Abstract The physical basis of the membrane resonance method of non-destructive testing has been investigated both theoretically and experimentally. The method involves exciting the structure and monitoring the response at the same point, and can be used to detect the presence of delaminations or disbonds at that location. Its advantage over ultrasonic testing is that no couplant is required between the transducer used and the structure, so the technique is convenient for use in the field. The method is most sensitive if the membrane resonance of the layer above the defect is in the frequency range of the excitation used, so it is desirable to employ wide-band exciation. It has been shown that the sensitivity of the method falls with increasing defect depth, but its performance at defect depths above about 4 mm is superior to that of the commonly used mechanical impedance and coin-tap tests. The method therefore seems to be an attractive possibility for the detection of delaminations in composite materials and disbonds in adhesive joints, and warrants further investigation.
[1]
O. Zienkiewicz.
The Finite Element Method In Engineering Science
,
1971
.
[2]
D. J. Ewins,et al.
Modal Testing: Theory and Practice
,
1984
.
[3]
P. Cawley,et al.
THE MECHANICS OF THE COIN-TAP METHOD OF NON-DESTRUCTIVE TESTING
,
1988
.
[4]
P. Cawley,et al.
The operation of NDT instruments based on the impedance method
,
1985
.
[5]
G. B. Warburton,et al.
The Vibration of Rectangular Plates
,
1954
.
[6]
Peter Cawley,et al.
The impedance method of non-destructive inspection
,
1984
.
[7]
P. Cawley,et al.
Errors in mechanical impedance data obtained with impedance heads
,
1980
.
[8]
Peter Cawley,et al.
A review of defect types and nondestructive testing techniques for composites and bonded joints
,
1988
.
[9]
R. J. Schliekelmann.
Non-destructive testing of adhesive bonded metal-to-metal joints 1
,
1972
.
[10]
P. Cawley.
The sensitivity of the mechanical impedance method of nondestructive testing
,
1987
.