Whirl Simulation of Drill Collar and Estimation of Cumulative Fatigue Damage on Drill-Collar Connection

SPE Journal ◽  
2017 ◽  
Vol 23 (02) ◽  
pp. 286-300 ◽  
Author(s):  
Dapeng Zhao ◽  
Sigve Hovda ◽  
Sigbjørn Sangesland
Keyword(s):  
Fatigue Damage ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Lumped Mass ◽  
Mass Model ◽  
Bending Vibration ◽  
Stick Slip ◽  
Lumped Element Model ◽  
Cumulative Fatigue Damage ◽  
Drill Collar

Summary Most drill-collar-connection failures are attributed to cumulative fatigue caused by bending vibration. An important class of bending vibration is whirl, which is formed by the eccentricity of the rotational drill collar. The contact between the drill collar and the borehole causes extreme harmful backward whirl, even chaotic whirl. A two-degree-of-freedom nonlinear lumped-mass model is used to represent the drill collar in whirl. Unlike other studies, the stick/slip vibration causing fluctuation of rotary speed is taken into account. In this lumped-element model, the contact forces obey the Hertzian contact law, which leads to lateral bounce of the drill collar and affects the borehole wall chaotically. The modified Karnopp friction model is adopted to simulate the stick/slip rotary vibration of the bottomhole assembly (BHA). On the basis of the time-domain responses of whirl, the continuous-bending-stress history is broken down into individual stress ranges with an associated number of stress cycles using the rainflow-counting method. The cumulative fatigue damage is estimated using Miner's rule. The conclusion of this paper indicates that chaotic lateral vibration and fatigue damage happen at a lower rotational speed than previously reported.

Coupled Torsional Vibration and Fatigue Damage of Turbine Generator Due to Grid Disturbance

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Chao Liu ◽  
Dongxiang Jiang ◽  
Jingming Chen
Keyword(s):  
Fatigue Damage ◽  
Torsional Vibration ◽  
Coupled System ◽  
Lumped Mass ◽  
Mass Model ◽  
Turbine Generator ◽  
Failure Prevention ◽  
Lumped Mass Model ◽  
Continuous Mass ◽  
Fatigue Evaluation

Crack failures continually occur in shafts of turbine generator, where grid disturbance is an important cause. To estimate influences of grid disturbance, coupled torsional vibration and fatigue damage of turbine generator shafts are analyzed in this work, with a case study in a 600MW steam unit in China. The analysis is the following: (i) coupled system is established with generator model and finite element method (FEM)-based shafts model, where the grid disturbance is signified by fluctuation of generator outputs and the shafts model is formed with lumped mass model (LMM) and continuous mass model (CMM), respectively; (ii) fatigue damage is evaluated in the weak location of the shafts through local torque response computation, stress calculation, and fatigue accumulation; and (iii) failure-prevention approach is formed by solving the inverse problem in fatigue evaluation. The results indicate that the proposed scheme with continuous mass model can acquire more detailed and accurate local responses throughout the shafts compared with the scheme without coupled effects or the scheme using lumped mass model. Using the coupled torsional vibration scheme, fatigue damage caused by grid disturbance is evaluated and failure prevention rule is formed.

The Bending Vibration Analysis on the Main Drive Axis of CNC Spiral Bevel Gear Milling Machine

2013 ◽  
Vol 655-657 ◽  
pp. 1296-1299
Author(s):  
Li Juan Yu ◽  
Zhao Jun Yang ◽  
Fu You Liu
Keyword(s):  
Drive Shaft ◽  
Resonance Problem ◽  
Parameter Method ◽  
Force Model ◽  
Lumped Mass ◽  
Mass Model ◽  
Bending Vibration ◽  
Lumped Parameter ◽  
Lumped Mass Model ◽  
Lumped Parameter Method

