Stiffness and damping model of bolted joint based on the modified three-dimensional fractal topography

2016 ◽  
Vol 231 (2) ◽  
pp. 279-293 ◽  
Author(s):  
Yongsheng Zhao ◽  
Jingjing Xu ◽  
Ligang Cai ◽  
Weimin Shi ◽  
Zhifeng Liu
Keyword(s):  
Contact Surface ◽  
Machine Tools ◽  
Contact Stiffness ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Roughness Parameter ◽  
Mode Shapes ◽  
Real Contact Area ◽  
Bolted Joint ◽  
Stiffness And Damping

The machine tools are consisted of many parts and most of them are connected by the bolts. Accurate modeling of contact stiffness and damping for bolted joint is crucial in predicting the dynamic performance of machine tools. This paper presents a modified three-dimensional fractal contact model to obtain the stiffness and damping of bolted joint. Topography of the contact surface of bolted joint is fractal featured and determined by fractal parameters. Asperities in microscale are considered as elastic, elastic–plastic, and full plastic deformation. The expand coefficient ψ is introduced to the size-distribution function of asperities. The real contact area, contact stiffness, and damping of the contact surface can be calculated by integrating the microasperities. The relationship of contact stiffness, damping, fractal dimension D, and fractal roughness parameter G can be obtained. Experiments are conducted to verify the efficiency of the proposed model. The results show that the theoretical mode shapes are in good agreement with the experimental mode shapes. The relative errors between the theoretical and experimental natural frequencies are less than 3.33%, which is less than those of the W-K model and L-L model. The presented model can be used to accurately predict the dynamic characteristic of bolted assembly in the machine tools.

Calculation of Gear Meshing Stiffness Considering Lubrication

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Gong Cheng ◽  
Ke Xiao ◽  
Jiaxu Wang ◽  
Wei Pu ◽  
Yanfeng Han
Keyword(s):  
Rough Surface ◽  
Calculation Method ◽  
Contact Stiffness ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Meshing Stiffness ◽  
Roughness Amplitude ◽  
Meshing Process

Abstract Gear meshing stiffness is the key parameter to study the gear dynamic performance. However, the study on the calculation of gear meshing stiffness considering lubrication, especially mixed lubrication, is still insufficient. Based on the three-dimensional linear contact mixed elastohydrodynamic lubrication model and the contact stiffness calculation method of rough surface, a method for calculating the gear meshing stiffness under mixed lubrication is proposed in this paper. According to the proposed calculation method, the effects of speed, external load, and roughness amplitude on gear meshing stiffness are further explored. The method can take into account the real rough surface topography and lubrication in the meshing process, so it may be more advantageous than the conventional method to some extent.

Modal Analysis of Boring and Milling Machine

2011 ◽  
Vol 105-107 ◽  
pp. 204-207
Author(s):  
Jian Dong Shang ◽  
Jun Qi Guo ◽  
Dong Fang Hu
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Great Influence ◽  
Element Model ◽  
Mode Shapes ◽  
Machining Accuracy ◽  
Element Analysis ◽  
Modes Of Processing

The vibration is a high-precision machine tool components in the design of the major issues, facing its precision has a great influence, so column parts of its modal analysis is necessary. Creating three-dimensional finite element model of the column, using finite element analysis software ANSYS modal analysis of the column, which can reached the first five natural frequencies and mode shapes. Column Part of our understanding of dynamic performance and improve the machining accuracy is helpful. Modal analysis method is the dynamic performance of the column on the main approach, which mainly is to determine the vibration characteristics of the column that is the natural frequency and vibration mode, which we can determine the modes of processing accuracy, and thus the relevant parts of the machine column can be optimized so that it meet the requirements.

A detachable design method of large-sized structure for heavy duty machine tool based on joint surface dynamics characteristic analysis

2019 ◽  
Vol 233 (13) ◽  
pp. 4476-4489 ◽  
Author(s):  
Qiang Cheng ◽  
Baobao Qi ◽  
Zhifeng Liu ◽  
Guojun Zhang ◽  
Caixia Zhang ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Machine Tools ◽  
Design Method ◽  
Contact Stiffness ◽  
Joint Surface ◽  
Optimized Design ◽  
Heavy Duty ◽  
Characteristic Analysis ◽  
Structural Part ◽  
Stiffness And Damping

Heavy duty and ultra-heavy duty machine tools are used to manufacture large parts or super large parts in aerospace, ship, transportation, and energy industries. The weight of a structural part of ultra-heavy duty machine tools will reach more than 100 tons, because of which both manufacturing and transportation become very difficult. In this paper, a detachable design method for large-sized structures of heavy duty machine tools is presented. The proposed method aims to make large-sized structure into several detachable sections that can be bolted together in order to be casted and transported and remanufactured more easily. To analyze the influence of the joint surface, a three-dimensional fractal contact model based on the influence of domain expansion factor is used to identify stiffness and damping of the joint surface. On the basis of the analysis of the dependence of contact stiffness and damping of joint surface on dynamic characteristics of structural part, a detachable optimization model of a super span beam is established, and the particle swarm optimization algorithm is adopted to carry out the optimization. After that, the dynamic characteristics of the optimized design is analyzed and verified by finite element analysis. Based on the simulated verification, a detachable beam of heavy duty gantry machine was designed by the proposed method and verified by the field test. The illustration example shows that the large span beam can be detached into three sections that can be bolted together by high strength bolts, and it also has satisfied performance.

