A NON-LINEAR FRICTION MODEL FOR SELF-EXCITED VIBRATIONS

1997 ◽  
Vol 205 (3) ◽  
pp. 323-335 ◽  
Author(s):  
A.J. McMillan
Keyword(s):  
Friction Model ◽  
Non Linear ◽  
Linear Friction

Non-linear friction compensation using backstepping control and robust friction state observer with recurrent fuzzy neural networks

2009 ◽  
Vol 223 (7) ◽  
pp. 973-988 ◽  
Author(s):  
B S Kim ◽  
S I Han
Keyword(s):  
State Observer ◽  
Fuzzy Neural Networks ◽  
Friction Model ◽  
Backstepping Control ◽  
Ball Screw ◽  
Control Scheme ◽  
Non Linear ◽  
Linear Friction ◽  
Fuzzy Neural ◽  
Lugre Friction

A robust precise tracking control for a servomechanical system with non-linear dynamic friction is presented. The LuGre friction that is adopted as a non-linear friction model contains both a directly immeasurable friction state variable and the uncertainty caused by incomplete parameter identification and change of the condition of contact surface. To provide an efficient solution to these problems, a composite robust control scheme is proposed, which consists of a robust friction state observer, a recurrent fuzzy neural network (RFNN) approximator, and an adaptive reconstructed error compensator with backstepping control. A robust friction state observer is designed to estimate the unknown internal state of the LuGre friction model. Next, a proposed RFNN scheme approximates the lumped friction torque uncertainty. Finally, an adaptive error compensator eliminates a reconstructed error arising from RFNN approximation. Some simulations and experiments for a ball-screw servosystem are carried out to demonstrate the performance of a proposed control scheme.

Microstructure and Mechanical Properties at the Unsteady Areas of Non-Linear Friction Stir Welding

2007 ◽  
Vol 561-565 ◽  
pp. 1059-1062 ◽  
Author(s):  
H. Takahara ◽  
Masato Tsujikawa ◽  
Sung Wook Chung ◽  
Y. Okawa ◽  
Kenji Higashi
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Welding Parameter ◽  
Butt Joints ◽  
Friction Stir ◽  
Non Linear ◽  
Linear Friction ◽  
Fsw Parameters ◽  
Five Axis ◽  
Welding Direction

The influence of tool control in non-linear friction stir welding (FSW) on mechanical properties of joints was investigated. FSW is widely applied to linear joints. It is impossible for five axis FSW machines, however, to keep all the FSW parameters in optimum conditions at non-linear welding. Non-linear FSW joints should be made by compromise with the order of priority for FSW parameters. The tensile test results of butt joints with rectangular change in welding direction on plate plane (L-shaped butt joints) with various welding parameter change. It was found that turn to the retreating side is encouraged when welding direction change. And the method of zero inclination tool angle is effective at non-linear and plane welding.

A non-linear friction work formulation for the analysis of self-excited vibrations

2019 ◽  
Vol 443 ◽  
pp. 328-340 ◽  
Author(s):  
Z. Zhang ◽  
S. Oberst ◽  
J.C.S. Lai
Keyword(s):  
Non Linear ◽  
Linear Friction

scholarly journals Comparison of Balance and Out of Balance Main Battle Tank Armaments

2001 ◽  
Vol 8 (3-4) ◽  
pp. 167-174 ◽  
Author(s):  
David J. Purdy
Keyword(s):  
Vertical Acceleration ◽  
Non Linear ◽  
Linear Friction ◽  
Moving Platform

It has been commonly thought that stabilising an out of balance gun on a moving platform (tank or ship) is very difficult or impossible to achieve. Using models of a balanced and out of balance gun on a main battle tank this is shown not to be the case. The models of the guns used, include the effect of non-linear friction and out of balance. To improve the stabilisation of the out of balance gun, trunnion vertical acceleration feedforward is used.

scholarly journals Variable Modal Parameter Identification for Non-Linear Mdof Systems. Part II: Experimental Validation and Advanced Case Study

2000 ◽  
Vol 7 (4) ◽  
pp. 229-240 ◽  
Author(s):  
Y.H. Chong ◽  
M. Imregun
Keyword(s):  
Modal Analysis ◽  
Experimental Validation ◽  
Element Model ◽  
Force Level ◽  
Friction Damper ◽  
Modal Parameter ◽  
Mdof Systems ◽  
Non Linear ◽  
Linear Friction

The purpose of Part II is to provide an experimental validation of the methodology presented in Part I and to consider a representative engineering case, the study of which requires a relatively large numerical model. A beam system with cubic stiffness type non-linearity was used in the experimental study. The non-linear response was measured at three locations and the underlying linear system was obtained via linear modal analysis of low-excitation response data. The non-linear parameter variations were obtained as a function of the modal amplitude and the response of the system was generated for other force levels. The results were found to agree very well with the corresponding measurements, indicating the success of the non-linear modal analysis methodology, even in the presence of true experimental noise. An advanced numerical case study that included both inherent structural damping and non-linear friction damping, was considered next. The linear finite element model of a high-pressure turbine blade was used in conjunction with three local non-linear friction damper elements. It was shown that the response of the system could be predicted at any force level, provided that that non-linear modal parameters were available at some reference force level. The predicted response levels were compared against those obtained from reference simulations and very good agreement was achieved in all cases.

Linear friction tester design and validation

2021 ◽  
pp. 135065012110454
Author(s):  
Mehran Shams Kondori ◽  
Saied Taheri
Keyword(s):  
Wear Rate ◽  
Normal Load ◽  
Lateral Force ◽  
Friction Model ◽  
Ball Screw ◽  
Dynamic Friction ◽  
Test Bed ◽  
Friction Tester ◽  
Linear Friction ◽  
Novel Design

Due to the complexity of friction phenomena, empirical analysis is the best way to predict the friction coefficient. To accomplish this, laboratory test rigs are needed. Although a rotary dynamic friction test bed was available to the authors, it had its limitations, such as low speed, inducement of lateral force, and the limitation of testing samples with different shapes. This paper will explain the process of designing and manufacturing a novel test setup for measuring friction and wear of the tire. The newly designed test rig can apply dynamic loading during the tests, and it can automatically measure the wear rate and temperature between cycles. In addition, it can be used for measuring the wear rate of rubber samples sliding on different types of surfaces. Therefore, experiments can be run under more controlled conditions. The designed linear friction tester can slide flat and round rubber samples approximately three meters across a large flat surface. The frictional force of rubber samples can be measured for various normal loads, velocities, and surface conditions. The new setup can automatically control the applied normal load on the sample using proportional–integral–derivative controller control. The important difference between this novel design and the existing testers used by other researchers is implementing the ball screw technology and the servo motor with high accuracy encoder to achieve highly accurate test results. In this design, the new mechanism for the ball screw is designed to increase the speed limit and eliminating vibrations while keeping the precision. In addition, in this design, the sample's mass can be measured automatically after each test cycle, thus providing a measure of the rate of wear of the rubber. In this study, the data collected by the linear friction tester is validated by comparing the data to the data collected by the dynamic friction tester (a validated rotary friction tester that exists in CenTiRe Lab). The data collected by the new setup was later used to benchmark the Persson analytical friction model.

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