Monitoring of Crack Growth in Advanced Adhesively Bonded Joints Using Acoustic Emission
Sprache des Vortragstitels:
European Workshop on Structural Health Monitoring
Sprache des Tagungstitel:
In aviation, carbon-fibre reinforced polymers and titanium alloys are widely used materials. Adhesive bonds are a lightweight option to transfer loads between different materials, and failure prediction of such adhesive joints is of great importance. This research is concerned with static damage detection of lap shear specimens with Structural Health Monitoring methods. The specimen design is derived from single-lap shear test specimens according to ASTM D5868, with one joining partner made of additively manufactured Ti6Al4V and the other one made of a carbon-fibre reinforced polymer laminate. The adhesive layer consists of the matrix material of the carbon-fibre reinforced polymer laminate. In order to enhance the lap shear, the additively manufactured part is printed in a comb-shape and on a number of specimens, pins are printed to yield additional interlocking of the parts. For assessment purposes, several different Structural Health Monitoring methods are available. Of these, Acoustic Emission measurements are evaluated in detail for this study. When the crack extends during linear increasing the load, acoustic waves propagate through the joining partners. To enable their detection, a piezoelectric element is bonded onto the surface of the Ti6Al4V adherend.
The Acoustic Emission results show hits which are well separated from a noise floor, facilitating the use of Acoustic Emission for this application. Damages can be detected earlier than by evaluating strain changes with a Digital Image Correlation system.