Modal Analysis on the Inclined Double-Column and Pre-Stress Combined Frame Structure of the 80MN Rapid Forging Hydraulic Press

2011 ◽  
Vol 317-319 ◽  
pp. 484-488
Author(s):  
Yi Gong Zhang ◽  
Hong Hong Yan ◽  
Zhi Qi Liu ◽  
Jian Li Song ◽  
Yong Tang Li
Keyword(s):  
Modal Analysis ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Noise Pollution ◽  
Hydraulic Press ◽  
Structure Design ◽  
Frame Structure ◽  
Mode Shapes ◽  
The Impact

In this paper, the first 80MN rapid forging hydraulic press in China was developed. The inclined double-column and pre-stress combined frame structure and the direct Pump-driven technologies were adopted for the first time in the design of this press. The linkage driving with the full-hydraulic orbital manipulator has been realized. A rapid forging frequency of 75~80 /min and a finishing precision of ±1mm for hot-state forgings can be obtained. The three dimensional full-contact solid model of the double-column combined frame structure of the 80 MN rapid forging hydraulic press has been set up. The modal analysis of the pre-tightened frame has been carried out with the FEM analysis software ANSYS. The first five-order inherent frequencies and the corresponding natural modes have been obtained, the mode shapes of various orders have also been analyzed in detail. It is shown from the research results that the inherent frequency of the frame is larger than the impact frequency. Therefore, resonant vibration of the structure will not occur. The analysis results will have an important significance for the understanding of the dynamic performance of the rapid forging hydraulic press, optimization of the structure design of the press and the decrease of vibration and noise pollution.

Modeling and analysis of a bolted joint under tension and shear loads

2019 ◽  
Vol 43 (3) ◽  
pp. 376-386
Author(s):  
Mohamed Tahar Nasraoui ◽  
Jamel Chakhari ◽  
Boubaker Khalfi ◽  
Mustapha Nasri
Keyword(s):  
Stiffness Matrix ◽  
Contact Stiffness ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Contact Layer ◽  
Contact Forces ◽  
Bolted Joint ◽  
Modeling And Analysis ◽  
Shear Loads ◽  
Applied Forces

In this paper, a prismatic bolted joint subjected to tensile and shear loads is studied. The two applied forces are in the same symmetry plane of the connection. A simplified numerical model is developed, which is constructed from unidirectional finite elements and contact elements. The elastic contact layer of connected parts is represented by a succession of springs. An algorithm computing both the free structure stiffness matrix and the contact stiffness matrix is developed. Due to the shear load, static or kinetic friction can occur at contact surfaces between assembled parts. In each iteration, tangential contact forces are calculated and taken into account in problem solving. A program in C language is developed and used to calculate the model unknowns. Three-dimensional finite element simulations are performed using ANSYS software to verify results obtained by the developed model. The model results are also compared with experimental test data.

scholarly journals Interval estimation for contact stiffness of bolted joint with uncertain parameters

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988370 ◽  
Author(s):  
Yongsheng Zhao ◽  
Hongchao Wu ◽  
Congbin Yang ◽  
Zhifeng Liu ◽  
Qiang Cheng
Keyword(s):  
Fractal Dimension ◽  
Contact Surface ◽  
Contact Stiffness ◽  
Interval Estimation ◽  
Roughness Parameter ◽  
Normal Pressure ◽  
Bolted Joints ◽  
Uncertain Parameters ◽  
Fractal Parameters ◽  
Fractal Roughness

Bolted joints are elements used to create resistant assemblies in the mechanical system, whose overall performance is greatly affected by joints’ contact stiffness. Most of the researches on contact stiffness are based on certainty theory whereas in real applications the uncertainty characterizes the parameters such as fractal dimension D and fractal roughness parameter G. This article presents an interval estimation theory to obtain the stiffness of bolted joints affected by uncertain parameters. Topography of the contact surface is fractal featured and determined by fractal parameters. Joint stiffness model is built based on the fractal geometry theory and contact mechanics. Topography of the contact surface of bolted joints is measured to obtain the interval of uncertain fractal parameters. Equations with interval parameters are solved to acquire the interval of contact stiffness using the Chebyshev interval method. The relationship between the interval of contact stiffness and the uncertain parameters, that is, fractal dimension D, fractal roughness parameter G, and normal pressure, can be obtained. The presented model can be used to estimate the interval of stiffness for bolted joints in the mechanical systems. The results can provide theoretical reference for the reliability design of bolted joints.

