Dynamic Model of the Piston-Ring Assembly Using Curved Beam Finite Elements

2011 ◽  
Author(s):  
Mohannad Hakeem ◽  
Nabil G. Chalhoub ◽  
Peter Schihl
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Piston Ring ◽  
Translational Motion ◽  
Total Duration ◽  
Variable Structure ◽  
Body Motion ◽  
Curved Beam ◽  
Connecting Rod

A dynamic model for the crankshaft/connecting-rod/piston-assembly for a single cylinder engine is developed. The model considers the rigid body motion of the crank-slider mechanism including the piston secondary motions such as the piston-slap and piston-tilting. The formulation considers the ring to have three rigid body degrees of freedom in addition to its longitudinal and in-plane transverse deformations. The structural flexibility terms are approximated by using curved beam finite element method. The dynamic model has a variable structure whereby the number of degrees of freedom depends on the piston-liner and piston-ring interactions. Its formulation does not include frictional losses. The simulation results illustrate the piston secondary motions along with the ring tilting angles relative to the piston orientation for the total duration of the engine cycle. In addition, they exhibit the translational motion of the ring within the piston groove.

Modeling the Dynamics of Five-Axis Machine Tool Using the Multibody Approach

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Hoai Nam Huynh ◽  
Yusuf Altintas
Keyword(s):  
Rigid Body ◽  
Machine Tool ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Dynamic Performance ◽  
Body Motion ◽  
Proposed Model ◽  
Multibody Dynamic ◽  
Machining Operations ◽  
Five Axis

Abstract A systematic modeling of multibody dynamics of five-axis machine tools is presented in this article. The machine is divided into major subassemblies such as spindle, column, bed, tool changer, and longitudinal and rotary drives. The inertias and mass center of each subassembly are calculated from the design model. The subassemblies are connected with elastic springs and damping elements at contact joints to form the complete multibody dynamic model of the machine that considers the rigid body kinematics and structural vibrations of the machine at any point. The unknown elastic joint parameters are estimated from the experimental modal analysis of the machine tool. The resulting position-dependent multibody dynamic model has the minimal number of degrees-of-freedom that is equivalent to the number of measured modes, as opposed to thousands used in finite element models. The frequency response functions of the machine can be predicted at any posture of the five-axis machine, which are compared against the directly measured values to assess the validity of model. The proposed model can predict the combined rigid body motion and vibrations of the machine with computational efficiency, and hence, it can be used as a digital twin to simulate its dynamic performance in machining operations and tracking control tests of the servo drives.

scholarly journals Modeling Legged Microrobot Locomotion Based on Contact Dynamics and Vibration in Multiple Modes and Axes

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Jinhong Qu ◽  
Clark B. Teeple ◽  
Kenn R. Oldham
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Beam Theory ◽  
Contact Dynamics ◽  
Body Motion ◽  
Small Scale ◽  
Robot Locomotion ◽  
Actuation Scheme ◽  
Dynamics And Vibration

A dynamic model is developed for small-scale robots with multiple high-frequency actuated compliant elastic legs and a rigid body. The motion of the small-scale robots results from dual-direction motion of piezoelectric actuators attached to the legs, with impact dynamics increasing robot locomotion complexity. A dynamic model is developed to describe the small-scale robot motion in the presence of variable properties of the underlying terrain. The dynamic model is derived from beam theory with appropriate boundary and loading conditions and considers each robot leg as a continuous structure moving in two directions. Robot body motion is modeled in up to five degrees-of-freedom (DOF) using a rigid body approximation for the central robot chassis. Individual modes of the resulting multimode robot are treated as second-order linear systems. The dynamic model is tested with two different centimeter-scale robot prototypes having an analogous actuation scheme to millimeter-scale microrobots. In accounting for the interaction between the robot and ground, a dynamic model using the first two modes of each leg shows good agreement with experimental results for the centimeter-scale prototypes, in terms of both magnitude and the trends in robot locomotion with respect to actuation conditions.

Control of Flexible Payloads Grasped by Actuated Grippers Undergoing Large Rigid-Body Motions: Part II — Controllability and Observability

2002 ◽  
Author(s):  
Edward J. Park ◽  
James K. Mills
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Time Scale ◽  
Body Motion ◽  
Deformation Control ◽  
Scale Modeling ◽  
Fixed Interface ◽  
Controllability And Observability ◽  
Scale Behavior ◽  
Selection Of

Part I of this work models the dynamics of a flexible payload grasped by an actuated gripper undergoing large rigid body motion by a robotic manipulator. In Part II, the controllability and observability conditions of the system are discussed. In Part I, the dynamic model of the actuated flexible payload is derived using the component mode synthesis (CMS) method with addition of actuator constraint, fixed-interface vibration and quasi-static modes. Here, the two-time scale modeling (TSM) technique is employed taking advantage of the two-time scale behavior between the quasi-static modes and vibration modes in the dynamic model. Due to the complexity of the resulting system, the controllability and observability conditions are not trivial. Hence, the controllability and observability study addressed herein becomes essential in showing the advantages of using the CMS and TSM techniques in control system design for the problem. A simulation example demonstrates that simultaneous vibration and quasi-static deformation control is achievable by proper selection of each type of modes.

