scholarly journals Tribofilm Formation of Simulated Gear Contact Along the Line of Action

2021 ◽  
Vol 69 (4) ◽  
Author(s):  
Reza Bayat ◽  
Arto Lehtovaara
Keyword(s):  
Growth Rate ◽  
Simulation Method ◽  
Sliding Contact ◽  
Test Method ◽  
Experimental Simulation ◽  
Threshold Pressure ◽  
Spacer Layer ◽  
Interferometry Method ◽  
Gear Contact ◽  
Ball On Disc

Abstract In this paper, an experimental simulation method was used for evaluating the tribofilm formation in rolling/sliding contact at different points in the line of action. A ball-on-disc test method was employed by which the pressure and slide to roll ratio of gear contact could be simulated. In order to reach a general conclusion, four different oils and two surface roughness were involved in the experiments. The tribofilm evolution was captured using spacer layer interferometry method, and the correlation of tribofilm with the location at the line of action was studied. Results showed that there is a threshold pressure for the tribofilm formation around which the tribofilm growth rate is maximum. Above this threshold pressure, the tribofilm formation is not stable, and the wear is dominant. Below this threshold pressure, the tribofilm growth rate rises by increasing the pressure and the gear contact is safely protected by a stable tribofilm. Graphic Abstract

Efficient Simulation of Gear Contacts Including Transient Elastohydrodynamic Effects

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Peter Fietkau ◽  
Bernd Bertsche
Keyword(s):  
Three Dimensional ◽  
Direct Determination ◽  
Simulation Method ◽  
Elastic Half Space ◽  
Operating Conditions ◽  
Multibody Simulation ◽  
Multibody Model ◽  
Gear Contact ◽  
Oil Films ◽  
Lubrication Conditions

This paper describes an efficient transient elastohydrodynamic simulation method for gear contacts. The model uses oil films and elastic deformations directly in the multibody simulation, and is based on the Reynolds equation including squeeze and wedge terms as well as an elastic half-space. Two transient solutions to this problem, an analytical and a numerical one, were developed. The analytical solution is accomplished using assumptions for the gap shape and the pressure in the middle of the gap. The numerical problem is solved using multilevel multi-integration algorithms. With this approach, tooth impacts during gear rattling as well as highly loaded power-transmitting gear contacts can be investigated and lubrication conditions like gap heights or type of friction may be determined. The method was implemented in the multibody simulation environment SIMPACK. Therefore it is easy to transfer the developed element to other models and use it for a multitude of different engineering problems. A detailed three-dimensional elastic multibody model of an experimental transmission is used to validate the developed method. Important values of the gear contact like normal and tangential forces, proportion of dry friction, and minimum gap heights are calculated and studied for different conditions. In addition, pressure distributions on tooth flanks as well as gap forms are determined based on the numerical solution method. Finally, the simulation approach is validated with measurements and shows good consistency. The simulation model is therefore capable of predicting transient gear contact under different operating conditions such as load vibrations or gear rattling. Simulations of complete transmissions are possible and therefore a direct determination of transmission vibration behavior and structure-borne noise as well as of forces and lubrication conditions can be done.

scholarly journals Molecular Dynamics Study on the Mechanism of Nanoscale Jet Instability Reaching Supercritical Conditions

2018 ◽  
Vol 8 (10) ◽  
pp. 1714 ◽  
Author(s):  
Qingfei Fu ◽  
Yunxiao Zhang ◽  
Chaojie Mo ◽  
Lijun Yang
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Theoretical Result ◽  
Molecular Model ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Jet Instability ◽  
Subcritical Region ◽  
Thermodynamic Conditions ◽  
Spatio Temporal

This paper investigates the characteristics of a nitrogen jet (the thermodynamic conditions ranging from subcritical to supercritical) ejected into a supercritical nitrogen environment using the molecular dynamics (MD) simulation method. The thermodynamic properties of nitrogen obtained by molecular dynamics show good agreement with the Soave-Redlich-Kwong (SRK) equation of state (EOS). The agreement provides validation for this nitrogen molecular model. The molecular dynamics simulation of homogeneous nitrogen spray is carried out in different thermodynamic conditions from subcritical to supercritical, and a spatio-temporal evolution of the nitrogen spray is obtained. The interface of the nitrogen spray is determined at the point where the concentration of ejected fluid component reaches 50%, since the supercritical jet has no obvious vapor-liquid interface. A stability analysis of the transcritical jets shows that the disturbance growth rate of the shear layer coincides very well with the classical theoretical result at subcritical region. In the supercritical region, however, the growth rate obtained by molecular dynamics deviates from the theoretical result.

