TWI Industrial Member Report Summary 1004/2011
By M J Doré and P J Tubby
The CrackFirstT sensor system was developed for use on welded steel structures where fatigue performance is a primary concern. When installed adjacent to a critical joint, the sensor responds to the applied cyclic stress, its output indicating the rate at which the fatigue design life of the joint is being consumed. The electronics package logs sensor output for subsequent analysis. Such information enables engineers to estimate a structure's remaining life and to set safe inspection intervals based on usage.
Since the original testing of the sensor, changes to the production route and significant modification of the attachment method have been introduced which may affect the sensor's fatigue characteristics. A series of fatigue tests was therefore conducted to check performance against the existing calibration S-N curve. Tests were also undertaken to investigate performance of the sensor and electronics at reduced temperature.
- Validate the current supply of CrackFirst sensors (Product No. P08-8229) and attachment method under axial constant amplitude loading.
- Compare results with those obtained previously.
- Check the performance of the CrackFirst sensor and electronics at ambient temperature and -35ºC under four-point-bending.