1. Structural health monitoring under changing environmental conditions Xueyan Zhao Ziqiang Lang University of Sheffield UKACC PhD Presentation Showcase

2. Slide 2 Main contents  Background and motivation  Methodology  Experimental case study on wind turbine  Conclusions

3. UKACC PhD Presentation Showcase Slide 3 Background and motivation  Structures, such as wind turbine and bridge, are prone to suffering damage due to long service time, improper use or hostile working environment.  Structural health monitoring (SHM) refers to the process of implementing damage detection and identification technique for structural systems.

4. UKACC PhD Presentation Showcase Slide 4 Background and motivation  SHM can be achieved by measuring various signals related to the structure health status (such as vibration, acoustic emission), such that the change of the features extracted from measurements can indicate a developing structural damage.  This is similar to the phenomenon that a doctor always concludes that a person is unwell if his body temperature is higher than normal one.

5. Background and motivation  Which factors can cause the change of the features extracted from measurements?  Damage?  Environmental factors: Temperature? Humidity?  How to distinguish the normal structural changes due to variations in system environmental or operating conditions from the changes which are induced by damage? UKACC PhD Presentation Showcase Slide 5

6. Methodology UKACC PhD Presentation Showcase Slide 6

7. Experimental study on wind turbine UKACC PhD Presentation Showcase Slide 7

8. Experimental study on wind turbine UKACC PhD Presentation Showcase Slide 8 On the top of gearbox At the back of generator Bin indexAE 1Vibration 1AE 2Vibration 2 Bin 10.9588610.8481010.9493670.958861 Bin 20.9696970.6363640.3333330.939394 Bin 30.9411760.8235290.0392160.960784 Bin 40.8098590.9718310.0070421 Bin 50.909091101 Indicating there is a condition change

9. UKACC PhD Presentation Showcase Slide 9 Conclusions  The technique has been applied to analyse the field data collected from AE and vibration sensors fitted in an operating wind turbine; the results have demonstrated the performance of the new technique.  After elimination the effect of environmental and operating parameters on the change of the features extracted from the sensor measurements, the technique can indicate the structural health status effectively.