Browsing by Author "Krack, M."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item A consistency analysis of phase-locked-loop testing and control-based continuation for a geometrically nonlinear frictional system(Elsevier, 2022) Abeloos, G.; Müller, F.; Ferhatoglu, E.; Scheel, M.; Collette, C.; Kerschen, G.; Brake, M.R.W.; Tiso, P.; Renson, L.; Krack, M.Two of the most popular vibration testing methods for nonlinear structures are control-based continuation and phase-locked-loop testing. In this paper, they are directly compared on the same benchmark system, for the first time, to demonstrate their general capabilities and to discuss practical implementation aspects. The considered system, which is specifically designed for this study, is a slightly arched beam clamped at both ends via bolted joints. It exhibits a pronounced softening–hardening behavior as well as an increasing damping characteristic due to the frictional clamping. Both methods are implemented to identify periodic responses at steady-state constituting the phase-resonant backbone curve and nonlinear frequency response curves. To ensure coherent results, the repetition variability is thoroughly assessed via an uncertainty analysis. It is concluded that the methods are in excellent agreement, taking into account the inherent repetition variability of the system.Item In situ, real-time measurements of contact pressure internal to jointed interfaces during dynamic excitation of an assembled structure(Elsevier, 2021) Dreher, T.; Brake, M.R.W.; Seeger, B.; Krack, M.Despite the ubiquitousness of jointed structures, the nonlinear interfacial behavior within bolted joints is still an insufficiently studied and poorly understood environment. For the development of effective simulation approaches, a deeper understanding of the salient physical effects within the contact surface is needed. This work studies the interfacial pressure distribution and pressure changes during static and dynamic loading within the contact interface of a bolted structure. An electronic pressure sensor is placed in the interface plane. After analyzing to what extent the system’s nonlinear stiffness and normal kinematics are changed by the measurement equipment, real-time measurements of the contact pressure are made for both impact hammer and sinusoidal shaker testing (both swept sine and steady-state excitations). The measurements invalidate many commonly held assumptions for contact models that were based on observations from static pressure films.