The Effects of Energy Dissipation of the Closure Bolted Joints Under Vibration Behavior

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Qiang Cheng ◽  
Wenxiang Xu ◽  
Zhifeng Liu ◽  
Congbin Yang ◽  
Ying Li
Keyword(s):  
Energy Dissipation ◽  
Vibration Frequency ◽  
Cyclic Load ◽  
Fractal Theory ◽  
Operator Method ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Modal Shape ◽  
Factors Affecting ◽  
Dissipation Model

Abstract Bolted joints are widely used in mechanical construction due to their ease of disassembly. When the bolting member is subjected to the alternating load, the pretightening force is gradually reduced, which may cause the interface contact performance to decrease, and the surface may be microslipped. Preload relaxation of threaded fasteners is the main factor that influences the joint failure under normal cyclic loading, but it is difficult to monitor the energy dissipation between the interface of the bolted joint. This paper presents an energy dissipation model for the bolted joint based on two-degree-of-freedom vibration differential mathematical model. The parameters of the model is calculated by using the fractal theory and differential operator method. The efficiency of the proposed model is verified by experiments. The results show that the experimental modal shape agrees well with the theoretical modal shape. According to the change of cyclic load and vibration frequency, the vibration response and the law of energy dissipation under different factors can be obtained. The results show that the vibration frequency and cyclic load are the main factors affecting the energy dissipation between interfaces. The energy dissipation of the contact surface of the bolted joints account for the main part of the energy dissipation of the bolted structure. The results provide a theoretical basis for reducing the looseness of the bolt connection and ensuring the reliability of the equipment.

Influence of Vibration Behavior on the Energy Dissipation of the Bolted Joints

2019 ◽  
Author(s):  
Wenxiang Xu ◽  
Ligang Cai ◽  
Zhifeng Liu ◽  
Qiang Cheng ◽  
Ying Li
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Vibration Frequency ◽  
Cyclic Load ◽  
Fractal Theory ◽  
Bolted Joints ◽  
Mode Shapes ◽  
Bolted Joint ◽  
Engineering Structures ◽  
Stick Slip

Abstract Bolted joints are widely used for the mechanical assembly of engineering structures. It has been widely observed that fasteners turn loose when subjected to dynamic loads in the form of vibration or cyclic loading. Preload relaxation of threaded fasteners is the main factor that influences the joint failure under normal cyclic loading, but it is difficult to monitor the energy dissipation between the interface of the bolted joint. This paper presents an energy dissipation model for the bolted joint based on two-degree-of-freedom vibration differential mathematical model. A non-uniform pressure at the interface is considered and the resulted distinct stick-slip transitions along the contact interface are presented. The parameters of the model is calculated by using the fractal theory and differential operator method. Experiments are conducted to verify the efficiency of the proposed model. The results show that the theoretical mode shapes are in good agreement with the experimental mode shapes. According to the change of cyclic load and vibration frequency, the vibration response and the law of energy dissipation under different factors can be obtained. The results show that the vibration frequency and cyclic load are the main factors affecting the energy dissipation between interfaces. The energy dissipation of the contact surface of the bolted joints account for the main part of the energy dissipation of the bolted structure. As the preload increases, its energy dissipation decrease gradually. The results provide a theoretical basis for reducing micro-slip at the bolted joints interface.

scholarly journals Energy dissipation in spacecraft structures incorporating bolted joints with viscoelastic layers

2008 ◽  
Vol 222 (2) ◽  
pp. 201-211 ◽  
Author(s):  
R Wang ◽  
A D Crocombe ◽  
G Richardson ◽  
C I Underwood
Keyword(s):  
Energy Dissipation ◽  
Bolted Joints ◽  
Model Parameters ◽  
Bolted Joint ◽  
Non Linear ◽  
Linear Spring ◽  
Energy Dissipation Capacity ◽  
Stiffness And Damping Coefficient ◽  
Viscoelastic Layers ◽  
Stiffness And Damping

The energy dissipation capacity of bolted joints with viscoelastic layers in a spacecraft structure was investigated. Initially, a linear spring dashpot model was used to represent the bolts in a satellite structure. A relationship was developed between the model parameters (stiffness and damping coefficient) and the viscoelastic material and geometric properties (shear modulus, loss factor, operating area, and thickness) of the actual bolted joint. This model was then developed into the non-linear domain. Experiments on bolted joints with viscoelastic layers were carried out to provide information for the non-linear joint model. These models were incorporated into a simple spacecraft model to investigate the effect on the spacecraft response. Based on these numerical analysis, it was found that the joints can dissipate much energy and the response of the spacecraft structure to vibrations during launch can be decreased significantly.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

scholarly journals Experimental study of lateral resistance of bolted joints using Japanese cedar (Cryptomeria japonica) treated with resin impregnation

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Keita Ogawa ◽  
Satoshi Fukuta ◽  
Kenji Kobayashi
Keyword(s):  
Short Pulse ◽  
Japanese Cedar ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Yield Load ◽  
Short Pulse Laser ◽  
Resin Impregnation ◽  
Lateral Resistance ◽  
Ultraviolet Wavelength ◽  
Resistance Performance

