Mechanical Properties of Al Foams Subjected to Compression by a Cone-Shaped Indenter.

Indentation tests and numerical simulations were conducted to investigate the effects of the indenter parameters (diameter and cone angle) and the relative density of Aluminum (Al) foams on the deformation mechanism of closed-cell Al foams, load response, and energy-absorbing capability. The results demonstrated that the densification occurred below the indenter, and cell tearing and bending occurred on both sides of the indenter, while the lateral plastic deformation insignificantly took place during the indentation tests. The load response and absorbed energy per unit volume dramatically increased with the cone angle of the indenter and the relative density of Al foams.

Experimental Investigation and Theoretical Modelling of a High-Pressure Pneumatic Catapult Considering Dynamic Leakage and Convection.

A high-pressure pneumatic catapult works under extreme boundaries such as high-pressure and rapid change of pressure and temperature, with the features of nonlinearity and gas-solid convection. In the thermodynamics processes, the pressure is much larger than the critical pressure, and the compressibility factor can deviate from the Zeno line significantly. Therefore, the pneumatic performance and thermo-physical properties need to be described with the real gas hypothesis instead of the ideal gas one.

Ion Doping Effects on the Lattice Distortion and Interlayer Mismatch of Aurivillius-Type Bismuth Titanate Compounds.

Taking Bismuth Titanate (Bi₄Ti₃O) as a Aurivillius-type compound with = 3 for example, the ion (W/Cr) doping effect on the lattice distortion and interlayer mismatch of Bi₄Ti₃O structure were investigated by stress analysis, based on an elastic model. Since oxygen-octahedron rotates in the ab-plane, and inclines away from the c-axis, a lattice model for describing the status change of oxygen-octahedron was built according to the substituting mechanism of W/Cr for Ti, which was used to investigate the variation of orthorhombic distortion degree () of Bi₄Ti₃O with the doping content. The analysis shows that the incorporation of W/Cr into Bi₄Ti₃O tends to relieve the distortion of pseudo-perovskite layer, which also helps it to become more stiff.

Predict human body indentation lying on a spring mattress using a neural network approach.

This article presents a method to predict and assess the interaction between a human body and a spring mattress. A three-layer artificial neural network model was developed to simulate and predict an indentation curve of human spine, characterized with the depth of lumbar lordosis and four inclination angles: cervicothoracic, thoracolumbar, lumbosacral and the back-hip (β). By comparing the spinal indentation curves described by the optimal evaluation parameters (depth of lumbar lordosis, cervicothoracic, thoracolumbar and lumbosacral), a better design of five-zone spring mattresses was obtained for individuals to have an effective support to the main part of the body.