Use of structural adhesives has increased as more manufacturers become aware of their advantages compared to conventional joining techniques. The increased use of these adhesives in the automotive industry, especially in safety-critical areas, makes it necessary to evaluate any possible decrease in performance that may occur when glued joints are subjected to impacts. Adhesive wedge peel test methods have been developed to evaluate fracture behavior of adhesively bonded joints when subjected to impact. The impact wedge peel test is an International Standard Organization (ISO) test method used to measure the resistance of structural adhesives to cleavage fracture at test speeds of 2 and 3 m/s, at various user defined temperatures.
Impact testing to this standard can deliver to manufacturers in the form of performance data for research and development of new adhesives. Once a suitable product has been established, both manufacturer and end-user can implement a quality control program utilizing baseline data from the impact performance tests to provide ongoing process validation.
For this test, we used our CEAST 9350 with High Energy option, instrumented with a 15.6kN tup, striker for ISO 11343, DAS (Data Acquisition System) and Visual Impact software were used to perform this testing. We also used an adhesive wedge peel fixture, designed in accordance to ISO 11343. Impact velocity was set at 2 and 3 m/s respectively; the time range for data acquisition was set to 45 milliseconds
ISO 11343 states that the specimens tested should be made from either steel or aluminum adhends 90 mm long by 20 mm wide with a thickness ranging from 0.6 – 1.7 mm. The specimens are bonded at one end over a 30 mm length with the unbonded arms being formed to give a tuning fork profile. The free legs of the specimen are clamped to the fixture with a spacer block between them. A wedge is then driven through the bonded section
This test configuration is well suited for determining the performance characteristics of high strength adhesive bonds under impact conditions. Both adhesive suppliers and their customers may use test results to verify product performance. Using an environmental chamber allows both parties to get an understanding of how the adhesives may perform in colder or warmer applications.