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.

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

2007 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Mitsutoshi Ishimura ◽  
Hiroshi Yamanaka ◽  
Yusuke Fukuba
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Room Temperature ◽  
Linear Thermal Expansion ◽  
Bolted Joints ◽  
Electric Heater ◽  
Screw Thread ◽  
Bolted Joint ◽  
Finite Element Analyses ◽  
Temperature Changes

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. 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 this study, rotational screw thread loosening in bolted joint under repeated temperature changes is examined. Effects of the linear thermal expansion coefficient of clamped parts and number of repeated temperature changes are examined by the measurements and finite element analyses. In the experiments, a bolted joint, which consist of two rectangular plates fastened at room temperature by two bolts and nuts, are put in a furnace and heated by an electric heater. Then, the bolted joint is cooled at room temperature. These thermal cycles are repeated. Bolt temperature and bolt load were measured. Loosening is evaluated from the reductions in the bolt load. Finite element analyses were carried out for clarifying the loosening mechanism. Discussion is made on the mechanism of rotational screw thread loosening in bolted joints under repeated temperature changes. The results show that loosening occurs under repeated temperature changes due to difference in the linear thermal expansion coefficients of the different clamped parts.

Modeling of Distortion in Girth-Welded Thin Pipes

1990 ◽  
Vol 112 (3) ◽  
pp. 266-272 ◽  
Author(s):  
H. Song ◽  
A. Moshaiov
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Temperature ◽  
Qualitative Agreement ◽  
Experimental Results ◽  
Temperature Changes ◽  
Welding Arc ◽  
Element Method

The axisymmetric distortion in girth-welded pipes is studied in this paper. A model is developed based on the fact that only a small part of the pipe near the welding arc undergoes high temperature changes, and thus behaves thermo-elastic-plastically, while the rest of the structure is elastic in nature and may, at most, have some thermo-elastic effects. The model is shown to match Finite Element Method in predicting the overall approximated axisymmetric shrinkage in girth-welded pipes. A qualitative agreement with published analytical and experimental results is achieved as well.

scholarly journals Life analysis of the bolted joint

2019 ◽  
Vol 254 ◽  
pp. 02004
Author(s):  
Milan Sapieta ◽  
Peter Sulka
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Analysis ◽  
Fatigue Damage ◽  
Computational Models ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Computation Model ◽  
Life Analysis ◽  
Element Method

The paper deals with the fatigue damage calculation of 2 types of computation model of bolted joints. The study is performed via a numerical analysis with support of finite element method (FEM) software ANSYS. One model was created with a thread on the bolt, another was only bolt with cylindrical surfaces, the second model was greatly simplified. It will be evaluated the fatigue damage for both types of models. Subsequently both types of computational models will be compared in dependence on the accuracy of the results and the speed of the calculation. There are also the theoretical backgrounds for preloaded bolted joint, which was used for calculation of preload load prescribed on body of screws.

Member Stiffness and Contact Pressure Distribution of Bolted Joints

1993 ◽  
Author(s):  
Terry F. Lehnhoff ◽  
Kwang-Il Ko ◽  
Matthew L. McKay
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Bolted Joints ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Bolted Joint ◽  
Dimensional Problem ◽  
The Finite Element Method ◽  
Contact Pressure Distribution ◽  
Percent Difference

Abstract Member stiffnesses and the stress distributions in the bolts and members of bolted joints have been calculated for various bolt sizes, as well as thicknesses and materials of the members. The finite element method has been used to calculate the displacements and the stress distributions in the components of the bolted joint. Using axisymmetric elements, the bolted joint was analyzed as a two-dimensional problem. Member stiffness ratios were calculated from the finite element results and compared with those calculated by a commonly used theory. The differences in values were significant (16–30 percent difference) for the assumptions under which the theory was applied. Formulas and dimensionless curves which can be used to estimate the member stiffness ratios for several kinds of bolted joints are presented.

Stress Analysis of Combination Joints of Adhesive With Tap Bolt Under External Tensile Loads

2002 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Akira Moriuchi
Keyword(s):  
Finite Element Method ◽  
Plastic Deformation ◽  
Stress Distribution ◽  
Adhesive Joints ◽  
Bolted Joints ◽  
Strain Gauges ◽  
Screw Thread ◽  
Clamping Force ◽  
Stress Distributions ◽  
Bolted Joint

The stress distributions in a combination joint of an adhesive with a tap bolt under external tensile loadings are analyzed in elasto-plastic deformation using a finite element method. The FEM code employed is MARC. The effects of the initial clamping force (preload), external loadings and the position of engagement screw thread on the interface stress distributions are analyzed. In addition, the stress distribution in the combination joints of the adhesive with the tap bolt is compared with that in tap bolted joint without an adhesive and the adhesive joints without the tap bolt. As the results, it is found that the stress distribution (compression) in the combination joint is less than that of bolt joints. In addition, the experiments were carried out to measure the strain of the combination joint under external tensile loads using strain gauges. Furthermore, the joint strengths under external loadings were measured. Fairly good agreements are observed between the numerical and the measured results. In addition, the usefulness of the combination joints is demonstrated in comparison with the bolted joints and the adhesive joints.

