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.

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.

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 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.

Stress Analysis of Bolted Joints of Flat Cover With Tap Bolts in a Pressure Vessel

1999 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Akihiro Karasawa ◽  
Akihiro Shimizu
Keyword(s):  
Contact Stress ◽  
Pressure Vessel ◽  
Three Dimensional ◽  
Bending Moment ◽  
Theory Of Elasticity ◽  
Contact Stresses ◽  
Ultrasonic Waves ◽  
Bolted Joints ◽  
Load Factor ◽  
Sealing Performance

Abstract Bolted joints with gaskets have been designed empirically, and the sealing performance is not made clear by theoretical analyses because the contact stress distribution between the gasket and the flanges are not clarified when an internal pressure is applied to the joint. The present paper, discusses the distribution of contact stresses in the bolted joints fastened with tap bolts, when a clamped part with a gasket is the cover of a pressure vessel and is a circular flange. The distribution of contact stresses is analyzed as a three-body contact problem, using the three-dimensional theory of elasticity. Moreover, the contact stress is measured by means of ultrasonic waves. In addition, the load factor (the ratio of an increment of the axial bolt force to an external load) and the maximum stress caused in bolts are analyzed taking into account the bending moment. For verification, experiments are carried out, and the analytical results are found in fairly good agreement with the experimental ones. It was found that the sealing performance was improved when Young’s modulus of the gaskets was decreased and the gasket thickness was increased.

Exact Stress Distribution in Standard Gear Teeth and Geometry Factors

1973 ◽  
Vol 95 (4) ◽  
pp. 1159-1163 ◽  
Author(s):  
C. N. Baronet ◽  
G. V. Tordion
Keyword(s):  
Stress Distribution ◽  
Gear Tooth ◽  
Theory Of Elasticity ◽  
Tooth Profile ◽  
Two Dimensional ◽  
Dimensional Theory ◽  
Concentrated Load ◽  
Gear Teeth ◽  
Pressure Angle ◽  
Surface Stresses

Using the two-dimensional theory of elasticity and an appropriate transform function, the stress distribution in a gear tooth acted on by a concentrated load has been obtained. Computations were carried out for the 20 and 25-deg pressure angle, standard full-depth system, for numbers of teeth ranging from 20 to 150. The intensities of the maximum static surface stresses along the root fillets are given for different loading positions on the tooth profile. Some of the results are compared with others found in the literature.

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