Non-destructive testing of adhesively bonded structures

Many widely used Tests of adhesion can be applied to the rubber to metal bonds Blister test. Fracture-mechanics test specimens. Non-destructive testing of adhesively-bonded structures. Peel tests. Shear tests. Tensile tests and Wedge test. This particular article is concerned with those aspects that are of practical concern in the rubber-processing industry. 

Non-destructive testing of adhesively-bonded structures G J CURTIS Acoustic wave techniques, resonance and pulse-echo testers... 

Tests to measure the bond which can be obtained with the concrete of the structure to be strengthened are best carried out on the structure itself. A possibility is to utilise a pull-off test as developed for the non-destructive testing of concrete(21). A circular steel probe is bonded to the concrete surface and specially designed portable apparatus is then used to pull off the probe, along with a bonded mass of concrete, by applying a direct tensile force. Any defects in bond would be revealed by the occurrence of failures at the adhesive-concrete interface. 

Adhesion Society. He is active in organising conferences and publishing and was a founder member of EURADH and WCARP, the main European and World series on Adhesion. He has been Joint Editor-in-Chief of the International Journal of Adhesion and Adhesives since 1999. His main research area is on adhesively bonded joints and he pioneered the application of finite element analysis for determining the stresses, strains, and strength of such joints. In addition to his adhesives research, he has also worked extensively on vibration properties in composites and developed low-velocity impact tests for non-destructively testing composites and sandwich structures. 

Also emphasised in this book are the various means of destructive and non-destructive testing of bonded joints, with special mention of structures fabricated by adhesive bonding. 

Appropriate test methods for the control of fabrication procedures and non-destructive testing (NDT) are basic requirements for the formation of structural adhesive joints. Such methods should be based upon relatively easily measurable parameters that have a close identity with the properties of the bonded assembly that need to be controlled. However the quality of bonded joints depends upon many factors, requiring a range of very different procedures. 

Figure 6.33 An example of holographic non-destructive testing. The test specimen was an adhesively bonded carbon fibre laminate honeycomb structure and a vacuum was applied to cause increased displacement of the face sheet when a defect was present. Debonds were present at the interface between the face sheet and honeycomb core (below the disturbance in the regular pattern that can be seen second from top and bottom) and crushed honeycomb core was also present (top and third from top) [149].

---