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This article is devoted to investigating sound insulation performance of a simply supported sandwich plate with an hourglass lattice core. The governing equations of lattice core sandwich plate are established using the Reissner sandwich plate theory. The solutions are derived using Fourier series expansion. The developed model is verified through the comparison with the results of the models from the existing literature, as well as finite element method (FEM). The effects of various structural and material parameters, the incident angle, and azimuth angle of the incident sound on sound insulation characteristics are investigated. It is demonstrated that the sandwich plate with the hourglass lattice core can outperform that with the traditional lattice cores. This work provides useful guidelines for the design of lightweight lattice sandwich structures in the application of sound insulation. [ABSTRACT FROM AUTHOR]

3D printing (also known as additive manufacturing) has been developed for more than 30 years. The applications of 3D printing have been increasingly extended to a variety of engineering fields in recent years. The sandwich material with a high strength and overall low density is a kind of artificial material that has been extensively used in various industrial and daily life applications. This paper presents a comprehensive vibration analysis and passive control technique for a cantilevered sandwich beam with an hourglass lattice truss core fabricated with 3D printing technology. The governing equation of the beam is established by using a homogenized model and the Hamilton's principle, from which the natural frequencies are determined. The theoretical model is verified by the results from the existing literature and the finite element analysis. The frequency response of the sandwich beam measured experimentally further validates the proposed model. Subsequently, a non-linear energy sink (NES) is proposed for being employed to passively suppress the vibration of the sandwich beam. A parametric study based on the theoretical model confirms the viability of using NES to effectively control the vibration of the sandwich beam. This work presents a good demonstration of using 3D printing technology for fabricating sandwich beams with a complicated lattice core. More importantly, some guidelines regarding the dynamic analysis of sandwich beams are provided. In addition, the analytical method presented in this work provides a potential means to theoretically explore the advantages of using sandwich beams for energy harvesting in the future.

The composite sandwich plate with hourglass lattice cores (CSP-HLC) is a novel cellular structure that can increase the width-to-length ratio and reduce the inter-node spacing. However, its static and dynamic behaviors are difficult to analyze due to the complex microstructures. In this work, a computational homogenization method is proposed for calculating the constitutive parameters. A reduced-order plate model is then derived through dimensional reduction from the three-dimensional orthotropic thermoelasticity framework. The effectiveness and accuracy of the proposed model were verified by comparing with the static-displacement and free-vibration results of 3D direct numerical simulations. The parameter analysis showed that the different material and structural parameters of the hourglass lattice core had different effects on the equivalent stiffnesses and natural frequencies of the CSP-HLC. Compared with the composite sandwich plate with pyramidal lattice cores, the displacement of the CSP-HLC was smaller under the same load and boundary conditions, and the natural frequencies were also smaller, which may have been because the additional equivalent density of the CSP-HLC influenced the frequency more predominantly than the extra equivalent stiffness. • The VAM was extended to establish the 2D-RPM of a CSP-HLC and was verified by comparing with 3D-DNS results. • The 2D-RPM has a high calculation efficiency due to the reduction of the degrees of freedom. • The static and dynamic behaviors of the CSP-HLC were systematically studied using the 2D-RPM. • The effects of the material and structural parameters on the equivalent stiffnesses and mode shapes were investigated. • The CSP-HLC had a higher stiffness than the CSP-PLC under the same material and structural conditions. [ABSTRACT FROM AUTHOR]