Shrinkage Internal Stresses in Adhesive-Bonded Joints

2 Shrinkage internal stresses in adhesive-bonded joints 

There are established methods for evaluating the shrinkage internal stresses in the adhesive-bonded joint using cantilevered three-layer beams [160, 175], but in practice these methods are frequently too complicated. 

A paper of Myshko and Garf [175] was the first to attempt to create a method of calculating the distribution of the shrinkage internal stresses along an adhesive-bonded joint cross-section for a cantilevered specimen made of two plates of different flexural rigidity with an adhesive layer between them—i.e., to generalize the equations from [160] for adhesive-bonded joints. 

Consider the effect of internal stresses in two cases between rigid substrates (only the adhesive layer deforms) and between flexible substrates (combined deformation). The pattern of the tension-contraction forces Po PiiP2 of th substrates and the adhesive layer and their bending moments Mq,Mi,M2 caused by shrinkage is represented by a system of four equations  

Analyzing equations (4.25) and (4.26), it is easy to note that the authors proceed from the equahty of the relative deformations of the adhesive layer and the substrates. Such an approach raises some doubts insofar as the bond between the adhesive and the substrate is not absolutely rigid, as a result of which Equation (4.27) has no definite solutions for real systems  

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