Volume 21, Issue 1 (January 1993)
Contoured Wood Double Cantilever Beam Specimen for Adhesive Joint Fracture Tests
The strain energy release rate and associated parameters are useful measures of adhesive bond quality. A properly contoured double cantilever beam specimen excels in measuring these properties. However, previous specimen designs presented experimental difficulties resulting in possible bias and poor reproducibility. A new composite specimen is described that overcomes these problems. The specimen is made of oriented strandboard (OSB) and has a concave taper; two contoured beams sandwich a wood laminate having the test bondline at its center. Unlike previous specimen designs, this new specimen allows bonding of the test joint under normal conditions and produces a linear relationship between specimen compliance and crack length. These changes improve the accuracy and reproducibility of the test results with adhesively bonded wood joints. This report describes how the new specimen was developed and how to experimentally determine the compliance and crack-length relationship used to calculate the strain energy release rate of an adhesive joint. Furthermore, the reproducibility of two sets of specimens and the use of the method to analyze differences in actual joint quality are shown and discussed.