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.

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.

Determination of normal force for optimal energy dissipation of harmonic disturbance in a semi-active device

2008 ◽  
Vol 311 (3-5) ◽  
pp. 633-651 ◽  
Author(s):  
Paulin Buaka Muanke ◽  
Patrice Masson ◽  
Philippe Micheau
Keyword(s):  
Energy Dissipation ◽  
Normal Force ◽  
Active Device ◽  
Optimal Energy

A New Approach for Determining Joint Stiffness of Bolted Joints

2014 ◽  
Vol 670-671 ◽  
pp. 1041-1044 ◽  
Author(s):  
Xi Wang Wang ◽  
Xiao Yang Li ◽  
Lin Lin Zhang ◽  
Xiao Guang Wang
Keyword(s):  
Accurate Determination ◽  
Joint Stiffness ◽  
Fatigue Loading ◽  
Bolted Joints ◽  
Analytical Models ◽  
Bolted Connection ◽  
New Approach ◽  
Axisymmetric Model ◽  
Force Equilibrium

Joint member stiffness in a bolted connection directly influence the safety of a design in regard to both static and fatigue loading as well as in the prevention of separation in the connection. Thus, the accurate determination of the stiffness is of extreme importance to predict the behavior of bolted assemblies. In this paper, An analytical 3D axisymmetric model of bolted joints is proposed to obtain the joint stiffness of Bolted Joints. Considering many different analytical models have been proposed to calculate the joint stiffness, the expression based force equilibrium can be a easy way to choose the best expression for the joint stiffness as a judgment criteria.

Determination of hydrogen ordering within the β-RH2+xphase (R= Ho, Y) using electron diffraction techniques

2000 ◽  
Vol 33 (5) ◽  
pp. 1246-1252 ◽  
Author(s):  
Elizabeth J. Grier ◽  
Amanda K. Petford-Long ◽  
Roger C. C. Ward
Keyword(s):  
Electron Diffraction ◽  
Neutron Scattering ◽  
Diffraction Pattern ◽  
Computer Simulations ◽  
Fluorite Structure ◽  
Long Range Order ◽  
Hydrogen Atoms ◽  
Ordered Structures ◽  
Diffraction Patterns

Computer simulations of the electron diffraction patterns along the [\bar{1}10] zone axes of four ordered structures within the β-RH2+xphase, withR= Ho or Y, and 0 ≤x≤ 0.25, have been performed to establish whether or not the hydrogen ordering could be detected using electron diffraction techniques. Ordered structures within otherRH2+x(R= Ce, Tb) systems have been characterized with neutron scattering experiments; however, for HoH(D)2+x, neutron scattering failed to characterize the superstructure, possibly because of the lowxconcentration or lack of long-range order within the crystal. This paper aims to show that electron diffraction could overcome both of these problems. The structures considered were the stoichiometric face-centred cubic (f.c.c.) fluorite structure (x= 0), theD1 structure (x= 0.125), theD1astructure (x= 0.2) and theD022structure (x= 0.25). In the stoichiometric structure, with all hydrogen atoms located on the tetrahedral (t) sites, only the diffraction pattern from the f.c.c. metal lattice was seen; however, for the superstoichiometric structures, with the excess hydrogen atoms ordered on the octahedral (o) sites, extra reflections were visible. All the superstoichiometric structures showed extra reflections at the (001)f.c.c.and (110)f.c.c.type positions, with structureD1 also showing extra peaks at (½ ½ ½)f.c.c.. These reflections are not seen in the simulations at similar hydrogen concentrations with the hydrogen atoms randomly occupying theovacancies.

scholarly journals WAVE TRANSMISSION THROUGH TRAPEZOIDAL BREAKWATERS

1978 ◽  
Vol 1 (16) ◽  
pp. 129 ◽  
Author(s):  
Ole Secher Madsen ◽  
Paisal Shusang ◽  
Sue Ann Hanson
Keyword(s):  
Energy Dissipation ◽  
Approximate Method ◽  
Cross Section ◽  
Wave Energy ◽  
Graphical Form ◽  
Dissipated Energy ◽  
Simple Method ◽  
Reflection And Transmission ◽  
Transmission Coefficients

In a previous paper Madsen and White (1977) developed an approximate method for the determination of reflection and transmission characteristics of multi-layered, porous rubble-mound breakwaters of trapezoidal cross-section. This approximate method was based on the assumption that the energy dissipation associated with the wave-structure interaction could be considered as two separate mechanisms: (1) an external, frictional dissipation on the seaward slope; (2) an internal dissipation within the porous structure. The external dissipation on the seaward slope was evaluated from the semi-theoretical analysis of energy dissipation on rough, impermeable slopes developed by Madsen and White (1975). The remaining wave energy was represented by an equivalent wave incident on a hydraulically equivalent porous breakwater of rectangular cross-section. The partitioning of the remaining wave energy among reflected, transmitted and internally dissipated energy was evaluated as described by Madsen (1974), leading to a determination of the reflection and transmission coefficients of the structure. The advantage of this previous approximate method was its ease of use. Input data requirements were limited to quantities which would either be known (water depth, wave characteristics, breakwater geometry, and stone sizes) or could be estimated (porosity) by the design engineer. This feature was achieved by the employment of empirical relationships for the parameterization of the external and internal energy dissipation mechanisms. General solutions were presented in graphical form so that calculations could proceed using no more sophisticated equipment than a hand calculator (or a slide rule). This simple method gave estimates of transmission coefficients in excellent agreement with laboratory measurements whereas its ability to predict reflection coefficients left a lot to be desired.