FEM Analysis and an Evaluation of the Sealing Performance in Flexible Box-Shape Flanged Bolted Joints With Gaskets Subjected to Internal Pressure

2006 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Ryo Kurosawa ◽  
Yasuaki Tatsumi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Fem Analysis ◽  
Bolted Joints ◽  
Stress Distributions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
The Difference ◽  
Element Method

The contact gasket stress distributions of rectangular box-shape flange connections with compressed joint sheet gaskets subjected to internal pressure were analyzed taking account hysteresis of the gaskets using finite element method (FEM). Leakage tests were also conducted using actual rectangular box-shape flange connections with compressed joint sheet gaskets under internal pressure. By using the contact gasket stress distributions and the results of the leakage tests, the new gasket constants were calculated. The difference in the new gasket constants between the values obtained from the present study and those by the PVRC procedure was substantial. In addition, a method to determine the initial clamping bolt force (bolt preload) for a given tightness parameter was demonstrated.

Member Stiffness and Contact Pressure Distribution of Bolted Joints

1994 ◽  
Vol 116 (2) ◽  
pp. 550-557 ◽  
Author(s):  
T. F. Lehnhoff ◽  
Kwang Il Ko ◽  
M. L. McKay
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Bolted Joints ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Bolted Joint ◽  
Dimensional Problem ◽  
The Finite Element Method ◽  
Contact Pressure Distribution ◽  
Percent Difference

Member stiffnesses and the stress distributions in the bolts and members of bolted joints have been calculated for various bolt sizes, as well as thicknesses and materials of the members. The finite element method has been used to calculate the displacement and the stress distributions in the components of the bolted joint. Using axisymmetric elements, the bolted joint could be analyzed as a two-dimensional problem. Member stiffness ratios were calculated from the finite element results and compared with those calculated by a commonly used theory. The values were approximately comparable (16–30 percent difference) for the assumptions under which the theory was applied. Formulas and dimensionless curves which can be used to estimate the member stiffness ratios for several kinds of bolted joints are presented.

A Bolt-Nut Loosening Mechanism in Bolted Connections Under Repeated Transverse Loadings (Effect of Inclined Bearing Surfaces on the Loosening)

2010 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Mitsutoshi Ishimura ◽  
Atsushi Karami
Keyword(s):  
Testing Machine ◽  
Bolted Joints ◽  
Incline Angle ◽  
Impact Loads ◽  
Screw Thread ◽  
Bolted Joint ◽  
Bearing Surface ◽  
Bolted Connections ◽  
Inclined Surfaces ◽  
Thermal Changes

Loosening accidents sometimes occur under several types of loadings such as winds, vibrations, earthquakes, impact loads and thermal changes. Recently, some studies have been conducted on the screw thread loosening in bolted joints under repeated transverse loadings. It is well known that bolted joints are easily loosened when repeated transverse loadings are applied. While, in assembling bolted joints, the contact surfaces between a bolt head/nut and a clamped part are inclined geometrically. However, a lot of researches have dealt with the bolted joints in which the bearing surfaces are perfectly contacted without the inclined surfaces. Thus, it is necessary to examine the incline of the bearing surfaces on the loosening in bolted joint. A lot of parts for preventing the loosening have been proposed and sold at market. Among these parts, the authors have demonstrated that eccentric nuts are especially expected to be the solution for preventing the loosening of the joints under repeated transverse loadings. However, a few studies have been carried out on the loosening and loosening mechanism in bolted joints with inclined bearing surface and the effective solution for preventing loosening of bolted joint with the inclined bearing surfaces under the repeated transverse loadings. Thus, it is necessary to examine the effect of the incline at the bearing surfaces on the loosening and to evaluate the solutions for preventing loosening of the bolted joints with the inclined bearing surfaces. In this study, the effect of the incline at the bearing surfaces on the loosening is examined using FEM calculations. In the FEM calculations, the incline angle at the bearing surfaces is changed as 0, 2 and 3 degree, respectively. The experiments to measure the loosening in bolted joints were carried out using Junker’s testing machine to validities of the FEM calculations for revealing the effect of the loosening in the joints with the inclined bearing surfaces. In addition, nut parts for preventing the loosening in bolted connections with the inclined bearing surface under repeated transverse loadings are examined using the FEM calculations. As the result, it is seen that the loosening increases as the angle of incline increases. In addition, it is observed that bolted joints in which almost nut parts for preventing loosening are applied are loosened easily while the eccentric nut does not loosened. Discussion is made on the loosening mechanism in bolted joints under repeated transverse loadings.

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.

Study on Effect of Gasket Stress Distribution on Bolted Flanged Connections

2012 ◽  
Vol 496 ◽  
pp. 239-242
Author(s):  
Lin Liu ◽  
Suo Long Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Distribution ◽  
Experimental Results ◽  
Outer Periphery ◽  
The Difference ◽  
Key Parameter ◽  
Element Method

The gasket stress distribution was analyzed by finite element method (FEM). The leakage of bolted flanged connections was predicted based on gasket stress distribution, and the results were investigated and compared with the experimental results. The effect of gasket stress distribution on connection leakage was studied. The results indicated that the flange rotate enlarged along with increasing of bolt load, and the inhomogeneity of gasket stress distribution improved, and then the difference value of average gasket stress and maximum gasket stress expanded. The maximum gasket stress located at the gasket outer periphery is found to be a key parameter that controls leakage.

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