Research on the Static and Dynamic Characteristics of the Sliding Rail Joint Surfaces of the Fe-Based Porous Oily Material

2014 ◽  
Vol 607 ◽  
pp. 422-426
Author(s):  
Jian Feng Ma ◽  
Qiang Li ◽  
Liang Sheng Wu ◽  
Chong Nian Qu
Keyword(s):  
Dynamic Characteristics ◽  
Unit Area ◽  
Test System ◽  
Joint Interface ◽  
Equivalent Stiffness ◽  
Characteristic Parameters ◽  
Single Degree Of Freedom ◽  
Joint Surfaces ◽  
Machine Tool Structures ◽  
Stiffness And Damping

The dynamic characteristics of joint interfaces have significant effect on both static and dynamic behaviors of the whole machine tool structures. A test system for identifying the unit area dynamic characteristic parameters of Fe-based joint interfaces in still and motion states were represented based on Equivalent Single Degree Of Freedom (ESDOF) system theory. Compared with the stiffness and damping parameters in stationary state, the stiffness is reduced and the damping is increased in motion. When the velocity increased, the equivalent stiffness and damping parameters of joint interface are both increased.

Dynamic Characteristics Optimization of Joint Interface of Machine Tool Based on Porous Oily Materials

2014 ◽  
Vol 709 ◽  
pp. 63-67
Author(s):  
Jian Feng Ma ◽  
Qiang Li ◽  
Ji Kun Feng ◽  
Liang Sheng Wu
Keyword(s):  
Porous Material ◽  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Unit Area ◽  
Test System ◽  
Joint Interface ◽  
Characteristic Parameters ◽  
Damping Characteristics ◽  
Stiffness And Damping

The joint interface plays a significant role in machine tools and other machineries. A novel type of joint which consists of oily porous material was proposed in the paper. A test system for identifying the unit area dynamic characteristic parameters of Fe-based joint interfaces were represented. The stiffness and damping parameters were compare to the conversional structures. The result showed that the joint which contains an oil film interlayer formed by porous and steel was superior to the joint with non-media formed by steel in stiffness and damping characteristics. In the case of the same preload, the former’s stiffness is increased by about 50 %, and the damping is increased about five to six times.

Research on Stiffness and Damping Characteristics of Fixed Oily Porous Materials Joint Interface

2011 ◽  
Vol 422 ◽  
pp. 575-579
Author(s):  
Chong Nian Qu ◽  
Liang Sheng Wu ◽  
Jian Feng Ma ◽  
Yi Chuan Xiao
Keyword(s):  
Porous Material ◽  
Porous Materials ◽  
Parallel Plate ◽  
Joint Interface ◽  
Force Model ◽  
Equivalent Stiffness ◽  
Contact State ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
Damping Model

In this document, using the anti-squeezed force model in the narrow parallel plate when fluid is squeezed, the equivalent stiffness and damping model is derived. It is further verified that it can increase the stiffness and damping while there are oil between the joint interfaces theoretically. Because the contact state of oily porous material can divide into liquid and solid parts, the document supposes that it is correct and effective to think the stiffness and damping of the two parts as shunt connection.

scholarly journals Research on Static and Dynamic Characteristics of Shear Spring of the Vibrating Flip-Flow Screen

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1644
Author(s):  
Guofeng Zhao ◽  
Xinwen Wang ◽  
Chi Yu ◽  
Shucheng Liu ◽  
Jun Zhou ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
High Efficiency ◽  
Dynamic Stiffness ◽  
Test System ◽  
Normal Operation ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Operation Conditions ◽  
Shear Spring ◽  
Stiffness And Damping

The vibrating flip-flow screen (VFFS) is a high-efficiency device currently used for deep screening of moist fine-grained materials. During VFFS operation, the normal operation of the screen is affected by fatigue damage to the shear springs arranged symmetrically on both sides of the screen, leading to equipment failures and disruption production. In this paper, the shear spring’s static and dynamic characteristics in different operation conditions were studied using the INSTRON 8801 fatigue test system and Dynacell dynamic sensors. Using an experimental test of shear spring stiffness and damping coefficients, the effects of some factors, i.e., temperature, hardness, amplitude and frequency, were studied. The results show that the temperature of the shear spring on the left side of the flip-flow screen was higher than that of the right side (driving side). With an increase in temperature, the stiffness of the shear spring decreased. With the increase in amplitude, the dynamic stiffness decreased and the damping coefficients did not change; with the increase in frequency, the dynamic stiffness increased and the damping coefficient decreased. At the same amplitude, with the increase in hardness of the shear spring, the dynamic stiffness increased. Finally, the stiffness and damping coefficients of the shear spring before and after tearing were obviously reduced. These research results reveal the relationship of the characteristics of a shear spring with operational conditions, and could provide a theoretical reference for the design of the VFFS and the selection of the shear spring.

