Study on a Chiral Structure with Tunable Poisson’s Ratio

A chiral structure with a negative Poisson’s ratio containing a hollow circle with varying diameters was designed, and the finite element method was used to investigate the variation in the Poisson’s ratio when the hollow circle diameter was varied (d = 0, 1, 2, 3, and 4 mm). The simulation results showed that the Poisson’s ratio was sensitive to the hollow circle diameter, and the minimum Poisson’s ratio was −0.43. Three specimens with different hollow circle diameters (d′ = 0, 1, and 3 mm) were 3D-printed from thermoplastic polyurethane, and the Poisson’s ratio and equivalent elastic modulus were measured. In the elastic range, the Poisson’s ratio increased and the equivalent elastic modulus decreased as the hollow circle diameter increased. The simulation and experimental results showed good agreement. The proposed structure is expected to be applicable to protective sports gear owing to its high energy absorption and the fact that its properties can be modified as required by adjusting the geometric parameters of the unit cell.

Numerical investigation of conveyor wing shape type effect on ocean waste collection behavior

In this paper, an attempt has been made to assess how effective waste-collecting uses the conveyor wing. This wing-equipped conveyor will later be installed in front of the ship. In this work, a simulation model is a conveyor and wing without the ship. A numerical investigation based on Reynolds Averaged Navier Stokes (RANS) for predicting the flow pattern characteristics, velocity contour, and resistance. The focus of the present study is the impact of wing shape on waste collection in calm water through the application of numerical methods. The three variations of wing shape used are solid wing shape, square hollow wing shape, and circle hollow wing shape. It is done using speed variations of 1 to 12 knots. From the analysis of velocity contour, circle hollow wing is faster in collecting waste, then followed by hollow square wing and solid wing. From the flow pattern analysis, the circle hollow wing model is easier to make ocean waste come closer to the winged conveyor than the square wing and solid wing model. It is known that winged conveyors can only be used to collect ocean waste at low speeds. Then based on resistance comparison, it is also known that the resistance of winged conveyors from the largest to the smallest is the solid wing, hollow circle wing, and hollow square wing, respectively.

Spatial Analysis on Livable City Public Transportation Satisfaction in Beijing

Based on a questionnaire survey responded by nearly 11000 people in Beijing, from a perspective of livable city, the general characteristics and the spatial autocorrelation of the public transportation satisfaction were analyzed. The overall evaluation of public transportation satisfaction in Beijing is 67.31, indicating that more great efforts should be paid to improve the public transportation satisfaction level in construction of the livable Beijing. The spatial structure of Livable City Public Transportation Satisfaction shows a “hot banding” distribution pattern, accompanying with 3 “cool spots”. To get a better understanding of the spatial pattern of the public transportation satisfaction, we used the Moran’s I and LISA to measure the spatial autocorrelation. The results illustrate that the public evaluation on the public transportation is spatial dependent and has tendency toward clustering. The cluster of areas with High-High association is located in the south of Beijing near Chang’an Avenue, highlighting and reshaping like a hollow circle, while the cluster of areas with Low-Low association is located in northwest Beijing and outside of the 4th ring road. Overall, the LCPTS in the north of Beijing lags obviously behind the overall level. The phenomenon is mainly due to the long-term accumulation of urban development.

The Compare and Analysis to the Hollow or Solid Circle Cross Section Shafts Being Twisted

From the angle of saving material, the author make the related computing, as well as compare and analysis to the biggest torsion shearing stress of the hollow or solid circle cross section shaft. Simultaneously it is elaborated, when the most torsion shearing stress of the hollow circular cross-section axis is smaller than the solid circular cross-section axis, the rule of economizing material and the change of the appearance size. Elaborate further, the related reasonable sizes are given, in order to have the prior adoptions during the design or transform. For example, the ratio of the hollow circle cross section shaft external diameter and inner diameter is two in the engineering, and the economical material is in 15%-inside 25% ranges.

Study on Lateral Stiffness for Flexicoil Circle Springs with Rubber Pads

In order to accurately obtain lateral stiffness of flexicoil circle spring with rubber pads, based on shear shape coefficient of solid and hollow thin-wall circle section, the shear shape coefficient of hollow circle section with different ratios between inner and outer diameter was obtained by difference method. By means of curve’s differential equations of elastic straight bar with uniform section, relations between forces and displacements as well as moments and rotation angles on end surfaces of spring and rubber pads was set up. According to the principle that force and moment under the connection surface between spring and rubber pad are the same and their signs are opposite, lateral stiffness of flexicoil circle spring with rubber pads was obtained. Calculation results show that in order to obtain accurate solution, correction factor of stiffness matrix must be considered when only lateral stiffness of spring is calculated, but the correction factor can not be considered when lateral stiffness of spring with rubber pads is calculated.