摘要
该文结合摄动理论和压电阻抗技术监测结构的损伤的发生和定位,用δ函数进行表达结构的裂纹损伤,建立损伤条件下简支梁的自由振动方程。利用一阶摄动方法给出了摄动项的一般表达式,并结合δ函数的性质,获得了受损简支梁的特征值和模态振型的解析表达式。通过受损梁的模态振型得到了受损梁的阻抗,结合PZT与结构的压电耦合电导纳公式得到受损梁的电导纳信号。通过分析比较梁在各种损伤发生前后的电导纳变化,采用CC损伤指标评定结构的损伤程度,从而识别损伤。以一个受损简支梁为数值算例,计算了不同损伤条件下其电导纳信号和损伤指标的变化。当结构损伤位置同PZT之间的距离相同情况下,PZT的CC指标随损伤程度增加有减小的趋势;结构损伤程度相同的情况下,各损伤工况下的RMSD指标随损伤位置与PZT之间的距离的增加有减小的趋势。基于此,得出结论:通过量测结构压电阻抗的变化,可以识别结构损伤的发生、位置和严重程度。
The perturbation theory and piezoelectric impedance technology are used to monitor the damage cause and position of structure.The Delta function is used to describe the crack damage of structure,and the free-vibration equation for the damaged simple-supported beam is established.The first order perturbation method gives the general representation of perturbation.And according to the character of the Delta function,the characteristic value of the damaged simple-supported beam and the analyzing representation of the modal vibrating mode are obtained.The modal vibrating mode of the damaged beam can give the impedance of the damaged beam,and the combination of PZT and structure of piezoelectric coupling admittance formula can receive the electrical admittance signal of the damaged beam.The article analyzes and compares the electrical admittance changes before and after various damages of beam,and CC damage index is used to assess the damage degree of structure so as to identify the damage.Taking a damaged simple-supported beam as a numerical example,the article calculates the varieties of its electrical admittance signal and damage index under the different damage conditions.CC index of PZT will decrease with the increase of damage degree if the distance between the structural damage location and PZT is fixed,and the RMSD indexes of various damage conditions will decrease with the increase of distance between PZT and the damage location if the damage degrees are fixed.Based on this,the conclusion shows that the measurement of the structural piezoelectric impedance variation can identify the cause,location and serious degree of the structure damage.
出处
《城市道桥与防洪》
2013年第5期100-105,13,共6页
Urban Roads Bridges & Flood Control
关键词
PZT传感器
压电阻抗法
摄动理论
损伤识别
简支梁
PZT transducer,piezoelectric impedance method,perturbation theory,damage identification,simple-supported beam
