Viscous Friction Effect During the Process of Tightening and Loosening of Bolted Joints

2021 ◽  
Author(s):  
Qingyuan Lin ◽  
Yong Zhao ◽  
Qingchao Sun ◽  
Kunyong Chen
Keyword(s):  
Friction Coefficient ◽  
Viscous Friction ◽  
Normal Pressure ◽  
Friction Model ◽  
Bolted Joints ◽  
Critical Parameters ◽  
Bolted Joint ◽  
Sliding Velocity ◽  
Friction Effect ◽  
Bearing Friction

Abstract Bolted connection is one of the most widely used mechanical connections because of its easiness of installation and disassembly. Research of bolted joints mainly focuses on two aspects: high precision tightening and improvement of anti-loosening performance. The under-head bearing friction coefficient and the thread friction coefficient are the two most important parameters that affect the tightening result of the bolted joint. They are also the most critical parameters that affect the anti-loosening performance of the bolted joint. Coulomb friction model is a commonly used model to describe under-head bearing friction and thread friction, which considers the friction coefficient as a constant independent of normal pressure and relative sliding velocity. In this paper, the viscous effect of the under-head bearing friction and thread friction is observed by measuring the friction coefficient of bolted joints. The value of the friction coefficient increases with the increase of the relative sliding velocity and the decrease of the normal pressure. It is found that the Coulomb viscous friction model can better describe the friction coefficient of bolted joints. Taking into account the dense friction effect, the loosening prediction model of bolted joints is modified. The experimental results show that the Coulomb viscous friction model can better describe the under-head bearing friction coefficient and thread friction coefficient. The model considering the dense effect can more accurately predict the loosening characteristics of bolted joints.

Numerical Investigation of Size Effect on Dry Friction Behavior in Micro Upsetting Process

2014 ◽  
Vol 997 ◽  
pp. 321-324
Author(s):  
Wei Zheng ◽  
Guang Chun Wang ◽  
Bing Tao Tang ◽  
Xiao Juan Lin ◽  
Yan Zhi Sun
Keyword(s):  
Friction Coefficient ◽  
Size Effect ◽  
Dry Friction ◽  
Normal Pressure ◽  
Friction Model ◽  
Strain Hardening Exponent ◽  
Forming Process ◽  
Friction Behavior ◽  
Initial Yield Stress ◽  
Coulomb’S Friction

After modifying the Wahime/Bay friction model, a new friction model suitable for micro-forming process without lubrication is established. In this model, it is shows that the friction coefficient is a function of strain hardening exponent, the normal pressure and the initial yield stress of material. Based on the experimental data, the micro-upsetting process is simulated using the proposed friction model. The simulation results are used to investigate the size effect on the dry friction behavior. It is found that the Coulomb’s friction coefficient is dropping with miniaturization of specimens when the amount of reduction is not too large.

Thread Friction Torque in Bolted Joints

2005 ◽  
Vol 127 (4) ◽  
pp. 387-393 ◽  
Author(s):  
Sayed A. Nassar ◽  
Payam H. Matin ◽  
Gary C. Barber
Keyword(s):  
Friction Coefficient ◽  
Current Practice ◽  
Weighted Average ◽  
High Accuracy ◽  
Friction Torque ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Average Value ◽  
Highly Sensitive

In this paper, formulas are developed for the calculation of the effective thread friction radius in fasteners, in order to determine the thread friction torque component. Due to the lack of exact formulas in the literature, current practice uses the average value of the minor and major thread radii, as an approximation, for determining the thread friction torque component. Results provided by these formulas are compared with those given by the current practice that uses the average value of the minor and major thread radii, instead of the exact value. It is well known that the torque-tension relationship in threaded fastener applications is highly sensitive to the friction torque components: between threads, and under the turning fastener head or nut. Even moderate variations or inaccuracies in determining the friction torque components would significantly impact the fastener tension and the joint clamp load. High accuracy in the estimation of the friction torque components is critical, as it directly affects the reliability, safety, and the quality of bolted assemblies. This analysis focuses on the thread friction torque component. The new formulas for the thread friction radius are developed for a mathematical model of a bolted joint using five assumed scenarios of the contact pressure between male and female threads. Because of the fact that the variation in the sliding speed of various points on a thread surface is insignificant, a uniform thread friction coefficient is used in the analysis. However, a contact area weighted average value is used for the thread friction coefficient. Numerical results and error analysis are presented in terms of a single nondimensional variable, namely, the ratio between the major and minor thread radii.

