The Methods to Study the Influence of the Clearance in the Case of Great Speeds and Small Speeds

2013 ◽  
Vol 837 ◽  
pp. 88-92
Author(s):  
Jan Cristian Grigore
Keyword(s):  
Dynamic Behavior ◽  
Reaction Force ◽  
Accurate Method ◽  
Angular Speed ◽  
Connecting Rod ◽  
Lagrange Equations ◽  
Joint Rotation ◽  
First Case ◽  
Multi Body ◽  
General Method

In kinematic couplings, clearances are inevitable for their operation. The size of these clearances but as a consequence of use, causes a malfunction of the mechanism to which it belongs. The law of motion of driveline changes, big clearances, non-technological system causes vibration, leading to discomfort, uncertainty, and thus reach its degradation. In the paper we shall make a few of geometric and mechanical type considerations about the clearances in the linkages, linkages planes with joint rotation links. Based on mathematical algorithm developed and applied crank mechanism, the model presented in [1], this paper scientifically developed mathematical model, proposing mathematical models to study the influence of the size of the clearance in general dynamic calculation mechanisms. Mechanism considered is crank connecting rod mechanism with clearance cinematic coupling between rod and crank rotation. The paper makes a study of the influence on the dynamic behavior of the crank rod mechanism at high speeds, but also general method algorithm is developed and accurate method to assess the dynamic behavior of multi-body mechanism. The first case is considered a constant angular speed motor and thus determine the elemental expressions that establish the mechanism position, velocity and acceleration expressions in the two directions heads elements. Finally we obtain the expression of the normal reaction force, as well as position expression that defines its angle. With reaction force can specify phase (contact, flight, impact) [1], the behavior of the journal. For the case of general method - the method multi-body - the exact method are established liaison relationships between the parameters , write matrices , inertia matrix. Use Lagrange equations, if non-holonomic constraints. Matrix differential equation of motion is written and it can be solved numerically using Runge-Kutta method of order four. Of the iterative method, we obtain the parameters used in calculating the reaction force expression that can be evaluated accurately in journal bearings behaviour. Any would be their source of appearance, they usually produce unwished effects during the mechanisms functioning.

Estimation of Counterweight for Shaking Force Balancing of a Crank-Rocker Mechanism

2014 ◽  
Vol 663 ◽  
pp. 135-140 ◽  
Author(s):  
S.E. Mohammed ◽  
M.B. Baharom ◽  
A. Rashid A. Aziz
Keyword(s):  
Numerical Computation ◽  
Dynamic Behavior ◽  
Angular Speed ◽  
Connecting Rod ◽  
Kinematic Synthesis ◽  
Adams Software ◽  
Concentrated Masses ◽  
Resultant Forces

This paper proposes a method of balancing the shaking force of a crank-rocker mechanism which rotates at a constant angular speed with zero-unbalanced angle. In this approach, the kinematic synthesis and dynamic behavior of the mechanism are combined. The method is realized by modeling the mass of the connecting rod to represent two concentrated masses placed at the crank and rocker pins. The shaking forces balancing are done by adding counterweight masses to the crank and the rocker. The verification and numerical computation of the proposed balancing technique were carried out using ADAMS Software. The results showed that the sum of all the resultant forces was completely eliminated for the newly-balanced crank rocker mechanism.

Modeling the inertial torque imbalance and foundation forces within an inline internal combustion engine : quantifying the equivalent mass approximation

2018 ◽  
Author(s):  
◽  
Muslim Muhsin Ali
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Reaction Force ◽  
Internal Combustion ◽  
Significant Loss ◽  
Cylinder Wall ◽  
Connecting Rod ◽  
Piston Engine ◽  
Mass Approximation ◽  
Inertial Torque

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The main object of this dissertation is to study the dynamic analysis of an inline internal combustion engine. This dissertation presents the kinematics and kinetic analyses of an inline internal combustion engine crank mechanism, the dynamic torque imbalance and foundation forces for a single-piston and multi-piston engines are studied as well. The objectives of this dissertation are to explore the inertial-torque characteristics and foundation forces of an inline, internal combustion engine with connecting-rod joints that are evenly spaced about the centerline of the crankshaft, and to evaluate the goodness of a mass approximation that is customarily used in machine design textbooks. In this dissertation the number of pistons within the internal combustion engine is varied from 1 to 8. In order to generalize the results, the reaction force between the ground and the crank in the x-direction and y-direction equations are nondimensionalized and shown to depend upon only six nondimensional groups, all related to the mass and geometry properties of the connecting rod and crank while the reaction force between the connecting rod and the piston in the x-direction y-direction, reaction force between the crank and the connecting rod in the x-direction y-direction, reaction force between the piston and the cylinder wall, and the inertial-torque equations are nondimensionalized all related to the mass and geometry properties of the connecting rod. As shown in this dissertation, the largest torque imbalance is exhibited by a 2-piston engine. The next largest torque imbalance is exhibited by a 3-piston engine, followed by a single-piston engine (this is not monotonic). The largest foundation forces are exhibited by a single-piston engine. The next largest foundation forces are exhibited by a 2-piston engine, followed by a 3e-piston engine, and that a dramatic reduction in the foundation forces and torque imbalance may be obtained by using 4 or more pistons in the design, when using as many as 8 pistons the foundation forces and torque imbalance essentially vanishes. It should be observed that the mass approximation captures 100 percent of the variability of the actual torque imbalance for engines that are designed with an odd number of pistons equal to or greater than three. The mass approximation captures 100 percent of the variability of the actual reaction force between the piston and cylinder wall for engines that are designed with single-piston and multi-pistons. The mass approximation captures 100 percent of the variability of the actual reaction force against piston pin for engines that are designed with single-piston. It is also shown in this dissertation that the customary mass approximations for the connecting rod may be used to simplify the analysis for all engine designs without a significant loss of modeling accuracy.