Gear machine tool main drive shaft to avoid resonance problem is studied.The force of the drive shaft is analyzed, and the vibration form of the drive shaft is confirmed. Using the lumped parameter method to simplify the main drive shaft, the lumped mass model and the force model were been obtained. When bending vibrating, the natural frequency of the main drive shaft is calculated using the transfer matrix method. The calculated critical speed is 43755r/min, which far outweighs the motor rated speed .It means that the drive shaft under normal work won't be resonance, which accords with the request of production.

scholarly journals Prediction of railway induced ground vibration through multibody and finite element modelling

2013 ◽  
Vol 4 (1) ◽  
pp. 167-183 ◽  
Author(s):  
G. Kouroussis ◽  
O. Verlinden
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Vertical Plane ◽  
Time History ◽  
Ground Vibration ◽  
Element Model ◽  
Contact Forces ◽  
Railway Transportation ◽  
Lumped Mass ◽  
Mass Model

Abstract. The multibody approach is now recognized as a reliable and mature computer aided engineering tool. Namely, it is commonly used in industry for the design of road or railway vehicles. The paper presents a framework developed for predicting the vibrations induced by railway transportation. Firstly, the vehicle/track subsystem is simulated, on the basis of the home-made C++ library EasyDyn, by mixing the multibody model of the vehicle and the finite element model of the track, coupled to each other through the wheel/rail contact forces. Only the motion in the vertical plane is considered, assuming a total symmetry between left and right rails. This first step produces the time history of the forces exerted by the ballast on the foundation, which are then applied to a full 3-D FEM model of the soil, defined under the commercial software ABAQUS. The paper points out the contribution of the pitch motion of the bogies and carbodies which were neglected in previous publications, as well as the interest of the so-called coupled-lumped mass model (CLM) to represent the influence of the foundation in the track model. The potentialities of the model are illustrated on the example of the Thalys high-speed train, riding at 300 km h−1 on the Belgian site of Mévergnies.

scholarly journals Dynamic analysis of railway vehicle-track interactions due to wheel flat with a pitch-plane vehicle model

1970 ◽  
Vol 39 (2) ◽  
pp. 86-94 ◽  
Author(s):  
Rajib Ul Alam Uzzal ◽  
Waiz Ahmed ◽  
Subhash Rakheja
Keyword(s):  
Contact Point ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Railway Vehicle ◽  
Vehicle Model ◽  
Lumped Mass ◽  
Dynamic Interactions ◽  
Lumped Parameter ◽  
Wheel Flat ◽  
Secondary Suspension

This paper presents the responses of the railway vehicle and track components in terms of contact forces and displacements. The considered vehicle model is a five-DOF pitch-plane lumped parameter quarter car model supported on two-dimensional track systems comprising three layers. The car body is linked with the vehicle bogie through secondary suspension springs and damper elements, which is further linked to the wheels through primary suspension springs and damper elements. In modeling of the track, the rail is considered as an infinitely long beam discretely supported by a series of springs, dampers and masses representing the elasticity and damping effects of the rail pads, ballasts, and subgrades respectively. The non-linear Hertzian contact theory is employed to accomplish the dynamic interactions between the lumped mass vehicle and the continuous rail. The drastic effect of one wheel flat to the other perfect wheel-rail contact point is also taken into account. Keywords: Wheel flat, pitch-plane vehicle, wheel-rail impact, component force. doi:10.3329/jme.v39i2.1851 Journal of Mechanical Engineering, Vol. ME39, No. 2, Dec. 2008 86-94

On the Analytical Lumped-Mass Model of an Elastic Four-Bar Mechanism

1975 ◽  
Vol 97 (2) ◽  
pp. 561-565 ◽  
Author(s):  
J. P. Sadler
Keyword(s):  
Nonlinear Differential Equations ◽  
Beam Theory ◽  
Parameter Method ◽  
Lumped Mass ◽  
Mass Model ◽  
Bending Vibration ◽  
Lumped Parameter ◽  
Lumped Mass Model ◽  
Four Bar Linkage ◽  
Euler Bernoulli Beam

The lumped-parameter method for the elastodynamic analysis of mechanisms is applied to a particular case for which existing experimental evidence is available. The mechanism analyzed is a planar four-bar linkage, and the calculated results include steady-state deflection and stress and strain responses associated with the bending vibration of the three moving links. The analytical model is based on nonlinear differential equations derived by way of Euler-Bernoulli beam theory, and numerical solution is obtained through the use of a digital computer. Comparison of the analytical and experimental results shows very good agreement, supporting the use of the lumped-parameter approach in analyses of this type.

