Structural Health Monitoring

In recent years, there has been a considerable demand for more accurate techniques to detect and locate damage, particularly in large structures. Damage will cause the stiffness distribution in the structure to change which may be detected by measuring its dynamic response. Two distinct philosophies have been considered to locate the damage in a structure using measured vibration data via inverse methods. The first group of methods use techniques of finite element model updating and error localisation to obtain a corrected set of physical parameters that reproduce the measured data. The alternative group of methods (called forward identification methods) assume a candidate set of possible damage scenarios which include both damage mechanism and location. The change in dynamic response due to the damage is predicted, usually in terms of the natural frequencies. The predicted change in response of the structure for all the damage scenarios is then compared to the measured change and the closest damage case is chosen. Statistical methods are often used to identify the most likely location of the damage. Techniques of subset selection may also be used to implement the forward identification approach.

Both of these approaches are being investigated and their practical implementation considered. One major application of this research is the detection of damage in civil engineering structures, particularly road bridges. As traffic densities increase and lorries become heavier it is important, for both safety and cost reasons, to determine whether these structures are liable to collapse.

The alternative is to locate damage using higher frequency information, for example acoustic emission. Most current methods use simple metrics to determine the character of the transient signals, such as energy, and time of flight to determine the location. For complex structures where the stress waves have propagated through joints and the measured response includes reflections, a model based approach is required to determine the source character and location.

Selected References

Inverse Methods

MI Friswell, Damage Identification using Inverse Methods. Special Issue of the Royal Society Philosophical Transactions A on Structural Health Monitoring, 365(1851), February 2007, 393-410.

C Zang, MI Friswell & M Imregun, Structural Health Monitoring using Frequency Response Correlation Criteria. ASCE Journal of Engineering Mechanics, 133(9), September 2007, 981-993.

C Zang, MI Friswell & M Imregun, Structural Damage Detection using Independent Component Analysis. Structural Health Monitoring: An International Journal, 3(1), March 2004, 69-84.

B Titurus, MI Friswell & L Starek, Damage Detection using Generic Elements: Part II, Damage Detection. Computers and Structures, 81(24-25), September 2003, 2287-2299.

JK Sinha and MI Friswell, The Use of Model Updating for Reliable Finite Element Modelling and Fault Diagnosis of Structural Components Used in Nuclear Plants. Nuclear Engineering and Design, 223(1), July 2003, 11-23.

MI Friswell & JET Penny, Crack Modelling for Structural Health Monitoring. Structural Health Monitoring: An International Journal, 1(2), October 2002, 139-148.

JK Sinha & MI Friswell, Simulation of the Dynamic Response of a Cracked Beam. Computers and Structures, 80(18-19), July 2002, 1473-1476.

H Ahmadian, JE Mottershead & MI Friswell, Damage Location Indicators from Substructure Mode Shapes. Inverse Problems in Engineering, 8(4), August 2000, 309-323.

JE Mottershead, MI Friswell & C Mares, A Method for Determining Model-Structure Errors and for Locating Damage in Vibrating Systems. Meccanica, 34(3), August 1999, 153-166.

MI Friswell, JET Penny & SD Garvey, A Combined Genetic and Eigensensitivity Algorithm for the Location of Damage in Structures. Computers and Structures, 69(5), September 1998, 547-556.

MI Friswell, JET Penny & SD Garvey, Parameter Subset Selection in Damage Location. Inverse Problems in Engineering, 5(3), 1997, 189-215.

MI Friswell, JET Penny & DAL Wilson, Using Vibration Data and Statistical Measures to Locate Damage in Structures. Modal Analysis: The International Journal of Analytical and Experimental Modal Analysis, 9(4), October 1994, 239-254.

Acoustic Emission

JJ Scholey, PD Wilcox, MR Wisnom & MI Friswell, A Practical Technique for Quantifying the Performance of AE Systems on Plate-like Structures. Ultrasonics, to appear.

CK Lee, JJ Scholey, SE Worthington, PD Wilcox, MR Wisnom, MI Friswell & BW Drinkwater, Acoustic Emission from Pitting Corrosion in Stressed Stainless Steel Plate. Corrosion Engineering, Science and Technology, 43(1), March 2008, 54-63.

ED Price, AW Lees & MI Friswell, Detection of Severe Sliding and Pitting Fatigue Wear Regimes Through the use of Broadband Acoustic Emission. IMechE Proceedings J: Journal of Engineering Tribology, 219(2), April 2005, 85-98.

JJ Scholey, PD Wilcox, MR Wisnom & MI Friswell, A Framework for Modelling the Complete AE Process in Composite Materials. 28th European Conference on Acoustic Emission Testing, Krakow, Poland, 17-19 September 2008, 268-273.

JJ Scholey, PD Wilcox, MR Wisnom & MI Friswell, Two-dimensional Source Location Techniques for Large Composite Plates. 28th European Conference on Acoustic Emission Testing, Krakow, Poland, 17-19 September 2008, 160-165.

Last updated February 2009 by M I Friswell