scholarly journals Multi-body Dynamic Modelling and Error Analysis of Planar Flexible Multilink Mechanism Considering Clearance and Thermal-mechanical Coupling Effect of the Crankshaft-bearing Structure

2021 ◽  
Author(s):  
Hongfan Long ◽  
Zhao Han ◽  
Shuyun Jiang ◽  
Enlai Zheng ◽  
Yongnian Zhang ◽  
...  
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Coupling Effect ◽  
Dynamic Modelling ◽  
Variable Stiffness ◽  
Position Error ◽  
Mechanical Coupling ◽  
Spindle Bearing ◽  
Bearing Structure ◽  
Bearing System

Abstract In order to study the dynamic position accuracy of bottom dead point (BDP) for multilink high-speed precision presses (MHSPPs), it’s essential to develop a dynamic model of planar multilink mechanism with clearance and spindle-bearing structure. Traditional models always neglect the effect of thermal characteristics of spindle-bearing structure, which reduces the prediction accuracy of dynamic model for multilink transmission mechanisms. To overcome the shortcomings of the previous models, a thermal network model (TNM) of the crankshaft-bearing system is established firstly considering the effects of thermal contact resistance and variable stiffness of bearing concerning the temperature rise. Then, dynamic model of the crankshaft-bearing system is built through the finite element method, which includes rigid disk, Timoshenko beam and quasi-statics model of ACBB. On this basis, an improved dynamic model of planar flexible multilink mechanism with clearance considering the thermal-mechanical coupling effect of the crankshaft-bearing structure is developed and the corresponding dynamic error dimension chain between slider and crankshaft is constructed in this work. Compared to the simulation from traditional models, the simulated slider’s BPD position error from the improved model agrees better with experimental data, which verifies the correctness of the proposed model. It’s demonstrated that the punching force and thermally induced variable stiffness of bearing lead to a significant increase of slider’s BDP position error, which reduces the machining precision of MHSPP. Furthermore, the influence of crankshaft speed, contact angle of bearing and clearance size on the slider’s BDP position error is also investigated.

Experimental and Numerical Studies on Spherical Roller Bearings Using Multivariable Regression Analysis

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
R. G. Desavale ◽  
R. Venkatachalam ◽  
S. P. Chavan
Keyword(s):  
Regression Analysis ◽  
Sugar Cane ◽  
High Speed ◽  
Roller Bearing ◽  
Vibration Characteristics ◽  
Multivariable Regression Analysis ◽  
Rotor Bearing ◽  
Multivariable Regression ◽  
Bearing Structure ◽  
Bearing System

Many industries make wide use of rotor bearing systems such as high speed turbines and generators. However, the vibration of antifriction rotor–bearings is a key factor in reducing the life of the bearings; thus significantly influencing the performance and working life of the whole power plant. In earlier research on the vibration characteristics of high speed rotor–bearing systems, such as in induced draft (ID) fans, an application used in sugar cane factories, the supporting antifriction bearings were simplified as a particle on a shaft with radial stiffness and damping coefficient. However, such simplification neglects the effects of the bearing structure on the vibration performance of the rotor–bearing system. This paper demonstrates the benefits of a more holistic approach and establishes a numerical model of the stiffness of the spherical roller bearing through Buckingham's π theorem (BPT). On the basis of this model, we argue for the benefits of a new dimensional analysis (DA) technique for rotor–bearing systems. Our new DA also considers the influences of the bearing structure parameters on the vibration of rotor–bearing systems. We demonstrate the effectiveness of our approach by conducting a comparative BPT study using an ID fan, a rotor–bearing system in use in sugar cane factories. We first analyzed an ID fan using the simplified model to obtain the defect frequencies and vibration amplitude responses of the ID fan system. Subsequently the same ID fan rotor was also analyzed using our new multivariable regression analysis (MVRA) approach to verify the validity of our new and holistic BPT. The results indicate that the new method we propose in this paper for the calculation of vibration characteristics of a high speed rotor–bearing (ID fan) is credible and will save time and costs by the accurate detection of imminent bearing failure.

scholarly journals Dynamic Modelling, Experimental Identification and Computer Simulations of Non-Stationary Vibration in High-Speed Elevators

2021 ◽  
Vol 67 (6) ◽  
Author(s):  
Radomir Đokić ◽  
Jovan Vladić ◽  
Milan Kljajin ◽  
Vesna Jovanović ◽  
Goran Marković ◽  
...  
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Dynamic Behaviour ◽  
Dynamic Modelling ◽  
Control Program ◽  
Specific Method ◽  
Unique Method ◽  
Stationary Vibration ◽  
Vertical Vibrations ◽  
Stiffness And Damping

