scholarly journals Experimental investigation on self-loosening of a bolted joint under cyclical temperature changes

2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110394
Author(s):  
Oybek Maripjon Ugli Eraliev ◽  
Yi-He Zhang ◽  
Kwang-Hee Lee ◽  
Chul-Hee Lee
Keyword(s):  
Experimental Investigation ◽  
Stainless Steel ◽  
Temperature Variation ◽  
The Self ◽  
Experimental Results ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Temperature Changes ◽  
Threaded Fasteners ◽  
Bolt Preload

The most commonly used part in engineering fields is threaded fasteners. There are a lot of advantages of fasteners. One of them is that they can be easily disassembled and reused, but a bolted joint can loosen easily when a transversal load is applied. The clamp load of a bolted joint can also loosen slowly when subjected to repeated temperature changes. This paper presents an experimental investigation of the self-loosening of bolted joints under cyclical temperature variation. Experiments are carried out under several cyclical temperature changes with different bolt preloads. Rectangular threaded bolted joints with M12 × 1.75 bolts and nuts are tested in a specially designed testing apparatus. Material of bolt, nut, and plates is a stainless steel. The experimental results show that the high initial bolt preload may prevent the joint from self-loosening and the bolted joint has loosened significantly in the first cycle of temperature changes. From this investigation, the loosening of the bolted joint can be considered as a first stage self-loosening.

Criterion for Preventing Self-Loosening of Preloaded Countersunk Head Threaded Fasteners

2011 ◽  
Author(s):  
Amro M. Zaki ◽  
Sayed A. Nassar ◽  
Xianjie Yang
Keyword(s):  
Test Procedure ◽  
Analytical Formula ◽  
Threshold Value ◽  
Excitation Amplitude ◽  
The Self ◽  
Bolted Joint ◽  
Minimum Threshold ◽  
Threaded Fasteners ◽  
Bolt Preload ◽  
Bearing Friction

This study develops an analytical formula for determining the minimum initial preload required to prevent the self-loosening of preloaded countersunk fasteners that are subjected to cyclic transverse loading. The formula is based on mathematical modeling of the self-loosening behavior of the fastener. The accurate prediction of the minimum bolt preload required for preventing loosening would reliably enable the use of that minimum threshold preload as a primary locking feature in critical bolted joint applications. An experimental setup and test procedure is established to compare the model prediction with the experimental data. The focus of this paper is to investigate the effect of thread pitch, excitation amplitude, as well as the bearing friction coefficient on the threshold value of the bolt preload that would prevent loosening.

Mechanical Behavior of Rotational Screw Thread Loosening in Bolted Joints Under Repeated Temperature Changes

2008 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Mitsutoshi Ishimura ◽  
Yasumasa Shoji ◽  
Yusuke Fukuba
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Mechanical Behavior ◽  
Experimental Results ◽  
Bolted Joints ◽  
Screw Thread ◽  
Bolted Joint ◽  
Temperature Changes ◽  
Thermal Changes ◽  
The Difference

Bolted joints have been used in mechanical structures. However, loosening accidents sometimes happen under several types of loadings. Recently, some studies have been conducted on the screw thread loosening in bolted joints. It is verified that bolted joints are loosened when transverse repeated loadings are applied. A lot of parts for preventing the loosening in the joints have been proposed. Among these parts, eccentric nut is especially expected to be the solution for preventing the loosening. Some studies on no rotational loosening in bolted joints under thermal changes have also conducted. However, few studies on rotational screw thread loosening in bolted joints have conducted. In our previous study, mechanism of rotational screw thread loosening in bolted joint under repeated temperature changes was examined. However, the difference in the loosening mechanism between the FEM results and the experimental results was substantial. In this study, the effect of the incline at the bearing surfaces was taken into consideration on the loosening. In addition, the loosening in the bolted joint with the eccentric nut under repeated temperature changes was examined using finite element method (FEM) calculations. Discussion is made on the mechanism and a solution of rotational screw thread loosening in the bolted joints under the repeated temperature changes. The results show that a reduction in axial bolt force was increased when the incline at the bearing surfaces was taken into consideration and the eccentric nut was shown for preventing the bolt loosening.

Analytical and Experimental Investigation of Self-Loosening of Preloaded Cap Screw Fasteners

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Xianjie Yang ◽  
Sayed Nassar
Keyword(s):  
Experimental Investigation ◽  
Excitation Amplitude ◽  
The Self ◽  
Transverse Displacement ◽  
Transverse Loading ◽  
Threaded Fasteners ◽  
Bolt Preload ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Insight Into

In an effort to establish a theoretical outline of a criterion for preventing the vibration-induced loosening of preloaded threaded fasteners, this paper provides an experimental and analytical insight into the effect of the initial bolt preload and the excitation amplitude on the self-loosening performance of a cap screw fastener. A nonlinear model is used for predicting the clamp load loss caused by the vibration-induced loosening of cap screw fasteners under cyclic transverse loading. Experimental verification was conducted on the twisting torque variation and the effect of the preload level and transverse displacement amplitude. Comparison of the experimental and analytical results on the clamp load loss with the number of cycles verifies that the proposed model accurately predicts self-loosening performance.

