Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content


What we do Banner
Innerpage Title Banner

The CrackFirst sensor system is ideal for use by all industries in which fatigue of steel welded structures presents a structural performance concern.

At the heart of the CrackFirst system is a fatigue sensor, which, when installed on a welded steel structure, indicates the portion of the design life that's been consumed and enables engineers to estimate its remaining life. The sensors, when suitably located, are subjected to the same loading history as the structure and provide an accurate record of cumulative weld fatigue damage.

The sensor comprises a steel coupon attached adjacent to a critical joint. Stress cycles cause fatigue crack growth in the coupon that is detected electrically. For a typical fillet welded joint the sensor output gives the proportion of the fatigue design life that has been used.

The CrackFirst system was developed through the collaboration of TWI Ltd, FMB, Micro Circuit Engineering Ltd, UMIST and Caterpillar Peterlee (a division of Caterpillar (UK) Ltd) in a project funded by the DTI's LINKSensor and Sensor Systems for Industrial Applications programme.

The CrackFirst system is currently licensed by Strainstall, through whom the sensor system is available to end users.

For more information please email: