Self-Loosening Behavior of the Nut Due to Tension Change Considering the Inclination of Bearing Surface

2021 ◽  
Author(s):  
Yasumasa Shoji
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Relative Displacement ◽  
The Self ◽  
The Other ◽  
Transverse Load ◽  
Finite Element Analyses ◽  
Bearing Surface ◽  
Tension Change ◽  
Surface Inclination

Abstract Self-loosening behavior is a topic which many researchers are tackling and the principle is coming clearer. Self-loosening occurs mainly when transverse load is applied to the bolt/nut system and the loosening also occurs when such other loads are applied as impact of the bolt (NAS3350 test type) or temperature difference between bolt and nut. The author reproduced the phenomena by using finite element analyses and found the self-loosening is caused by radial relative displacement between bolt and nut threads. On the other hand, some researchers say the self-loosening occur when the tension changes repeatedly while others say it doesn’t. This axial force phenomenon is not yet clear even in experiment. In this paper, the self-loosening phenomenon by the tension change is examined using Finite Element Analyses. The results show that the self-loosening depends on the inclination of the bearing surface. The loosening does not occur when the inclination of the bearing surface is small enough and it occurs when the inclination is large. As the inclination of the bolt head and nut is allowed within the engineering tolerance and flanges rotate when it fastened making the bolt head or nut bearing surface inclination, the self-loosening may happen for any bolts in nature if tension changes repeatedly.

Effect of Friction Coefficients Regarding Bolt Self-Loosening

2020 ◽  
Author(s):  
Yasumasa Shoji
Keyword(s):  
Finite Element ◽  
Torque Control ◽  
Tension Control ◽  
Friction Reduction ◽  
The Other ◽  
Finite Element Analyses ◽  
Bearing Surface ◽  
Friction Coefficients ◽  
Male And Female ◽  
Other Hand

Abstract As there have been many researches for bolt self-loosening and a lot of knowledge have been accumulated, the phenomena has been understood more and more clearly. On the other hand, it is quite difficult to achieve both non-self-loosening and easy bolting tasks. In practical situations, easy and stable bolting is more focused and torque control is employed for tension control in the fields. For the stable bolting, friction of the threads is reduced by lubrication. However, the effect of this friction reduction is not yet investigated in the aspect of self-loosening. In this paper, the effect of frictions between male and female threads and between nut and bearing surface is investigated by FEA simulations. This provides information how self-loosening can be controlled. In this paper, the motion of the fastened plate transverse to the bolt axis is considered. This motion is known as the easiest motion to make self-loosening in experience and also as shown so in the author’s previous researches. The friction seems to increase self-loosening and also decrease self-loosening at the same time. It seems that the friction on the bearing surface drives self-loosening and friction on the thread surfaces prevents it. In this paper, both the frictions are examined in the relative manner with the Finite Element Analyses.

An Experimental Investigation of the Effects of Clamped Length and Loading Direction on Self-Loosening of Bolted Joints

2004 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Experimental Investigation ◽  
Fatigue Curve ◽  
Relative Displacement ◽  
The Self ◽  
Bolted Joints ◽  
Transverse Load ◽  
External Loading ◽  
Loading Direction ◽  
Controlling Parameter ◽  
Load Carrying

An experimental investigation was conducted to study the effects of clamped length and loading direction on the self-loosening behavior of bolted joints. Specially designed fixtures were used for the study. The experiments mimicked two plates jointed by an M12×1.75 Class 10.9 bolt and a nut. The joints were subjected to cyclic external loading. A constant preload of 25 kN was used for all the experiments conducted. During an experiment, the relative displacement between the two clamped plates, δ, was a controlling parameter. The reduction in clamping force, the applied transverse load, and the nut rotation were measured cycle by cycle. The relationship between, Δδ/2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening is referred to as self-loosening curve and was obtained for different clamped lengths and applied load directions. Similar to a fatigue curve, an endurance limit can be identified from the self-loosening curve. It was found that increasing the clamped length can enhance the self-loosening endurance limits in terms of the controlled relative displacement of the two clamped plates. However, the load carrying capability was not influenced significantly due to the thickness of the clamped plates. For a given bolted jointed structure, an angle of the external load from the pure shearing direction resulted in an increase in self-loosening resistance.

