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In this paper, the critical buckling temperature of a lattice sandwich panel was investigated using FE analysis. In the previous study[Sebata, Y., Ushijima, K., Study on thermal buckling temperature of a lattice sandwich panel, Transaction of the JSME (in Japanese), Vol. 88, No. 905 (2022)], a Pyramid-shaped core unit was selected and the effects of unit-cell height and width on the buckling temperature were investigated. In the present study, two kinds of lattice core, BCC and f2BCC were added for investigation, and the effects of the core stiffness and micro-architecture on the buckling temperature were discussed. It was revealed from this study that the constraint of rotational angle at the connection point between the face sheet and the core strands could enhance the local buckling temperature. Also, enlarging the core stiffness could enhance the local buckling temperature. Moreover, the local buckling temperature can be predicted theoretically based on the thick shell theory by considering the effective width of the face sheet for one unit-cell reflected by the cross-sectional area for a strut.

In this study, the critical buckling temperature of a lattice sandwich panel was investigated by using FEM. In particular, the effects of geometric properties, for example a core height h, a core length L, and the number of cells Nc on the buckling temperature, were discussed. It is confirmed that the lattice sandwich panel also has the global and local buckling modes that are common in a latticed members, and a correction factor which includes the effect of the number of cells Nc is presented for estimating the global buckling temperature of the panel. Multiplying the analytical equation of the buckling temperature which was derived from the conventional homogenization method by the correction factor, the buckling temperature can be estimated with a good accuracy. On the other hand, the local buckling temperature can be estimated by considering the buckling behaviour of a small plate surrounded by the cells and supported by four corners.

In this paper, a new method to evaluate performance of sound insulating plates in closed medium is investigated by using acoustic finite element method (FEM) under such two conditions that plates are having free ends and that plates are simply supported. The proposed method is able to compute sound transmission loss by using sound pressures at the small numbers of properly selected nodes considering acoustical symmetry of modal shapes in the closed medium, which is equivalent to the theoretical transmission loss without using all nodes existing in the medium. By the proposed method, the computed transmission loss does not depend on sizes or shapes of the medium; it is the unique transmission loss of the sound insulating plate itself. As sound insulating plates, the following three models are constructed; a single plate, double-leaf plates and the high-rigid sandwich panel called “trusscore panel”. It is also shown that sandwich trusscore panel works effectively at low frequency range since it is sufficiently rigid and that computed sound transmission loss of the trusscore panel has tendency as observed on a single plate having the equivalent weight and stiffness to the trusscore panel. Trusscore panels can be applied widely in industrial fields in the future such as walls or floors in a car, train or building to reduce interior noise.