CAJ | 학술논문

以海洋平台结构整体损伤检测中的测量噪声作为研究对象，提出损伤单元模态影响系数的概念。通过一系列冲击激励的物理模型试验，采用基于局部测量的模态应变能法，分析振动信号信噪比和损伤单元模态影响系数对损伤检测的影响规律。试验结果表明当模态影响系数较大(大于5)时，用很小的信噪比数据就可以准确识别出损伤单元位置和损伤程度；当系数较小(小于0.5)时，用最大的信噪比数据也无法准确识别；当系数为临界值(0.9～1.5)时，信噪比对结果影响较大，只有信噪比较大(大于20)时，才能准确识别损伤位置，当信噪比小到一定值(小于10)时，损伤定位和损伤程度评估均无法实现。
이해양평태결구정체손상검측중적측량조성작위연구대상，제출손상단원모태영향계수적개념。통과일계렬충격격려적물리모형시험，채용기우국부측량적모태응변능법，분석진동신호신조비화손상단원모태영향계수대손상검측적영향규률。시험결과표명당모태영향계수교대(대우5)시，용흔소적신조비수거취가이준학식별출손상단원위치화손상정도；당계수교소(소우0.5)시，용최대적신조비수거야무법준학식별；당계수위림계치(0.9～1.5)시，신조비대결과영향교대，지유신조비교대(대우20)시，재능준학식별손상위치，당신조비소도일정치(소우10)시，손상정위화손상정도평고균무법실현。
Noise of Measurement itself is a crucial factor in in-situ health monitoring of structures. In this paper, the influence of measurement noise on global damage detection of offshore platform was studied. And a new concept of Damage Element Modal Influence Index (DEMI) was also proposed. A scaled physical experimental model of an offshore jacket platform was employed and a series of damage scenarios under impact excitation were simulated. By means of the mode strain energy method based on local measurement, the relationship between damage detection result and signal-noise ratio (SNR) of impulse response and DEMI were obtained. The experiment result indicates that when DEMI is larger than 5, the damage location and damage severity can be identified correctly even with small SNR signals;when the DEMI is smaller than 0.5, the damage identification cannot be realized even with largest SNR signals;when DEMI reaches the critical value of 0.9-1.5, SNR becomes the key influencing factor of damage identification, namely when the SNR is larger than 20, the damage location can be identified correctly, as SNR decreases to a value of 10, neither damage location nor damage severity can be evaluated correctly.