scholarly journals Study on Residual Vibration Suppress of a 3-DOF Flexible Parallel Robot Mechanism

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4145 ◽  
Author(s):  
Qinghua Zhang ◽  
Qinghua Lu ◽  
Xianmin Zhang ◽  
Junjun Wu
Keyword(s):  
Numerical Simulation ◽  
Strain Rate ◽  
Parallel Robot ◽  
Motion Equation ◽  
Residual Vibration ◽  
Vibration Displacement ◽  
Flexible Links ◽  
Rate Feedback ◽  
Strain And Strain Rate ◽  
General Motion

Residual vibration suppression of a 3-DOF flexible parallel robot mechanism is implemented in this paper. Considering the direct and inverse piezoelectric effect of PZT (lead zirconium titanate) material, a general motion equation is established which includes an input equation of PZT actuators and an output equation of PZT sensors. A strain and strain rate feedback (SSRF) controller is designed based on the established general motion equation. A numerical simulation is implemented to verify the effectiveness of the SSRF controller in driving the proposed robotic mechanism. The simulation results reveal that the SSRF controller can decrease the elastic vibration displacement of the flexible links rapidly and improve the position accuracy of the moving platform. In the experimental study, one scheme with three passive flexible links is controlled by the SSRF controller at the same time as the performance of the introduced solutions. The experimental results show that the strain and strain rate feedback controller is able to effectively suppress the residual vibration of the 3-DOF flexible parallel robot mechanism. The results of the numerical simulation and experiment are completely consistent.

scholarly journals Experimental Study of Active Vibration Control of Planar 3-RRR Flexible Parallel Robots Mechanism

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Qinghua Zhang ◽  
Xianmin Zhang ◽  
Junyang Wei
Keyword(s):  
Strain Rate ◽  
Vibration Control ◽  
Active Vibration Control ◽  
Elastic Vibration ◽  
Parallel Robots ◽  
Flexible Link ◽  
Flexible Links ◽  
Rate Feedback ◽  
Active Vibration ◽  
General Motion

An active vibration control experiment of planar 3-RRR flexible parallel robots is implemented in this paper. Considering the direct and inverse piezoelectric effect of PZT material, a general motion equation is established. A strain rate feedback controller is designed based on the established general motion equation. Four control schemes are designed in this experiment: three passive flexible links are controlled at the same time, only passive flexible link 1 is controlled, only passive flexible link 2 is controlled, and only passive flexible link 3 is controlled. The experimental results show that only one flexible link controlled scheme  suppresses elastic vibration and cannot suppress the elastic vibration of the other flexible links, whereas when three passive flexible links are controlled at the same time, they are able to effectively suppress the elastic vibration of all of the flexible links. In general, the experiment verifies that a strain rate feedback controller is able to effectively suppress the elastic vibration of the flexible links of plane 3-RRR flexible parallel robots.

The Numerical Simulation Research of Thermal Mechanical Simulation Compression Behavior with Uneven Temperature on End

2013 ◽  
Vol 762 ◽  
pp. 368-373
Author(s):  
Lei Yao ◽  
Zheng Fang ◽  
Zhang Ge
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Friction Coefficient ◽  
Strain Rate ◽  
Deformation Resistance ◽  
Simulation Research ◽  
Compression Behavior ◽  
Mechanical Simulation ◽  
Strain And Strain Rate ◽  
Lubrication Condition

The study has been performed concerning the influence of temperature field created by heat conduction between sample and the anvils, and the influence of lubrication condition (friction coefficient) on thermal mechanical compression test with numerical simulation, with regard to deformation resistance and distributions of strain and strain rate. The results show that temperature field has an effect on deformation resistance and distributions of strain and strain rate. That will influence on the results from thermal mechanical simulation tests. Further, the results also show that friction coefficient has no influence on deformation resistance, but the friction coefficient will result in uneven distribution of strain and strain rate.

Numerical Simulation of Stress Wave Propagation in Coal-Rock Combination Media

2012 ◽  
Vol 594-597 ◽  
pp. 542-551 ◽  
Author(s):  
Dong Jie Xue ◽  
Hong Wei Zhou ◽  
Jia Dun Liu ◽  
Hai Yang Yi
Keyword(s):  
Numerical Simulation ◽  
Strain Rate ◽  
Stress Wave ◽  
Incident Wave ◽  
Constant Strain Rate ◽  
Stress Wave Propagation ◽  
Propagation Mode ◽  
Reflected Wave ◽  
Strain And Strain Rate ◽  
Coal Rock

By establishing numerical simulation model of SPBH and comparing dynamic response of four kinds of coal-rock combination media subjected to three different stress waves, changes law of the reflected wave, incident wave, strain and strain rate were obtained. The results show that rock-rock combination has almost the same rules of reflected waves as rock-coal combination, coal-coal combination and coal-rock combination, while the coal-coal combination has the largest peak of reflected wave, followed by the coal-rock combination and the rock-coal combination, and the rock-rock combination ranks last. With increasing incident wave peak, the coal-rock combination weakens the peak more apparently. Strain softening occurs in coal samples under stress wave of peak value with the law that strain rate firstly increases, and then maintains a constant value, continues to increase and then decreases, increases reversely and then decreases. Constant strain rate of the phenomenon over time occurs. The results provide guidelines for both the study on propagation mode of stress wave in coal and rock combination media and the prevention of mining-induced dynamic disasters.

