Comparative Vacuum Monitoring: A New Method of In-Situ Real-Time Crack Detection and Monitoring
Comparative Vacuum Monitoring (CVM) offers a novel method for in-situ, real-time monitoring of crack initiation and/or propagation. CVM is a measure of the differential pressure between fine galleries containing a low vacuum alternating with galleries at atmosphere in a simple manifold. If no flaw is present, the vacuum will remain at a stable level. If a flaw develops, air will flow through the passage created from the atmosphere to the vacuum galleries. Sensors may either take the form of self-adhesive polymer “pads” or may form part of the component. A transducer measures the fluid flow between the galleries.
CVM has been developed for use in both a laboratory environment or on operating equipment. The laboratory testing equipment has rapidly gained acceptance in testing facilities within the aviation industry; often used to control a fatigue testing program due to its proven reliability and built-in fail-safe properties. A portable unit is available to allow monitoring of components in operating equipment where access to critical components is difficult, time consuming and costly.