One of the most powerful capabilities of Acoustic Emission (AE) monitoring is source location — the ability to not just detect that an AE event occurred, but to calculate where in the structure it originated. Here's how it works and what it requires from a sensor deployment and data acquisition standpoint.
The physics of AE source location
When a crack grows, a weld cracks, or a leak develops, it generates a stress wave that propagates outward from the source in all directions. This wave reaches different sensors at different times, depending on their distance from the source.
By measuring the time difference of arrival (TDOA) between sensor pairs, and knowing the acoustic wave velocity in the material, the source location can be calculated through hyperbolic triangulation:
For 2 sensors: the source lies on a hyperbola defined by the TDOA.
For 3 sensors: two hyperbolas intersect at the source location (2D).
For 4+ sensors: redundant measurements improve accuracy and enable 3D location.
Sensor deployment requirements
Minimum sensors for location: 3 for 2D planar source location, 4 for 3D volumetric location. More sensors improve accuracy and provide redundancy if one fails.
Sensor spacing: Must be appropriate for the attenuation characteristics of the material. Steel has low attenuation — sensors can be spaced meters apart. Concrete has high attenuation — spacing may need to be under 1 meter for reliable signal reception.
Timing precision: TDOA calculations require sensor timing synchronized to microsecond precision. Acoustic Testing Pro's Ultrasonic Data Acquisition Systems provide hardware-triggered simultaneous multi-channel acquisition with timing accuracy sufficient for source location in most industrial materials.
Wave velocity calibration: The material wave velocity must be known or measured in the actual structure (not just the nominal material value) to calculate accurate source distances. Velocity varies with temperature, stress state, and material microstructure.
Data acquisition architecture for source location
Each AE hit record must include: arrival time (hardware timestamp), amplitude, sensor ID, and waveform data. The source location algorithm (running on the Edge Processor or cloud platform) processes these hit records across sensor pairs to calculate TDOA values and solve the hyperbolic equations.
Acoustic Testing Pro's full stack — AE Sensors → Signal Conditioners → Ultrasonic DAQ → Edge Processors → IoT Gateways → Cloud Platforms — supports multi-sensor AE source location for permanent monitoring installations across tanks, pipelines, pressure vessels, and structural elements.
👉 acoustictestingpro.com/sensor-technologies/acoustic-emission-sensors/
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