Abstract The development of wooden joints possessing high resistance performance has become an important issue for the construction of newer buildings. This study attempts to strengthen the lateral resistance of bolted joints using the previously reported plasticizing technique. This technique consists of two processing stages: incising the surface of the wood using an ultraviolet wavelength short-pulse laser and impregnating the resin into the incised area. This technique makes it possible to plasticize only a local part of the wood surface. Bolted joint specimens were assembled using plasticized wood around the bolt hole, and the lateral tests were conducted. Acrylic monomer and urethane prepolymer were used as the impregnating resins and their incision depths were set as 4 and 10 mm. When the lateral load acted parallel to the grain, changes in the lateral resistance characteristics were observed, especially for the stiffness and yield load. For example, when acryl was used, and the incision depth was 10 mm, an increment of 73% in the yield load was observed, as compared to the non-impregnated specimens. The specimen groups impregnated with acryl exhibited greater changes in their properties than those using urethane. When loaded perpendicular to the grain, an increase in properties were observed; however, these increments were lower than those of the groups loaded parallel to the grain.

scholarly journals Scale Characteristics and Optimization of Park Green Space in Megacities Based on the Fractal Measurement Model: A Case Study of Beijing, Shanghai, Guangzhou, and Shenzhen

2021 ◽  
Vol 13 (15) ◽  
pp. 8554
Author(s):  
Zhen Li ◽  
Wanmin Zhao ◽  
Miaoyao Nie
Keyword(s):  
Fractal Dimension ◽  
Evaluation System ◽  
Goodness Of Fit ◽  
Green Space ◽  
Fractal Theory ◽  
Measurement Model ◽  
Scale Structure ◽  
Qualitative Description ◽  
Urban Spatial Structure ◽  
Factors Affecting

This paper applies fractal theory to research of green space in megacity parks due to the lack of a sufficient qualitative description of the scale structure of park green space, a quantifiable evaluation system, and operable planning methods in traditional studies. Taking Beijing, Shanghai, Guangzhou, and Shenzhen as examples, GIS spatial analysis technology and the Zipf model are used to calculate the fractal dimension (q), the goodness of fit (R2), and the degree of difference (C) to deeply interpret the connotation of indicators and conduct a comparative analysis between cities to reveal fractal characteristics and laws. The research results show that (1) the fractal dimension is related to the complexity of the park green space system; (2) the fractal dimension characterizes the hierarchical iteration of the park green space to a certain extent and reflects the internal order of the scale distribution; (3) the scale distribution of green space in megacity parks deviates from the ideal pyramid configuration; and (4) there are various factors affecting the scale structure of park green space, such as natural base conditions, urban spatial structure, and the continuation of historical genes working together. On this basis, a series of targeted optimization strategies are proposed.

Factors Affecting the Strength of Flexor Tendon Repair

1992 ◽  
Vol 17 (5) ◽  
pp. 550-552 ◽  
Author(s):  
D. BHATIA ◽  
K. E. TANNER ◽  
W. BONFIELD ◽  
N. D. CITRON
Keyword(s):  
Cyclic Load ◽  
Suture Material ◽  
Flexor Tendon ◽  
Tendon Repair ◽  
Flexor Tendon Repair ◽  
Factors Affecting ◽  
Full Strength ◽  
Load Tests

The effects of different thicknesses and configurations of core sutures were studied in human cadaveric flexor tendon repairs. Both straight and cyclic load tests were employed. To exploit the full strength of 4/0 suture material, the Kessler repair using four locked single knots would seem to be appropriate.

Accurate Evaluation of Bolt and Clamped Members Stiffnesses Of Bolted Joints

2021 ◽  
Author(s):  
Rashique Iftekhar Rousseau ◽  
Abdel-Hakim Bouzid ◽  
Zijian Zhao
Keyword(s):  
Finite Element ◽  
Joint Stiffness ◽  
Element Model ◽  
Fe Analysis ◽  
Bolted Joints ◽  
Analytical Models ◽  
Fe Modeling ◽  
Bolted Joint ◽  
A New Technique ◽  
External Loads

Abstract The axial stiffnesses of the bolt and clamped members of bolted joints are of great importance when considering their integrity and capacity to withstand external loads and resist relaxation due to creep. There are many techniques to calculate the stiffnesses of the joint elements using finite element (FE) modeling, but most of them are based on the displacement of nodes that are selected arbitrarily; therefore, leading to inaccurate values of joint stiffness. This work suggests a new method to estimate the stiffnesses of the bolt and clamped members using FE analysis and compares the results with the FE methods developed earlier and also with the existing analytical models. A new methodology including an axisymmetric finite element model of the bolted joint is proposed in which the bolts of different sizes ranging from M6 to M36 are considered for the analysis to generalize the proposed approach. The equivalent bolt length that includes the contribution of the thickness of the bolt head and the bolt nominal diameter to the bolt stiffness is carefully investigated. An equivalent bolt length that accounts for the flexibility of the bolt head is proposed in the calculation of the bolt stiffness and a new technique to accurately determine the stiffness of clamped members are detailed.

