Development of a Method for Measuring Damping in Bolted Joints

2011 ◽  
Author(s):  
Hugh Goyder ◽  
Philip Ind ◽  
Daniel Brown
Keyword(s):  
Signal Processing ◽  
Computer Simulations ◽  
Vibration Damping ◽  
Bolted Joints ◽  
Significant Source ◽  
Bolted Joint ◽  
Lap Joint ◽  
Experiment Data ◽  
Joint Behaviour

Bolted joints are a significant source of vibration damping but are extremely difficult to model within computer simulations. In order to make progress, good quality experiment data is needed to provide a basis for modelling and an understanding of the mechanisms involved. An apparatus for measuring damping in a lap joint has been developed in which bolted joints are exercised by swinging masses in a resonant configuration. The apparatus is set into vibration and then released so that the vibration decays with the bolt damping controlling the decay. After some signal processing the energy lost per cycle is extracted. The repeatability of the bolted joint behaviour is an issue of concern and this is examined by analysing a series of tests. Although largely successful the system probably applies too large a force to the joint which exhibits some slip which then contributes to the lack of repeatability observed.

A Numerical Quasi-Static Method for the Identification of Frictional Dissipation in Bolted Joints

2012 ◽  
Author(s):  
Hugo Festjens ◽  
Gael Chevallier ◽  
Jean-Luc Dion
Keyword(s):  
Static Method ◽  
Bolted Joints ◽  
Mode Shapes ◽  
Bolted Joint ◽  
Lap Joint ◽  
Element Analysis ◽  
Linear Dynamics ◽  
Frictional Dissipation ◽  
Static Approach ◽  
Modal Coordinates

The hereby paper investigates a way to compute the micro-sliding dissipations that occurs in built-up structure using modal coordinates. This numerical method extends the former quasi-static approach to modal displacements through the use of finite element analysis. Considered structures are supposed to behave linearly except for a lumped bolted joint. It is firstly assumed that mode shapes of such structures are few affected by contact non-linearities in joint interfaces. This assumption allows to apply the normal eigenmodes of the linearized structure as boundary conditions on a model reduced to the bolted joint. The method relies on a corrected quasi-static analysis associated with the Masing rules. Those assumptions enables to avoid the considerable numerical expense due to non-linear dynamics. In order to improve the simulation, a mode shapes correction is also implemented. The formulation of the method is detailed and investigated on the classical lap-joint benchmark.

Measurement of Damping in Bolted Joints

2012 ◽  
Author(s):  
Hugh Goyder ◽  
Philip Ind ◽  
Daniel Brown
Keyword(s):  
Energy Dissipation ◽  
Computer Simulations ◽  
Significant Contribution ◽  
Vibration Damping ◽  
Measurement Process ◽  
Bolted Joints ◽  
Experimental Apparatus

A structure may be built-up from subsystems that are attached to each other by bolted joints. If the structure is allowed to vibrate the bolted joints provide a significant contribution to the absorption of energy and are thus an important source of vibration damping. The details of such damping should be included in computer simulations but unfortunately too little is known about joints to make this possible. An experimental apparatus has been developed to investigate damping and is described in this paper together with two sets of experiments. The experimental apparatus consists of two masses and a spring which can be set into vibration and exercise the bolted joints. The decay of the vibration enables the rate of energy dissipation to be measured. The accuracy of the measurement process is examined in detail and a relationship between the noise in the measurements and the errors in the determination of damping formulated.

Numerical Modeling and Experimental Validation of Bolted Lap Joints With 1D Hysteresis Finite Elements

2009 ◽  
Author(s):  
J. Abad ◽  
J. M. Franco ◽  
L. Lezaun ◽  
F. J. Martinez
Keyword(s):  
Numerical Modeling ◽  
3D Modeling ◽  
Laboratory Tests ◽  
Experimental Validation ◽  
3D Model ◽  
Lap Joints ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Lap Joint ◽  
3D Numerical Model

The work presented in this paper is part of a larger project for the modeling of dynamic behavior in bolted joints, and it is a further work on the adjustment of bolted joint 3D numerical model. This work shows the study and conclusions of the numerical modeling of a bolted lap joint by means of 1D hysteresis finite element and its validation with dynamical tests. The modeled joint is made up of two plates with a bolt, nut and washer. The behavior curve of the hysteresis element used was obtained by means of a 3D model of the joint, whose parameters and validation were carried out from the results of quasi-static laboratory tests. This procedure could be advantageously extended to any other lap joint given that its computational requirements are less than those required for a detailed 3D modeling.

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.

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.

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.

Non-Linear Analysis and Modeling of the Structure with Bolted Joints

2015 ◽  
Vol 656-657 ◽  
pp. 694-699
Author(s):  
Xin Liao ◽  
Jian Run Zhang ◽  
Dong Lu
Keyword(s):  
Dynamic Stiffness ◽  
Element Model ◽  
Outer Radius ◽  
Bolted Joints ◽  
Structure Model ◽  
Test Results ◽  
Bolted Joint ◽  
Joint Structure ◽  
Non Linear ◽  
Simulation Results

In this study, a non-linear finite element model for a simplified single-bolted joint structure model is built. Static analysis on the structure under different shear force and pretension effect is done, and the non-linear contact behavior is analyzed. Through comparing datum, it is found that interface area of each bolted joint region can be described an annular region around bolt hole, whose outer radius has increased by 85% compared with radius of bolt hole. Also, the frequency responses of the multi-bolted joint structure under sinusoidal excitation are investigated. Simulation results show that the resonance regions basically remain unchanged in different pretension effect and the largest amplitude will increase with the increasing preloads. Finally, the vibration experiments are conducted. Interface nonlinear affect dynamic stiffness considerably. The test results illustrate that dynamic behaviors of bolted joint agree with the simulation results and the proposed non-linear contact model was reasonable.

Experimental Investigation of Dynamics of Assembly with Typical Mechanical Joint

2016 ◽  
Vol 693 ◽  
pp. 324-331
Author(s):  
Xin Liu ◽  
Bei Bei Sun ◽  
Jian Dong Chen ◽  
Fei Xue ◽  
Ren Qiang Jiao
Keyword(s):  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Bolted Joints ◽  
Damping Capacity ◽  
Bolted Joint ◽  
Vibration Data ◽  
Mechanical Joints ◽  
Vibration Behavior ◽  
Frictional Damping ◽  
Reference Specimens

Mechanical joints have a significant influence on the dynamics of assembled structure due to its discontinuity, uncertainty, frictional contact and micro-slip along the interface. To study the effect of mechanical interface on vibration behavior of industrial product, it is necessary to capture vibration data and investigate modal properties. In order to study effects of typical mechanical joints, double plates coupled with bolted joint are manufactured. Corresponding welded specimen was also manufactured for comparison and reference. Specimens were suspended by two flexible nylon cords for a free–free boundary condition and series of modal tests were carried out. Experimental results reveal that the preload in bolted joint affects the vibration behavior of assembly greatly, and the dynamic stiffness and natural frequency could be enhanced by increasing preload values of specimen. Bolted joints give rise to more frictional damping capacity within lower preload range in this test and welded specimen shows up much higher frequency and similar damping ratio.

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