Fracture Toughness of PVC/NBR Blends Evaluated by the J-Integral

1993 ◽  
Vol 66 (4) ◽  
pp. 634-645
Author(s):  
N. Nakajima ◽  
J. L. Liu
Keyword(s):  
Fracture Toughness ◽  
Energy Dissipation ◽  
Crack Initiation ◽  
Crack Tip ◽  
J Integral ◽  
Integral Methods ◽  
Locus Method ◽  
Two Phases ◽  
Fracture Processes

Abstract The effect of gel on the fracture toughness of four PVC/NBR (50/50) blends was characterized by two different J- integral methods. Three of these blends are compatible blends with 33% acrylonitrile in NBRs, and the fourth with 21% acrylonitrile content, is an incompatible blend. Two types of gel are involved in this study microgels and macrogels. The J-integral methods are (1) conventional method proposed by Bagley and Landes and (2) crack initiation locus method proposed by Kim and Joe. The same load-displacement curves are used in both methods. However, the latter eliminates the energy dissipation away from the crack tip in the determination of Jc, while the former does not. Both methods produced almost the same results indicating that the energy dissipation away from the crack tip is negligible in these samples. The fracture toughness of a macrogel-containing blend is much greater than that of a microgel-containing blend, which, in turn, is only slightly greater than that of a gel-free blend. This implies that the two gel-containing blends have different fracture processes. The incompatible blend has the lowest fracture toughness due to weak interaction at the boundaries of the two phases.

An Archaeological Approach to the Study of Cultural Stability

1955 ◽  
Vol 11 ◽  
pp. 32-57 ◽  
Author(s):  
Emil W. Haury ◽  
Robert L. Rands ◽  
Albert C. Spaulding ◽  
Walter W. Taylor ◽  
Raymond H. Thompson ◽  
...  
Keyword(s):  
Stability Problem ◽  
Significant Contribution ◽  
Time Perspective ◽  
Problem Area ◽  
Cultural Development ◽  
Instability Problem ◽  
Long Span ◽  
The Stability ◽  
Definition Of

The study of cultural stability requires a knowledge of cultural development over a reasonably long span of time. The definition of this time perspective is one of the major contributions of archaeology to the study of culture. The archaeologist therefore should be in a position to make a significant contribution to the appraisal of the stability problem itself. However, the lack of a commonly accepted anthropological definition of the concept of cultural stability imposes semantic difficulties which hinder the determination of practical limits for the stability- instability problem area. Moreover, the nature of the data available to the archaeologist conditions the kind of contribution he can make.

scholarly journals Effect of Seawater Exposure on Impact Damping Behavior of Viscoelastic Material of Pounding Tuned Mass Damper (PTMD)

2019 ◽  
Vol 9 (4) ◽  
pp. 632 ◽  
Author(s):  
Peng Zhang ◽  
Devendra Patil ◽  
Siu Ho
Keyword(s):  
Energy Dissipation ◽  
Viscoelastic Material ◽  
Hysteresis Loops ◽  
Tuned Mass Damper ◽  
Control Device ◽  
Impact Behavior ◽  
Lateral Impact ◽  
Experimental Apparatus ◽  
Mass Damper ◽  
The Impact

The pounding tuned mass damper (PTMD) is a novel vibration control device that can effectively mitigate the undesired vibration of subsea pipeline structures. Previous studies have verified that the PTMD is more effective and robust compared to the traditional tuned mass damper. However, the PTMD relies on a viscoelastic delimiter to dissipate energy through impact. The viscoelastic material can be corroded by the various chemical substances dissolved in the seawater, which means that there can be possible deterioration in its mechanical property and damping ability when it is exposed to seawater. Therefore, we aim to conduct an experimental study on the impact behavior and energy dissipation of the viscoelastic material submerged in seawater in this present paper. An experimental apparatus, which can generate and measure lateral impact, is designed and fabricated. A batch of viscoelastic tapes are submerged in seawater and samples will be taken out for impact tests every month. Pounding stiffness, hysteresis loops and energy dissipated per impact cycle are employed to characterize the impact behavior of the viscoelastic material. The experimental results suggest that the seawater has little influence on the behavior of the viscoelastic tapes. Even after continuous submersion in seawater for 5 years, the pounding stiffness and energy dissipation remains at the same level.

Intellectual Measuring Complex for Control of Geometrical Parameters of Aviation Details

2020 ◽  
pp. 352-371
Author(s):  
Mariia Kataieva ◽  
Alina Yurchuk
Keyword(s):  
Computer Simulation ◽  
Measurement Error ◽  
Three Dimensional ◽  
Geometric Parameters ◽  
Measurement Process ◽  
Geometrical Parameters ◽  
Automated Method ◽  
Measuring Complex ◽  
Graphic Depiction

This chapter proposes a new automated method of measuring complex three-dimensional surfaces of aircraft parts in static and dynamic modes. The method allows conducting measurements in closed conditions and at the site of the aircraft disposition. The method consists in the continuous determination of the coordinates of the points of the surface of the detail and their representation in a three-dimensional graphic depiction. New methods of measuring the geometric parameters of parts with the complex spatial surface are suggested. This opens the prospect for the development of new ways of measuring geometric parameters of parts in real-time with high metrological characteristics and computer simulation of the measurement process. The differential-digital method is based on the suggested zero-coordinate principle of the measurement process which involves simultaneous parts availability check, and connects measurement result obtained which provided a reduction in the order of measurement error.

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