Multichannel impact response for material characterization

A method comprising:

• triggering a release of a first impact device of a plurality of impact devices by a controller;
• triggering a release of a second impact device of the plurality of impact devices by the controller;
• detecting, by a first microphone, at least one first acoustic wave associated with a first portion of a surface resulting from an impact by the first impact device, the first acoustic wave being in a direction normal to the first portion of the surface, the first microphone not being in contact with the first portion of the surface;
• detecting at least one second acoustic wave associated with a second portion of a surface resulting from an impact by the second impact device;
• identifying a first characteristic in the first portion of the surface based on the at least one first acoustic wave;
• and
• identifying a second characteristic in the second portion of the surface based on the at least one second acoustic wave.

A non-destructive test system comprising:

• a plurality of impact devices including a knob configured to generate at least one flexural mode in a material when a surface of the material is impacted by the knob;
• a controller configured to independently control each of the plurality of impact devices, the controller having a communications channel for each of the plurality of impact devices;
• a microphone configured to detect an acoustic response generated upon impact of the knob on the surface of the material, the acoustic response being in a direction normal to the surface of the material, the microphone not being in contact with the surface of the material;
• and
• an encoder configured to generate a signal based on a bounce of the knob off the surface after impact on the surface.