Although the title of this book includes the word “introduction”, the treatment of the subject is extensive and complete. The material goes well beyond the coverage of bolted joint design received in a typical undergraduate machine design course. The easy-to-read text begins with the fundamentals of bolt strength, deformation, and material selection and proceeds to cover the topics of preload, torque, and stretch control. The emphasis is on practical considerations for the efficient design of joints, including cost, ease of assembly, inspection, and disassembly. This second, revised edition has expanded the coverage of corrosion, fatigue, gaskets, and ultrasonic measurement of bolt strain. Also included are discussions of the failure modes and mechanisms of bolted joints. Case histories from industry are presented throughout the text to illustrate key points. Many up-to-date references are presented at the end of each chapter to allow the reader to pursue individual topics further, if desired. The text contains several appendices with useful tables and formulas for quick reference. The author has broad experience in the subject area from many years as a consultant to the power generation and nuclear industry, active participation on society working groups such as ASME and PVRC, as well as the presentation of numerous seminars on the topic. This book would serve as a valuable desk reference for engineers concerned with the design and performance of bolted joints.

An Introduction to the Design and Behavior of Bolted Joints

Study on self-loosening of bolted joints excited by dynamic axial load

By considering the tightening process, a three-dimensional elastic finite element analysis is conducted to explore the mechanism of bolt self-loosening under transverse cyclic loading. According to the geometrical features of the thread, a hexahedral meshing is implemented by modifying the node coordinates based on cylinder meshes and an ABAQUS plug-in is made for parametric modeling. The accuracy of the finite element model is verified and validated by comparison with the analytical and experimental results on torque-tension relationship. And, then, the fastening states acquired by different means are compared. The results show that the tightening process cannot be replaced by a simplified method because its fastening state is different from the real process. With combining the tightening and self-loosening processes, this paper utilizes the relative rotation angles and velocities to investigate the slip states on contact surfaces instead of the Coulomb friction coefficient method, which is used in most previous researches. By contrast, this method can describe the slip states in greater detail. In addition, the simulation result reveals that there exists a creep slip phenomenon at contact surface, which causes the bolt self-loosening to occur even when some contact facets are stuck.

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Self-Loosening Failure Analysis of Bolt Joints under Vibration considering the Tightening Process

On controlling preload and estimating anti-loosening performance in threaded fasteners based on accurate contact modeling

Virtual material parameter acquisition based on the basic characteristics of the bolt joint interfaces

Conventional analytical and numerical methods for the mechanical properties of helical threads are relied on many assumptions and approximations and thus hardly yield satisfied results. A parameterized 3D finite element model of bolted joints with real helical thread geometry is established and meshed with refined hexahedral elements. The Von Mises plasticity criterion, kinematic hardening rule of materials and interfacial contacts are employed to make it possible for the suggested model be able to approach real assembly conditions. Then, the mechanical properties of bolted joints with different thread pitches, thread numbers and modular ratios are investigated, including the contact pressure distribution at joint interfaces, the axial load distribution and stress concentration in screw threads during the loading and unloading process. Simulation results indicate that the load distribution in screw threads produced by the suggested model agrees well the results from CHEN’s photoelastic tests. In addition, an interesting phenomenon is found that tightening the bolt with a large preload first and then adjusting the clamping force by unloading can make the load distribution more uniform and reduce the maximum residual equivalent stress in thread roots by up to 40%. This research provides a simple and practical approach to constructing the 3D finite element model and predicting the mechanical properties of helical thread connection.

Three-dimensional finite element analysis of the mechanical properties of helical thread connection

The invention discloses a threaded fastener transverse vibration test device and method. The device comprises a transverse vibration platform, a transmission system, a clamp system, an installation base and a measuring device; one end of the transmission system is fixed to the vibration platform through a bolt, and the other end of the transmission system is fixed to a movable plate in the clamp system; a fixed base of the clamp system is fastened to the installation base through a T-shaped groove; the transmission system is provided with a pull pressure sensor, and the clamp system is provided with a gasket type force sensor. The device and method can simulate high-frequency vibration, achieve electrodeless amplitude modulation, monitor changes of transverse shear force and axial pre-tightening force of a threaded fastener in a vibration process in real time, and test the anti-loose characteristic of single bolts and bolt sets (distributed in a linear, rectangular and circular mode) with different specifications. The device and method provide a basis platform and data support for engineering technicians to analyze anti-loose performance of various threaded fasteners and assess effectiveness of various anti-loose methods.

Threaded fastener transverse vibration test device and method

Analytical method for contact performance of junction surface containing microcosmic surface shape

Bolted joints are widely used in mechanical structures due to their easy installation and maintenance. However, self-loosening of bolted joints caused by cyclic transverse loads has remained unsolved. In this study, the parametric finite element (FE) model is established to simulate the self-loosening. The slippage state at bearing surface and thread surface is investigated based on the FE model. Moreover, the influences of transverse frequency, amplitude, friction coefficient and initial preload on residual preload are discussed under a certain amount of time; the variations in back-off angle of nut and residual preload with time are analyzed under multi transverse loops. The results show that thread surface undergoes complete slip prior to the bearing surface, which provides theoretical guidance for looseness-proof design of bolted joints to some degree. The FE model can also be used to design the initial preload and predict the connections life under given vibration environment.Copyright © 2012 by ASME

The Slippage Analysis at Bearing Surface of Bolted Joints due to Cyclic Transverse Loads

Bolted joints including bolts and members act like elastic springs under assembly and operating conditions. The bearing and transferring of the initial preload and the operating force are mainly dependent on the stiffness of both the bolts and their corresponding members. To obtain the deformation mechanism of bolted members, a systematic study on the prediction of the member stiffness and the characterization of the interface contact conditions is developed in this paper. Firstly, a parameterization process is performed to relate all the geometric dimensions of each bolted joint with the corresponding bolt diameter, so the corresponding dimensionless dimensions can be conveniently gotten by dividing the dimensions by the bolt diameter. Based on this, a novel and efficient finite element (FE) model is constructed to simulate the behaviors of bolted joints with different geometrical sizes and material properties. After characterizing the member stiffness, the interface contact characteristics of bolted joints including contact pressure and the dimensionless contact diameter are further identified through special FE post-processing efforts. Finally, a series of semi-apex angles are obtained through an inverse calculation approach in which an author-modified empirical formula is adopted. The calculation results based on the proposed method may be considered as a simple and practical guideline for the design and assembly processes of bolted joints.

Yang Guoqing

Papers

Three-dimensional finite element analysis of the mechanical properties of helical thread connection

Threaded fastener transverse vibration test device and method

Analytical method for contact performance of junction surface containing microcosmic surface shape

The Slippage Analysis at Bearing Surface of Bolted Joints due to Cyclic Transverse Loads

Member stiffnesses and interface contact characteristics of bolted joints