A Study of the Conservatism in ASME BPVC Section VIII Division 2 Opening Design for External Pressure

2019 ◽  
Author(s):  
Barry Millet ◽  
Kaveh Ebrahimi ◽  
James Lu ◽  
Kenneth Kirkpatrick ◽  
Bryan Mosher
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
External Pressure ◽  
The Other ◽  
Finite Element Analyses ◽  
Division 1 ◽  
Section Viii ◽  
Allowable Compressive Stress ◽  
Division 2

Abstract In the ASME Boiler and Pressure Vessel Code, nozzle reinforcement rules for nozzles attached to shells under external pressure differ from the rules for internal pressure. ASME BPVC Section I, Section VIII Division 1 and Section VIII Division 2 (Pre-2007 Edition) reinforcement rules for external pressure are less stringent than those for internal pressure. The reinforcement rules for external pressure published since the 2007 Edition of ASME BPVC Section VIII Division 2 are more stringent than those for internal pressure. The previous rule only required reinforcement for external pressure to be one-half of the reinforcement required for internal pressure. In the current BPVC Code the required reinforcement is inversely proportional to the allowable compressive stress for the shell under external pressure. Therefore as the allowable drops, the required reinforcement increases. Understandably, the rules for external pressure differ in these two Divisions, but the amount of required reinforcement can be significantly larger. This paper will examine the possible conservatism in the current Division 2 rules as compared to the other Divisions of the BPVC Code and the EN 13445-3. The paper will review the background of each method and provide finite element analyses of several selected nozzles and geometries.

An Experimental Investigation of the Effects of Clamped Length and Loading Direction on Self-Loosening of Bolted Joints

2005 ◽  
Vol 128 (3) ◽  
pp. 388-393 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Experimental Investigation ◽  
Fatigue Curve ◽  
Relative Displacement ◽  
The Self ◽  
Bolted Joints ◽  
Transverse Load ◽  
External Loading ◽  
Loading Direction ◽  
Controlling Parameter ◽  
Load Carrying

An experimental investigation was conducted to study the effects of clamped length and loading direction on the self-loosening behavior of bolted joints by using specially designed fixtures. The experiments mimicked two plates jointed by an M12×1.75 class 10.9 bolt and a nut. The joints were subjected to cyclic external loading. A constant preload of 25kN was used for all the experiments conducted. During an experiment, the relative displacement between the two clamped plates, δ, was a controlling parameter. The reduction in clamping force, the applied transverse load, and the nut rotation were measured cycle by cycle. The relationship between, Δδ∕2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening is referred to as self-loosening curve and was obtained for different clamped lengths and applied load directions. Similar to a fatigue curve, an endurance limit can be identified from the self-loosening curve. It was found that increasing the clamped length can enhance the self-loosening endurance limits in terms of the controlled relative displacement of the two clamped plates. However, the load carrying capability was not influenced significantly due to the thickness of the clamped plates. For a given bolted jointed structure, an angle of the external load from the pure shearing direction resulted in an increase in self-loosening resistance.

Loosening Resistance Evaluation of Double-Nut Tightening Method, Spring Washers, and Conical Spring Washers: Finite Element Study

2008 ◽  
Author(s):  
Takashi Yokoyama ◽  
Satoshi Izumi ◽  
Shinsuke Sakai
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Rotation Angle ◽  
Three Dimensional ◽  
Bearing Surface ◽  
Surface Slip ◽  
Dimensional Finite Element ◽  
Negative Effect ◽  
Three Dimensional Finite Element ◽  
Positive Effect

The mechanisms of loosening resistance components are investigated within the framework of the three-dimensional finite element method (FEM). Here, the results of the double-nut tightening method (DN), spring washers (SW), and conical spring washers (CSW) are shown. This paper focuses on the comparison among the components above based on the results that have been published separately. For details on each analysis, readers are referred to [10–12]. We have found that DN shows significant loosening resistance if the locking is properly realized in the tightening process. However, if the locking is not performed properly, its ability to resist loosening completely disappears. SW shows negative loosening resistance because the sticking area on the contact surfaces is limited to two corner edges of the SW and the rotational force around these edges thus drastically leads to loosening. In regard to CSW, in the case of high axial force, it shows no apparent effect on preventing loosening. On the other hand, in the case of low axial force, it shows two opposite effects. The negative effect is an increase in the loosening rotation angle, while the positive one is the prevention of a decrease in axial force. When complete bearing-surface slip occurs, a CSW can prevent loosening because the positive effect becomes larger than the negative one. However, when only small bearing-surface slip occurs, a CSW cannot prevent loosening because the negative effect cancels the positive one.

scholarly journals Preliminary Finite Element Analysis of Locomotive Crashworthy Components

2011 ◽  
Author(s):  
Patricia Llana ◽  
Richard Stringfellow
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Energy Management ◽  
New Technologies ◽  
The Other ◽  
Finite Element Models ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Passenger Trains ◽  
Deformation Modes

The Office of Research and Development of the Federal Railroad Administration (FRA) and the Volpe Center are continuing to evaluate new technologies for increasing the safety of passengers and operators in rail equipment. In recognition of the importance of override prevention in train-to-train collisions in which one of the vehicles is a locomotive, and in light of the success of crash energy management technologies in cab car-led passenger trains, the Volpe Center seeks to evaluate the effectiveness of components that could be integrated into the end structure of a locomotive that are specifically designed to mitigate the effects of a collision and, in particular, to prevent override of one of the lead vehicles onto the other. A research program is being conducted that aims to develop, fabricate and test two crashworthy components for the forward end of a locomotive: (1) a deformable anti-climber, and (2) a push-back coupler. Preliminary designs for these components have been developed. This paper provides details on the finite element models of the crashworthy components and how the component designs behave in the finite element analyses. The component designs will be evaluated to determine if the requirements have been met, such as the energy absorption capability, deformation modes, and force/crush characteristics.

