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AbstractAttaching viscoelastic materials (VEMs) to structures has been widely used to improve structural dynamic properties. Nevertheless, the adhesion of VEMs inevitably leads to the increase in overall structural mass. Topology optimization is one of the most effective methods to tackle this contradiction. In the traditional topology optimization, VEMs damping cores in constrain layer damping (CLD) sandwich structures are often simplified into linear elastic materials with constant parameters, usually ignoring their frequency-dependent and temperature-dependent dynamic characteristics, which will cause the distortion of the optimization results. Therefore, we propose a topology optimization method for CLD sandwich panels with a frequency-dependent VEM damping core considering steady-state free vibration in this study, where the anelastic displacement fields (ADF) model is adopted to combine the derived frequency-dependent complex constitutive relationship with the layerwise finite element (LFE) model, and the iterative modal strain energy (IMSE) method is used to determine the modal parameters of the CLD sandwich panels. The results of numerical examples show that the proposed method in this study not only has the advantages of simple and intuitive model, high calculation efficiency, and accuracy but also can achieve relatively good dynamic properties of the CLD sandwich structures. [ABSTRACT FROM AUTHOR]

We propose a polygonal topology optimization method combined with the alternating active-phase algorithm to address the multi-material problems. During the process of topology optimization, the polygonal elements generated by signed distance functions are utilized to discretize the structural design domain. The volume fraction of each material is considered as a design variable and mapped to its corresponding element variable through a filtering matrix. This method is used to solve a multi-material structural topology optimization problem of minimizing compliance, in which a descriptive model is established by using the alternating active-phase algorithm and the solid isotropic microstructure with penalty theory. This method can accomplish the topology optimization of multi-material structures with complex curve boundaries, eliminate the phenomena of checkerboard patterns and a one-node connection, and avoid sensitivity filtering. In addition, this method possesses fine numerical stability and high calculation accuracy compared to the topology optimization methods that use quadrilateral elements or triangle elements. The effectiveness and feasibility of this method are demonstrated through several commonly used and representative numerical examples. [ABSTRACT FROM AUTHOR]

The solid isotropic microstructure with penalization (SIMP) model is widely used in structural topology optimization. When the optimality criterion (OC) method is used for solving the SIMP model, the optimization solution process not only has relatively low computational efficiency, but also causes a large number of grey-scale elements in the obtained structure. To enhance the computational efficiency, an advance and retreat golden searching scheme is proposed to update the Lagrange multiplier, thereby improving the OC method for solving the SIMP model. To eliminate the grey-scale elements and also to enhance the computational efficiency, the improved OC method combined with the tanh-based density filtering is proposed for solving the SIMP model of structural topology optimization. Furthermore, the improved OC method combined with the sigmoid-based Heaviside density filtering is proposed for solving the SIMP model of multi-material structural topology optimization to eliminate the grey-scale elements and to enhance the computational efficiency. [ABSTRACT FROM AUTHOR]