TOFD method of acoustic control

Time-of-flight diffraction method of acoustic control is a software and hardware suite used for material strength testing based on TOFD method of acoustic control.

Controlled parameters

Signal amplitude
Pulse fall time
Signal rise time
Number of threshold crossings
Energy of acoustic emission signal
Precise time of the event
Time of wave propagation
Material strength control

Operating principles

The main operational principle of time-of-flight diffraction method (TOFD) is based on the reaction of material nonuniformities to the ultrasonic waves, which results in the emission of diffraction waves in a wide frequency range.

The parameters of the material non-uniformities are determined by the wavefront time, while the wave amplitude is of no relevance for the defect dimensions estimation.

The main informational characteristic of this method is the wavefront time.

The hardware suite for measurements performance includes:

  • acoustic emission sensors  ZET 601;
  • high-frequency generator ZET 7191;
  • digital acoustic emission sensor ZET 7140-E;
  • interface converter (ZET 7174 or ZET 7176 – depending on the data transfer format)

High-frequency generator ZET 7191 in together with the acoustic emission sensor ZET 601 operates as longitudinal waves source: it generates single-phase waves of certain amplitude in accordance with the set time interval.

Digital acoustic emission sensor ZET 7140-E together with acoustic emission sensor ZET 601 is used as a receiver of diffraction waves: acoustic emission sensor ZET 601 converts the acoustic signal of acoustic emission process into electrical signal. The digital module ZET 7140-E performs amplification, filtration and analog-to-digital conversion of the electrical signal, received from ZET 601, as well as the transfer of the digitized data via CAN interface.

Interface converter ZET 7174 (CAN↔USB) or ZET 7176 (CAN↔Ethernet) are used for data transfer to the PC.

Detection of acoustic emission events and calculation of the corresponding parameters is performed in accordance with the set algorithm.

The project “Time-of-flight diffraction method” enables visual representation of the data obtained.

The following parameters have graphical representation:

  • time of wave propagation;
  • estimated strength of the material.

Prior to starting the project in is necessary to configure the elements “Events generator” and “Events detector” 

Advantages of the system


is attributed to high precision of Time of Flight Diffraction (TOFD) method

Operational efficiency

instant data processing and information display


calculation of the parameters in accordance with the set algorithm


high operational stability

System components

The price of the system depends on its configuration

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