Interfacial stresses contact methods

The DIG method has great potential in measuring the 2D and 3D surface deformations and strain values of structural components at extreme environmental exposures. It has been adopted in a few interfacial adhesive lap-shear stress analyses of FRP-concrete joints yet the same drawbacks of accurate stress estimation in contact methods persist in the DIG as well. 

The profiles of pendant and sessile bubbles and drops are commonly used in determinations of surface and interfacial tensions and of contact angles. Such methods are possible because the interfaces of static fluid particles must be at equilibrium with respect to hydrostatic pressure gradients and increments in normal stress due to surface tension at a curved interface (see Chapter 1). It is simple to show that at any point on the surface... 

An important chemical modification method is the chemical coupling method, which improves the interfacial adhesion. The fibre surface is treated with a compound, that forms a bridge of chemical bonds between fibre and matrix. The increase in the mechanical properties of the fibreboards due to chemical modification is an indication of improved interaction and stress transfer between the components. Some authors have reported that softening and increased thermo-plasticity of wood fibre surface facilitates contact and dispersion of the fibre with thermoplastics [61, 62]. 

Pinchin, D. J., Taboi D. J. (1978) Interfacial contact pressure and frictional stress transfer in steel fibre cement , in Proc. RILEM Symp. Testing and Test Methods of Fibre Cement Composites, R. N. Swamy ed., Sheffield, Lancaster The Construction Press, pp. 337—44. 

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