Acoustic emission control products: basic requirements
Acoustic emission control products are used for acoustic emission level control in the course of large-scale objects testing. Acoustic emission control products are represented by multi-channel control systems allowing to detect acoustic emission source and AE characteristics as well as to register load parameters (pressure, temperature, etc.).
Multi-channel acoustic emission control system should include:
- set of preamplifiers;
- cable lines;
- data preliminary processing and acoustic emission signals conversion modules;
- PC with corresponding mathware;
- data display instruments;
- system calibration modules.
Acoustic emission control system can be both stationary and mobile. In the case of simple configuration objects control or when the fault position finding is not required, it is possible to use less complex instruments (for instance, a single-channel system (-s) or a multi-channel system in zone control mode).
Acoustic emission control system should provide prompt data processing and representation in real-time mode as well as data transfer to peripheral devices for the purpose of data storage in the course of test procedures and upon their completion.
The above mentioned data includes:
- acoustic emission transducers group numbers, which have registered AE impulse or AET number;
- each registered acoustic emission impulse coordinates (this option is not required in zone control mode);
- AE impulse amplitude (AE process amplitude distribution function);
- AE impulses energy, or «MARSE» (Measured Area of the Rectified Signal Envelope), as well as any other energy parameter value;
- emission amount (number of discrimination level exceedings by the signal);
- signal time characteristics;
- load parameters, at which AE pulse has been registered (pressure, deformation or temperature);
- pulse register time;
- signals arrival time difference value (this option is not required in zone control mode);
List of acoustic emission control products requirements (to be approved with corresponding certificates):
- operational frequency range: fom 10 kHz up to 500 kHz;
- FR uneveness within the frequency range – max. value: ±3 dB;
- preamplifier amplification ratio: 20-60 dB;
- main amplifier amplification ratio: 0-40 dB with step regulation of 1 dB;
- preamplifier amplitude dynamic range: min 70 dB;
- dynamic measuring range of AE signal amplitude: min 60 dB;
- AE system should provide possibility of measuring channels sensitivity alignment, so that the difference between sensitivity levels would not exceed ±1 dB.
AE control system should provide false events processing both at hardware and software levels. The system part of the software should enable operator’s interaction with PC as well as task commands entry and parameters change in dialog window. Basic AE control system parameters and operation mode data should be saved in the protocol. If these parameters are changed in the course of tests performance, a corresponding comment should be made.