Stress analysis of finite orthotropic plates loaded by a bolted joint

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.

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Development of Modelling Guidelines for Stress Analysis of Pressure Vessel Bolted Closures

ASME 2010 Pressure Vessels and Piping Conference: Volume 2 ◽

10.1115/pvp2010-25597 ◽

2010 ◽

Author(s):

A. Towse ◽

A. Mills ◽

D. Griffin ◽

P. Hurrell ◽

D. Rowe ◽

...

Keyword(s):

Finite Element ◽

Stress Analysis ◽

Pressure Vessels ◽

Service Performance ◽

Bolted Joints ◽

Model Complexity ◽

Bolted Joint ◽

Joint Models ◽

Software And Hardware ◽

Modelling Methods

This paper describes some of the outcomes of the development of finite element modelling guidelines for the stress analysis of bolted joints in pressure vessels and piping. The modelling methods originally developed at Rolls-Royce typically used 2D axisymmetric models as this was deemed adequate at the time. However, computing software and hardware improvements have subsequently been made which enable more realistic 3D bolted joint models to be solved where a greater level of geometric detail is required. For example the bolts, nuts and perforated flanges can now be represented more realistically reducing the degree of geometric abstraction that is required. Also, modern finite element codes such as ABAQUS and ANSYS now offer gasket elements which enable the initial compression, in-service performance and unloading of the joint to be modelled more realistically. Additionally, contact techniques can also be used to simulate the axial and radial distribution of thread load in the joint which will affect the stress distribution remote from the threaded region. Consequently, the modelling guidelines have been updated and provide guidance for stress engineers to decide which degree of model complexity is warranted.

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P125 Stress Analysis for Bolted Joint and Anti-loosing Outer Cap Nut

Proceedings of the 1992 Annual Meeting of JSME/MMD ◽

10.1299/jsmezairiki.2005.0_669 ◽

2005 ◽

Vol 2005 (0) ◽

pp. 669-670

Author(s):

Nao-Aki NODA ◽

Shunsuke NOMA ◽

Takuma FUKAZAWA ◽

Atsushi YUMOTO ◽

Kinjiro SAITO ◽

...

Keyword(s):

Stress Analysis ◽

Bolted Joint

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

Volume 7: 5th International Conference on Micro- and Nanosystems; 8th International Conference on Design and Design Education; 21st Reliability, Stress Analysis, and Failure Prevention Conference ◽

10.1115/detc2011-48247 ◽

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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Impact of Bolt-Nut Interface Modeling Assumptions on the Calculated Low Cycle Fatigue Life of Aircraft Engine Turbine Rotor Bolted Joints

Volume 1: Advances in Aerodynamics ◽

10.1115/imece2013-63706 ◽

2013 ◽

Author(s):

Anil Saigal ◽

Luke Jensen ◽

Thomas James

Keyword(s):

Finite Element ◽

Stress Analysis ◽

Low Cycle Fatigue ◽

Aircraft Engine ◽

High Energy ◽

Bolted Joint ◽

Cycle Fatigue ◽

Element Analysis ◽

Joint Stress ◽

Interface Modeling

Finite element analysis is used extensively in the aircraft turbine engine industry to predict stresses to calculate low cycle fatigue (LCF) life of life-limited parts (LLP’s). A failure of an LLP can lead to a potentially catastrophic event such as a noncontainment of high energy debris. Under-predicted stress can cause the life limits to be set too high, which is a safety hazard. Over-predicted stress can cause the life limits to be set too low, which adds cost due to the need to replace expensive engine hardware more frequently. As such, high fidelity stress analysis is necessary to appropriately set LCF life limits. This study focuses on the nut-bolt interface modeling assumptions associated with a rotor bolted joint stress analysis for LCF predictions. A 3D finite element model of an actual aircraft engine rotor bolted joint is created. Different cases are analyzed and compared to investigate how the thread modeling assumptions might affect the calculated life in the mated rotor LLP hardware. Walker-adjusted alternating stress, σ0,alt, is used to measure the affect on life impact. It is shown that elastic versus elastic-plastic nut/bolt materials properties and the inclusion of the helical thread shape have minor impact on the calculated stresses. However, inclusion of contact elements with friction at the thread interface instead of couples has a moderate impact on the calculated stresses and therefore expected life.

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