Understanding kinematics of the orthogonal cutting using digital image correlation – measurement and analysis

2021 ◽  
pp. 1-15
Author(s):  
Dong Zhang ◽  
Markus Meurer ◽  
Xiao-Ming Zhang ◽  
Thomas Bergs ◽  
Han Ding
Keyword(s):  
Numerical Simulation ◽  
Digital Image Correlation ◽  
Strain Rate ◽  
Digital Image ◽  
Orthogonal Cutting ◽  
Great Influence ◽  
Image Correlation ◽  
Optical Parameters ◽  
Stagnation Zone ◽  
Strain And Strain Rate

Abstract Due to the development of advanced image correlation and high speed filming techniques, the kinematic field during the cutting process can be experimentally determined including the displacement, strain, and strain rate fields. As known, the setting parameters for the digital image correlation (DIC) as well as the optical parameters of the given camera and lighting system have a great influence on the spatial resolution and accuracy of the DIC results. In this study, the speckle pattern in terms of speckle size and intensity distribution are analyzed when using two different surface preparation methods. Moreover, the influences of the subset sizes for the image correlation on the strain and strain rate are numerically studied. Interlaboratory measurements of the kinematic field during the orthogonal cutting of AISI 4140 were conducted with two different in-situ imaging setups. The material flow near the cutting tool edge determined from the velocity field were compared with the numerical simulation. The experiments showed that no stagnation zone exists, however a considerable large stagnation zone was found from the numerical simulation. Furthermore, slip-line fields were constructed from the experimentally determined strain rate components, from which the boundary conditions along the chip free and chip-tool interface were derived.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

scholarly journals Application of the Strain Compensation Model and Processing Maps for Description of Hot Deformation Behavior of Metastable β Titanium Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2021
Author(s):  
Oleksandr Lypchanskyi ◽  
Tomasz Śleboda ◽  
Aneta Łukaszek-Sołek ◽  
Krystian Zyguła ◽  
Marek Wojtaszek
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Flow Behavior ◽  
Microstructural Analysis ◽  
Calculated Data ◽  
Processing Temperature ◽  
Processing Maps ◽  
Compression Tests ◽  
Strain And Strain Rate ◽  
Average Absolute Relative Error

The flow behavior of metastable β titanium alloy was investigated basing on isothermal hot compression tests performed on Gleeble 3800 thermomechanical simulator at near and above β transus temperatures. The flow stress curves were obtained for deformation temperature range of 800–1100 °C and strain rate range of 0.01–100 s−1. The strain compensated constitutive model was developed using the Arrhenius-type equation. The high correlation coefficient (R) as well as low average absolute relative error (AARE) between the experimental and the calculated data confirmed a high accuracy of the developed model. The dynamic material modeling in combination with the Prasad stability criterion made it possible to generate processing maps for the investigated processing temperature, strain and strain rate ranges. The high material flow stability under investigated deformation conditions was revealed. The microstructural analysis provided additional information regarding the flow behavior and predominant deformation mechanism. It was found that dynamic recovery (DRV) was the main mechanism operating during the deformation of the investigated β titanium alloy.

A Study of Strain and Strain-Rate Dependent Properties of a Superplastic Zn-Al Alloy Under Biaxial Stresses

1982 ◽  
Vol 104 (1) ◽  
pp. 41-46
Author(s):  
T. C. Hsu ◽  
I. M. Bidhendi
Keyword(s):  
Strain Rate ◽  
Stress Ratio ◽  
Local Stress ◽  
Biaxial Stress ◽  
Al Alloy ◽  
Local Geometry ◽  
Forming Process ◽  
Rate Dependent ◽  
Strain And Strain Rate ◽  
Liquid Behavior

A superplastic Zn-Al alloy in sheet form is formed into a bulge over a circular hole by pneumatic pressure. The geometry, the stress, the strain, and the strain-rate are determined at various points covering the whole specimen and at various stages of the forming process. The complicated shape, and its complicated changes, are represented by introducing an index for the local geometry, called “prolateness,” which is also related to the local stress ratio in a simple way. The biaxial stress is analyzed into a strain-proportional and a strain-rate-proportional component, which represent, respectively, the quasi-solid and the quasi-liquid behavior of the superplastic material.

Effect of Strain Rate on Nb(C,N) Precipitation in Micro Alloy Steel Slab

2012 ◽  
Vol 535-537 ◽  
pp. 633-638 ◽  
Author(s):  
Zheng Hai Zhu ◽  
Sheng Tao Qiu
Keyword(s):  
Continuous Casting ◽  
Strain Rate ◽  
Alloy Steel ◽  
Casting Speed ◽  
Casting Process ◽  
Continuous Casting Process ◽  
Precipitation Model ◽  
Strain And Strain Rate ◽  
Steel Slab

It was analyzed by strain-induced precipitation model that Nb(C,N) precipitation in micro alloy steel slab was effected by strain rate during continuous casting process. The results are as follows: The changing of casting speed could effect the time for 5%precipitation of Nb(C,N), which was decreasing with increasing casting speed at certain temperature and strain rate. Slab strain and strain rate were too small in bending zone and leveling zone. The effect of slab strain rate on Nb(C,N) precipitation could be ignore when Nb(C,N) precipitation in continuous casting process was studied.

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