Computational Modeling for the Dynamic Simulation of Paper and its Application to Some Paper Handling Problems

1998 ◽  
Author(s):  
Shinya Sekimoto ◽  
Makoto Ukai
Keyword(s):  
Finite Element ◽  
Rigid Wall ◽  
The Self ◽  
Bending Test ◽  
Flexible Plate ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Linear Finite Element ◽  
The Finite Element Analysis ◽  
Simulation Results

Abstract This paper deals with the paper handling problems in highspeed labor saving machines. Non-linear finite element analyses are done for a lightweight and flexible plate or beam leaping from a sliding constraint and colliding against a rigid wall. The fluid force of air and the paper elasticity are taken into account. The elastic property of paper is identified by comparing the “self-bending test” and the finite element analysis. The effect of geometrical stiffness with an initial deformation is studied. The change of the flying orbit is shown with flat paper and geometrically stiffened paper. The behavior of paper after colliding against a rigid wall is also simulated with the parameters of the paper velocity and the friction coefficient between the paper and the wall. The simulation results agree well with the designers’ experiences and help the designers design new machines with higher speed.

Numerical Analysis on Mechanical Property of Bolted Joint

2013 ◽  
Vol 834-836 ◽  
pp. 1459-1463
Author(s):  
Lihua Yang ◽  
Zhi Li ◽  
Lie Yu
Keyword(s):  
Mechanical Property ◽  
Finite Element ◽  
Numerical Analysis ◽  
Axial Force ◽  
Transverse Load ◽  
Clamping Force ◽  
Bolted Joint ◽  
Stress Strain ◽  
Contact Models

The bolted joint is the important fastening parts of structures. Its fatigue and self-loosing will affect the safety of the system. In this paper, the finite element contact models are built to analyze the mechanical property of bolted joint numerically. The stress, strain and clamping force when the bolted joint is subjected to preload, axial force and transverse load are investigated. The results show that the bolt is the most dangerous part of bolt-nut connected member. The clamping force of bolted joint will gradually lose with the increasing loading cycles of cyclic transverse load which generally explains the stress loosing rule of bolted joint.

The Slippage Analysis at Bearing Surface of Bolted Joints due to Cyclic Transverse Loads

2012 ◽  
Author(s):  
Linbo Zhu ◽  
Jun Hong ◽  
Guoqing Yang ◽  
Baotong Li ◽  
Zhaohui Yang
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
The Self ◽  
Bolted Joints ◽  
Fe Model ◽  
Bearing Surface ◽  
Transverse Loads ◽  
Thread Surface

Bolted joints are widely used in mechanical structures due to their easy installation and maintenance. However, self-loosening of bolted joints caused by cyclic transverse loads has remained unsolved. In this study, the parametric finite element (FE) model is established to simulate the self-loosening. The slippage state at bearing surface and thread surface is investigated based on the FE model. Moreover, the influences of transverse frequency, amplitude, friction coefficient and initial preload on residual preload are discussed under a certain amount of time; the variations in back-off angle of nut and residual preload with time are analyzed under multi transverse loops. The results show that thread surface undergoes complete slip prior to the bearing surface, which provides theoretical guidance for looseness-proof design of bolted joints to some degree. The FE model can also be used to design the initial preload and predict the connections life under given vibration environment.

Providing Freshmen with a Good “Starting-Block”

2019 ◽  
Vol 78 (1-2) ◽  
pp. 69-75 ◽  
Author(s):  
Mikaël De Clercq ◽  
Charlotte Michel ◽  
Sophie Remy ◽  
Benoît Galand
Keyword(s):  
The Self ◽  
The Other ◽  
Student Adjustment ◽  
Social Psychological ◽  
Pivotal Phase ◽  
Study Program ◽  
Study Task ◽  
The Social ◽  
Social Belonging ◽  
Intention To Persist

Abstract. Grounded in social-psychological literature, this experimental study assessed the effects of two so-called “wise” interventions implemented in a student study program. The interventions took place during the very first week at university, a presumed pivotal phase of transition. A group of 375 freshmen in psychology were randomly assigned to three conditions: control, social belonging, and self-affirmation. Following the intervention, students in the social-belonging condition expressed less social apprehension, a higher social integration, and a stronger intention to persist one month later than the other participants. They also relied more on peers as a source of support when confronted with a study task. Students in the self-affirmation condition felt more self-affirmed at the end of the intervention but didn’t benefit from other lasting effects. The results suggest that some well-timed and well-targeted “wise” interventions could provide lasting positive consequences for student adjustment. The respective merits of social-belonging and self-affirmation interventions are also discussed.

Sign in / Sign up

Export Citation Format

Share Document