An Extensometer for Measuring Adhesive Shear Strain versus Stress

AN EXTENSOMETER FOR MEASURING ADHESIVE SHEAR STRAIN VERSUS STRESS 

The foregoing analysis of the skin-doubler specimen shows that it is essential to know the stiffness characteristics of the adhesive. Since good design practice places bond lines in shear, it was decided that the shear modulus is the primary stiffness parameter. Furthermore, it is recognized that more than the initial portion of the shear stress-strain curve was required. It was clear that the total curve was not linear. It was anticipated that the nonlinearity portion would bear heavily on creep and fatigue performance. Accordingly, the primary requirements for the strain measuring device were set as follows  

A fully detailed design and accuracy report on the KGR-1 extensometer, designed to fulfill the above requirements, can be found elsewhere.(2) 

Not shown are locking devices. These give a fixed reference setting between the front- 

FIGURE 3. KGR-1 extensometer mounted on a thick adherend lap shear specimen. 

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KGR-1, AN EXTENSOMETER FOR MEASURING ADHESIVE SHEAR STRAIN VERSUS STRESS... 

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