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.

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.

FEM Contact Stress Analysis at the Bearing Surfaces in Bolted Joints Under External Loadings

2018 ◽  
Author(s):  
Atsushi Shirakawa ◽  
Toshiyuki Sawa ◽  
Tomohiro Naruse
Keyword(s):  
Stress Analysis ◽  
Contact Stress ◽  
Permanent Deformation ◽  
Bolted Joints ◽  
External Loading ◽  
Bearing Surface ◽  
Stress Strain ◽  
Bolt Preload ◽  
Plastic Displacement ◽  
Critical Contact

The higher bolt preload is better for increasing the integrity of bolted joints. However, the bearing surface could be permanently deformed with too much high preload and the bolt preload decreases with permanent deformation. Thus, an upper limit of bolt preload per contact area at the bearing surfaces, which is called as the critical contact stress, must be examined for various materials of clamped parts. In the previous research, the critical contact stresses were obtained by compressing a cylindrical bar. However, the contact stress distribution of compressing a cylindrical bar is much different to that of an actual bolted joint. In addition, a lot of previous researches used the stress-strain curves under tensile loadings for analyzing the contact stress distributions at the bearing surfaces. In this study, the Finite Element Method is used for contact stress analysis at the bearing surfaces in clamped bolted joints under external loading. Various materials for clamped part are chosen such as steel, aluminum alloy, cast iron and stainless steel. Firstly, the stress-strain curves for the above materials were measured under compressive loadings. The differences in the stress-strain curves under tensile and compressive loadings are evaluated with the above materials. Next, using actual bolts, the displacements at the bearing surfaces in cylindrical clamped parts consisting of the above materials were measured. Finally, elasto-plastic FEM contact stress analyses are carried out for analyzing the plastic displacements at the bearing surfaces under compressive loadings. The mean displacement at the bearing surfaces are compared with those obtained from the experiments for each material. The FEM results of the relationship between the contact stress and the plastic displacement at the bearing surface are in a fairy good agreement with the experimental results for each clamped material. In addition, the critical contact stress at the bearing surface is discussed for each material. Two proposals for the critical contact stress at the bearing surface are described and compared with the critical contact stress of VDI2230.

Stress Analysis and the Characteristics of T-Shape Bolted Joints Under Tensile Loadings

2005 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Seiichi Hamamoto
Keyword(s):  
Bending Moment ◽  
Theory Of Elasticity ◽  
Bolted Joints ◽  
Load Factor ◽  
Two Dimensional ◽  
Bolted Joint ◽  
Dimensional Theory ◽  
Matching Method ◽  
Point Matching ◽  
Bolt Stress

In designing a bolted joint, it is important to examine the interface stress distribution (clamping effect) and to estimate the load factor, that is the ratio of an additional axial bolt force to a load. In order to improve the clamping effect raised faces of the interface have been used. But these interfaces in bolted joints have been designed empirically and the theoretical grounds are not made clear. In the present paper, in the case of T-shaped flanges with raised faces the clamping effect is analyzed by a two-dimensional theory of elasticity and the point matching method. Then, the load factor is analyzed. Moreover, with the application of the load a bending moment is occurred in bolts and the stress is added due to this bending moment. The bending moment in the bolt is also analyzed. In order to verify these analyses experiments to measure the load factor and the maximum bolt stress were carried out. The values of the load factor and the load when interface start to separate are compared with those of the joints with flat-faces. The analytical results are in fairly good agreements with the experimental ones.

