Tubular joints

Design aspects of adhesively bonded tubular joints... 

Keywords Adhesive modulus Adhesys expert system Co-axial joints Compression Concealed joints Creep Elastic limit Epoxy Epoxy composite Einite element analysis Glue line thickness Goland and Reissner Hart-Smith Heat exchanger Hooke s Law Joint designs Joint thickness Lap shear strength Peel Plastic behaviour Polyurethane Pipe bonding Shear stresses Shear modulus Stress distribution Thick adherend shear test Tubular joints Volkersen equation Young s modulus... 

From a stress distribution viewpoint, a co-axial tubular joint is much preferred since this type of joint cannot be subjected to the destructive peel stresses. We can consider a tube which slides inside the second tube such that the adhesive fills the annular gap (Fig. 29). 

Figure 29 A section through a co-axial tubular joint.

Butt joints are strong in tension and very strong in compression. However, they are very weak if subjected to transverse loading owing to the large cleavage stresses. The type of joint shown earlier in Fig. 5(g) is satisfactory in most types of loading, and is really the same joint discussed above (Fig. 74(b)) for tubular joints. 

Xu W, Li G (2010) Finite difference three-dimensional solution of stresses in adhesivdy bonded composite tubular joint subjected to torsion. Int J Adhes Adhes 30 191-199... 

Kwon and Lee (2000) studied the influence of surface roughness on the strength of tubular joints by modeling the stiffness of the interfacial layer between the adherends and the adhesive as a normal statistical distribution function of the surface roughness of the adherends. The authors found that the optimum surface roughness was dependent on the bond thickness and applied load. 

Tubular joint with square end (a) and with a taper (b)... 

However, most of these improvement methods are traditionally based on the mechanical stiffening m ods. They cannot adaptively adjust the stress distribution. In order to smartly and efficiently improve the joint strength, Cheng and his-coworkers have recently introduced a smart joint concept into the traditional adhesively bonded joint by integrating with piezoelectric materials, which have been confirmed as a very effective method to smartly reduce the stress concentration in the adhesive layer. Here, we will give an overview on the state-of-the-art of the adhesively bonded smart beam-like and tubular joints [9-13]. 

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