Dynamic Performance Analysis for Milling Head Box of Spiral Drill Collar Machine

2012 ◽  
Vol 605-607 ◽  
pp. 1236-1239
Author(s):  
Ke Wang ◽  
Yu Xiao Song ◽  
Xing Wei Sun
Keyword(s):  
3D Model ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Machining Process ◽  
Practical Significance ◽  
Mode Shapes ◽  
Element Analysis ◽  
Box Structure ◽  
Dynamic Performance Analysis ◽  
Drill Collar

Milling head box is an important supporting part of spiral drill collar machine. Its dynamic performance has a big effect to the machine tool working accuracy. The three-dimensional (3D) model of milling head box was built in this paper. With finite element analysis software, the dynamic performance of the box was analyzed. The first six natural frequencies, relevant vibrations and mode shapes of the box were obtained. The results indicate that the milling head box structure is reasonable. No resonance will be induced during the machining process. It also provides thoughts and reference for further dynamic performance researches with practical significance.

scholarly journals Contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions

Friction ◽  
2021 ◽  
Author(s):  
Zongzheng Wang ◽  
Wei Pu ◽  
Xin Pei ◽  
Wei Cao
Keyword(s):  
Contact Stiffness ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Dry Contact ◽  
Spiral Bevel ◽  
Stiffness And Damping ◽  
Lubrication Conditions ◽  
Film Lubrication

AbstractExisting studies primarily focus on stiffness and damping under full-film lubrication or dry contact conditions. However, most lubricated transmission components operate in the mixed lubrication region, indicating that both the asperity contact and film lubrication exist on the rubbing surfaces. Herein, a novel method is proposed to evaluate the time-varying contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions. This method is sufficiently robust for addressing any mixed lubrication state regardless of the severity of the asperity contact. Based on this method, the transient mixed contact stiffness and damping of spiral bevel gears are investigated systematically. The results show a significant difference between the transient mixed contact stiffness and damping and the results from Hertz (dry) contact. In addition, the roughness significantly changes the contact stiffness and damping, indicating the importance of film lubrication and asperity contact. The transient mixed contact stiffness and damping change significantly along the meshing path from an engaging-in to an engaging-out point, and both of them are affected by the applied torque and rotational speed. In addition, the middle contact path is recommended because of its comprehensive high stiffness and damping, which maintained the stability of spiral bevel gear transmission.

scholarly journals Identification of Mode Shapes of a Composite Cylinder Using Convolutional Neural Networks

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2801
Author(s):  
Bartosz Miller ◽  
Leonard Ziemiański
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Composite Structures ◽  
Three Dimensional ◽  
Mode Shapes ◽  
Identification Algorithm ◽  
Material Degradation ◽  
Local Material ◽  
Noisy Input ◽  
Shape Vector

The aim of the following paper is to discuss a newly developed approach for the identification of vibration mode shapes of multilayer composite structures. To overcome the limitations of the approaches based on image analysis (two-dimensional structures, high spatial resolution of mode shapes description), convolutional neural networks (CNNs) are applied to create a three-dimensional mode shapes identification algorithm with a significantly reduced number of mode shape vector coordinates. The CNN-based procedure is accurate, effective, and robust to noisy input data. The appearance of local damage is not an obstacle. The change of the material and the occurrence of local material degradation do not affect the accuracy of the method. Moreover, the application of the proposed identification method allows identifying the material degradation occurrence.

A Nonlinear Rail Vehicle Dynamics Computer Program SAMS/Rail: Part 1—Theory and Formulations

2009 ◽  
Author(s):  
Khaled E. Zaazaa ◽  
Brian Whitten ◽  
Brian Marquis ◽  
Erik Curtis ◽  
Magdy El-Sibaie ◽  
...  
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Contact Element ◽  
Contact Forces ◽  
Simulation Code ◽  
Vehicle Performance ◽  
Normal Contact ◽  
Advantages And Disadvantages ◽  
High Speed Trains

Accurate prediction of railroad vehicle performance requires detailed formulations of wheel-rail contact models. In the past, most dynamic simulation tools used an offline wheel-rail contact element based on look-up tables that are used by the main simulation solver. Nowadays, the use of an online nonlinear three-dimensional wheel-rail contact element is necessary in order to accurately predict the dynamic performance of high speed trains. Recently, the Federal Railroad Administration, Office of Research and Development has sponsored a project to develop a general multibody simulation code that uses an online nonlinear three-dimensional wheel-rail contact element to predict the contact forces between wheel and rail. In this paper, several nonlinear wheel-rail contact formulations are presented, each using the online three-dimensional approach. The methods presented are divided into two contact approaches. In the first Constraint Approach, the wheel is assumed to remain in contact with the rail. In this approach, the normal contact forces are determined by using the technique of Lagrange multipliers. In the second Elastic Approach, wheel/rail separation and penetration are allowed, and the normal contact forces are determined by using Hertz’s Theory. The advantages and disadvantages of each method are presented in this paper. In addition, this paper discusses future developments and improvements for the multibody system code. Some of these improvements are currently being implemented by the University of Illinois at Chicago (UIC). In the accompanying “Part 2” and “Part 3” to this paper, numerical examples are presented in order to demonstrate the results obtained from this research.

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