An Experimental Investigation on Frictional Properties of Bolted Joints

2002 ◽  
Author(s):  
Yanyao Jiang ◽  
Ming Zhang ◽  
Tae-Won Park ◽  
Chu-Hwa Lee
Keyword(s):  
Experimental Investigation ◽  
Contact Area ◽  
Direct Determination ◽  
Organic Coating ◽  
Bolted Joints ◽  
Marginal Effect ◽  
Bolted Joint ◽  
Bearing Surface ◽  
Frictional Properties ◽  
Bearing Friction

By using an approach developed to determining the torque-tension relationship for bolted joints, frictional properties of several typical bolted joints were studied experimentally. The approach allows for the direct determination of the thread friction and the bearing friction between the nut and its bearing surface independently. Detailed studies were made on the influences of the size and shape of the hole, the use of a slot in a bolted joint, contact area and position, and other factors such as turning speed, coating, and the use of wax on the bearing surface. The contact area and position of the washer have a marginal effect on the bearing friction. The organic coating on the nuts reduces the bearing friction significantly. Nuts with organic coating over a washer with zinc finish provide the smallest and the most consistent bearing friction. Experiments on thread friction shows that prevailing torque nuts with distorted threads and nylon inserts provided trivial benefits for preventing “self-loosening” of the nut. Repeated tightening-loosening generally increases frictions in a bolted joint. It was noted that the data scatter of the experimental results of frictions in a bolted joint may overshadow the influence of size, speed, and contact positions. The results from the experimental investigation will help to better design bolted joints.

On the Modeling of Quasi-Steady and Unsteady Dynamic Friction in Sliding Lubricated Line Contact

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
H. Sojoudi ◽  
M. M. Khonsari
Keyword(s):  
Experimental Data ◽  
Friction Coefficient ◽  
Reynolds Equation ◽  
Friction Model ◽  
Sliding Contact ◽  
Dynamic Friction ◽  
Line Contact ◽  
Sliding Velocity ◽  
Friction Behavior ◽  
Lubricated Sliding

A simple but realistic dynamic friction model for the lubricated sliding contact is developed based on decoupling the steady and unsteady terms in Reynolds equation. The model realistically captures the physics of friction behavior both when speed is increased unidirectionally or when operating under oscillating condition. The model can simulate the transition from boundary to mixed to full film regimes as the speed is increased. Two different classes of simulations are performed to show the utility of the model: the so-called quasisteady, where the sliding velocity is varied very slowly, and the oscillating sliding velocity, where the friction coefficient exhibits a hysteresis type behavior. Both categories of simulation are verified by comparing the results with published experimental data.

Bolted Joints Modeling Techniques, Analytical, Stochastic and FEA Comparison

2012 ◽  
Author(s):  
Yosef Amir ◽  
S. Govindarajan ◽  
Saravanakumar Iyyanar
Keyword(s):  
Analytical Method ◽  
Failure Modes ◽  
Extreme Values ◽  
Bolted Joints ◽  
Critical Parameters ◽  
Stochastic Methods ◽  
Bolted Joint ◽  
Advantages And Disadvantages ◽  
Parameter Variations ◽  
Modeling Techniques

