Universal Mechanism Simulation of Tracked Vehicle Dynamics with Universal Mechanism @umlab.ru Universal mechanism.

Universal Mechanism

Simulation of Tracked Vehicle Dynamicswith

Universal Mechanism

www.umlab.ru [email protected]

Universal mechanism

Universal Mechanism

Contents

Examples of tracked vehicle (TV) models

Main components of TV models

Development of a model of TV

Models of force elements

Simulation of TV dynamics

Universal Mechanism

Examples of TV models

Tank371 bodies, 1916 d.o.f.

TV of different types

Crawler transporter263 bodies, 1332 d.o.f.

Excavator138 bodies, 128 d.o.f.

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Jump by speed 15 m/s

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Model developed in 2003

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Main components of TV model

Sprocket

Rollers

Idler with tension device

Track links Suspension and road wheels

Components of a track model

Main system of coordinates for TV model

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Standard suspensions as subsystems

Torsion bar suspension Suspension bogie

Suspension torsion bogie Fixed suspension

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Standard models of idler with tension device

Simplified model of idler on a crank

Advanced model of idler on a crank

Idler on a slider

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Sprocket

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RoRo Ro

r

Rs

h

μ/2

Ro

μ/2

h

Rs

LJ

RT

RP

r

Generator of sprocket tooth profile

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Generator of tooth profiles

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Standard track link models

Track link with rigid joint Track link with flexible joint (bushing)

Track link with two parallel bushings (double pin)

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Support roller

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User defined components Registration of a new component of TV

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Development of TV model

Track is generated automatically with the help of components from the database

Step.1 Setting track structure

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Step.2 Suspension

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Step.3 Adding sprocket

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Step.4 Adding idler

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Step.5 Creation the track chain. Enveloping curve

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Step.6 Completion of track model. Adding dampers

Dampers

Characteristics of shock absorber

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Set.7 Adding a hull

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Set.8 Adding the second track

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Pin-sprocket interactions

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Pin-sprocket interaction

Compliant contact model

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Wheel-link interaction

S

R

δ

Normal contact force is proportional to the area S of penetration

SF

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21

02

3

0 )()(,)(

cd

dFcPF


Force versus penetration model

Here δ0 is the deflection under the load P; c(δ) is the stiffness versus penetration law

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The obtained relations are generalized for a contact of a wheel with a polyline corresponding to the track chain.

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Restrictive force and moment

C

ht

T

yx

y αx

.

,

xaxxaxx

yyy

dcM

ydycF

The force and moment prevent the lateral shift and rotation of a link

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Track-ground interaction

Two main model of the ground: Spring-damper model without sinkage Soil with sinkage

Contact point

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Bekker ground model

nc zkb

kp

Here p is the normal link-ground pressureb is the minimal size on the contact patch b (length of a track link)n, kc , k are the model parametersz is the sinkage depth

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Examples of terrain models

Normal force versus sinkage depth for different soils

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Example of track load force versus sinkage by loading and unloading/reloading processes

Loading

Unloading/Reloading

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Модели силовых взаимодействий

Tangential strength(Janosi, Hanamoto)

Kjepczj 1tan),(

Here j is the shear displacement of the link since the first contact with soilp is the normal pressurec is the cohesion is the angle of internal frictionK is an empirical constant

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Модели силовых взаимодействий

Database of terrain parameters

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Dynamic analysis of TV as a set of tests

List of auxiliary tests:EquilibriumTrack tensionComputation of initial velocities

List of main tests:Vertical harmonic loadingStraight motionOpen loop steeringTest with driver:

2D curve 3D testing area

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Test: equilibrium

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Test: track tension

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Test: Computation of initial velocities

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Test: Vertical harmonic loading

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Test: straight motion

Harmonic irregularities in opposite phase

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Тест: движение по прямой

In-phase harmonic irregularities


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Jump

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Trench

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Barrier

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Gunshot

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Simulation of TV dynamics. Open steering test

Longitudinal speed 8 m/s Difference in sprocket speeds 0.7 m/s

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Simulation of TV dynamics. Open steering test

Longitudinal speed 0 m/s Difference in sprocket speeds 0.7 m/s

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Driver model: closed loop control for TV turning

Desired path

TV

Lp

x

y

)( dttyKV

Closed loop control

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Simulation of TV dynamics: test with driver

Test: motion on a 2D curve

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Simulation of TV dynamics: testing area

Testing area is created in one of the CAD programs (SolidWorks, Inventor, PRO/E…)

A set of routes is specified by the user

Speed along the route can be variable

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Testing area

Speed history along the route

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Simulation results

Any kinematic variables (trajectories, velocities, accelerations of any point, angles of rotation, angular velocities and accelerations of bodies) Plots of applied forces Plots of reaction forces Plots of special variables related to TV dynamics Animation files Special tools for multivariant calculations and processing of their results Factorial experiments

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Special variables in the wizard of variables

Animation of hystograms

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Processor requirements

UM implements parallel computation of TV dynamics with the help of multithreading

It is strongly recommended to use

multi-core processors

The highest performance is achieved on eight-core processors

(four physical + four logical cores)

Universal Mechanism

Simulation of Tracked Vehicle Dynamicswith

Universal Mechanism

www.umlab.ru [email protected]

Universal mechanism

Universal Mechanism Simulation of Tracked Vehicle Dynamics with Universal Mechanism @umlab.ru Universal mechanism.

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