Dynamic substructuring enables the prediction of the dynamic response of complex mechanical systems based on the separate characterization of individual substructures and their subsequent coupling into a final assembly. This procedure is based on the introduction of compatibility and equilibrium conditions, which are formulated for collocated pairs of degrees of freedom on each side of the interface.
In experimental applications, the interface degrees of freedom are often inaccessible for the placement of measurement devices, or the degrees of freedom between substructures do not spatially coincide. For this reason, the interface is commonly described using the virtual point transformation. The virtual point transformation allows arbitrary degrees of freedom in the vicinity of the interface to be mapped onto generalized degrees of freedom at a chosen point, thereby resolving issues related to interface inaccessibility and the non-colocation of measurement coordinates. However, this approach relies on rigid-body kinematic assumptions and does not directly account for local deformations in the joint.
The master's thesis presents an extension of the classical frequency-based substructuring formalism by introducing strain as an additional coupling condition. A theoretical formulation of the extended compatibility and equilibrium conditions is developed and experimentally evaluated on a laboratory test structure through both coupling and decoupling of individual substructures.
Due to the ill-conditioning of the decoupling problem, the influence of different regularization methods is also analyzed. The results show that incorporating strain improves the stability of the substructuring procedure and leads to improved agreement between predicted and reference frequency response functions.
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