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The crushing behaviour of hexagonal thin-walled tube with partition plates subjected to axial compression is studied by using finite element method. It is found that, in the crushing process, the folds, which generate along the full length of the tube, come to be crushed simultaneously and the compressive load will not descend, since the compressive load produced in the central part does not descend with the folds forming on outer walls. Therefore, in order to suppress a fluctuation of the compression load in crushing of the tube and to raise its average compression load, it is an effective method to introduce corner parts, especially corner parts where three plates intersect, in the geometry of the thin-walled tube. [ABSTRACT FROM AUTHOR]

The equivalent elastic moduli of asymmetrical hexagonal honeycomb are studied by using a theoretical approach. The deformation of honeycomb consists of two types of deformations. The first is deformation inside the unit, which is caused by bending, stretching, and shearing of cell walls and rigid rotation of the unit; the second is relative displacement between units. The equivalent elastic modulus related to a direction parallel to one cell wall of the honeycomb is determined from the relative deformation between units. In addition, a method for calculating other elastic moduli by coordinate transformation is described, and the elastic moduli for various shapes of hexagon, which are obtained by systematically altering the regular hexagon, are investigated. It is found that the maximum compliance Cyy|max and the minimum compliance Cyy|min of elastic modulus Cyy in one rotation of the (x, y) coordinate system vary as the shape of the hexagon is changed. However, Cyy|max takes a minimum and Cyy|min takes a maximum when the honeycomb cell is a regular hexagon, for which the equivalent elastic moduli are unrelated to the selected coordinate system, and are constant with C11 = C22. [ABSTRACT FROM AUTHOR]

In the present study, the bending collapse of an elastoplastic cylindrical tube subjected to static pure bending is investigated using the finite element method (FEM). The moment of the elastoplastic cylindrical tube is controlled by the flattening rate of the tube cross-section. For a long tube, the flattening rate can be expressed in terms of the axial and circumferential stresses that, in turn, depend on the material and geometrical properties and the curvature of the tube. On the other hand, for a short tube, the boundary condition of the fixed walls prevents the flattening rate. In order to account for the length effect of tubes, we propose a new method in which flattening is considered as a deflection problem of a fixed curved beam. The proposed method was able to predict the change in the flattening rate as the curvature was increased. A rational prediction method is proposed for estimating the maximum bending moment of cylindrical tubes that accounts for the length effect. Its validity is demonstrated by comparing it predictions with numerical results obtained using the finite element method. [ABSTRACT FROM AUTHOR]

In this paper, a new type of honeycomb structure is proposed to enhance the energy absorption capacity for a honeycomb structure, and investigated its energy absorption efficiency (absorbed energy per unit volume) by finite element method (FEM). This model has small arc-shaped parts on the double cell wall, and can be manufactured by a similar way of standard honeycomb structures. Also, the proposed structure has large rigidity of plastic bending without increasing the mass. In this paper, effects of geometrical properties on the energy absorption characteristics are discussed. [ABSTRACT FROM AUTHOR]