DEVELOPMENT OF A NON-DESTRUCTIVE TEST FOR THE ADHESIVE BOND IN WOOD SCARF JOINTS
WASHINGTON STATE UNIV PULLMAN
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A series of 120 scarf-joint specimens prepared from selected Douglas fir were made with 4 types of glue-line defects in addition to non-defective control specimens. Each joint was inspected nondestructively 1 in double vibration, 2 by transmission of ultrasonic energy, and 3 electrically. The specimens were then tested to failure in bending, torsion, shear, and tension attempts were made to correlate the results. With the vibration method the higher mass ratio of wood to glue masked the contribution of the glue bond to over-all joint characteristics. With the ultrasonic data, the specimens could be segregated into relative quality classes, but individual defective joints could not be consistently segregated. The segregation of joints by the electrical test was also qualitative. The developnt of 2 new tests, shea andrsion, improved the quality of the destructive testing. The non-destructive test data were not indicative of a proven quality measurement method.