Fatigue life diagnosis of steel structures with a fatigue damage sensor

Abstract

There is a growing tendency to require increased service, beyond the design life, for steel structures such as bridges, vehicles, railways, vessels and construction machinery etc. by the implementation of regular maintenance procedures. During this maintenance products are inspected at relatively short intervals and, based upon the results of inspection and diagnosis, repair and reinforcement work is carried out as the need arises in order to prolong the lifespan. In addition to visual observation, the acoustic tapping method, magnetic powder flaw detection, penetration inspection, ultrasonic flaw detection and the latest measurement apparatus are employed for inspection; however, these conventional flaw detecting methods aim to detect unfavourable conditions, such as defects, cracks, corrosion, deformation, abrasion etc., which are already present within the structure, and are incapable of detecting latent defects and barely valid for fatigue cracks which are likely to occur in the future. Furthermore, after the detection of flaws it may be difficult to carry out corrective maintenance or to put a maintenance expenditure plan in place so the operating plan may fail in the long term.