Understanding the nonlinear dynamical contact interactions within joints is crucial for understanding and predicting the dynamics of assembled structures. In spite of this, most experimental investigations focused on the global vibration behavior, since the local interactions at the interface cannot be observed with standard techniques. In the present work, an advance contact pressure measurement system is used in a unique way to analyze, in situ, the interfacial contact pressures and the contact area inside a bolted lap joint connecting two beams (Brake-Reuß beam). An important feature of the measurement system is that it is designed for frequency ranges including the typical vibration frequency of the Brake-Reuß beam's first eigenmode, and thus permits measurement under dynamic excitation. The dynamics of the contact pressures were investigated with different bolt torque levels and with different excitation levels. The experiments found that significant variations of the contact state occurred and that the contact pressure measurement system could adequately resolve this effect. The influence of the measurement system itself on the global vibration response of the Brake-Reuß beam was shown to be tolerable.
Experimental dynamic substructuring is a means whereby a mathematical model for a substructure can be obtained experimentally and then coupled to a model for the rest of the assembly to predict the response. Recently, various methods have been proposed that use a transmission simulator to overcome sensitivity to measurement errors and to exercise the interface between the substructures; including the Craig-Bampton, Dual Craig-Bampton, and Craig-Mayes methods. This work compares the advantages and disadvantages of these reduced order modeling strategies for two dynamic substructuring problems. The methods are first used on an analytical beam model to validate the methodologies. Then they are used to obtain an experimental model for structure consisting of a cylinder with several components inside connected to the outside case by foam with uncertain properties. This represents an exceedingly difficult structure to model and so experimental substructuring could be an attractive way to obtain a model of the system.
Experimental dynamic substructuring is a means whereby a mathematical model for a substructure can be obtained experimentally and then coupled to a model for the rest of the assembly to predict the response. Recently, various methods have been proposed that use a transmission simulator to overcome sensitivity to measurement errors and to exercise the interface between the substructures; including the Craig-Bampton, Dual Craig-Bampton, and Craig-Mayes methods. This work compares the advantages and disadvantages of these reduced order modeling strategies for two dynamic substructuring problems. The methods are first used on an analytical beam model to validate the methodologies. Then they are used to obtain an experimental model for structure consisting of a cylinder with several components inside connected to the outside case by foam with uncertain properties. This represents an exceedingly difficult structure to model and so experimental substructuring could be an attractive way to obtain a model of the system.
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