scholarly journals Estimating thermal transmittance of the aluminium window profiles in practice

2020 ◽  
Vol 172 ◽  
pp. 24003
Author(s):  
Arkadiusz Witek ◽  
Barbara Pietruszka
Keyword(s):  
Heat Exchange ◽  
Accurate Method ◽  
Radiative Heat Exchange ◽  
Conductivity Method ◽  
Equivalent Thermal Conductivity ◽  
Thermal Transmittance ◽  
Radiation Exchange ◽  
First Case ◽  
Air Cavities ◽  
The Impact

Calculation of the heat flow through the air cavities in the EN ISO 10077-2:2017 standard for the determination of the thermal transmittance of window profiles uses models based on the equivalent thermal conductivity method. The method takes into account the radiative heat exchange in a simplified or accurate manner. In the first case, the heat exchange depends on the average temperature in cavity, in the second case - it is determined accurately by the ray tracing method. It is also of importance to differentiate emissivity of surfaces due to aging or painting what influences calculation time. In this work, the impact of the calculation method and the impact of simplifications in modelling of the untreated surfaces on the value of the thermal transmittance of aluminium profiles was analysed on the example of a real series of products. Comparing the simplified and accurate method of determining the radiation exchange in cavities, the differences in the thermal transmittances of window profiles were up to 22%. The differences between the most simplified and the most accurate modelling of the surfaces emissivity reached 23%.

EHD Lubrication of Multi-Body Common-Pin Conrod Big End Bearings System

2007 ◽  
Author(s):  
Aurelian Fatu ◽  
Dominique Bonneau
Keyword(s):  
Reynolds Equation ◽  
Film History ◽  
Mass Conservation ◽  
Connecting Rod ◽  
Thrust Bearings ◽  
Ehd Lubrication ◽  
Cylindrical Coordinate ◽  
Real Behavior ◽  
Multi Body ◽  
Fully Coupled

This paper describes a model for the analysis of elastohydrodynamic (EHD) lubrication of a multi-body common-pin connecting-rod (conrod) big end bearing system. Two conrod and three thrust bearings are fully coupled in order to simulate real behavior of the system. An extended Reynolds equation including mass conservation and oil film history is solved in the big end conrod bearings. The HD behavior of the thrust bearings is simulated by a cylindrical coordinate Reynolds equation. By comparisons with classical single rod analysis results show the pertinancy of simulating twin moving conrods.

Display of Feel for the Manipulation of Dynamic Virtual Objects

1995 ◽  
Vol 117 (4) ◽  
pp. 554-558 ◽  
Author(s):  
Tsuneo Yoshikawa ◽  
Yasuyoshi Yokokohji ◽  
Tomoharu Matsumoto ◽  
Xin-Zhi Zheng
Keyword(s):  
Dynamic Behavior ◽  
Display Device ◽  
Virtual Objects ◽  
Single Body ◽  
Calculation Algorithms ◽  
Multi Body ◽  
Measuring Force

A system for displaying feel information, while manipulating virtual objects, which takes their dynamic behavior into account is introduced. The display is realized using multiple link mechanisms. New concept of impedance display and two ways of its realization, “measuring force and displaying motion” and “measuring motion and displaying force,” are proposed. Calculation algorithms for the driving input to the display device for the operation of both single-body and multi-body virtual objects are established. The validity of the proposed method is verified experimentally using a newly developed two-finger display device.

scholarly journals Input retrieval in finite dimensional linear systems

1982 ◽  
Vol 23 (4) ◽  
pp. 357-382 ◽  
Author(s):  
P. G. Howlett
Keyword(s):  
Linear Systems ◽  
Type System ◽  
System Matrix ◽  
Fundamental Idea ◽  
Finite Dimensional ◽  
First Case ◽  
Direct Linkage ◽  
Explicit Formulae ◽  
Output Only ◽  
General Method

