Analysis of Thermo-Magneto-Elastic Nonlinear Dynamic Response of Shallow Conical Shells

The dynamic response study on thermo-magneto-elastic behavior of shallow conical shell in a time-dependent magnetic field is investigated, and the dynamic responses of displacement of shallow conical shell under mechanical loads, electromagnetic fields and temperature field coupling are analyzed. Based on Maxwell’s equations, heat conduction equation and nonlinear equations of classical plates and shells, the nonlinear dynamic response governing equations are derived. The electromagnetic field and temperature field equations are solved using variable separating technique, the nonlinear elastic field equations are solved by Galerkin method. The variation of temperature, magnetic field intensity and displacement with time under the coupling effect of the applied magnetic field and the surface uniform load were obtained. The influence of frequency of the applied magnetic field on the displacement wave forms is discussed.

Energy Absorption Characteristics of a Novel Asymmetric and Rotatable Re-entrant Honeycomb Structure

Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure were produced by the 3D printing technology.Through experimental test and finite element simulation,the deformation mechanism and energy absorption characteristics of the AR-RH structure and the S-RH structure with negative Poisson’s ratios at different impact velocities were compared.The experimental test and finite element simulation results show that the novel AR-RH structure with negative Poisson’s ratios has stronger energy absorption capacity than the S-RH structure,and it has been verified that the rotatability of AR-RH can indeed absorb energy.Furthermore,the degree of asymmetry of the AR-RH structure was discussed.

Buckle Propagation in Steel Pipes of Ultra-high Strength:Experiments,Theories and Numerical Simulations

In this paper,experimental,theoretical and numerical approaches were employed to scrutinize the buckle propagation events occurring in pipes subjected to external pressure.Two groups of samples with different radius-to-thickness ratios were fabricated using steel pipes of ultra-high strength and were subjected to compression of external pressure in a sealed pressure vessel specially designed and customized for the experiment.Experimental results were recorded through a data acquisition system.For facilitating the theoretical calculations,uniaxial tensile tests were performed on tensile pieces cut from the same pipes to obtain the material properties.It was found from the experimental results that once a buckle is initiated in a pipe,the external pressure dropped to a specific value called buckle propagation pressure and kept at this level until the whole pipe is flattened into a dog-bone shape.Based on the measured material properties and geometric parameters,theoretical solutions were computed using established ring models and shell model,and finite element predictions were also obtained from ABAQUS software.The efficiency and accuracy of the shell model and finite element model were expounded by comparing various theoretical solutions and numerical predictions with the experimental results.With the authenticated shell model and finite element model,a deep insight into the phenomenon of buckle propagation of pressurized long pipes was provided by performing a series of parametric study.