Bolted joints Design analyses are in general, very complex and it is very difficult to find a single technique to study the complete behavior of the bolted joints. The most popular analytical method is the well-known VDI 2230 which addresses most of the cases very well. This analytical method uses extreme values for critical parameter variations and is considered to be conservative, but the quickest method. Stochastic analysis is a more advanced method where variations in critical parameters are modeled as statistical distributions and Monte Carlo simulations allow predicting the behaviors of bolted joints through selective parameter variations. Finite element analysis of bolted joints is another methodology to analyze complex bolted joint designs. Though advances in FE modeling techniques help to model bolted joints more accurately, different failure modes require different modeling techniques. For practical complex bolted joints design analysis, a hybrid of analytical and different FEA models is needed for a full analysis; but a combination of FEA techniques can be used to study any bolted joint in detail for all the failure modes. Hence, it is important to study and understand the limitations of each of the modeling techniques. This paper looks at analytical and stochastic methods of bolted joints as well as three different FEA methods — 3D, Axisymmetric and Beam & Rigid Spider — to study different failure modes. Parametric (DOE) FEA simulation technique for variation parameters bolted joint behavior prediction was investigated; this paper examined the DOE parameter of coefficient of friction. A general case study is used as benchmark for comparison between the techniques and to quantify the advantages and disadvantages of each method.

Cutting performance investigation based on the variable friction model by considering sliding velocity and limiting stress

2020 ◽  
Vol 234 (8) ◽  
pp. 1113-1123
Author(s):  
Xin Li ◽  
Zhenyu Shi ◽  
Ningmin Duan ◽  
Peng Cui ◽  
Shuai Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
Cutting Force ◽  
Element Model ◽  
Friction Model ◽  
Rake Face ◽  
Sliding Velocity ◽  
Variable Friction ◽  
Simulation Results

Fast and accurate cutting force prediction is still one of the most complex problems and challenges in the machining research community. In this study, a modified finite element model is presented to predict cutting force and cutting length in turning operations of AISI 1018. Unlike the existing research, in which the mean friction coefficient μ was taken, a variable friction coefficient μ involving the sliding velocity between chip and tool is presented in this article. The sticking–sliding friction model is adopted, and the maximum limiting stress in sticking region is calculated by considering the thermal softening and normal stress distribution. Experiments have been performed for machining AISI 1018 using tungsten carbide tool, and simulation results have been compared to experiments. The simulation results of the modified finite element model have shown better outputs in predicting cutting force, tangential force, and tool–chip contact length on the rake face. The results of this article not only are meaningful to optimize tool design and cutting parameters but also can provide a clear understanding of contact behavior between tool rake face and chip.

scholarly journals Bolted Joint Preload Distribution from Torque Tightening

2021 ◽  
Vol 71 (2) ◽  
pp. 329-342
Author(s):  
Welch Michael
Keyword(s):  
Friction Coefficient ◽  
Static Friction ◽  
Bolted Joints ◽  
Dynamic Friction ◽  
Bolted Joint ◽  
Classical Analysis ◽  
Joint Design ◽  
Static Friction Coefficient ◽  
Bolt Preload ◽  
Torque Wrench

Abstract The purpose of this paper is to develop an understanding of how bolt preloads are distributed within a joint as each bolt is tightened in turn by the use of a calibrated torque wrench. It discusses how the order that the joints nuts/bolts are tightened can affect the final bolt preload. It also investigates the effect on incrementally increasing the bolt preload through a series of applications of the controlled torque tightening sequence. Classical analysis methods are used to develop a method of analysis that can be applied to most preloaded bolted joints. It is assumed that the static friction coefficient is approximately 15% less than the dynamic friction. It is found that the bolt preload distribution across the joint can range from slightly above the target preload to significantly less than the target preload. The bolts with a preload greater than the target preload are found to be those tightened towards the end of the tightening sequence, usually located close to the outer edges of the joint’s bolt array. The bolts with a preload less than the target preload are those tightened early in the tightening sequence, located centrally within the joints bolt array. The methods presented can be used to optimise bolted joint design and assembly procedures. Optimising the design of preloaded bolted joints leads to more efficient use of the joints.

Analysis of Dual Mass Flywheel Using Discrete Arcspring Model

2006 ◽  
Vol 326-328 ◽  
pp. 1607-1610 ◽  
Author(s):  
Tae Hyun Kim ◽  
Han Lim Song ◽  
Sung Ho Hwang ◽  
Hyun Soo Kim
Keyword(s):  
Viscous Friction ◽  
Friction Model ◽  
Experimental Result ◽  
Nonlinear Friction ◽  
Sliding Velocity ◽  
Discrete Elements ◽  
Stribeck Effect ◽  
Mass Spring ◽  
Friction Surfaces ◽  
Test Result

