Sonic resonator system for testing the adhesive bond strength of composite materials
Disclosed herein is a sonic resonator system for use in testing the adhesive bond strength of composite materials. Also disclosed herein are a method of calibrating the sonic resonator system to work with a particular composite bond joint, and a method of non-destructive testing the “pass-fail” of the bonded composite bond strength, based on a required bond strength.
1. A method of applying a power pulse in the form of a rarefaction wave at a selected location within a bonded composite structure for purposes of non-destructive testing of the bond, said method comprising:
providing a sonic resonator system which includes: a computer containing software algorithms for signal reconstruction and a wave form generator; a sonic resonator assembly which transmits sonic energy into said bonded composite structure, where said sonic energy includes a wide-banded rarefaction sonic wave power pulse; and, a coupling device which couples said sonic energy from said resonator assembly to a surface of said composite structure;
calibrating said sonic resonator system to work in combination with said composite structure; and
applying a wide-banded rarefaction sonic wave which includes a power pulse at a point in time, so that the time required to traverse said composite structure places said power pulse at a selected location within said composite structure.
2. A method in accordance with claim 1 , wherein said sonic resonator system includes a receiver assembly and said system is operated in pulse echo mode subsequent to application of said rarefaction power pulse, so that a determination can be made whether there was delamination of the bond or whether the bond passed the test.
3. A method in accordance with claim 1 , wherein said wide-banded rarefaction sonic wave produces a concentration of sonic energy of a desired shape and amplitude at said selected location within said composite structure, and wherein said desired shape and amplitude is determined by signal reconstruction algorithms in said computer.
4. A method in accordance with claim 3 , wherein a transducer present within said sonic resonator system has a bandwidth which exceeds one decade so that short duration power pulses are produced.
5. A method in accordance with claim 4 , wherein said transducer may also be driven with a signal having a bandwidth lower than one decade.
6. A method in accordance with claim 3 or claim 4 , wherein said amplitude is created by putting an amplitude function through a window to limit an acoustic bandwidth of said power pulse.