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The Boeing wedge test (ASTM D3762) is well established for assessing the integrity and long term bond strength of adhesively bonded joints in the aircraft industry. The method has recently been applied by NPL to composite aircraft repairs using cold-epoxy adhesives. Specimens are typically bonded using commercial adhesives and surface preparation techniques, typical both of the initial construction, or those more suited to repair situations.
A wedge inserted in the specimen preparation simulates in a qualitative manner the forces and effects on an adhesive bond joint at metal-adhesive/primer interface. It has proven to be highly reliable in determining and predicting the environmental durability of adherend surface preparations
To evaluate environmental durability and long term performance of adhesive joints
ASTM D3762-03 Standard Test Method for Adhesive-Bonded Surface Durability of Aluminum (Wedge Test) This test method, simulates in a qualitative manner the forces and effects on an adhesive bond joint at metal-adhesive/primer interface. It has proven to be highly reliable in determining and predicting the environmental durability of adherend surface preparations. The method has proven to be correlatable with service performance in a manner that is much more reliable than conventional lap shear or peel tests (Note 2).
While this test method is intended for use in aluminum-to-aluminum applications it may be used for determining surface durability of other metals and plastics provided consideration is given to thickness and rigidity of the adherends.
This test method is not a quantitative fracture strength test method. To measure fracture strength see Test Method D 3433.
Case study E6 on aircraft repair using adhesive bonding techniques evaluates the applicability of the Boeing Wedge Test to composite aircraft structures: