Tensile test on overlap bonding

Including measurement of the shear path with integrated Kelber thickness measurement

For a shear tensile test, two wood samples were glued together. A clamp-on extensometer was used for the most precise displacement measurement

By using a clamp-on extensometer, the finest displacement of the glued wooden surfaces can be measured.

A special feature of this test is that an additional bonding of an adapter piece creates a thickness compensation. This test setup allows a conventional clamp-on extensometer to be used for the finest displacement of the bonding surfaces. This has a measuring path resolution of 0,000.1 mm.

In order to make the results comparable, the area of the bond is measured before the test (sample width and length of the overlap). The determined maximum test force is divided by this area to determine a shear stress.

Since the test pieces are relatively stiff, the clamping device must be offset to avoid bending influences on the bonding point. This was achieved by a special clamping device realized. In this case, a center offset of the upper to the lower clamping plane can be achieved by manually adjusting the left clamping surface.