Research on Gear Contact Fatigue Stress Test

2011 ◽  
Vol 86 ◽  
pp. 825-828
Author(s):  
Tie Wang ◽  
Hong Mei Li ◽  
Rui Liang Zhang ◽  
Zhi Fei Wu
Keyword(s):  
Damage Accumulation ◽  
Stress Test ◽  
Contact Fatigue ◽  
Test Method ◽  
Fatigue Stress ◽  
Accumulation Curve ◽  
Limit Value ◽  
Fatigue Damage Accumulation ◽  
Gear Contact ◽  
The Cost

This paper put forward the rapid measure method of the gear contact fatigue stress value with a few gear samples, which can get the estimated value of the gear fatigue limit value precisely and rapidly. And the gear fatigue life curve and fatigue damage accumulation curve are simulated by MATLAB. Comparing with the traditional test method, this method can reduce the cost and save the time.

scholarly journals Hybrid Method of Modal Analysis and Laser Shock Scanning to Visualize the Pyroshock Propagation in a Tension Joint

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Yong-Woon Kim ◽  
Jae-Kyeong Jang ◽  
Jung-Ryul Lee ◽  
Hak-Seong Gim
Keyword(s):  
Modal Analysis ◽  
Hybrid Method ◽  
Response Spectrum ◽  
Near Field ◽  
Low Frequency ◽  
Simulation Method ◽  
Experimental Simulation ◽  
Laser Shock ◽  
Simulation Results ◽  
Tension Joint

The use of pyrodevices in the aerospace industry has been increasing because of their ability to implement separation missions with a small weight, for example, space launchers, spacecrafts, and missiles. During operation, pyrodevices generate pyroshock, which causes failures of electronic devices. Recently, a pyroshock simulation method using laser shock has been developed to evaluate the risk of pyroshock before flight mission. However, depending on the structure, the laser shock showed some difficulty simulating pyroshock in the low-frequency regime accompanying vibration. Therefore, in this study, we developed a hybrid method of numerical modal analysis and laser shock-based experimental simulation to visualize the pyroshock propagation in all the relevant frequency regimes. For the proof of concept of the proposed method, we performed experiments of explosive bolt-induced shock and pyrolock-induced shock in the open-box-type tension joint and compared the hybrid simulation results with actual pyroshock. From the results, we obtained the simulated time-domain signal with an averaged peak-to-peak acceleration difference (PAD) of 11.2% and the shock response spectrum (SRS) with an averaged mean acceleration difference (MAD) of 28.5%. In addition, we were able to visualize the simulation results in the temporal and spectral domains to compare the pyroshock induced by each pyrodevice. A comparison of the simulations showed that the pyrolock had an impulse level of 1/12 compared to the explosion bolt. In particular, it was confirmed that the pyrolock-induced shock at the near field can cause damage to the electronic equipment despite a smaller impulse than that of the explosive bolt-induced shock. The hybrid method developed in this paper demonstrates that it is possible to simulate pyroshock for all the frequency regimes in complex specimens and to evaluate the risk in the time and frequency domain.

scholarly journals Effect of Cold Working on the Driving Force of the Crack Growth and Crack Growth Rate of Welded Joints under One Overload

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Hongliang Yang ◽  
He Xue ◽  
Fuqiang Yang ◽  
Shuai Wang
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Creep Rate ◽  
Crack Growth ◽  
Heat Affected Zone ◽  
Driving Force ◽  
Cold Working ◽  
Crack Tip ◽  
Simulation Method ◽  
Fusion Line

To understand the effect of cold working of welding heat-affected zone on the driving force of the crack growth and crack growth rate of stress corrosion cracking (SCC) near the welding fusion line, the finite element simulation method was used to analyze the effect of cold working on the tensile stress of the crack tip at different locations near the fusion line. On this basis, the strain rate of the crack tip in the Ford-Andresen model is replaced by the creep rate of the crack tip, and the creep rate of the crack tip is used as driving force for the crack growth of SCC. The effect of the cold working level at the heat-affected zone on the driving force of the crack growth and crack growth rate of SCC are analyzed, and driving force of the crack growth and crack growth rate of SCC after one overload was compared.

