Non-iterative mode shape expansion for three-dimensional structures based on coordinate decomposition

The direct mode shape expansion method is an iterative technique, one can conclude that the convergence performance maybe challenged when applied to three-dimensional structures. In addition, mode shape values at different DOFs (degrees-of-freedom) sometimes are not in a same order of magnitude, which will produce much error for the estimation of small values of unmeasured mode components. Therefore this paper proposed a non-iterative mode shape expansion method based on coordinate decomposition technique. The advantage of coordinate decomposition is that the unmeasured components of mode shape values could be estimated with different weighting coefficients, even in a physical meaningful interval. Numerical studies in this paper are conducted for a 30-DOF cantilever beam with multiple damaged elements, as the measured modes are synthesized from finite element models. The numerical results show that the approach can estimate unmeasured mode shape values at translational and rotational DOFs in x, y and z directions with different weighting coefficients, respectively; and better mode shape expansion results can be obtained when proper constraints are employed. A numerical three dimensional structure is also investigated, and results indicate that the estimation of unmeasured components can be improved by imposing reasonable constraints based on the coordinate decomposition technique, even only translational DOFs of two diagonal nodes of the first floor are measured

A Facile and Simple Method for Preparation of Novel High-Efficient Form-Stable Phase Change Materials Using Biomimetic–Synthetic Polydopamine Microspheres as a Matrix for Thermal Energy Storage

Polydopamine microspheres (PDAMs), synthesized using a biomimetic method, were used as a matrix for polyethylene glycol (PEG) to develop a novel high-efficient form-stable phase change material (PEG/PDAM) using a simple vacuum impregnation strategy. The PDAMs were first used as a support for the organic phase change materials, and the biomimetic synthesis of the PDAMs had the advantages of easy operation, mild conditions, and environmental friendliness. The characteristics and thermal properties of the PEG/PDAMs were investigated using SEM, FTIR, XRD, TGA, DSC, and XPS, and the results demonstrated that the PEG/PDAMs possessed favourable heat storage capacity, excellent thermal stability, and reliability, and the melting and freezing latent heats of PEG/PDAM-3 reached 133.20 ± 2.50 J/g and 107.55 ± 4.45 J/g, respectively. Therefore, the PEG/PDAMs possess great potential in real-world applications for thermal energy storage. Additionally, the study on the interaction mechanism between the PEG and PDAMs indicated that PEG was immobilized on the surface of PDAMs through hydrogen bonds between the PEG molecules and the PDAMs. Moreover, the PDAMs can also be used as a matrix for other organic materials for the preparation of form-stable phase change materials

Hydro- and aerodynamic analysis for the design of a sailing yacht

The results of the design analysis for a sailing yachts hull and sails are reported. The results were used to confirm the design of a 30 ft long sloop, which was planned, designed, and built in Korea for the first time in history. Flows around a sailing yacht above and under the free surface were analyzed separately using both computational and experimental methods. For the underwater flow analysis, turbulent flow simulations with and without free surface wave effects were carried out for the canoe hull with keel/rudder. The computed drag and side forces on the hull model were compared with the measurement data obtained from the towing tank experiments. In order to assess the sail performance, another set of computations was carried out for the flow around a sail system composed of main and jib sails with a mast. The present study demonstrates that, for the design analysis of a sailing yacht, computational fluid dynamics techniques can be utilized with a reasonable level of confidence.Ministry of Knowledge Economy (MKE) through the Regional Innovation Center and by the Ministry of Education, Science and Technology (MEST) through NRF Grant No. 2009-0087863 MEST through a World Class University project (R32-10161) and the Multi-phenomena CFD Research Center (NRF Grant No. 2009-0083510