The Load Factor and Permanent Set at the Bearing Surfaces in Hollow Cylindrical Bolted Joints Under External Axial Loads

2011 ◽  
Author(s):  
Yukio Morozumi ◽  
Masahiko Okumura ◽  
Toshiyuki Sawa ◽  
Kengo Kuwaki
Keyword(s):  
Contact Stress ◽  
High Reliability ◽  
Fem Analysis ◽  
High Strength ◽  
Theory Of Elasticity ◽  
Bolted Joints ◽  
Load Factor ◽  
Axial Forces ◽  
Bolt Preload ◽  
Plastic Displacement

High strength bolts are utilized widely for high reliability and to reduce the weight of the bolted joints. The usage of the high strength bolts may increase the contact stress at the bearing surfaces. When a bolted joint is under external axial load W, the axial bolt force increases by Ft and the contact stress increases at the bearing surface. This may cause the plastic deformation and a decrease in the axial bolt force. Consequently, it is important to determine the initial axial bolt force (bolt preload) considering external load. In this paper, (load factor) Φ = (Ft/W) is investigated by axi-symmetrical theory of elasticity, FEM analysis and experiments. The results obtained from these methods showed in a fairly good agreement. Then the contact stress distributions and the plastic displacement distributions under external loads were studied for three different initial axial forces by elasto-plastic FEM analyses. The prediction for the reduction in axial bolt force, which is obtained by multiplying the setting factor by the mean plastic displacement, was compared with the experiment. As a result, it was found that a higher bolt preload shows a small reduction in axial bolt force.

FEM Stress Analysis of Mechanical Behaviors in Bolted Joints Under External Loadings

2010 ◽  
Author(s):  
Kengo Kuwaki ◽  
Toshiyuki Sawa ◽  
Yukio Morozumi ◽  
Masahiko Okumura
Keyword(s):  
Stress Distribution ◽  
Contact Stress ◽  
External Load ◽  
Bolted Joints ◽  
External Loading ◽  
Load Factor ◽  
Mechanical Behaviors ◽  
Permanent Set ◽  
Load Factors ◽  
Stress Changes

In designing bolted joints, it is necessary to know the stress-changes in bolt loads and the stress distribution at the interfaces between clamped parts when external load is applied to the joints. The ratio of variation of bolt load to external load is called the load factor. The load factors have been studied. However, the load factors for bolted joints using bolt with flange have not been studied. In the present paper the mechanical behaviors of bolted joints in which bolt with flange are used such as the load factor and the contact stress distributions at the bearing surfaces are analyzed using Finite Element Method calculations in the case where the clamped parts are two hollow cylinders. The effects of factor such as flange slope angle on the value of the load factor, the contact stress distribution and permanent set at the bearing surfaces are examined. Variation of permanent set at the bearing surface when the external load is applied has not studied. In the experiments, to examine the load factor for the joints using a bolt/nut with flange, the variations of bolt load under the external loading were measured. The calculated results of the load factor show a fairy good agreement with the measured results. In addition, engineering formula for calculating the spring constant of bolt and nut with flanges are proposed.

FEM Contact Stress Analysis at the Bearing Surfaces in Bolted Joints With Washer Under Tensile Loadings

2013 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yuya Omiya ◽  
Kengo Kuwaki
Keyword(s):  
Contact Stress ◽  
External Load ◽  
High Reliability ◽  
High Strength ◽  
Bolted Joints ◽  
Load Factor ◽  
Stress Distributions ◽  
Bolted Joint ◽  
Bolt Preload ◽  
Plastic Displacement

High strength bolts with washers are utilized widely for high reliability. The usage of the high strength bolts enables higher bolt preload, thus the contact stress at the bearing surfaces increase. When a bolted joint is under external axial load W, the axial bolt force increases by Ft and the contact stress increases at the bearing surface. This may cause the plastic deformation and a decrease in the axial bolt force. Consequently, it is important to determine the initial axial bolt force (bolt preload) considering external load. In this paper, The characteristics of hollow cylindrical bolted joints with plain washers under external tensile loadings are analyzed using elasto-plastic FEM such as the contact stress distributions, plastic displacement (permanent set) at the bearing surfaces and the load factor Φ = (Ft/W). The effect of thickness of the plain washers on the contact stress distributions and the plastic displacements are clarified. It is found that the effect of the plain washer specified in JIS B 1256 is small on the contact stress distributions and the plastic displacements. Also, the effect of the external load on the changes in the contact stress distributions and the plastic displacements at the bearing surfaces using the values of load factor is observed to be small. The prediction for the reduction in axial bolt force was compared with the experiment. As a result, it was found that a higher bolt preload shows a small reduction in axial bolt force.