Small Vibrations Superimposed on Non-Linear Rigid Body Motion

1997 ◽  
Author(s):  
A. L. Schwab ◽  
J. P. Meijaard
Keyword(s):  
Rigid Body ◽  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Rigid Motion ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Connecting Rod ◽  
Non Linear ◽  
Linear Differential

Abstract In the case of small elastic deformations in a flexible multi-body system, the periodic motion of the system can be modelled as a superposition of a small linear vibration and a non-linear rigid body motion. For the small deformations this analysis results in a set of linear differential equations with periodic coefficients. These equations give more insight in the vibration phenomena and are computationally more efficient than a direct non-linear analysis by numeric integration. The realization of the method in a program for flexible multibody systems is discussed which requires, besides the determination of the periodic rigid motion, the determination of the linearized equations of motion. The periodic solutions for the linear equations are determined with a harmonic balance method, while transient solutions are obtained by averaging. The stability of the periodic solution is considered. The method is applied to a pendulum with a circular motion of its support point and a slider-crank mechanism with flexible connecting rod. A comparison is made with previous non-linear results.

Dynamic Response of Composite Pressure Vessels to Inertia Loads

1991 ◽  
Vol 113 (1) ◽  
pp. 86-91
Author(s):  
J. C. Prucz ◽  
J. D’Acquisto ◽  
J. E. Smith
Keyword(s):  
Rigid Body ◽  
Combustion Engine ◽  
Pressure Vessels ◽  
Body Motion ◽  
Connecting Rod ◽  
Filament Wound ◽  
Potential Benefits ◽  
Rigid Body Motions ◽  
Crank Mechanism ◽  
Selection Of

A new analytical model has been developed in order to investigate the potential benefits of using fiber-reinforced composites in pressure vessels that undergo rigid-body motions. The model consists of a quasi-static lamination analysis of a cylindrical, filament-wound, pressure vessel, combined with an elastodynamic analysis that accounts for the coupling effects between its rigid-body motion and its elastic deformations. The particular type of motion investigated in this paper is that of an oil-pressurized, tubular connecting rod in a slider-crank mechanism of an internal combustion engine. A comprehensive parametric study has been focused on the maximum wall stresses induced in such a rod by the combined effect of internal pressure and inertia loads associated with its motion. The numerical results illustrate potential ways to reduce these stresses by appropriate selection of material systems, lay-up configurations and geometric parameters.

Multiple-Mode Dynamic Model for Piezoelectric Micro-Robot Walking

2016 ◽  
Author(s):  
Jinhong Qu ◽  
Kenn R. Oldham
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Beam Theory ◽  
Body Motion ◽  
Six Degrees Of Freedom ◽  
Robot Locomotion ◽  
Multiple Mode ◽  
Micro Robot ◽  
Actuation Scheme ◽  
Robot Body

A multiple-mode dynamic model is developed for a piezoelectrically-actuated micro-robot with multiple legs. The motion of the micro robot results from dual direction motion of piezoelectric actuators in the legs, while the complexity of micro robot locomotion is increased by impact dynamics. The dynamic model is developed to describe and predict the micro robot motion, in the presence of asymmetrical behavior due to non-ideal fabrication and variable properties of the underlying terrain. The dynamic model considers each robot leg as a continuous structure moving in two directions derived from beam theory with specific boundary condition. Robot body motion is modeled in six degrees of freedom using a rigid body approximation. Individual modes of the resulting multimode robot are treated as second order linear systems. The dynamic model is tested with a meso-scale robot prototype having a similar actuation scheme as micro-robots. In accounting for the interaction between robot and ground, the dynamic model with first two modes of each leg shows good match with experimental results for the mesoscale prototype, in terms of both magnitude and the trends of robot locomotion with respect to actuation conditions.

Dynamic Analysis of a Slider-Crank Mechanism With Flexible Connecting Rod and Viscous Friction

2001 ◽  
Author(s):  
Jinfu Zhang ◽  
Qingyu Xu ◽  
Ling Zhang
Keyword(s):  
Rigid Body ◽  
Dynamic Analysis ◽  
Elastic Deformation ◽  
Coupling Effect ◽  
Lagrange Equation ◽  
Viscous Friction ◽  
Equation Of Motion ◽  
Body Motion ◽  
Connecting Rod ◽  
Crank Mechanism

Abstract The equation of motion for the slider-crank mechanism with flexible connecting rod and viscous friction are formulated using Lagrange equation. Viscous friction and coupling effect between rigid body motion and elastic deformation are considered in the formulation. Numerical results show that viscous friction and flexibility of connecting rod have effects on motion of the mechanism.

