Engineering adhesive joints

It is evident from this brief discussion that engineering adhesive joints are complex and ill-understood. The simplistic criterion of adhesive strength often... 

The performance of the classifier has been verified using a number of practical applications, such as civil engineering [3], inspection of aerospace composite structures, ball bearings and aircraft multi-layer structures. Here we present shortly some results, focusing on detection of disbonds in adhesively joint multi-layer aerospace structures using Fokker Bond Tester resonance instrument, details can be found in [1]. 

R. D. Adams and W. C. Wake, Structural adhesive Joints in Engineerings Elsevier, New York, 1984. 

Table 1 contains the metal-to-metal engineering property requirements for Boeing Material Specification (BMS) 5-101, a structural film adhesive for metal to metal and honeycomb sandwich use in areas with normal temperature exposure. The requirements are dominated by shear strength tests. Shear strength is the most critical engineering property for structural adhesives, at least for the simplistic joint analysis that is commonly used for metal-to-metal secondary structure on commercial aircraft. Adhesive Joints are purposefully loaded primarily in shear as opposed to tension or peel modes as adhesives are typically stronger in shear than in Mode I (load normal to the plane of the bond) loading. 

Adhesive Disadvantages. There are some limitations in using adhesives to form assemblies. The major limitation is that the adhesive joint is formed by means of surface attachment and is, therefore, sensitive to the substrate surface condition. Another limitation of adhesive bonding is the lack of a nondestructive quality control procedure. Finally, adhesive joining is still somewhat limited because most designers of assemblies are simply not familiar with the engineering characteristics of adhesives. 

Sung, N. H., Moisture Effect on Adhesive Joints, Adhesives and Sealants, vol. 3, Engineered Materials Handbook, ASM International, Materials Park, OH, 1990, p. 622. 

An adhesive is a material capable of holding together solid materials by means of surface attachment. Adhesion is the physical attraction of the surface of one material for the surface of another. An adherend is the solid material to which the adhesive adheres and the adhesive bond or adhesive joint is the assembly made by joining adlierends together by means of an adhesive. Practical adhesion is the physical strength of an adhesive bond It primarily depends on the forces of adhesion, but its magnitude is determined by the physical properties of the adhesive and the adherend, as well as the engineering of the adhesive bond. 

Adams RD, Comyn J, Wake WC, Structural adhesives joints in engineering, Chapman Hall, 2" edition, 1997. 

Paraschi, M., A fracture mechanics approach to the failure of adhesive joints, PhD thesis. Department of Mechanical Engineering. 2002, Imperial College, University of London London. 

A1 Adams, R. D. Comyn, J. Wake, W. C. Structural Adhesive Joints in Engineering. Chapmann Hall, London, 1997 (ISBN 0-412-70920-1). 

R.D. Adams, J. Comyn, W.C. Wake, Effect of the environment on structural adhesives, in Structural Adhesive Joints in Engineering, Chapman Hall, London, 1997, Chap. 8. 

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