【作者】 谢波；

【导师】 孙瑞；

【作者基本信息】 重庆大学 ， 土木工程， 2020， 硕士

【摘要】 近年来压电智能材料在结构健康监测领域的应用越来越广泛,本文利用压电阻抗技术和模糊推理开展了结构损伤识别研究。首先对压电阻抗法在结构损伤识别领域的理论模型和研究现状进行了综述;然后,建立了铝梁的有限元模型,利用数值分析方法研究了铝梁损伤状况与压电传感器阻抗信号的关系,并从电阻抗信号中提取均方根指数(RMSD)做损伤指标,结果显示,损伤程度越高,RMSD值越大;传感器与损伤的距离越近,RMSD值越大。此外,利用数值模拟手段研究了环境温度对压电阻抗信号的影响,结果显示温度的升高与RMSD值成正比,且呈近似线性关系。为了验证有限元数值模拟结果的正确性,论文开展了试验研究,利用压电传感器对铝梁开展了损伤识别试验研究,结果显示,试验测试结果与数值模拟结果吻合较好,验证了有限元数值模拟的结论。本文还制作了ECC(高延性水泥基复合材料)钢筋混凝土梁,用以验证压电阻抗技术对土木工程结构的损伤识别能力,测试了混凝土梁在不同损伤工况下的电导信号(电阻抗倒数的实部),从测量电导信号中提取RMSD做为损伤指标,试验结果表明,随着损伤程度的增加,电导信号的RMSD值增大;布置在混凝土梁跨中位置压电传感器的RMSD值相对更大,证明了压电传感器对其附近的局部损伤更敏感;利用压电传感器阵列RMSD值的相对大小,可对结构损伤的程度和位置进行识别。文章最后利用模糊逻辑理论,分别对铝梁有限元数值模拟结果和铝梁损伤试验结果进行了分析,基于部分电阻抗数据建立了模糊规则库,并利用剩余数据作为测试组验证模糊推理系统的正确性。结果显示,损伤程度和损伤位置的预测值基本接近真实值,误差在可以接受的范围内。考虑到电阻抗信号在实际测量中会受到环境噪声的影响,本文对压电阻抗数据中加入了不同程度的噪声,并利用模糊逻辑系统对不同噪声水平的铝梁数值模拟结果和铝梁损伤试验结果进行分析,得到了损伤状况预测值,结果表明模糊逻辑系统具有较好的抗噪声能力。本文利用模糊逻辑系统结合压电阻抗技术,为压电阻抗法在的结构损伤识别领域的应用提供了一种新思路。更多还原

【Abstract】 In recent years,the application of piezoelectric smart materials has become more and more extensive in the field of structural health monitoring.In this paper,the use of piezoelectric impedance technology and fuzzy logic system to conduct structural damage identification research.First,the theoretical model and research status of the piezoelectric impedance method in the field of structural damage identification are reviewed;then,a finite element model of the aluminum beam is established,and the relationship between the aluminum beam damage status and the impedance signal of the piezoelectric sensor is studied by numerical analysis,and the root mean square index(RMSD)is extracted from the electrical impedance signal as the damage index.The results show that the higher the damage,the larger the RMSD value;the closer the sensor is to the damage,the larger the RMSD value.In addition,the effect of ambient temperature on the piezoelectric impedance signal was studied using numerical simulation methods.The results show that the temperature increase is proportional to the RMSD value and has an approximately linear relationship.In order to verify the correctness of the finite element numerical simulation results,the paper carried out experimental research,using piezoelectric sensors to carry out damage identification test research on aluminum beams,the results show that the experimental test results are in good agreement with the numerical simulation results,in which the finite element simulation is verified.In this paper,an ECC(Engineering Cementious Composites)reinforced concrete beam was also produced to verify the ability of piezoelectric impedance technology to identify damage to civil engineering structures,and to test the conductance signal(the real part of reciprocal of electrical impedance)of the concrete beam under different damage conditions,extract the RMSD as the damage index from the measured conductance signal.The test results show that the RMSD value of the conductance signal increases with the increase of the damage;the RMSD values of the piezoelectric sensors placed in the middle of the concrete beam span are relatively larger,which proves that the piezoelectric sensor is more sensitive to local damage in the vicinity.Hence,the RMSD value of the piezoelectric sensor array can be used to identify the degree and location of structural damage.Finally,the paper uses fuzzy logic theory to analyze the aluminum beam finite element numerical simulation and experimental test results,based on the electrical impedance data to establish a fuzzy rule base,and use the remaining data as a test group to verify the correctness of the fuzzy inference system.The results show that the predicted values of damage and location are basically close to the real value with satisfied accuracy.Considering that the electrical impedance signal will be affected by environmental noise in the actual measurement,different level of noise was added to the piezoelectric impedance data,and uses a fuzzy logic system to conduct damage prediction for the FE and test data of aluminum beam,and the results show that the fuzzy logic system has good anti-noise ability.In conclusion,the paper uses fuzzy logic system combined with piezoelectric impedance technology to provide a new idea for the application of piezoelectric impedance method in the field of structural damage identification.更多还原