A Review of Novel Architectures of Servovalves Driven by Piezoelectric Actuators

This paper is a thorough review of innovative architectures of electro-hydraulic servovalves that exploit actuation systems based on piezo-electric materials. The use of commercially available piezo-electric actuators, namely, piezo stacks, amplified piezo stacks, rectangular benders, and ring benders, is very promising for the actuation of the main stages and of the pilot stages of servovalves given the fast response and low weight of piezoelectric materials. The use of these actuators can also allow novel designs to be developed, thus helping manufacturers to overcome the typical drawbacks of commercial servovalves, such as the high complexity and the high internal leakage of the pilot stages of two-stage servovalves as well as the large size and weight of direct-drive servovalves. First, the piezoelectric actuators that can be used for driving servovalves are presented in the paper, and their characteristics are thoroughly discussed. The main novel architectures present in the literature are then explained and compared with the commercial ones, and their performance parameters are discussed to draw conclusions on the prospect that some of these architectures can be used by manufacturers as future designs.

A Review of Novel Architectures of Servovalves Driven by Piezo-Electric Actuators

This paper is a thorough review of innovative architectures of electro-hydraulic servovalves that exploit actuation systems based on piezo-electric materials. The use of commercially available piezo-electric actuators, namely, piezo-stacks, amplified piezo-stacks, rectangular benders and ring benders, is very promising for the actuation of the main stages and of the pilot stages of servovalves, given the fast response and low weight of piezoelectric materials. The use of these actuators can also allow novel designs to be developed, thus helping manufacturers to overcome the typical drawbacks of commercial servovalves, such as the high complexity and the high internal leakage of the pilot stages of two stage servovalves, as well as the large size and weight of direct drive servovalves. Firstly, the piezoelectric actuators that can be used for driving servovalves are presented in the paper and their characteristics are thoroughly discussed. Then, the main novel architectures present in the literature are explained and compared with the commercial ones, and their performance parameters are discussed to draw conclusions on the prospect that some of these architectures can be used by manufacturers as future designs.

A tough, anti-freezing and conductive nanocomposite interpenetrating organohydrogel mediated by hydrogen bonding

Conductive hydrogels have received extensive attention in the field of stretchable electric materials due to their good flexibility and conductivity. However, inferior strength and poor freezing tolerance of the hydrogels...

The Effect of Mn and Ca Addition on the Microstructure and Mechanical Properties of the Al–Cu–Fe–Si–Zn Based Alloys

High conductivity Al alloys are widely used for electric materials, heat exchangers, and heat dissipation parts such as electric conductors, transmission lines, communication cables, automobile wires and so on. In this study, the effects of Ca and Mn addition on the microstructure and mechanical properties of Al–0.3Cu–0.2Fe–0.15Si–0.15Zn alloys were investigated. The melt was held at 800 °C for 20 minutes and poured into a mold. The cast Al alloy was hot extruded with a rod having a diameter of 12 mm and a reduction ratio of 38:1. Al–0.3Cu–0.2Fe–0.15Si–0.15Zn–0.9Mn–0.4Ca alloy consists of Al, Al–(Fe, Mn)–Si, Al–(Fe, Mn) and Al–(Ca) intermetallic compounds. The formation of the intermetallic compound and this phase was broken in to small particles during extrusion. As the Ca content increased from 0 to 0.4 wt.%, the electrical conductivity of the extruded Al–0.3Cu– 0.2Fe–0.15Si–0.15Zn alloys increased by 57.3, 57.9 and 59.0 %IACS (International annealed copper standard). Al–0.3Cu–0.2Fe–0.15Si–0.15Zn–0.9Mn alloy with element additions of Ca, ultimate tensile strength was decreased from 178.3 to 163.2 and 151.8 MPa. However, the elongation was improved to 18.6, 21.6 and 23.15%.

Modeling stationary moving medium by static magneto-electric material

The electromagnetic equivalence of a stationary moving medium to magneto-electric materials is studied. The equivalent material characteristics of the medium at rest is obtained in terms of the diffusion tensor coefficient of the governing partial differential equation. Special attention is paid to the transition condition of field quantities on the boundary of the moving medium; it is found that the nonmoving magneto-electric equivalent model must be supplied with surface sources. The method is demonstrated through examples and verified by finite element simulation.