Researchers from the Faculty of Mechanical Engineering at the University of Ljubljana have presented an improved experimental approach to joint identification, which through several independent enhancements enables more reliable estimation of mass, damping, and stiffness properties, thereby providing more accurate predictions of the dynamic behavior of assembled structures. The approach was published in one of the leading scientific journals in the field, Mechanical Systems and Signal Processing (Impact Factor = 8.9).
Dynamic properties of assemblies strongly depend on joints between substructures, which are influenced by various factors such as preload, temperature, and vibration amplitude, complicating purely analytical and numerical predictions. Due to the complexity of real joints, experimental modeling and frequency-based substructuring are often used. However, accuracy is limited by measurement noise, inconsistencies between coupled and uncoupled models, and incomplete representation of rotational degrees of freedom.
The research presents an improved experimental approach that more reliably estimates mass, damping, and stiffness of joints, thus improving dynamic behavior predictions of assemblies. The approach is based on Lagrange-multiplier frequency-based substructuring and introduces four independent enhancements: model sparsification using LASSO, rigid-body mode (RBM) constraints for physically consistent system matrices, updating of excitation directions for a more consistent virtual point transformation (VPT), and indirect parametrization that first estimates dynamic stiffness, followed by the system parameters.
The approach was tested on numerical and experimental cases; indirect parametrization combined with RBM constraints and updated excitation directions consistently improves agreement with reference responses. (Article: “Towards an improved experimental joint identification in frequency-based substructuring,” Mechanical Systems and Signal Processing, doi: 10.1016/j.ymssp.2025.113115).
Physically consistent, parameterized joint models are suitable for direct inclusion in engineering simulations, enabling more precise product design and reducing risks in the development of assembled structures.