scholarly journals A New Online Dynamic Testing Method for Noise of Broadcast Transmitter

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shan-Shan Li ◽  
Jian Zhou ◽  
Xuan Wang
Keyword(s):  
Real Time ◽  
Data Storage ◽  
Dynamic Testing ◽  
Noise Figure ◽  
Estimation Algorithm ◽  
Test Method ◽  
Noise Estimation ◽  
Experimental Simulation ◽  
Spectrum Estimation ◽  
Low Efficiency

Aiming at the shortcomings of traditional broadcast transmitter noise test methods, such as low efficiency, inconvenient data storage, and high requirements for testers, a dynamic online test method for transmitter noise is proposed. The principle of system composition and test method is given. The transmitter noise is real-time changing. The Voice Active Detection (VAD) noise estimation algorithm cannot track the transmitter noise change in real time. This paper proposes a combined noise estimation algorithm for VAD and dynamic estimation. By setting the threshold of the double-threshold VAD detection to be low, it can accurately detect the silent segment. The silent segment is used as a noise signal for noise estimation. For the nonsilent segment detected by the VAD, a minimum value search dynamic spectrum estimation algorithm based on the existence probability of the speech (IMCRA) is used for noise estimation. Transmitter noise is measured by calculating the noise figure (NF).The test method collects the input and output data of the transmitter in real time, which has better accuracy and real-time performance, and the feasibility of the method is verified by experimental simulation.

scholarly journals The correlation between gear contact friction and ball on disc friction measurements

2015 ◽  
Vol 83 ◽  
pp. 114-119 ◽  
Author(s):  
M. Björling ◽  
J. Miettinen ◽  
P. Marklund ◽  
A. Lehtovaara ◽  
R. Larsson
Keyword(s):  
Contact Friction ◽  
Friction Measurements ◽  
Gear Contact ◽  
Ball On Disc

scholarly journals Study on Compaction Effect and Process of Reclaimed Soil of Nonmetallic Mines in Xinjiang, China

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Kaikai Wang ◽  
Zizhao Zhang ◽  
Guobin Tang ◽  
Xiaodong Tan ◽  
Qianli Lv ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Land Reclamation ◽  
Simulation Method ◽  
Test Method ◽  
Soil Thickness ◽  
In Situ Test ◽  
Factors Affecting ◽  
Reclaimed Soil ◽  
Different Thickness

Reclaimed soil is the key substrate for land reclamation and ecological restoration in the mine areas. The change of the density of reclaimed soil of the nonmetallic mines in Xinjiang during the land reclamation process was studied in this paper. Firstly, the in situ test method of static load was used to simulate the compaction of reclaimed soil with different thickness of overlying soil by different compaction times of mines reclamation machinery, and field in situ test compaction data were obtained. Then, the numerical simulation method was used to simulate the variation process of displacement and porosity at different depths for different thickness of the reclaimed soil under different compaction conditions. The numerical simulation and the in situ test results verified each other to acquire the compaction process and results of reclaimed soil under different compaction. The results showed that the numerical simulation results were consistent with the in situ test. The reclaimed soil thickness and compaction times were crucial factors affecting the compaction effect of the soil. The difference between the three times compaction and the uncompacted soil was obvious, and the effect of single compaction was weakened with the increase of compaction times. Under the same compaction action, the thicker the soil was, the less obvious the compaction effect would be. In the process of reclamation, the compaction effect of the surface part (at the depth of 10 cm) was visible, and the amount of compression and springback was larger. The research results can provide a reference to the land reclamation of nonmetallic mines in Xinjiang, China.

scholarly journals A test method to measure fatigue crack growth rate of rubbery materials

2006 ◽  
Vol 25 (3) ◽  
pp. 347-352 ◽  
Author(s):  
Shinyoung Kaang ◽  
Young Woong Jin ◽  
Yang-il Huh ◽  
Wan-Jin Lee ◽  
Wan Bin Im
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Test Method
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