Dynamic Analysis of Flexible Supercavitating Vehicles Using Modal Based Elements

2003 ◽  
Author(s):  
Jou-Young Choi ◽  
Massimo Ruzzene ◽  
Olivier A. Bauchau
Keyword(s):  
Numerical Model ◽  
Rigid Body ◽  
Degrees Of Freedom ◽  
Structural Characteristics ◽  
Rigid Body Motion ◽  
Operating Conditions ◽  
Flight Mechanics ◽  
Body Motion ◽  
Supercavitating Vehicles ◽  
Elastic Modes

This presents a numerical model for the simulation of the flight mechanics behavior of flexible supercavitating vehicles. Supercavitating vehicles exploit supercavitation as a means to reduce drag and increase the underwater speed. In the proposed formulation, the vehicle’s rigid body motion is described by 6 degrees of freedom, which define pitch, yaw and roll motion and the displacement of the center of gravity with respect to a fixed inertial reference system. The forces applied to the vehicle include the control actions at the nose and at the fins, propulsion, gravity and cavity/vehicle periodic interactions associated to typical operating conditions. The elastic displacements are superimposed to the rigid body motion through a modal superposition technique. The mode synthesis is performed using Herting’s Transformation, which provides maximum flexibility in the selection of the elastic modes to be used for the used for the superposition, and the possibility of easily handling free-free modes. The developed numerical model predicts the dynamic response of the considered class of supercavitating vehicles resulting from assigned maneuvers. The analysis is motivated by the need of accurately modeling the structural characteristics of supercavitating vehicles in order to estimate vibrations in the structure and to envision and design systems that improve their guidance and control efficiency.

scholarly journals Dynamic Model and Fault Feature Research of Dual-Rotor System with Bearing Pedestal Looseness

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
Nanfei Wang ◽  
Hongzhi Xu ◽  
Dongxiang Jiang
Keyword(s):  
Finite Element ◽  
Rigid Body ◽  
Dynamic Model ◽  
Rigid Motion ◽  
Rotor System ◽  
Experimental Results ◽  
Body Motion ◽  
Combination Frequency ◽  
Recovery Coefficient ◽  
Vibration Displacement

The paper presents a finite element model of dual-rotor system with pedestal looseness stemming from loosened bolts. Dynamic model including bearing pedestal looseness is established based on the dual-rotor test rig. Three-degree-of-freedom (DOF) planar rigid motion of loose bearing pedestal is fully considered and collision recovery coefficient is also introduced in the model. Based on the Timoshenko beam elements, using the finite element method, rigid body kinematics, and the Newmark-βalgorithm for numerical simulation, dynamic characteristics of the inner and outer rotors and the bearing pedestal plane rigid body motion under bearing pedestal looseness condition are studied. Meanwhile, the looseness experiments under two different speed combinations are carried out, and the experimental results are basically the same. The simulation results are compared with the experimental results, indicating that vibration displacement waveforms of loosened rotor have “clipping” phenomenon. When the bearing pedestal looseness fault occurs, the inner and outer rotors vibration spectrum not only contains the difference and sum frequency of the two rotors’ fundamental frequency but also contains2Xand3Xcomponent of rotor with loosened support, and so forth; low frequency spectrum is more, containing dividing component, and so forth; the rotor displacement spectrums also contain fewer combination frequency components, and so forth; when one side of the inner rotor bearing pedestal is loosened, the inner rotor axis trajectory is drawn into similar-ellipse shape.

Calculations of non-linear waves generated by complex body motion

2000 ◽  
Vol 214 (6) ◽  
pp. 771-780 ◽  
Author(s):  
T Chen ◽  
A T Chwang
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Grid Method ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Promising Alternative ◽  
Potential Flows ◽  
Linear Waves ◽  
Non Linear ◽  
Marine Engineering

A structured and unstructured hybrid overlapping grid method is developed for simulating free-surface waves generated by submerged arbitrary bodies undergoing rigid body motion in multi-degrees of freedom. Exact boundary conditions are applied to the transient free and body surfaces. The accuracy, efficiency and generality of the present two-dimensional code for potential flows are validated by comparisons with available theories and experiments. Numerical experiments are reported in this paper to investigate the non-linear behaviour of waves due to the complex rigid body motion, in terms of wave patterns and the pressure distribution. Combining the best features of both grid systems for finite elements and finite differences, the present method provides a promising alternative in computational fluid dynamics for the design and analysis in marine engineering.

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