CGM-7 ACPD Crack Growth Monitor
Data sheet, features and applications for the CGM-7.
ACPD Instrument
CGM-7 ACPD Crack Growth Monitor
The CGM-7 is a modern, microprocessor-based instrument for measuring crack depth in metals undergoing materials testing. Building on the success of the CGM-5R, it adds two-channel operation, higher frequency and current outputs, full computer control and a variety of expansion options.
It uses the alternating current potential drop method (ACPD), an established technique covered by the ASTM E647 standard. An alternating current is passed through the metal under test and the resultant voltage drop across the specimen is measured; a growing defect alters this voltage, and with suitable calibration a measure of defect depth can be obtained.
Features
- Continuously variable frequency output, 10Hz–500kHz in 1Hz increments
- Advanced filtering with 3 user-selectable ranges (and out)
- 10 preset gains built in, user-selectable from 1,000 to 30,000
- Two channels as standard on all models
- High output currents up to 5A, continuously variable in 1mA increments
- User-selectable offsets, variable from −4V to +4V
- Resistive and inductive components displayed simultaneously
- Pre-amplifiers provided as standard for each channel for superior SNR
Applications
- Slow crack growth
- Crack sizing
- Dynamic crack growth studies
- Crack closure studies
- Crack initiation
- Fatigue crack initiation
- Condition monitoring
- Stress corrosion testing