Dynamic Characteristics of Structure With Bolted Joint Considering Some Factors

2004 ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Random Excitation ◽  
Pressure Vessels ◽  
Bolted Joints ◽  
Piping System ◽  
Bolted Joint ◽  
Earthquake Excitation ◽  
Applied Torque

Bolted joints are widely used for pressure vessels and piping system. Many studies on strength and stiffness of bolted joint are carried out. However, few studies on the dynamic characteristics of structure with bolted joint are carried out. The dynamic characteristics are important for design of structure subjected to earthquake excitations. In this paper, the effect of bolted joints on dynamic characteristics of structure is examined. First, the damping ratio and the natural frequency of specimens with some types of bolted joints are measured. Those are obtained for some factors, amplitude of excitation, applied torque. Obtained results are compared with those for the specimen without bolted joint. It is found that the damping ratio increases and the natural frequency becomes lower. Next, modeling of the bolted joint is presented. The bolted joint is modeled using additional mass, stiffness and damping elements. Finally, using model of bolted joint, response of the structure with bolted joint subjected to earthquake excitation is examined. Earthquake excitation is modeled as stationary random excitation. Mean square values of the response are obtained. Standard deviation of the acceleration response of the structure with bolted joint are lower than those without bolted joint.

Dynamic Characteristics of Structures With Bolted Joint

2002 ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Random Vibration ◽  
Damping Ratio ◽  
Pressure Vessels ◽  
Bolted Joints ◽  
Simplified Model ◽  
Piping System ◽  
Bolted Joint ◽  
Acceleration Response

Bolted joints are widely used for pressure vessels and piping system. Many studies on strength of bolted joint are carried out. However, few studies on dynamic characteristics of structure with bolted joint are carried out. In this paper, the effect of bolted joints on dynamic characteristics of structure is examined. First, the damping ratio and the natural frequency of specimens with some types of bolted joints are measured. Obtained results are compared with those for the specimen without bolted joint. It is found that damping ratio increases and the natural frequency becomes lower. Next, the effect of bolted joint on random vibration response of structure using simplified model is examined. Standard deviation of acceleration response of structure with bolted joint is lower than that of structure without bolted joint.

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.

The Impact of Qualified Bolting Specialists on the Safe, Reliable Assembly and Operation of Bolted Flanged Connections

2015 ◽  
Author(s):  
A. Fitzgerald (Jerry) Waterland ◽  
David Lay ◽  
Michael Dodge
Keyword(s):  
Work Force ◽  
Pressure Vessels ◽  
Bolted Joints ◽  
Critical Area ◽  
Bolted Joint ◽  
Learning Program ◽  
Guideline Document ◽  
The Impact ◽  
Joint Assembly

Why do we certify welders but require no evidence of training or competence from those performing the critical bolted flanged joint assembly of pressure vessels and piping throughout the same industries? To remedy this situation ASME has recently released the first comprehensive standard in ASME PCC-1-2013 Appendix A that establishes uniform criteria, not just for the quality of the bolted joints but for the workers who assemble them. To support this critical training and qualification standard, ASME Training & Development has created a unique blended learning program for pipe fitters and mechanics to become Qualified Bolting Specialists (QBS), per the requirements outlined in PCC-1-2013 Appendix A. The purpose of this technical presentation is to explain the opportunities presented by this new standard and how industry can benefit from a better-trained work force in this critical area of bolted joint assembly. The authors have been integrally involved in the development of both the PCC-1 guideline document, and the ASME qualification program, and can authoritatively answer industry’s questions.

Influence of Bolted Joint on Dynamic Characteristics of Combined Three-Section Crossbeam

2010 ◽  
Vol 37-38 ◽  
pp. 534-539
Author(s):  
Tie Neng Guo ◽  
Dong Liang Guo ◽  
Li Gang Cai ◽  
Bin Song ◽  
Jing Nan Zhao
Keyword(s):  
Machine Tool ◽  
Dynamic Analysis ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Bolted Joints ◽  
Experimental Result ◽  
Bolted Joint ◽  
Cnc Milling ◽  
Characteristic Parameters

The combined three-section crossbeam is an important component in the heavy gantry CNC milling-lathing machine tool and the dynamic characteristics are key precision factors for the machine tool. Three sections of the combined crossbeam are bolted by large industrial bolts and the influence of bolted joints should be evaluated in the dynamic analysis of the combined crossbeam. The dynamic characteristics of the combined three-section crossbeam were extracted by the modal experiment. The FEM of the monolithic crossbeam was modeled to analyze the dynamic characteristic parameters. The comparison of the analysis result and experimental result were shown. The experimental result matched well with the FEM of the monolithic crossbeam without bolted joints. As a result, the influence of the bolted joints could be ignorable in dynamic characteristic for the combined three-section crossbeam.

