The Effect of Section Optimization on the Double Nonlinear Global Stability of Latticed Shell

In order to grasp how the sectional sizing optimum design imposes effect on the global stability of latticed shell, with an example of K6 single-layer reticulated shell whose span is 60 meters and vector height is 6 meters, the impact of different ways in rods grouping and valuing sectional size on bars buckling discipline and mechanical performance was analyzed. Factors like the strength and slenderness ratio of members, local and overall stability of structure are entirely taken into account to guarantee the accuracy of the analysis results. The results show that optimum design of sectional sizing on single-layer latticed shell can reduce the steel consumption, change the buckling discipline and improve the ultimate stable bearing capacity of structure, but simultaneously it would bring about a smaller deformation, and no significant early warning of damage comes up when structural instability failure occurs.

Porous convection with local thermal non-equilibrium temperatures and with Cattaneo effects in the solid

There is increasing interest in convection in local thermal non-equilibrium (LTNE) porous media. This is where the solid skeleton and the fluid may have different temperatures. There is also increasing interest in thermal wave motion, especially at the microscale and nanoscale, and particularly in solids. Much of this work has been based on the famous model proposed by Carlo Cattaneo in 1948. In this paper, we develop a model for thermal convection in a fluid-saturated Darcy porous medium allowing the solid and fluid parts to be at different temperatures. However, we base our thermodynamics for the fluid on Fourier's law of heat conduction, whereas we allow the solid skeleton to transfer heat by means of the Cattaneo heat flux theory. This leads to a novel system of partial differential equations involving Darcy's law, a parabolic fluid temperature equation and effectively a hyperbolic solid skeleton temperature equation. This system leads to novel physics, and oscillatory convection is found, whereas for the standard LTNE Darcy model, this does not exist. We are also able to derive a rigorous nonlinear global stability theory, unlike work in thermal convection in other second sound systems in porous media.