With a view to increasing efficiency, saving resources and energy, and reducing greenhouse gas emissions, lightweight construction methods are becoming increasingly important. Classic areas of application can be found in automotive engineering, mechanical and plant engineering, aerospace technology or construction. For lightweight structures, the structural dynamic response under ambient excitations or excitations due to operating conditions is often the limiting factor, especially with regard to proofs of serviceability, durability or comfort. Lightweight structures often exhibit large vibration amplitudes under dynamic loads due to unfavorable excitation to natural frequency ratios due to excitations near or in the resonant range of the structures. The resulting large vibration amplitudes lead to negative effects on functionality, operational safety and fatigue strength, or result in undesirable acoustic emissions from the components.
The reduction of mass and stiffness of the system is counteracted by increasing damping in the project Leicht_Diss: "Weight reduction in lightweight structures of dynamically loaded systems by new energy dissipative elements". Among all damping mechanisms, joint damping has been found to be the type of damping that reduces amplitudes the most. Joints are investigated by bolted joints, which are adjusted by parameters such as the material pairing, frequency spectrum, surface roughness and contact pressure to deliberately allow relative displacements between the surfaces. The displacement ensures a Coloumb-like behavior in the macro-slip area; if, on the other hand, the displacement is smaller, effects occur in the micro-slip. In a joint with bolted connections, both phenomena can occur simultaneously with respect to the distance of the point under consideration from the bolted joint. Therefore, a new material law is established, which is able to combine both phenomena in one model. In addition, the long-term behavior of such a joint is considered, since wear is also involved with the friction caused.
This model will be transferred into a finite element environment, which allows the new energy dissipative joint elements to be integrated and numerically recorded in various applications. In the project, the application is tested on a tailgate of a car in which the vibration damper is replaced by the new energy dissipative elements. If the test is successful, further fields of application are the entire body of automobiles up to bridge construction.