Viscous Friction Effect During the Process of Tightening and Loosening of Bolted Joints

2021 ◽  
Author(s):  
Qingyuan Lin ◽  
Yong Zhao ◽  
Qingchao Sun ◽  
Kunyong Chen
Keyword(s):  
Friction Coefficient ◽  
Viscous Friction ◽  
Normal Pressure ◽  
Friction Model ◽  
Bolted Joints ◽  
Critical Parameters ◽  
Bolted Joint ◽  
Sliding Velocity ◽  
Friction Effect ◽  
Bearing Friction

Abstract Bolted connection is one of the most widely used mechanical connections because of its easiness of installation and disassembly. Research of bolted joints mainly focuses on two aspects: high precision tightening and improvement of anti-loosening performance. The under-head bearing friction coefficient and the thread friction coefficient are the two most important parameters that affect the tightening result of the bolted joint. They are also the most critical parameters that affect the anti-loosening performance of the bolted joint. Coulomb friction model is a commonly used model to describe under-head bearing friction and thread friction, which considers the friction coefficient as a constant independent of normal pressure and relative sliding velocity. In this paper, the viscous effect of the under-head bearing friction and thread friction is observed by measuring the friction coefficient of bolted joints. The value of the friction coefficient increases with the increase of the relative sliding velocity and the decrease of the normal pressure. It is found that the Coulomb viscous friction model can better describe the friction coefficient of bolted joints. Taking into account the dense friction effect, the loosening prediction model of bolted joints is modified. The experimental results show that the Coulomb viscous friction model can better describe the under-head bearing friction coefficient and thread friction coefficient. The model considering the dense effect can more accurately predict the loosening characteristics of bolted joints.

Study on the critical loosening condition toward a new design guideline for bolted joints

2018 ◽  
Vol 233 (9) ◽  
pp. 3302-3316 ◽  
Author(s):  
Hao Gong ◽  
Jianhua Liu ◽  
Xiaoyu Ding
Keyword(s):  
Three Dimensional ◽  
Element Model ◽  
Simulation Method ◽  
Bolted Joints ◽  
Design Guideline ◽  
Factors Affecting ◽  
Dimensional Finite Element ◽  
Frictional Coefficients ◽  
Three Dimensional Finite Element ◽  
Fit Tolerance

An understanding of conditions that trigger the loosening of bolted joints is essential to ensure joint reliability. In this study, a three-dimensional finite element model of a typical bolted joint is developed, and a new simulation method is proposed to quantitatively identify the critical transverse force for initiating loosening. This force is used to evaluate the anti-loosening capacity of bolted joints. Using the proposed simulation method, the effects of factors affecting critical loosening are systematically studied. It is found that the preload, frictional coefficients at the thread and the bearing surfaces, clamped length, and fit tolerance mainly affected loosening. When the preload and friction coefficients are increased, and the clamped length and fit tolerance are reduced, loosening is inhibited. Experiments are performed to demonstrate the reliability of the results. Finally, a suggestion is proposed to improve the design guideline VDI 2230 for bolted joints, which considers the requirement of avoiding loosening under vibrational loading.

scholarly journals Nonlinear Axial Stiffness Characteristics of Axisymmetric Bolted Joints

1990 ◽  
Vol 112 (3) ◽  
pp. 442-449 ◽  
Author(s):  
I. R. Grosse ◽  
L. D. Mitchell
Keyword(s):  
Finite Element ◽  
Linear Theory ◽  
Design Theory ◽  
Joint Stiffness ◽  
Bolted Joints ◽  
Axial Stiffness ◽  
Outer Diameter ◽  
Bolted Joint ◽  
Element Analysis ◽  
Stiffness Characteristics

A critical assessment of the current design theory for bolted joints which is based on a linear, one-dimensional stiffness analysis is presented. A detailed nonlinear finite element analysis of a bolted joint conforming to ANSI standards was performed. The finite element results revealed that the joint stiffness is highly dependent on the magnitude of the applied load. The joint stiffness changes continuously from extremely high for small applied loads to the bolt stiffness during large applied loads, contrary to the constant joint stiffness of the linear theory. The linear theory is shown to be inadequate in characterizing the joint stiffness. The significance of the results in terms of the failure of bolted joints is discussed. A number of sensitivity studies were carried out to assess the effect of various parameters on the axial joint stiffness. The results revealed that bending and rotation of the joint members, interfacial friction, and the bolt/nut threading significantly influence the axial stiffness characteristics of the bolted joint. The two-dimensional, axisymmetric finite element model includes bilinear gap elements to model the interfaces. Special orthotropic elements were used to model the bolt/nut thread interaction. A free-body-diagram approach was taken by applying loads to the outer diameter of the joint model which correspond to internal, uniformly distributed line-shear and line-moment loads in the joint. A number of convergence studies were performed to validate the solution.

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