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

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.

Study on Dynamic Characteristics and Dynamic Response of Woodworking Four-Side Planer

2011 ◽  
Vol 291-294 ◽  
pp. 1970-1976
Author(s):  
Shao Qun Zhang ◽  
Jun Hua ◽  
Wei Xu
Keyword(s):  
Mathematical Model ◽  
Dynamic Response ◽  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Feed Rate ◽  
Reference Data ◽  
Damping Ratio ◽  
Vibration Test ◽  
Vibration Magnitude ◽  
The Mathematical Model

Through woodworking four-side planer vibration test, this article studiesits dynamic characteristics and dynamic response to identify the vibration magnitudes law of each feed roll shafts of the four-side feed beam; then finds the natural frequency and damping ratio of the feed beam and lathe bed; obtains the mathematical model of feed roll shaft vibration magnitude changing with the feed rate U under different process thicknesses. The analysis of feeding quantity and the rationality of lathe bed from the perspective of vibration design supplies the designs and operation staff with reference data.

Integrated Dynamic Characteristics and Application in Semi-Active Dynamic Absorber of Magneto-Rheological Fluids

2012 ◽  
Vol 220-223 ◽  
pp. 601-606
Author(s):  
Shi Zhen Li ◽  
Gong Yu Li ◽  
Xiao Wu Kong ◽  
Jian Hua Wei
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Dynamic Test ◽  
Shear Mode ◽  
Vibration Absorption ◽  
New Type ◽  
Dynamic Absorber ◽  
Magneto Rheological ◽  
Squeeze Effect

As a new type of controllable rheological smart material, Magneto-rheological Fluids (MRF) are widely used in the field of vibration control. This article investigated their integrated dynamic characteristics in squeeze mode and shear mode. Two prototypes were designed and fabricated. The dynamic test for the two prototypes was performed on a simply supported beam vibrating device with the methods of drop-hammering and sweep-frequency measuring. The experimental results demonstrate that the damping ratio of the prototype in squeeze effect presents linearly and widely controllable from 0.0948 to 0.2268 with the increase of the coils’ excitation current, behaving as a variable MR damper. However, its natural frequency remains unchanged. It is also shown that the natural frequency of the prototype in shear effect increases significantly from 18Hz to 24 Hz, acting as a semi-active dynamic vibration (SDVA) absorber with broadband vibration absorption for the maximum attenuation of up to 74.3%. This study provides guidance for engineering applications of MRF.

The Dynamic Characteristics of a Couple System by Pedestrian Bridge and Walking Persons

2011 ◽  
Vol 71-78 ◽  
pp. 1499-1506 ◽  
Author(s):  
Dong Wang ◽  
Shi Qiao Gao ◽  
Michael Kasperski ◽  
Hai Peng Liu ◽  
Lei Jin
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Couple System ◽  
Damping Capacity ◽  
Single Beam ◽  
Simplified Approach ◽  
Beam Experiment ◽  
External Loads

The human body forms a complex dynamic system with more than one natural frequency and provides considerable damping capacities. In a simplified approach active persons can be modeled as external loads. While this approach may be sufficient for an activity like jumping, it has been shown already that for a bobbing person some interaction effects may occur. The question arises if also pedestrians are able to influence the dynamic characteristics of the structure they are actually crossing. Observations during a mass event with several thousand persons crossing a 66 m long bridge indicate that the damping capacity of the coupled structure may have increased. In this paper a single beam experiment was operated. The basic idea is to use a known background excitation induced by a shaker. It can be seen that both natural frequency and damping ratio have been changed comparing with empty structure. The change with passive person is stronger that an active person. Meanwhile, the linear sweep method which was used in measurement provides a good result for the analysis of dynamic properties of a structure.

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