Modelling the dynamic behaviour of elevators with high lifting velocities (contemporary elevators in building construction and mine elevators) is a complex task and an important step in the design process and creating conditions for safe and reliable exploitation of these machines. Due to high heights and lifting velocities, the standard procedures for dynamic exploitation are not adequate. The study presents the method of forming a dynamic model to analyse nonstationary vibrations of a rope with time-varying length with nonholonomic boundary conditions in the position where the rope is connected with the cabin (cage) and in the upcoming point of its winding onto the pulley (drum). A unique method was applied to identify the basic parameters of the dynamic model (stiffness and damping) based on experimental measures for a concrete elevator. Due to the verification of this procedure, the experiment was conducted on a mine elevator in RTB Bor, Serbia. Using the obtained computer-experimental results, the simulations of the dynamic behaviour of an empty and loaded cage were shown. In addition, the study shows the specific method as the basis for forming a control program that would enable the decrease in vertical vibrations during an elevator starting and braking mode.

Modelling Approach for a High Speed Machine Tool Spindle-Bearing System

2005 ◽  
Author(s):  
Vincent Gagnol ◽  
Belhassen C. Bouzgarrou ◽  
Pascal Ray ◽  
Christian Barra
Keyword(s):  
Finite Element ◽  
Dynamic Behavior ◽  
High Speed ◽  
Modal Identification ◽  
Coordinate Frame ◽  
Mass Unbalance ◽  
Spindle Bearing ◽  
Milling Forces ◽  
Bearing System ◽  
Modelling Approach

This paper presents a modelling approach of a high-speed spindle-bearing system based on a finite-element model analysis coupled to an experimental modal identification. Dynamic equations of the rotating entity are obtained using Lagrangian formulation associated with a numerical finite element method based on Timoshenko beam theory. Element kinematics is formulated in a co-rotational coordinate frame. A method for the experimental characterization of the dynamic behavior of a High Speed Machining (HSM) spindle is proposed. The goal of this method is to understand the influence of spindle structure elements on overall dynamic behavior. Each element is individually characterized and is integrated or not into the global model depending on the results. The choice of the finite element type for generating the numeric model is carried out on the basis of modal and harmonic experimental results. High-speed rotational effects including gyroscopic coupling and spin softening effects are investigated. The Campbell diagram indicates the potential critical speed for mass unbalance response and for synchronous excitation representative of the milling forces at tooth impact frequency. Excessive vibration levels at specific node location enable spindle component stress or failure during manufacturing processes to be predicted. The model is a useful tool for qualifying spindles in the manufacturing process and predicting their reliability. The proposed modeling approach can be transferred to other type of spindle.

Dynamic Modelling of Small Scale and High Temperature ORC System Using Simulink and CoolProp

2020 ◽  
Author(s):  
Radheesh Dhanasegaran ◽  
Antti Uusitalo ◽  
Teemu Turunen-Saaresti
Keyword(s):  
High Temperature ◽  
Dynamic Model ◽  
High Speed ◽  
Waste Heat ◽  
Fluid Pressure ◽  
Dynamic Modelling ◽  
Working Fluid ◽  
Small Scale ◽  
Condensation Process ◽  
Feed Pump

Abstract In the present work, a dynamic model has been developed for the small-scale high-temperature ORC experimental test rig at the LUT University that utilizes waste heat from a heavy-duty diesel engine exhaust. The experimental facility consists of a high-speed Turbogenerator, heat exchanger components such as recuperator, condenser, and evaporator with a pre-feed pump to boost the working fluid pressure after the condensation process constituting a cycle. The turbogenerator consists of a supersonic radial-inflow turbine, a barske type main-feed pump, and a permanent magnet type generator components connected on a single shaft. Octamethyltrisiloxane (MDM) is the chosen organic working fluid in this cycle. Matlab-Simulink environment along with the open-source thermodynamic and transport database Cool-Prop has been chosen for calculating the thermodynamic properties of the dynamic model. A functional parameter approach has been followed for modeling each block component by predefined input and output parameters, aimed at modeling the performance characteristics with a limited number of inputs for both design and off-design operations of the cycle. The dynamic model is validated with the experimental data in addition to the investigation of exhaust gas mass flow regulation that establishes a control strategy for the dynamic model.