This paper presents a discrete analysis approach to investigate performance of the DMF. An arcspring installed between the flywheels is modeled as n - discrete elements. Each element consists of mass, spring and nonlinear friction element. The nonlinear friction model is proposed to describe Stribeck effect and viscous friction depending on the relative sliding velocity. The DMF performance such as hysterisis characteristics are investigated by comparing the experimental result. In addition, the torque characteristics transmitted to the driveshaft are evaluated by comparing the test result from manual transmission bench tester. It is found that discrete DMF model described the automotive driveline behavior closely. It is also found that the friction characteristics of the arcspring depends on the relative sliding velocity between the friction surfaces, which varies depending on the relative position of the DMF arcspring.

Research on Self-Loosening Mechanism of Bolted Joints Under Transversal Vibration

2014 ◽  
Author(s):  
Wei Wang ◽  
Qingli Wang ◽  
Shuai Zheng ◽  
Xiaowei Liu ◽  
Haiping Liu
Keyword(s):  
Friction Coefficient ◽  
Three Dimensional ◽  
Surface Friction ◽  
The Self ◽  
Bolted Joints ◽  
Friction Coefficients ◽  
Cyclic Shear ◽  
Transversal Vibration ◽  
Thread Pitch ◽  
Bearing Friction

Bolted joints are widely used in the auto industry, energy field and Construction, and so on. Due to the wide use of the bolted joints, the degradation of bolts has significant effect on the performance of a whole machine. Under transversal vibration, the self-loosening of bolted joints, which is the biggest form of failure ranked only second to fatigue failure [1], will happen, due to the cyclic shear load. This paper is to study the mechanism of bolted joints’ self-loosening. Aiming at analyzing the self-loosening mechanism of bolted joints under vibration, a three dimensional FEA model of bolted joints, which had taken thread into consideration, was built with the application of APDL, and the preload was applied on the bolted joints by dropping temperature, then FEA transient analysis of the bolted joints under transverse cyclic excitation was conducted. Effect of transverse cyclic excitation’s amplitude, initial preload, thread and bearing friction coefficients, the joints’ surface friction coefficient, the thread pitch and the hole clearance on self-loosening was investigated. The results show that the complete thread slip occurs prior to the complete bearing surface slip under transverse vibration; the smaller amplitude, the smaller thread pitch and the smaller hole clearance is, and the greater initial preload, thread and bearing friction coefficients are, the more difficult self-loosening is to happen; the joints’ surface friction coefficient has little relationship with self-loosening, however, the larger joints’ surface friction coefficient makes the needed shearing force, which induces the transversal vibration, larger. These are of great significance for understanding of fasteners’ self-loosening and designing of bolted joints’ anti-loosening.

Thread Friction Torque in Bolted Joints

2004 ◽  
Author(s):  
Sayed A. Nassar ◽  
Payam H. Matin ◽  
Gary C. Barber
Keyword(s):  
Friction Coefficient ◽  
Current Practice ◽  
Weighted Average ◽  
Friction Torque ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Average Value ◽  
Highly Sensitive ◽  
Dimensional Variable

In this paper, formulas are developed for the calculation of the effective thread friction radius in fasteners, in order to determine the thread friction torque component. Results provided by these formulas are compared with those given by current practice that uses the average value of the minor and major thread radii. It is well known that the torque-tension relationship in threaded fastener applications is highly sensitive to the friction torque components: between threads, and under the turning fastener head or nut. Even moderate variations or inaccuracies in determining the friction torque components would significantly impact the fastener tension and the joint clamp load. This makes critical the accuracy in the estimation of the friction torque components, as it directly affects the reliability, safety, and the quality of bolted assemblies, especially in critical applications. This analysis focuses on the thread friction torque component. The new formulas for the thread friction radius are developed for a mathematical model of a bolted joint using three assumed scenarios of the contact pressure between male and female threads. Because of the fact that the variation in the sliding speed of various points on thread surface is insignificant, a uniform thread friction coefficient is used in the analysis. However, a contact area weighted average value is used for the thread friction coefficient. Numerical results and error analysis are presented in terms of a single non-dimensional variable; namely, the ratio between the major and minor thread radii.

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