieve the three seismic fortification objectives. For the studied factory buildings with the SFI of 6, they satisfied the seismic fortification requirements of “no damage in moderate earthquakes, mendable in strong earthquakes”; for those buildings with SFIs of 7 and 8, the requirement of “no collapsing in super strong earthquakes” was generally met; while for those with SFIs of 9, the requirement of “mendable in moderate earthquakes” was almost satisfied. The results showed factory buildings designed with low SFIs are better at achieving the seismic fortification objectives than those designed with high SFIs.
由于国内缺乏设防工事厂房地震震害数据,本文采用数值模拟的方法进行地震易损性分析。建立了考虑地震动不确定性和结构模型参数影响的地震-结构分析模型。采用拉丁超立方抽样法和正交设计法进行小样本抽样。采用非线性分析方法,得到了不同设防烈度下的地震易损性曲线和损伤概率矩阵。然后对厂房的抗震能力进行了评估。结果表明,厂房在不同的抗震设防点进行不同的设计,均能一致地达到3个抗震设防目标。对SFI为6的厂房,满足“中震不破坏,强震可修复”的抗震设防要求;sf值为7和8的建筑物,基本满足“超强地震不倒塌”的要求;而sf指数为9的,则基本满足“可在中地震中修复”的要求。结果表明:采用低抗震设防系数设计的厂房比采用高抗震设防系数设计的厂房更能达到抗震设防目标。
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引用次数: 4
期刊
SDHM Structural Durability and Health Monitoring
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