One of the abundant energy sources around us to be harvested is a human body movement, which entirely depends on joint movements with exclusive characteristics of limited displacement with a high ...degree of directional freedom. In this study, we firstly propose a novel type of the direction-switchable triboelectric nanogenerator, called a STRING, which incorporates an appropriate power transmission unit and the rotational triboelectric nanogenerator. A flexible string plays the critical role in universally transferring power regardless of direction and displacement of the applied force. It is shown that the impulse as well as the speed of the human body movement are the key parameters determining the output performance of the STRING. The lightweight STRING (total weight less than 160 g) is applied to more than 5 joints and the ability to easily generate output current more than 10 μA from natural body movements is shown. The generated electricity is directly utilized to continuously generate the DC 5 V in real time, which is favorable for practical operation of electronic devices. Furthermore, simple adoption of voltage doubling circuit significantly boosts the open circuit voltage (more than 2 kV). The present STRING with universal biomechanical energy harvesting would not only power electronic devices effectively, but also could be used in a wide range of applications by enabling portability and self-powered operation.
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•Universal biomechanical energy harvesting achieved by specially designed TENG.•Converting any kinds of human body movements into preferred form to operate TENG.•Minimizing the uncomfortableness as a wearable energy harvester by lightweighting.•Facile and real time generation of reliable DC voltage as well as high voltage micro-plasma.
In India, One of the most important problem is Infected Public Toilets especially Urinals that no one worried about the Flushing of Urinals. Hence, the infected urinals cause diseases to the users by ...spreading infectious germs, therefore complete cleaning of urinals is essential to maintain the hygienic conditions. In this paper, to tackle this problem by the development of Urinal flushing system with a less usage of water. This flushing system is made of mechanical elements. Automatic flushing system is one of the essential technologies in India as it is used for maintaining hygienic conditions especially in public urinals. This flushing system does not require an electric power as making it highly useful and reliable in public places like garden and public urinals. Also, this system conserves the water and the electricity. In this setup, Rocker Disc is connected with the mechanical linkages for the flexibility of valve operations.
•MPA is normally used with one end fixed to ground/base and the other end joined with other mechanical part(s).•The vibration characteristics of a MPA coupled with mechanical elements is simplified ...and mathematically modelled.•Simulations are conducted to study the impacts including vibration resonant frequency and phase shifts.
Multi-layer piezoelectric actuators (MPA) have been widely used as linear actuators for various applications including micro/nano-positioning. When MPA is employed to drive a positioning mechanism, the arrangement normally involves one of its ends being fixed to the ground/base and the other end being joined with other mechanical part(s) of the device to be driven. Based on the IEEE standards on piezoelectricity and the verified assumptions, the vibration characteristics of a MPA, which has one end fixed and the other end coupled with mechanical elements, namely the equivalent mass, spring and damper is mathematically modelled. The derived equations are coded in Matlab and various values of the coupled mass, spring and/or damper are implemented to investigate the resulted impacts including changes of the vibration magnitudes at off-resonance frequencies and the shifts of resonant frequencies and phases.
Normally, electrical and mechanical systems are designed and analysed in separate domains but, in this study, interactions between electric and mechanical elements are analysed looking for ...improvement in the performance of electromechanical drivetrains. The work considers a doubly fed induction generator, evaluated with a frequency analysis of the full electromechanical drivetrain developed and applied to identify how tuning gains and system parameters affect the electromechanical interactions. Analytical transfer functions are presented and validated by simulation and test results.
This paper presents a novel methodology of introducing virtual mechanical elements for motion control of transferred objects in modeling of a five-axle, three-steering coupled-vehicle system. The ...coupled-vehicle system consists of two car-like mobile robots, two carriers and one steering unit, and it is capable of forming straight-bed and V-bed carriers depending on shapes of objects. In the kinematical model of the coupled-vehicle system, two virtual car-like mobile robots, a virtual carrier and two virtual revolute joints are newly introduced, although these virtual mechanical elements are redundant on converting the kinematical equations of the coupled-vehicle system into time differential equations in a chained form. The objective of introducing these virtual mechanical elements is to set the position of one of the virtual revolute joints and the orientation of the virtual carrier to be state variables in the chained form. Through the state variables, it is possible to specify the motion of an object placed on the V-bed carrier whose manipulation point is put on the virtual joint as the movement of the manipulation point and the rotation of the virtual carrier linked with the V-bed carrier around the point. Especially, the virtual revolute joint can be located inside a supporting triangle whose vertices are the three real revolute joints between the first car-like mobile robot, the first carrier, the second carrier and the second car-like mobile robot so that stable transportation is achieved when the manipulation point of the object is its center of mass. The validity of the control method based on the model in which the virtual mechanical elements are introduced is experimentally verified in transportation of an object placed on the V-bed carrier by following an 8th-order Bezier curve path while avoiding collision with an obstacle.
Renewable energy research has been advocated to slow down climate change and maintain economic growth. Streamflow is valued as a source of energy, and an environmentally friendly, low-friction ...sealing system that employs biomimetic technologies is proposed for its utilization. To test this biomimetic seal, a dynamo-electric generator with waterproof ancillary systems is installed under water. This system uses lip seals over the rotating shaft which function to prevent the ingress of water. To improve the power generation efficiency with the constantly changing water flow, excellent frictional properties of the seal across varying rotational speeds is required. A sealing system was successfully developed using a hydrated material (polyvinyl formal; PVF), which mimics articular cartilage in a natural synovial joint. Polyethylene glycol (PEG) dissolved in distilled water, a non-Newtonian fluid, was used as a lubricant. These materials have low toxicity and low environmental impact should they become exposed to nature. It is shown that the biomimetic sealing system exhibits excellent frictional properties with extremely low ingress of water.
A representative volume element is developed based on the Voronoi tessellation to reveal the mechanism of shape instability behavior. In the model, a damage-coupled crystal plastic model is ...established to describe the shape instability behavior. The heterogeneity of materials is introduced into the model with the aim of simulating the microstructure of materials. The experimental and simulation results show that the fatigue damage in the elastic deformation stage with high cyclic stress level is the initial motivation of shape instability behavior. The cyclic softening and ratcheting properties of materials accelerate the plastic strain accumulated rate.
Shape instability life, a new standard to evaluate the capacity of materials working at high stress instead of the failure fracture life in the mechanical elements design, is defined as the cyclic ...number where the plastic strain in specimen reaches 0·2% in the fatigue process. The stress controlled experiments are performed to research the factors influencing shape instability life of steel 40Cr, including stress ratio, maximum stress, load rate, peak maintaining time and load sequence. According to the experimental results, the maximum stress and the stress ratio both show linear-logarithmic relations with the shape instability life. However, load rate and peak maintaining time have no obvious effect on shape instability life. Stress sequence tests indicated that the damage accumulation corresponds with the Miner rule in the shape instability stage. The research will be the foundation for fatigue strength design of disposable mechanical elements.
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