Mechanical Characteristics and Design of Bolted T-Shape Flange Joints Subjected to Tensile Loadings

2014 ◽  
Author(s):  
Shunichiro Sawa ◽  
Yuya Omiya ◽  
Mitsutoshi Ishimura ◽  
Toshiyuki Sawa
Keyword(s):  
Maximum Stress ◽  
Bending Moment ◽  
Tensile Loading ◽  
Theory Of Elasticity ◽  
Bolted Joints ◽  
Spring Constant ◽  
Load Factor ◽  
Two Dimensional ◽  
Bolted Joint ◽  
Dimensional Theory

Bolted joints have been widely used in mechanical structures. However, a design of bolted joints has been carried out empirically. In designing a bolted joint, it is necessary to know a ratio of increment Ft in axial bolt force to an external tensile loading W, that is, the load factor φ=Ft/W. In our previous paper, the new formulation for obtaining the value of the load factor φ for a bolted joint in which two hollow cylinders were clamped was proposed by introducing the tensile spring constant Kpt for clamped parts. Then, it is shown that the values of the load factor of bolted joint obtained from our formulation are in a fairly good agreement with the experimental values. In addition, the effect of the position where an external load is applied to the joint is significant on the value of the load factor. In the present paper, a method for obtaining the value of the load factor for bolted T-shape flange joints in which two T-shape flanges are clamped by two bolts and nuts under tensile loadings is demonstrated using two-dimensional theory of elasticity. In the analysis of the load factor φ, the compressive spring constant Kc for a hollow cylinder around the bolt hole is calculated. The value of the correction factor Kc′/Kpt is also analyzed using the two-dimensional theory of elasticity. When the external tensile loads are applied to the joints, the bolts are inclined and as the result, the bending moment occurs in the bolts. A method for analyzing the bending stress in the bolts is also demonstrated. In the numerical calculations, the distance C between the bolt position and the center of T-shape flange is varied and the effect of the distance C on the load factor is examined. For the validation of the analyses, calculations are also carried out. Experiments to measure the load factor and the maximum stress due to the bending moment occurred in the bolts were carried out. The numerical results of the load factor and the maximum stress in the bolts are fairly coincided with the experimental results. Furthermore, a design method for the joints is discussed, that is, how to determine the bolt position C, the bolt preload for the external tensile loading, how to choose the bolt strength.

FEM Stress Analysis and Design for Bolted Circular Flange Joints Under Tensile Loading

2015 ◽  
Author(s):  
Shunichiro Sawa ◽  
Mitsutoshi Ishimura ◽  
Yasuhisa Sekiguchi ◽  
Toshiyuki Sawa
Keyword(s):  
Design Method ◽  
Tensile Loading ◽  
Theory Of Elasticity ◽  
Load Factor ◽  
Bolted Joint ◽  
Analysis And Design ◽  
Bolt Preload ◽  
Experimental Values ◽  
New Formulation ◽  
Circle Diameter

In designing a bolted joint, it is necessary to know a ratio of increment Ft in axial bolt force to an external tensile loading W, that is, the load factor φ=Ft/W. In our previous paper, the new formulation for obtaining the value of the load factor φ for a bolted joint in which two hollow cylinders and two T-shape flanges were clamped was proposed by introducing the tensile spring constant Kpt for clamped parts. Then, the values of the load factor of bolted joint obtained from our formulation are shown to be in a fairly good agreement with the experimental values. In the present paper, the mechanical characteristics of bolted circular flange joints are analyzed by Finite Element Method (FEM) and axi-symmetrical theory of elasticity such as the load factor, the contact stress distributions at the interfaces and a load when a separation occurs at the interfaces. For verification of the analyses, experiments were carried out to measure the load factor, the maximums stress and a load when a separation occurs. In the analyses, the effect of the bolt pitch circle diameter D on the value of the load factor is examined. The numerical results of the load factor are fairly coincided with the experimental results. As the results, it is found that the load factor decreases as the bolt pitch circle diameter D increases and that the value of the load factor is less than 0.1. It is also found that the load when the interfaces start to separate decreases as the value of D increases. Based on the obtained results, a design method for the bolted circular flange joints under tensile loadings is demonstrated, that is, the method how to determine the bolt nominal diameter, bolt strength grade, the bolt preload for the external tensile loading are described.

