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The multi-axis manned centrifuge is an important device for training pilots' directional cognitive ability and overcoming illusions. Its intensity check is a necessary part of structural design. The traditional quasi-static static analysis method can only directly analyze the structural strength problem of no more than two-axis nested rotation, but the multi-axis manned centrifuge has three or more than three-axis nested rotation. The flexible multi-body dynamics method can be used to analyze and determine the strength of the multi-axis rotating structure of the motion path, but the calculation time is long and the resource consumption is large, so it is difficult to fully assess the intensity of the structure. In this paper, a multi-axis centrifuge intensity check method based on multi-body dynamics combined with random sampling and finite element calculation is proposed. The calculation results can be obtained in a relatively short period of time, it is highly efficient and feasible, which is conducive to improve the accuracy of structural intensity verification of multi-axis nested rotating equipment, and provides important support for its structural design.

As a type of typical cellular foams,the macro-mechanical performances of rubber foams are mainly determined by its micro-structure and cell material properties.In the work reported here,several two dimensional（ 2D） finite element（ FE）models having regularly and randomly arranged elliptical and circular cells were constructed.The effects of cell shapes,cell distributing,and porosities on the hyperelastic large compressive deformations of rubber foams were explored.Obtained FE analysis results show that the compressive stress-strain curves of rubber foams present three deforming regions.The compressive stress-strain curves of circular cell models have longer plateau stage than those of elliptical cell models,and circular cell models have more steady mechanical performances than elliptical cell models do.If worked as shockproof cushions,circular cell structures are thus better than elliptical cell structures.

The suppression of soot generated from acetylene nonpremixed combustion was investigated by following the numerical simulation method. The combustion and soot formation were predicted by the eddy-dissipation and Moss–Brookes models, respectively. The rate of soot formation was decreased by applying acoustic oscillation. The influences of oscillating velocity, frequency, flow rate of acetylene, and Reynolds number on the rate of soot formation were studied. Results showed that the maximum efficiency of soot suppression exceeded 90%. An increase in Reynolds number resulted in enhanced soot suppression efficiency. It is considered that the boundary layer of the soot particles was reduced when the Reynolds number increased. This could potentially result in the enhancement of mass transfer, thus causing the reoxidation of the soot in the oxidation zone. Reoxidation of soot resulted in reduced soot generation. The flame temperature increased simultaneously. [ABSTRACT FROM AUTHOR]

Microencapsulated phase change materials (microPCMs) using urea-formaldehyde as the shell material and tetradecane as the phase change material were successfully prepared via in situ polymerization reaction in an oil-in-water emulsion. Four groups of emulsifiers containing ionic or nonionic kinds were investigated through the performance of the as-prepared microPCMs including micro-topography, thermal energy storage, and thermal stability. The emulsifying capacity and the underlying mechanism of the emulsifiers were also evaluated and discussed. Experimental results showed that the combined emulsifier group of Triton X-100/sodium dodecyl benzene sulfonate as the emulsifier provided the optimal emulsification for the preparation of microPCMs. The as-prepared microPCMs were then combined with expanded polyurethane in two manners to fabric thermal insulation composites with the phase change energy storage (PES) function. The thermal insulation and PES properties of the functional composites were evaluated using a thermal imager and wireless thermocouple. Both the composites revealed a distinct temperature transition region in their temperature–time curves, which demonstrated that the PES functional composites had been successfully fabricated. The research results may provide reliable data support for practical applications of microPCMs in the PES functional composite field. [ABSTRACT FROM AUTHOR]

In soft lithography roof collapse is frequently observed on the stamp surface consisting of rectangular micro-grooves which yields unwanted contact between the sagged surface and the substrate. Deep understanding of the adhesive contact behavior is a key to design of high-performance collapse-resistant stamp. Both theoretical and numerical studies are presented for a single rectangular micro-groove in the middle of the stamp surface under applied pressure. The JKR-type adhesion solution is established by the principle of superposition and equivalent energy release rate, with a series of closed-form expressions derived which are consistent with previous studies. Finite element analysis (FEA) is performed based on virtual crack closure technique (VCCT) to investigate the roof collapse mechanism with interfacial adhesion and applied pressure considered. Comparison of theoretical, numerical, and experimental results demonstrates that both size effect and constitutive nonlinearity of the stamp on the self-collapse contact width are not obvious for shallow grooves but become prominent for deep grooves, so that the obtained analytical solution is limited to shallow grooves due to its assumptions of half-plane and linear elasticity adopted for the stamp. For deep grooves, the present FEA method shows potential to capture more accurate results. [ABSTRACT FROM AUTHOR]

The effect of the energy of forced acoustics on the soot suppression from an acetylene-air diffusion flame is experimentally investigated. The acoustic energy is calculated by integrating the acoustic power in the positive period. Results show that the suppression efficiency of soot increases linearly with the increase of acoustic energy. In addition, the acoustic energy is similar under different acoustic waveforms when achieving the same soot suppression effect. The acoustic waves cause the flame to periodically stretch and compress, and the flame brush shows the range of fluctuations in the flame front. When the fluctuation velocity is greater than 2 m/s, the suppression efficiency reaches 50%. However, as the premixed level increases, the flame height decreases, resulting in a decrease of fluctuation velocity. [ABSTRACT FROM AUTHOR]