THERMOSTIMULATED CREEP FOR THE STUDY OF MECHANICAL ENERGY LOSSES IN POLYMERS

1981 ◽  
Vol 42 (C5) ◽  
pp. C5-563-C5-568
Author(s):  
P. Demont ◽  
D. Chatain ◽  
T. Elsayed ◽  
C. Lacabanne ◽  
D. Ronarc'h ◽  
...  
Keyword(s):  
Mechanical Energy ◽  
Energy Losses

Investigation of Thermal Effects in Direct Driven Hydraulic System for Off-Road Machinery

2016 ◽  
Author(s):  
Niko Karlén ◽  
Tatiana Minav ◽  
Matti Pietola
Keyword(s):  
Energy Efficiency ◽  
Hydraulic System ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Hydraulic Model ◽  
Energy Losses ◽  
Total Efficiency ◽  
Ambient Temperatures ◽  
Wheel Loaders ◽  
Save Energy

Several types of off-road machinery, such as industrial trucks, forklifts, excavators, mobile cranes, and wheel loaders, are set to be operated in environments which can differ considerably from each other. This sets certain limits for both the drive transmissions and working hydraulics of these machines. The ambient temperature must be taken into account when selecting the hydraulic fluid since the viscosity and density of the fluid are changing at different operating temperatures. In addition to the temperature, energy efficiency can also be a problem in off-road machinery. In most off-road machines, diesel engines are employed to produce mechanical energy. However, there are energy losses during the working process, which causes inefficiency in produced energy. For better energy efficiency, hybridization in off-road machinery is an effective method to decrease fuel consumption and increase energy savings. One of the possible methods to save energy with hybrids is energy regeneration. However, it means that the basic hydraulic system inside off-road machinery needs to be modified. One solution for this is to utilize zonal or decentralized approach by means of direct driven hydraulic (DDH) system. This paper aims to investigate a DDH system for off-road machinery by means of modelling and analyzing the effect of the temperature. In the direct-driven hydraulic system, the actuator is controlled directly by the hydraulic pump which is operated by the electric motor. Specifically, it is a valveless closed-loop hydraulic system. Thus, there will be no energy losses caused by the valves, and the total efficiency is assumed to be significantly higher. In order to examine the DDH system, a thermo-hydraulic model was created. Additionally, a thermal camera was utilized in order to illustrate the temperature changes in the components of the DDH system. To reproduce the action of the system in different circumstances DDH system was run at different ambient temperatures, and the component temperatures in the system were measured and saved for the analysis. The thermo hydraulic model was proven capable to follow the general trend of heating up.

A universal approach for mean mechanical energy losses analysis

2006 ◽  
Vol 61 (6) ◽  
pp. 2085-2088 ◽  
Author(s):  
Chengwen Liu ◽  
Lianze Wang ◽  
Qiusheng Liu
Keyword(s):  
Mechanical Energy ◽  
Energy Losses ◽  
Universal Approach

scholarly journals Effect of the working liquid compressibility on the picture of volumetric and mechanical losses in a high pressure displacement pump used in a hydrostatic drive part ii mechanical losses in a pump

2012 ◽  
Vol 19 (3) ◽  
pp. 36-44 ◽  
Author(s):  
Zygmunt Paszota
Keyword(s):  
Mathematical Model ◽  
High Pressure ◽  
Mechanical Energy ◽  
Drive System ◽  
Energy Losses ◽  
Liquid Compressibility ◽  
Displacement Pump ◽  
The Mathematical Model ◽  
Working Liquid

ABSTRACT Working liquid compressibility may considerably change the values and proportions of coefficients of the volumetric and mechanical energy losses in the displacement pump used in a hydrostatic drive system. This effect can be particularly seen in the operation under high pressure and also in the system, where aeration of the working liquid can occur. In the Part II the mathematical model is presented of the torque of mechanical losses in the pump and its laboratory verification. Conclusions are drawn regarding the effect of working liquid compressibility on the mechanical and volumetric losses in the pump.

scholarly journals Mechanical losses in glassy silicon dioxide: results of atomistic simulation

2017 ◽  
pp. 381-386
Author(s):  
Ф.В. Григорьев ◽  
В.Б. Сулимов ◽  
А.В. Тихонравов
Keyword(s):  
Molecular Dynamics ◽  
Fourier Transform ◽  
Silicon Dioxide ◽  
Quality Factor ◽  
Atomistic Simulation ◽  
Mechanical Energy ◽  
Dynamics Simulation ◽  
Energy Losses ◽  
Reverse Time ◽  
Solid Materials

Предложены методы расчета потерь механической энергии в твердых материалах на основе моделирования методом молекулярной динамики внешнего воздействия и последующей релаксации системы. Рассчитывается обратная добротность и фурье-образ обратной добротности на частоте, равной обратному времени релаксации системы. Для обратной добротности получена оценка сверху, равная $10^{-4}$, что находится в интервале экспериментальных значений; для фурье-образа обратной добротности получена оценка сверху, равная $10^{-2}$. Two methods to estimate the mechanical energy losses in solid materials are proposed. These methods are based on the molecular dynamics simulation of external actions on the body's structure, followed by its relaxation. The inverse quality factor and its Fourier transform are estimated on the frequency equal to the reverse time of relaxation. The inverse quality factor is estimated from above by $10^{-4}$, which corresponds to experimental data.The Fourier transform is estimated from above by $10^{-2}$.

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