Analyzing the rotational motion of a rectangular board via smartphone sensors: a conservation-of-mechanical-energy approach

2021 ◽  
Vol 56 (2) ◽  
pp. 023005
Author(s):  
Chokchai Puttharugsa ◽  
Samuk Pimanpang
Keyword(s):  
Rotational Motion ◽  
Mechanical Energy ◽  
Energy Approach ◽  
Smartphone Sensors

scholarly journals A high efficiency pneumatic drive system using vane-type semi-rotary actuators

2021 ◽  
Vol 34 (3) ◽  
pp. 415-433
Author(s):  
Alfred Rufer
Keyword(s):  
Rotational Motion ◽  
High Efficiency ◽  
Mechanical Energy ◽  
Compressed Air ◽  
Energetic Efficiency ◽  
Pneumatic Drive ◽  
Mechanical Motion ◽  
Set Up ◽  
Energetic Performance ◽  
New System

A compressed air driven generator is proposed, where the pneumatic energy is converted into mechanical energy using two vane-type rotational actuators. The use of a second actuator with a higher displacement in order to produce a thermodynamic expansion allows to reach a better energetic efficiency in comparison to the classical operation of such actuators. The alternating movement of the angular actuators is transformed into a unidirectional rotational motion with the help of a mechanical motion rectifier. The paper analyses the enhancement of the energetic performance of the system. An experimental set-up is also described. The performance of the new system is described, and the limits of its realization is commented on the base of experimental recordings of the evolution of the pressure in the chambers.

scholarly journals The Gantry as a Drive for a Horizontal Bike: Initial Investigation of Rotary Work

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Łukasz Bereś ◽  
Paweł Pyrzanowski
Keyword(s):  
Mathematical Analysis ◽  
Rotational Motion ◽  
Mechanical Energy ◽  
Gear Wheel ◽  
Static Tests ◽  
Initial Investigation ◽  
Full Rotation ◽  
Drive Systems ◽  
To Receive

The gantry drive (also, “the gantry”) is a mechanism that receives human-generated mechanical energy. The gantry used in a horizontal bike is a type of drive, and it is an alternative to a typical crankset. The purpose of this paper was to compare rotary work generated by the gantry and the crankset. The comparative criterion for the gantry and the crankset was work in rotational motion. The comparison was based on static tests; forces put into both drive systems were measured, and the rotary work was mathematically calculated. The forces put into the drive systems were measured for a man 177 cm tall and of 76 kg mass. To facilitate analysis and tests, the first gear wheel to receive force from the toothed rack (the gantry drive) was assumed to have the same radius as the crank (the crankset drive). Mathematical analysis performed for one full rotation (360°) of the first gear wheel and crankset showed that rotary work for the gantry was 2117.31 J and for the crankset 804.81 J. Ultimately, it was shown that the gantry can better receive mechanical energy from the human than the crankset. This means that a human will be less tired when riding a horizontal bike equipped with the gantry compared to a horizontal bike equipped with the crankset; assuming that in both cases, the bike speed is the same. Additionally, thanks to the use of the gantry drive in a horizontal bike, it is possible to achieve higher speeds compared to a horizontal bike equipped with the crankset.

Fluid Particles Straightly Forward and Circularly Forward Movements in the Direction of Tangent at Trailing Edge of Impeller Outlet in Centrifugal Turbomachinery

2003 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Centrifugal Force ◽  
Flow Rate ◽  
Rotational Motion ◽  
Mechanical Energy ◽  
Centripetal Force ◽  
Impeller Outlet ◽  
Water Turbine ◽  
Fluid Particles ◽  
Centripetal Forces ◽  
Acting Force

Flow rate, which is caused in the direction radial outward in pump and radial inward in water turbine, is caused by the fluid particles straightly forward tangential movement in the direction of acting force perpendicular to impeller blades rotational radius. Impeller blades rotational motion is caused under the radial balance of centrifugal and centripetal forces. Centrifugal force is caused by the transferred energy from mechanical to hydraulic energy in pump and from hydraulic to mechanical energy in water turbine. Centripetal force is equivalent to discharge head in pump and equivalent to suction head in water turbine.

scholarly journals Quantifying the physical intensity of construction workers, a mechanical energy approach

2018 ◽  
Vol 38 ◽  
pp. 404-419 ◽  
Author(s):  
Liulin Kong ◽  
Heng Li ◽  
Yantao Yu ◽  
Hanbin Luo ◽  
Martin Skitmore ◽  
...  
Keyword(s):  
Mechanical Energy ◽  
Energy Approach ◽  
Construction Workers

A Simple Energy Approach to Assess Vibration and Fretting-Wear Damage in Process Equipment

2007 ◽  
Author(s):  
Michel J. Pettigrew ◽  
Metin Yetisir ◽  
Nigel J. Fisher ◽  
Colette E. Taylor ◽  
Bruce A. W. Smith
Keyword(s):  
Heat Exchanger ◽  
Mechanical Energy ◽  
Work Rate ◽  
Energy Approach ◽  
Fretting Wear ◽  
Process Equipment ◽  
Nuclear Fuels ◽  
Heat Exchanger Tube ◽  
Wear Damage ◽  
Exchanger Tube

Excessive flow-induced vibration causing fretting-wear damage can seriously affect the performance of process equipment such as heat exchangers, condensers, nuclear steam generators, nuclear fuels, reactor internals, and piping systems. Fretting-wear damage generally takes place between a vibrating structure and its supports. It can be predicted with a fretting-wear coefficient obtained experimentally and a parameter called work-rate that formulates the dynamic interaction between structure and support. The work-rate is essentially the rate of mechanical energy dissipated at the support. On the other hand, the total available mechanical vibration energy in a structure is related to its mass, vibration frequency, mode shape, damping, and vibration amplitude. This leads to the development of a simplified formulation based on energy considerations to relate the vibration response of a structure to fretting-wear damage at its supports. The basic energy equations and the formulation of a simplified energy relationship to predict fretting-wear damage are outlined in this paper. The relationship is verified against experimental data for a multi-span heat exchanger tube. The energy approach is also compared to time domain calculations performed with a non-linear finite element code. The results indicate that the simple energy approach may be very useful to estimate fretting-wear damage in practical situations. Finally, the application of the method is illustrated for a typical heat exchanger tube and for nuclear fuels.

Reduction of structural vibrations with the piezoelectric stacks ring

2020 ◽  
Vol 64 (1-4) ◽  
pp. 729-736
Author(s):  
Jincheng He ◽  
Xing Tan ◽  
Wang Tao ◽  
Xinhai Wu ◽  
Huan He ◽  
...  
Keyword(s):  
Vibration Control ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Structural Vibrations ◽  
Rotor Systems ◽  
Fea Model ◽  
Piezoelectric Stacks ◽  
Shunt Damping ◽  
Reduction Effect ◽  
Euler Bernoulli Beam

It is known that piezoelectric material shunted with external circuits can convert mechanical energy to electrical energy, which is so called piezoelectric shunt damping technology. In this paper, a piezoelectric stacks ring (PSR) is designed for vibration control of beams and rotor systems. A relative simple electromechanical model of an Euler Bernoulli beam supported by two piezoelectric stacks shunted with resonant RL circuits is established. The equation of motion of such simplified system has been derived using Hamilton’s principle. A more realistic FEA model is developed. The numerical analysis is carried out using COMSOL® and the simulation results show a significant reduction of vibration amplitude at the specific natural frequencies. Using finite element method, the influence of circuit parameters on lateral vibration control is discussed. A preliminary experiment of a prototype PSR verifies the PSR’s vibration reduction effect.

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