Comparative Studies on the Dynamic Performances of High Speed Turbocharger Rotor Supported on Oil-Free Bearings Versus Conventional Floating Ring Systems

2017 ◽  
Author(s):  
Rajasekhara Reddy Mutra ◽  
J. Srinivas
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Equations Of Motion ◽  
Dynamic Modelling ◽  
Dynamic Responses ◽  
Effect Of Temperature ◽  
Time Step ◽  
Foil Bearing ◽  
Dynamic Performances ◽  
Bearing System

Present work focuses on the dynamic modelling of the dual-disc rotor supported on oil-free bearings idealizing a turbocharger rotor bearing system. The equations of motion of the rotor system are formulated and solved by finite element method to obtain the dynamic response of the system. The gas-foil bearing forces obtained from finite-difference approach at each time-step of solution. The same rotor model is used with the conventional floating ring bearing system where, the bearing forces are provided as displacement dependent time-varying oil and floating ring forces. As a practical environmental condition, the effect of temperature on the viscosity is studied using Dowson equation. The dynamic responses are illustrated both for rotor supported on both gas-foil and floating-ring type bearings. The effects of changes in bearing clearances on the overall dynamic characteristics of the rotor are reported. In order to utilize the gas foil bearing model, an identification study is performed to predict the operating clearance and air viscosity using dynamic response data.

Thermal-structure interaction characteristics of a high-speed spindle- bearing system

2019 ◽  
Vol 137 ◽  
pp. 42-57 ◽  
Author(s):  
Jialan Liu ◽  
Chi Ma ◽  
Shilong Wang ◽  
Sibao Wang ◽  
Bo Yang ◽  
...  
Keyword(s):  
High Speed ◽  
Thermal Structure ◽  
Structure Interaction ◽  
Spindle Bearing ◽  
Bearing System

scholarly journals Effect of preload on the dynamic characteristics of ceramic bearings based on a dynamic thermal coupling model

2020 ◽  
Vol 12 (1) ◽  
pp. 168781402090385
Author(s):  
Ke Zhang ◽  
Zinan Wang ◽  
Xiaotian Bai ◽  
Huaitao Shi ◽  
Qi Wang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Thermal Deformation ◽  
Coupling Model ◽  
Transfer Model ◽  
Thermal Coupling ◽  
Motorized Spindle ◽  
Rotating Speed ◽  
Spindle Bearing ◽  
Bearing System

Ceramic bearings have a good dynamic output performance under an ultra-high, ultra-low temperature due to their small deformation property. Based on the Harris and Palmgren empirical equation, this article establishes the thermal transfer model of a ceramic motorized spindle. The thermal deformation of a ceramic angular contact ball bearing is calculated. A dynamic and thermal coupling model of the ceramic motorized spindle is built using the Hertz contact theory, which can determine the optimal preload force under different rotating speed conditions. The influence of different temperatures, preload, and rotation speeds on the bearing vibration characteristics was studied. The accuracy of the dynamic and thermal coupling model was verified by the motorized spindle experimental platform. The results show that the thermal deformation of the bearing is an important influencing factor for the output of the dynamic characteristics. Considering the thermal displacement of the bearing, the simulation accuracy of the ceramic motorized spindle-bearing system is in good agreement with the experimental results. By adjusting the bearing preload, the parameters of the rotating speed can effectively reduce the temperature rise and suppress the vibration. The spindle-bearing system model provides a theoretical basis for the dynamic development of a high-speed ceramic bearing.

Thermo-mechanical coupling behaviour when milling titanium alloy with micro-textured ball-end cutters

2020 ◽  
Vol 234 (6) ◽  
pp. 562-575
Author(s):  
Minli Zheng ◽  
Chunsheng He ◽  
Shucai Yang
Keyword(s):  
Titanium Alloy ◽  
High Speed ◽  
Simulation Analysis ◽  
End Milling ◽  
Coupling Effect ◽  
Theoretical Calculations ◽  
Milling Cutter ◽  
Ball End Milling ◽  
Mechanical Coupling ◽  
Coupling Behavior

The high-speed milling of titanium alloy is a very complex nonlinear dynamic cutting process, and there are mutual coupling effects between multiple physical fields of the tool. Therefore, the thermo-mechanical coupling behavior of micro-textured ball-end milling cutters during the cutting of titanium alloy was studied in depth, combined with theoretical calculations, milling experiments and simulation analysis. First, based on the experimental data of milling titanium alloy, the stress field of the micro-textured ball-end milling cutter was solved. Then, the dimensional method was used to solve the temperature field of the micro-textured ball-end milling cutter. Finally, the thermo-mechanical coupling simulation analysis of the micro-textured ball-end milling cutter was carried out, and the stress concentration area and tool breakage area of the micro-textured ball-end milling cutter under the thermo-mechanical coupling effect are obtained. This in turn gives a theoretical basis for further improving the performance and tool life of micro-textured cutters.

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