Change in Dynamic Characteristics of Spindle for Machining Centers Caused by Chucking Mechanism of Clamped Toolholders

2012 ◽  
Vol 523-524 ◽  
pp. 521-526 ◽  
Author(s):  
Haruhisa Sakamoto ◽  
Yuhei Maeki ◽  
Shinji Shimizu
Keyword(s):  
Dynamic Characteristics ◽  
Transfer Functions ◽  
Dynamic Stiffness ◽  
Characteristic Parameters ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Machining Center ◽  
Vibration Model ◽  
Order Of Magnitude ◽  
Response Method

In this study, the effects of clamping toolholders on the dynamic characteristics of spindle systems are evaluated experimentally. In the experiments, the transfer functions are obtained by the impulse response method, and then, the dynamic characteristic parameters are identified based on the vibration model of single-degree of freedom. Two types of machining center spindles and four types of toolholders are evaluated. From the experimental results, the following are revealed: (1) the clamping toolholder enhances the vibration amplitude markedly compared with that of the spindle not clamping toolholder. (2) The different chucking mechanisms clearly change the dynamic stiffness of the spindle systems. (3) The order of magnitude of the dynamic stiffness of the spindle systems agrees well with that of the isolated toolholders. It is confirmed experimentally that clamping of the appropriate toolholder improves the dynamics stiffness of the spindle systems for machining centers.

An Approach to Investigate Dynamic Parameters of Bearings Joint Surfaces Based on the SDOF System

2013 ◽  
Vol 470 ◽  
pp. 504-509
Author(s):  
Lian Bao Wang ◽  
Xiao Qiu Hu ◽  
Xiang Long Dong
Keyword(s):  
Dynamic Characteristics ◽  
Hot Spot ◽  
Dynamic Stiffness ◽  
Modal Testing ◽  
Ball Bearings ◽  
Dynamic Parameters ◽  
Cnc Machine ◽  
Sdof System ◽  
Joint Surfaces ◽  
Stiffness And Damping

As commonly supporting parts of the spindle and the feed systems on the high-end grade CNC machine tool, the dynamic characteristics of angular contact ball bearings had been a research hot spot in the current. Aiming at solving the problem that obtained dynamic stiffness and damping of angular contact ball bearings, an approach to investigate dynamic parameters of bearings joint surfaces was proposed based on the single degree of freedom (SDOF) system, and several groups of modal testing were carried out. The dynamic characteristics of bearings joint surfaces were viewed as several viscoelastic units of spring and damper. Then, models of bearings dynamic parameters in the axial and radial directions were established, and several groups of modal simulation were carried out. The comparison of experiment and simulation results showed that the proposed approach could accurately identify dynamic stiffness and damping of bearings under different load conditions, and the errors were controlled within 7.6%.

Experimental Research on Tangential Dynamic Characteristics of Joint Surface in Motor Frame

2012 ◽  
Vol 197 ◽  
pp. 41-45
Author(s):  
Hao Tian Moqi ◽  
Yang Xiang ◽  
Xue Bao Xia ◽  
Hui Liu
Keyword(s):  
Dynamic Characteristics ◽  
Contact Stiffness ◽  
Experimental System ◽  
Dynamic Contact ◽  
Joint Surface ◽  
Characteristic Parameters ◽  
Joint Surfaces ◽  
Exciting Frequency ◽  
Test Platform ◽  
Set Up

Characteristic parameters of joint surfaces are needed in kinetic modeling of the motor frame while analyzing its vibration behavior. In this paper, research on tangential dynamic characteristics of mechanical joint surfaces in the motor frame is executed. In order to get the tangential contact stiffness and contact damping of interfaces in the motor frame under different joint conditions, an experimental method is proposed according to the structure feature and running condition of motors. A test platform is specially designed and set up. The kinetic model of test specimens (including the test joint surfaces) is derived. The experimental system is developed. The tangential dynamic contact stiffness and contact damping are identified by the experimental system. The variation rules of the contact stiffness and contact damping with changing of pre-load, exciting frequency and surface roughness are got and summarized. And the rules are consistent with the physical essence of joint surfaces.

Experimental Investigation of Dynamic Normal Characteristics of Machined Joint Surfaces

2000 ◽  
Vol 122 (4) ◽  
pp. 393-398 ◽  
Author(s):  
W. P. Fu ◽  
Y. M. Huang ◽  
X. L. Zhang ◽  
Q. Guo
Keyword(s):  
Experimental Investigation ◽  
Dynamic Characteristics ◽  
Static Pressure ◽  
Dynamic Stiffness ◽  
Relative Displacement ◽  
Test Range ◽  
Joint Surfaces ◽  
Exciting Frequency ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

This paper presents an experimental investigation on the normal dynamic characteristics of several machined joint surfaces, i.e., the varying principle of the normal dynamic stiffness and damping with exciting frequency, relative displacement and static pre-load under different joint conditions, including joint materials, mediums, machining methods and surface roughness, etc.. The joint parameters are extracted from experimental data by establishing the theoretical model of the joint surfaces, and the mechanism is analyzed qualitatively. The studied results show that, in the test range of this paper, the stiffness and damping coefficient of the joint surfaces increase with the static pre-load; the stiffness for a dry joint is independent of the exciting frequency, while the damping coefficients for both a dry and an oiled joint decrease with the exciting frequency; little relative displacement has no marked effect on the dynamic characteristics. The amount of influence of exciting frequency and static pressure is related to the joint conditions. [S0739-3717(00)00804-7]

