Dynamic Substructuring Method for Vibration Analysis of Complex Structures

Dynamic sub-structuring technique is often employed to determine the structural dynamics of the large complex structural system. This technique reduces the complexity of numerical models obtained during structural analysis and eventually helps obtain accurate, efficient, and cost-effective model reduction. In this paper, Craig–Bampton method is adopted to evaluate the performance of model reduction. The structural system is considered to be an assembly of sub-systems and these sub-systems are called component modes. Vibration mode for each component is determined separately and is used to get overall dynamics of the whole structural system. The components at interface degrees of freedom satisfy the compatibility conditions of the interconnected components. Natural frequency of each components is determined, using the free-free condition and the fix condition. Durability of the test specimen is estimated by sine sweep test under 30 Hz and 50 Hz. Experimental data are combined with the sub-structural components to get an efficient model of the system. Krylov reduction technique is introduced in this paper to obtain the tactile response. The wind turbine blade is discretized to nodes and elements. The discretized blade consists of solid shell elements with 11,376 elements and tetra solid volume elements having 35,598 elements and the approximate spacing between two nodes is 5 mm. The finite-element model is reduced to sub-structure model with 8937 super-elements. Furthermore, this sub-structure model is reduced to 12 super-elements with 2 at the tip of the blade and 10 at the other end using Krylov reduction.