Fracture mechanics characterization of structural adhesive joints under short-term dynamic loading

• Applicant: Professor Dr.-Ing. Stephan Marzi
• Subject Area: Mechanics ; Polymeric and Biogenic Materials and Derived Composites
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556959923

In highly dynamic speed ranges, mechanical experiments can only be carried out with specially designed testing devices and measurement technology. As part of the large-scale equipment funding for HAWs, the DFG granted the University of Applied Sciences Mittelhessen a servo-hydraulic high-speed testing machine and a transient recorder for rapid data acquisition specifically for this type of testing. The project is dedicated to the experimental characterization of the fracture behavior of structural adhesive joints under short-term dynamic loading. In addition to determining the fracture energy, the focus is on the possibility of directly identifying interface models for failure prediction. In this context, particular importance is attached to the experimental procedures, the selection of measuring equipment, the selected evaluation methods and the handling of the dynamic effects that occur. In particular, the aim is to develop several novel test devices that not only expand the range of test speeds currently possible according to the present state of the art, but also allow tests in fracture mode III for the first time. While fracture mechanics test types in cantilever and bending configurations are equivalent under quasi-static boundary conditions, these test types differ under short-term dynamic boundary conditions. The main reason for this is the load propagation in the sample through bending waves, which leads to different stresses on the respective crack tip in the two configurations mentioned. At this point, the project aims to investigate the influences of dynamic effects on the test results and evaluate their consequences for the determination of constitutive interface models.

• DFG Programme: Research Grants