Comprehensive Analysis for Influence of Controllable Damper Time Delay on Semi-Active Suspension Control Strategies

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Yechen Qin ◽  
Feng Zhao ◽  
Zhenfeng Wang ◽  
Liang Gu ◽  
Mingming Dong
Keyword(s):  
Time Delay ◽  
Dynamic Characteristics ◽  
Ride Comfort ◽  
Hybrid Control ◽  
Sliding Mode ◽  
Control Strategies ◽  
Active Suspension ◽  
Test System ◽  
Suspension Control ◽  
Simulation Results

This paper presents a comprehensive comparison and analysis for the effect of time delay on the five most representative semi-active suspension control strategies, and refers to four unsolved problems related to semi-active suspension performance and delay mechanism that existed. Dynamic characteristics of a commercially available continuous damping control (CDC) damper were first studied, and a material test system (MTS) load frame was used to depict the velocity-force map for a CDC damper. Both inverse and boundary models were developed to determine dynamic characteristics of the damper. In addition, in order for an improper damper delay of the form t+τ to be corrected, a delay mechanism of controllable damper was discussed in detail. Numerical simulation for five control strategies, i.e., modified skyhook control SC, hybrid control (HC), COC, model reference sliding mode control (MRSMC), and integrated error neuro control (IENC), with three different time delays: 5 ms, 10 ms, and 15 ms was performed. Simulation results displayed that by changing control weights/variables, performance of all five control strategies varied from being ride comfort oriented to being road handling oriented. Furthermore, increase in delay time resulted in deterioration of both ride comfort and road handling. Specifically, ride comfort was affected more than road handling. The answers to all four questions were finally provided according to simulation results.

Dynamic characteristics of squeeze-type mount using magnetorheological fluid

2005 ◽  
Vol 219 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Y K Ahn ◽  
J-Y Ha ◽  
Y-H Kim ◽  
B-S Yang ◽  
M Ahmadian ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Vibration Isolation ◽  
Dynamic Behaviour ◽  
Electrical Current ◽  
Magnetorheological Fluid ◽  
Test Set ◽  
Mr Fluid ◽  
Set Up ◽  
Stiffness And Damping

This paper presents an analytical and experimental analysis of the characteristics of a squeeze-type magnetorheological (MR) mount which can be used for various vibration isolation areas. The concept of the squeeze-type mount and details of the design of a squeeze-type MR mount are discussed. These are followed by a detailed description of the test set-up for evaluating the dynamic behaviour of the mount. A series of tests was conducted on the prototype mount built for this study, in order to characterize the changes occurring as a result of changing electrical current to the mount. The results of this study show that increasing electrical current to the mount, which increases the yield stress of the MR fluid, will result in an increase in both stiffness and damping of the mount. The results also show that the mount hysteresis increases with increase in current to the MR fluid, causing changes in stiffness and damping at different input frequencies.

Rotordynamic Performance of a Rotor Supported on Bump Type Foil Gas Bearings: Experiments and Predictions

2006 ◽  
Vol 129 (3) ◽  
pp. 850-857 ◽  
Author(s):  
Luis San Andrés ◽  
Dario Rubio ◽  
Tae Ho Kim
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Load Capacity ◽  
Test System ◽  
Foil Bearings ◽  
Rotor Imbalance ◽  
Synchronous Motion ◽  
Damping Characteristics ◽  
Rotor Surface ◽  
Stiffness And Damping

Gas foil bearings (GFBs) satisfy the requirements for oil-free turbomachinery, i.e., simple construction and ensuring low drag friction and reliable high speed operation. However, GFBs have a limited load capacity and minimal damping, as well as frequency and amplitude dependent stiffness and damping characteristics. This paper provides experimental results of the rotordynamic performance of a small rotor supported on two bump-type GFBs of length and diameter equal to 38.10mm. Coast down rotor responses from 25krpm to rest are recorded for various imbalance conditions and increasing air feed pressures. The peak amplitudes of rotor synchronous motion at the system critical speed are not proportional to the imbalance introduced. Furthermore, for the largest imbalance, the test system shows subsynchronous motions from 20.5krpm to 15krpm with a whirl frequency at ∼50% of shaft speed. Rotor imbalance exacerbates the severity of subsynchronous motions, thus denoting a forced nonlinearity in the GFBs. The rotor dynamic analysis with calculated GFB force coefficients predicts a critical speed at 8.5krpm, as in the experiments; and importantly enough, unstable operation in the same speed range as the test results for the largest imbalance. Predicted imbalance responses do not agree with the rotor measurements while crossing the critical speed, except for the lowest imbalance case. Gas pressurization through the bearings’ side ameliorates rotor subsynchronous motions and reduces the peak amplitudes at the critical speed. Posttest inspection reveal wear spots on the top foils and rotor surface.

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