Numerical analysis of aluminum alloy reticulated shells with gusset joints under fire conditions

In this study,a numerical analysis was conducted on aluminum alloy reticulated shells(AARSs)with gusset joints under fire conditions.First,a thermal-structural coupled analysis model of AARSs considering joint semirigidity was proposed and validated against room-temperature and fire tests.The proposed model can also be adopted to analyze the fire response of other reticulated structures with semi-rigid joints.Second,a parametric analysis was conducted based on the numerical model to explore the buckling behavior of K6 AARS with gusset joints under fire conditions.The results indicated that the span,height-to-span ratio,height of the supporting structure,and fire power influence the reduction factor of the buckling capacity of AARSs under fire conditions.In contrast,the reduction factor is independent of the number of element divisions,number of rings,span-to-thickness ratio,and support condition.Subsequently,practical design formulae for predicting the reduction factor of the buckling capacity of K6 AARSs were derived based on numerical analysis results and machine learning techniques to provide a rapid evaluation method.Finally,further numerical analyses were conducted to propose practical design suggestions,including the conditions of ignoring the ultimate bearing capacity analysis of K6 AARS and ignoring the radiative heat flux.

Transient Response in a Bi-material Cylinder of Soft Ferromagnetic Material Subjected to Magnetic Shock

The transient response in a bi-material cylinder of soft ferromagnetic material under magnetic shock is investigated in this study.The analytical solutions for displacement and stress have been derived using the finite Hankel transform and the Laplace transform.The numerical examples show that the displacement and stress fields respond dynamically in the bi-material cylinder under magnetic shock.The derived displacement at the center and radial stress on the surface of the cylinder satisfy the boundary conditions,showing the correctness of calculation.The displacement and stress waves propagate from the surface to the center of the cylinder when the magnetic field is loaded.The stress fields increase from the center to the surface of the cylinder and are much larger than the quasi-static state since the waves reflect,collide and concentrate in the body of the cylinder.The method of this paper can be used in the design of soft ferromagnetic structures.