Maximum Instantaneous Force Research Articles

Enhancing output performances and output retention rates of triboelectric nanogenerators via a design of composite inner-layers with coupling effect and self-assembled outer-layers with superhydrophobicity

Abstract Low output performances and output retention rates in high humid environments represent serious challenges that have interrupted the large-scale application of triboelectric nanogenerators (TENGs) as portable power supplies and self-powered sensors. Existing approaches of tribo-material optimization and device structure design remain limited in solving the problems of low electrical outputs and output retention rates for TENGs. Here, achieving high electrical outputs and output retention rate in a TENG based on a multi-effect inner-layer and a superhydrophobic outer-layer is first proposed by an organic-inorganic composite and simple self-assembly electrospinning. The inner-layer consisting of polyimide (PI) and 0.85Na0.5Bi0.5TiO3-0.15SrTiO3 (NBT-15ST) ceramic particles (CPs) can distinctly enhance the electrical performances of the device by coupling charge storage effect and hysteretic dielectric polarization. Under a maximum instantaneous force of 50 N, the device delivers a voltage of 1020 V and a current density of 32.5 μA cm−2. Meanwhile, the superhydrophobic outer-layer with novel biomimetic multilevel structures endowing the device with a superior output retention rate of 50% at a high relative humidity of 80%. This work provides a new strategy to optimize the electrical outputs of the TENG and extends its application in humid conditions.

The pressure distribution beneath a solitary wave reflecting on a vertical wall

Abstract In this paper we conducted laboratory experiment to study the spatial and temporal variation due to solitary wave collides with a vertical wall which is placed at right angle to the direction of propagation of the wave. Under various dimensionless amplitude ratios (H/h, initial wave amplitude over constant water depth), the bottom dynamic pressure, the maximum instantaneous force and the pressure on the vertical wall due to solitary wave reflecting from a vertical wall are analysed. It is interesting to note that at higher normalized amplitude (H/h>0.4), the dynamic wave pressure at the bottom and the force distribution on a vertical wall appear asymmetry double peaks, which is first shown by our experiment. From the statistical analysis, we can obtain an asymptotic formulation for the maximum instantaneous force which is proportional to the normalized amplitude ratio (H/h). Furthermore, these experimental result is used to compare with the available numerical model and theoretical solution and show a quantitative agreement.

Shift Force Loading Rules Research for Automated Mechanical Transmission

To improve the system reliability and reduce the shift shock of Automated Mechanical Transmission, shift force loading rules is researched on the basis of strength and stiffness analyzing of shift fork. The shift mechanism of A-5- speed manual transmission is used as an example to illustrate the simulation, co-relation and validation of the shift fork strength and stiffness. The three-dimensional model of the shift fork is built and the finite element analysis model based on ABAQUS is established. And then, the influence of strength and stiffness of shift fork on the shift force loading rules can be analyzed. The fork tends to deflect with the synchronizer sleeve during synchronization thus acting as a damper and storing energy, the maximum instantaneous force output by driving device under the strength requirement of shift fork is determined. The shift control strategy is corrected according to the stiffness analysis of shift fork. The results shown that, in order to meet the strength requirement of shift fork, the maximum instantaneous force for the 4 gear fork is 1185.5N. In the same time, the maximum deformation on fork legs is 0.617 mm. The research provides a sufficient theoretical basis for formulating the shift control strategy.

Fabrication and characterization of arbitrary shaped μIPMC transducers for accurately controlled biomedical applications

This paper presents a novel micromachined method for fabricating microfeature sized ion polymer–metal composite (IPMC) devices with arbitrary shapes and demonstrates the technique to develop tiny accurately controlled surgical devices [G.-H. Feng, R.-H Chen, Universal concept for fabricating arbitrary shaped μIPMC transducers and its application on developing accurately controlled surgical devices, in: IEEE MEMS Conference, Kobe, Japan, 2007, pp. 4–7]. This technology is beyond current state-of-the-art approaches in manufacturing large-scale IPMC devices, and provides a universal solution to construct microsize-featured IPMC transducers with fine contours and no short-circuits. Also, the stiffness of the devices for different process parameters of fabrication is characterized by using a microtensile tester. To demonstrate the usefulness of the method, hand-shaped grips (Fig. 2) for laparoscopic operation are designed, fabricated and tested. The fabricated device with the dimensions of 6 mm × 6 mm × 80 μm shows that it could reach a displacement of 300 μm at the location 1 mm away from the anchor when a 0.5 Hz square wave of 12 V is applied, and a maximum instantaneous force of 5 mN output when it is driven with a 0.5 Hz square wave of 12 V.