With Prof. Hui Li's gracious invitation, Prof. Satish Nagarajaiah from Rice University will visit Centre of Structural Monitoring and Control (SMC) at Harbin Institute of Technology and make a presentation on June 21, 2015. We sincerely welcome the interested faculties and students to join in.

The lecture room: 402, School of Civil Engineering
June 21, 8:30am-10:00am
Topic: Structural Integrity Assessment of Deepwater Drilling and Production Risers subjected to Vortex Induced Vibrations based on Wavelet/Blind Identification Techniques

ABSTRACT

The safety of deepwater risers is essential for sustainable operation of offshore platforms. Designing a suitable structural health monitoring system for deepwater risers subjected to vortex induced vibration is a great challenge. Combining the global and local monitoring can greatly increase the accuracy of damage detection and fatigue estimation of deepwater risers. 
A new structural health monitoring system for deepwater risers is developed to monitor the damage in the risers with both global and local monitoring methods proposed in this paper. The global monitoring is achieved by the proposed wavelets and second order blind identification (SOBI) method.  Once the location of damage location is identified by the proposed Wavelets/SOBI method, local monitoring using robotic crawler with magnetic flux leakage (MFL) sensor is performed to further estimate the extent of damage. 
The local monitoring with MFL is verified by experimental results and finite element analysis. The global monitoring with Wavelets/SOBI is verified by a nonlinear finite element analytical model with dynamic property changes to simulate the damage [developed specifically for this study]. Wavelets/SOBI method is also verified using  MIT—Gulfstream test data. Fatigue estimation is performed using rain flow cycle count method. Global monitoring results from the proposed blind output only identification technique and fatigue estimation is found to be accurate. Local inspection using robotic MFL sensors is efficient and provides high resolution results. 
The proposed structural integrity assessment framework can be applied to deepwater risers, floating platforms and for cable stayed bridges. Robotic MFL crawler can be used for in-line inspection for various pipelines.

Biosketch of Prof. Satish Nagarajaiah

Satish Nagarajaiah is a Professor of Civil and Environmental Engineering at Rice University in Houston, Texas. He is affiliated with the Mechanical Engineering Department, Material Science and Nano-Engineering Department at Rice. His teaching and research interests are in the areas of structural engineering, structural dynamic systems, seismic protection, earthquake engineering, structural control, system identification, structural health monitoring, offshore structures, and applied nanotechnology. His research is funded by the National Science Foundation (NSF), NASA, DOE, AFOSR, ONR, other State, Federal, Private Agencies and Industries. NSF has awarded him the prestigious faculty early CAREER award for innovative research in Adaptive Stiffness Structures (1998). He and his coworkers were awarded the American Society of Civil Engineers (ASCE) Moisseiff award in 2015, for their 2014 Journal of Structural Engineering on Adaptive Negative Stiffness Structural Systems. His editorial activities include service as the Managing Editor of the Journal of Structural Engineering [ASCE International journal] (2011—present), Editor of the Structural Control and Health Monitoring [Wiley International Journal] (2008—present) and Editor-in-chief [North America] of Structural Monitoring and Maintenance [Techno-press International Journal] (2014—present). ASCE Structural Engineering Institute (SEI) elected him as an inaugural fellow in 2012 for his service to structural engineering community. He has served on numerous founded and chaired numerous committees in SEI, EMI, and IASCM on Structural Control and Monitoring. For further details visit his website satishnagarajaiah.rice.edu.