Yucheng Ding

Bio: Yucheng Ding is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Bearing (mechanical) & Bolted joint. The author has an hindex of 1, co-authored 2 publications receiving 9 citations.

Member stiffnesses and interface contact characteristics of bolted joints

Abstract: 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.

Theoretical method to reduce the non-repetitive run-out (NRRO) of angular contact ball bearings

Abstract: As ultra-precision index of bearings, the value of non-repetitive run-out (NRRO) directly influences the rotation precision of rotating mechanism of complex mechanical system. However, the value of NRRO is very difficult to predict and control due to various causes. This paper develops a mathematical model to study the constrictive relationship between the geometrical errors and the NRRO of an angular contact ball bearing based on Hertzian contact theory and solution method of dimensional chain, so as to reduce the NRRO by optimizing the manufacturing process of bearing components. Firstly, based on the motion relationship of parts in bearings and the dimensional chain theory, a kinematic model is built with taking into account the regularities of variation of contact angle under different axial load. In the model, the geometrical errors of rings raceway and balls are described through superposition of sinusoidal function. Secondly, the nonlinear equations of force balance of balls are built based on Hertzian contact theory. Finally, by solving nonlinear equations, the trajectory of rotation center is calculated to quantitatively analyze the NRRO of bearings caused by the geometrical errors of rings raceway and balls. Findings of this paper provide theoretical supports to reduce the NRRO by optimizing manufacturing process of bearing components.

An Introduction to the Design and Behavior of Bolted Joints

Abstract: 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.

Effects of raceway roundness and roller diameter errors on clearance and runout of a cylindrical roller bearing

Abstract: The actual radial clearance and runout of the bearing are different from design ones, because of the unavoidable raceway roundness and roller diameter errors of a cylindrical roller bearing. Howeve...

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

Abstract: 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.

Entropy-Based Method to Evaluate Contact-Pressure Distribution for Assembly-Accuracy Stability Prediction.

Abstract: Assembly accuracy and accuracy stability prediction are significant research directions for improving the reliability and efficiency of precision assembly. In this study, an improved method for assembly accuracy stability prediction, based on the contact-pressure distribution entropy, is presented. By using the contact-pressure distribution as the evaluation parameter instead of the strain-energy distribution, the improved method can not only predict the assembly accuracy of precision assembly more efficiently, but also predict the stability of the assembly accuracy with variations in the ambient temperature. The contact pressure has a clearer mechanical significance than strain energy density in the assembly process, which can be used to distinguish the actual contact area from the contact surface. Hence, the improved method is more efficient and accurate than the original. This study utilizes the same case used in the original method and an additional case from the actual production process to verify the improved method. The correctness and validity of the improved method are proved by these case studies.

Stiffness Calculation Method and Stiffness Characteristic Analysis of Bolted Connectors

Abstract: At present, few scholars have studied the effect of surface roughness on assembly stiffness. The influence of the joint surface stiffness on the overall stiffness is neglected. In this paper, a new method for calculating the stiffness of bolted joints is presented. The effect of joint surface stiffness on the overall stiffness is considered. Firstly, the relationship between load and displacement between cylinder and cylinder (including the joint surface with certain roughness) is studied, and the stiffness characteristic expression of the joint surface is obtained; the results are compared with the traditional stiffness calculation theory, and then, the influence of bolt connection surface on bolt connection is studied and compared with the stiffness calculation results of traditional bolt connection. The results show that the theoretical model presented in this paper is more practical.