Vibration-Induced Loosening Performance of Preloaded Threaded Fasteners

2010 ◽  
Author(s):  
Xianjie Yang ◽  
Sayed Nassar
Keyword(s):  
Nonlinear Model ◽  
Excitation Amplitude ◽  
The Self ◽  
Transverse Displacement ◽  
Transverse Loading ◽  
Threaded Fasteners ◽  
Bolt Preload ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Insight Into

In an effort to establish a theoretical outline of a criterion for preventing the vibration-induced loosening of preloaded threaded fasteners, this paper provides an experimental and analytical insight into the effect of the initial bolt preload and the excitation amplitude on the self loosening performance of cap screw fastener. A nonlinear model is used for predicting the clamp load loss caused by the vibration-induced loosening of cap screw fasteners under cyclic transverse loading. Experimental verification was conducted on the twisting torque variation and the effect of the preload level and transverse displacement amplitude. Comparison of the experimental and analytical results on the clamp load loss with the number of cycles verifies that the proposed model accurately predicts self-loosening performance.

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.

Effect of Temperature Variation on Clamp Load of Bolted Joints

2014 ◽  
Vol 633-634 ◽  
pp. 1179-1186
Author(s):  
Shi Yuan Hou ◽  
Ri Dong Liao ◽  
Zheng Kun Cheng
Keyword(s):  
Mathematical Model ◽  
Elevated Temperature ◽  
Temperature Variation ◽  
Creep Behavior ◽  
Bolted Joints ◽  
Effect Of Temperature ◽  
Bolted Joint ◽  
One Dimensional ◽  
Nonlinear Variation ◽  
Relevant Factors

Considering the elastic-plastic and creep behavior of the material of bolted joint, and the nonlinear variation of its properties with temperature, this paper proposed a one-dimensional mathematical model for predicting clamp load variation with cyclic elevated-temperature. Then, relevant factors which may affect the process are studied, and some measures to enhance the threaded fitting reliability are proposed.

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.

Elasto-Plastic Stress Analysis of the Characteristics for T-Flange Bolted Joints Under External Loading

2013 ◽  
Author(s):  
Yuya Omiya ◽  
Toshiyuki Sawa
Keyword(s):  
Stress Analysis ◽  
Tensile Load ◽  
Bending Moment ◽  
Bolted Joints ◽  
External Loading ◽  
Load Factor ◽  
Bolted Joint ◽  
Bearing Surface ◽  
Permanent Set ◽  
Bolt Preload

In designing bolted joints, it is necessary to know the contact stress distributions in bolted joints. Recently, high strength bolts have been used with a higher bolt preload. As the results, the permanent set occurs sometimes at the bearing surfaces of clamped parts in the bolted joint. In addition, when external loads such as tensile loads, transverse loads and bending moments are applied to the bolted joint, the permanent set can be extended at the bearing surfaces. As the permanent set increases, the reduction in the bolt preload increases. Thus, it is important to estimate the reduction in the bolt preload from the reliability stand point. However, no study on the permanent set at the bearing surface under the external loading taking into account the bending moment has been carried out. In this study, the stress distribution and the extension of the permanent set at the bearing surface of the T-flange bolted joint under the external tensile loading are examined using Finite Element Method (FEM), where two T-flanges are clamped with a hexagon bolt and a nut. Using the obtained results, an increment in the axial bolt force and the reduction in the bolt preload are estimated. For verification of the FEM stress analysis, the load factor of hexagon bolt was measured. The FEM results of the load factor (the ratio of the increment in the axial bolt force to the tensile load) and the axial bolt force are in a fairly good agreement with the experimental results.

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.

FEM Stress Analysis of the Characteristics of Bolted Joints Under External Loadings (In the Case Where Two Hollow Cylinders Are Clamped)

2011 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Kengo Kuwaki ◽  
Yukio Morozumi ◽  
Masahiko Okumura
Keyword(s):  
Stress Analysis ◽  
Theory Of Elasticity ◽  
Bolted Joints ◽  
External Loading ◽  
Load Factor ◽  
Bolted Joint ◽  
Bearing Surface ◽  
Permanent Set ◽  
Bolt Preload ◽  
Hollow Cylinders

In designing bolted joints, it is necessary to know the stress distributions in bolted joints. Recently, high strength bolts have been used with a higher bolt preload. As the results, the permanent set occurs sometimes at the bearing surfaces of clamped parts in a bolted joint. In addition, when an external load is applied to the bolted joint, the permanent set can be extended at the bearing surfaces. As the permanent set increases, the reduction in the bolt preload increases. Thus, it is important to estimate the reduction in the bolt preload from the reliability stand point. However, no study on the permanent set at the bearing surface under the external loading has been carried out. In this study, the stress distribution and the extension of the permanent set at the bearing surface of the bolted joint under the external tensile loading are examined using finite element Method (FEM), where two hollow cylinders are clamped with a hexagon bolt and a nut. The spring constants for the hexagon bolt and the clamped parts are analyzed using an axi-symmetrical theory of elasticity. Using the obtained results, an increment in the axial bolt force and the reduction in the bolt preload are estimated. For verification of the FEM stress analysis, the load factor of hexagon bolt was measured. The FEM results of the load factor (the increment in the axial bolt force) and the axial bolt force are in a fairly good agreement with the experimental results and the reduction of the axial bolt force. Finally, discussion is made on the appreciate bolt preload.

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