Suppression of Lateral and Torsional Stick–Slip Vibrations of Drillstrings With Impact and Torsional Dampers

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Lingnan Hu ◽  
Alan Palazzolo ◽  
Mansour Karkoub
Keyword(s):  
Vibration Suppression ◽  
Axial Loading ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Drilling Process ◽  
Damping Force ◽  
Restoring Force ◽  
Stick Slip ◽  
Premature Failure ◽  
Tangential Contact

Violent drillstring vibrations in a well should be suppressed to prevent premature failure of the drillstring parts and borehole wall and enhance the drilling process. This paper presents novel centralized impact dampers and torsional vibration dampers for lateral and torsional stick–slip vibration suppression which will function well in the harsh environment in the well due to their all-metal construction. A drillstring vibration model is used in this paper to simulate coupled lateral and torsional vibrations of the drillstring with impact and torsional dampers installed in the drill collar (DC). The high-fidelity model utilizes Timoshenko beam finite elements (FEs) and includes stress-stiffening effects to account for the gravity and axial loading effect on the transverse string stiffness. The rotational motions of the impactors result from dry friction tangential contact forces that occur when they contact the DC or sub. The tangential forces utilize a nonlinear Hertzian contact restoring force and a nonlinear, viscous contact damping force, in place of the typical coefficient of restitution (COR) model that cannot provide the required normal and tangential contact forces. The primary conclusions drawn from the simulation results are: (1) both the lateral vibration of the drillstring that is close to the bending critical speeds and the vibration induced by destabilizing forces can be suppressed by impact dampers and (2) the torsional stick–slip motion of the drillstring can be mitigated by the torsional damper.

Friction-Induced Vibration, Chatter, Squeal, and Chaos—Part II: Dynamics and Modeling

1994 ◽  
Vol 47 (7) ◽  
pp. 227-253 ◽  
Author(s):  
R. A. Ibrahim
Keyword(s):  
Nonlinear Modeling ◽  
Turbine Blades ◽  
Cutting Tools ◽  
Rotating Disk ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Experimental Investigations ◽  
Stick Slip ◽  
Nonlinear Dynamical ◽  
Research Activities

This part provides a comprehensive account of the main theorems and mechanisms developed in the literature concerning friction-induced noise and vibration. Some of these mechanisms are based on experimental investigations for classical models. Bilinear and nonlinear dynamical models have been considered to explain such friction phenomena as stick-slip, chatter, squeal, and chaos. Nonlinear modeling includes two types of nonlinearities which differ from those encountered in structural dynamics. These nonlinearities, in addition to the observed uncertainty of friction between sliding surfaces, form a formidable difficulty in developing accurate and reliable modeling. They include the inherent nonlinearity of contact forces (eg, Hertzian contact), and the nonlinear relationship between friction and sliding relative velocity. Research activities in this area are a mixture of theoretical, numerical, and experimental investigations. Theoretical investigations are prevailed by deterministic analysis with few attempts of stochastic treatment. The models include classical and practical engineering models such as the mass-spring model sliding on a running belt or on a surface with Hertzian contact, a pin sliding on a rotating disk, beams with friction boundaries, turbine blades, water-lubricated bearings, wheel-rail systems, disc brake systems and machine cutting tools. There is a strong need for further research to promote our understanding of the various friction mechanisms and to provide designers of sliding components with better guidelines to minimize the deteriorating effects of friction.