FEM Stress Analysis and the Load Factor of Bolted Joints Consisting of Dissimilar Hollow Cylinders Under Tensile Loads

2017 ◽  
Author(s):  
Shunichiro Sawa ◽  
Mitsutoshi Ishimura ◽  
Yasuhisa Sekiguchi ◽  
Toshiyuki Sawa
Keyword(s):  
Hollow Cylinder ◽  
Design Method ◽  
Tensile Load ◽  
Bolted Joints ◽  
Load Application ◽  
Load Factor ◽  
Application Point ◽  
Bolt Preload ◽  
Hollow Cylinders ◽  
Bolt Diameter

In designing a bolted joint consisting of dissimilar hollow cylinders, the load factor (the ratio of an increment in axial bolt force to an external tensile load) is important. In the present paper, the effect of the load application point, the ratio b/a of the outside diameter to the inside diameter of dissimilar hollow cylinders, Young’s modulus ratio between the dissimilar hollow cylinders on the load factor and the interface stress distribution are examined using FEM calculations. As a result, it is found that the values of the load factor decrease as the ratio b/a increases and the positions where the load application point approaches the interfaces while the value of the load factor is independent of the bolt preload. In addition, it is found that the value of the load factor is less than 0.1 for steel and steel hollow cylinder joints, it is less than 0.2 for aluminum and aluminum hollow cylinder joints and it is less than 0.15 for aluminum and steel hollow cylinder joints while the material of bolt is steel in the present study. For verification of the FEM calculations, experiments to measure the load factor and a load when the interfaces start to separate were carried out. The FEM results are in a fairly good agreement with the experimental results. Finally, based on the obtained results, a design method for bolted joints with dissimilar hollow cylinders is demonstrated for determining the nominal bolt diameter and the bolt strength grade.

Axisymmetric Stress Analysis and Strength Evaluation of Bonded Shrink Fitted Joints of Circular Pipes Subjected to Internal Pressure and Tensile Loads

2000 ◽  
Author(s):  
Masahide Katsuo ◽  
Toshiyuki Sawa ◽  
Masahiro Yoneno
Keyword(s):  
Internal Pressure ◽  
Stress Analysis ◽  
Joint Strength ◽  
Tensile Load ◽  
Theory Of Elasticity ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Strength Evaluation ◽  
Circular Pipes ◽  
Hollow Cylinders

Abstract This study deals with the stress analysis and the strength evaluation of a bonded shrink fitted joint of circular pipes subjected to an internal pressure and a tensile load. In the analysis, two pipes and the adhesive are replaced with finite hollow cylinders, and the stress distributions in the joint are analyzed by using the axisymmetric theory of elasticity. From the numerical calculations, the following results are obtained: (1) Both the compressive and shear stresses at the interface between the adherend and the adhesive increase as Young’s modulus of the adherend increases. (2) The stress becomes singular at the edges of the interfaces. (3) The joint strength can be evaluated using the compressive and shear stresses near the edge of the interface. In the experiments, bonded shrink fitted joints consisting of dissimilar circular pipes were manufactured, and rupture tests of the joints were carried out by applying an internal pressure, and a tensile load to the joints. From the results, the joint strength of the bonded shrink fitted joint was found to be greater than that of the shrink fitted joint. Furthermore, the numerical results are in fairly good agreement with the experimental ones.

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