AbstractFor finite dimensional linear systems it is known that in certain circumstances the input can be retrieved from a knowledge of the output only. The main aim of this paper is to produce explicit formulae for input retrieval in systems which do not possess direct linkage from input to output. Although two different procedures are suggested the fundamental idea in both cases is to find an expression for the inverse transfer function of the system. In the first case this is achieved using a general method of power series inversion and in the second case by a sequence of elementary operations on a Rosenbrock type system matrix.

scholarly journals Analysis of a Biomechanical Model for Safe Lifting Using Matlab Simulation

2012 ◽  
pp. 294-299
Author(s):  
Neeraj Saraswat ◽  
Shikhar Sharma ◽  
Rahul Jain ◽  
Deepak Pathak
Keyword(s):  
Material Handling ◽  
Geometric Model ◽  
Reaction Force ◽  
Biomechanical Model ◽  
Force Balance ◽  
Matlab Simulation ◽  
Load Shape ◽  
Moment Load ◽  
Multi Body ◽  
Biomechanical Factors

This paper describes the development of a multi-body biomechanical model that can be used to assess the risk of low back disorders. A multi-segment link model is considered in this paper which represents a human body in which links represent various limbs such as arms, leg, foot, thigh, thorax etc. Force balance and moment balance equations are formed at different joints. Equations formed are written in form of a MATLAB program to determine the relationship between load lifted and muscle moment generated due to load. This biomechanical model was employed to clarify the role of various biomechanical factors such as magnitude of load, shape, size and location of load involved in the load lifting process. To determine safe lifting postures on the basis of model such that the reaction force at the L4 / L5 joint is minimum subjected to other joints not being overstressed is carried out. Various moment-load relationships between various joints are computed along with momentmoment relationships between various joints. The model is able to suggest the safe posture in manual material handling tasks. A geometric model for simulations of postural control is obtained with Matlab/Simulink software .

Simulation of EHD Lubrication of Common-Pin Conrod Big End Bearings in High Speed IC Engines

2005 ◽  
Author(s):  
Ming-Tang Ma ◽  
Bernhard Loibnegger
Keyword(s):  
High Speed ◽  
Internal Combustion ◽  
Inertial Effect ◽  
Body System ◽  
Connecting Rod ◽  
Tribological Behaviour ◽  
Ehd Lubrication ◽  
Ic Engines ◽  
Multi Body

This paper describes a methodology for the analysis of elastohydrodynamics (EHD) of connecting-rod (conrod) big end bearings in high-speed internal combustion (IC) engines. In addition to the elasticity of the conrod structure and crankpin, the dynamic and inertial effect of conrod motion on the bearing tribological behaviour is considered realistically based on a multi-body system (MBS) approach. Results show that it is necessary to simulate two big end bearings of common-pin simultaneously with the inclusion of a complete crankthrow in the MBS model.

scholarly journals Analysis of couple-stresses and piezo-viscous effects in a layered connecting-rod bearing

2018 ◽  
Vol 19 (6) ◽  
pp. 607
Author(s):  
Bouzid Laouadi ◽  
Mustapha Lahmar ◽  
Benyebka Bou-saïd ◽  
Hamid Boucherit ◽  
Ahcene Mouassa
Keyword(s):  
Dynamic Behavior ◽  
Reynolds Equation ◽  
Thickness Distribution ◽  
Continuum Theory ◽  
Algebraic Equations ◽  
Connecting Rod ◽  
Viscous Effects ◽  
Time Step ◽  
Compression Ignition Engine ◽  
Couple Stresses

In this work, the combined effects of couple-stresses and piezo-viscosity on the dynamic behavior of a compression ignition engine big-end connecting-rod bearing with elastic layer are investigated using the V. K. Stokes micro-continuum theory. It is assumed that the journal (crankpin) is rigid and the big-end bearing consists of a thin compressible elastic liner fixed in an infinitely stiff housing. The governing Reynolds' equation and the viscous dissipation term appearing on the RHS of energy equation are modified using the V. K. Stokes micro-continuum theory. The non-Newtonian effect is introduced by a new material constant η, which is responsible for couple-stress property, and the piezo-viscosity effect by the pressure–viscosity coefficient α appearing in the well-known Barus' law. In the proposed model, the nonlinear transient modified Reynolds equation is discretized by the finite difference method, and the resulting system of algebraic equations is solved by means of the subrelaxed successive substitutions method to obtain the fluid-film pressure field as well as the film thickness distribution. The crankpin center trajectories for a given load diagram are determined iteratively by solving the nonlinear equilibrium equations of the journal bearing system with the improved and damped Newton–Raphson method for each time step or crankshaft rotation angle. According to the obtained results, the effects of couple-stresses and piezo-viscosity on the nonlinear dynamic behavior of dynamically loaded bearings with either stiff or compliant liners are significant and cannot be overlooked.

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