On Uncertainty Assessment of Fatigue Damage of Propulsion Shaft Under Ice Impact

2021 ◽  
Author(s):  
Etienne Purcell ◽  
Amir R. Nejad ◽  
Mostafa Valavi ◽  
Anriëtte Bekker
Keyword(s):  
Fatigue Damage ◽  
Model Simulation ◽  
Uncertainty Assessment ◽  
Assessment Method ◽  
Remaining Useful Life ◽  
Lumped Mass ◽  
Short Term ◽  
Mass Model ◽  
Sources Of Uncertainty ◽  
Ice Loads

Abstract In this paper, the importance of maintenance of marine propulsion is discussed with specific focus on the use of condition monitoring to inform maintenance schedules. The design requirements of DNV GL for shafts expected to operate in ice infested waters is adapted and a method is proposed to calculate the short-term fatigue damage during ice impacts. This method uses the Palmgren-Miner rule to calculate fatigue damage based on a transient, lumped-mass model simulation of the shaft with ice loads calculated from shaft measurements using inverse methods. Relevant sources of uncertainty in this assessment method are identified and quantified in order to express the short-term fatigue damage in a stochastic form. Sources of uncertainty include uncertainty in the calculation of ice loads, uncertainty of the transient analysis and uncertainty regarding the actual failure of the shaft as predicted by the S-N material curve and the Palmgren-Miner method. Uncertainties that influence the stress history are found to be the greatest contributor to fatigue damage uncertainty. A method is discussed that calculates the remaining useful life of the shaft as a function of short-term fatigue damage and the identified sources of uncertainty. The S.A. Agulhas is used as a case study to quantify the fatigue damage.

The calculation of a human lumped-mass model from acceleration and force-plate data

2002 ◽  
Vol 216 (5) ◽  
pp. 333-340 ◽  
Author(s):  
J Shippen
Keyword(s):  
Motion Tracking ◽  
Tracking System ◽  
Kinematic Model ◽  
Force Plate ◽  
Three Dimensional ◽  
Contact Forces ◽  
Lumped Mass ◽  
Mass Model ◽  
Individual Subject ◽  
The Individual

This paper describes a technique for the calculation of a lumped-mass representation of a human based on acceleration of body locations, typically obtained from a three-dimensional motion tracking system, and external forces and torques, typically measured from a force plate. The inverse problem of solving for lumped masses is presented, which results in a mass model of the individual subject via a fast, fully automated approach. This method can be used to obtain the mass model per se for the identification of growth deformities or together with a kinematic model for inverse and forward dynamics. Furthermore the mass model and acceleration trajectories subsequently can be used to calculate the contact forces between the floor and the subject at locations remote to a force plate.

Improved Dynamic Friction Models for Simulation of One-Dimensional and Two-Dimensional Stick-Slip Motion

2000 ◽  
Vol 123 (4) ◽  
pp. 661-669 ◽  
Author(s):  
Fitsum A. Tariku ◽  
Robert J. Rogers
Keyword(s):  
Mechanical Systems ◽  
Friction Model ◽  
Contact Forces ◽  
Force Balance ◽  
Two Dimensional ◽  
Lumped Mass ◽  
Stick Slip ◽  
Normal Contact ◽  
One Dimensional ◽  
Friction Models

In many mechanical systems, the tendency of sliding components to intermittently stick and slip leads to undesirable performance, vibration, and control behaviors. Computer simulations of mechanical systems with friction are difficult because of the strongly nonlinear behavior of the friction force near zero sliding velocity. In this paper, two improved friction models are proposed. One model is based on the force-balance method and the other model uses a spring-damper during sticking. The models are tested on hundreds of lumped mass-spring-damper systems with time-varying excitation and normal contact forces for both one-dimensional and two-dimensional stick-slip motions on a planar surface. Piece-wise continuous analytical solutions are compared with solutions using other published force-balance and spring-damper friction models. A method has been developed to set the size of the velocity window for Karnopp’s friction model. The extensive test results show that the new force-balance algorithm gives much lower sticking velocity errors compared to the original method and that the new spring-damper algorithm exhibits no spikes at the beginning of sticking. Weibull distributions of the sticking velocity errors enable maximum errors to be estimated a priori.

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