Cosmos work motion essential

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation. COSMOSMotion Essentials Training COSMOSMotion 2007
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Transcript of Cosmos work motion essential

Page 1: Cosmos work  motion essential

Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

COSMOSMotion Essentials Training

COSMOSMotion 2007

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2 © 2007 SolidWorks Corp. Confidential.

About this course

Prerequisites

Course Design Philosophy

Using this book

A note about files

Conventions used in this book

Class Introductions

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COSMOSWorks

Adv. Professional

Professional

Design Validation Products

Designer

Static

Vibration

& Buckling Thermal

Drop Test

Fatigue

Nonlinear

Post-dynamics

COSMOSEMS

Electromagnetic

COSMOSMotion

COSMOSFloWorks

Flow Simulation

Optimization

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4 © 2007 SolidWorks Corp. Confidential.

What is Motion Simulation ?

Study of moving systems or mechanisms

Motion of a system is determined by

– Mechanical joints connecting the parts

– The mass and inertia properties of the components

– Applied forces to the system (Dynamics)

– Driving motions (Motors or Actuators)

– Time

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Mechanism types

Kinematic System

– Movement of part(s) under enforced or constrained motion

– Fully controlled and only one possible motion result irrespective of force and mass

– Zero degree of freedom

Dynamic System

– Movement of part(s) under free motion subject to forces

– Partially controlled and infinite number of results depending on forces

– Greater than zero degrees of freedom

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Understanding Basics

Mass and Inertia – Newton’s First Law

– Conservation of momentum

Degrees of freedom – Rigid body

– Grounded parts

– Moving parts

Constraints – Restrictions placed on a part’s

movement in specific degrees of freedom

– Mechanical joints are connections that restrict the movement of one part to another

Joint motion

Gravity

x

y Pendulum restrained

to pivot about mounting

point

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Mapping of SolidWorks assembly mates (constraints) to COSMOSMotion joints.

100+ ways of defining SolidWorks mates.

Basic constraint types are merged to simplified mechanical joints.

– One Orthogonal Concentric mate in SolidWorks becomes a Concentric joint.

– One Coincident and One Orthogonal Concentric mates in SolidWorks becomes a Revolute joint.

– One Point to Point coincident mate in SolidWorks becomes a spherical joint

Constraint Mapping

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User Interface

Pull down menu

Intellimotion builder

Motion toolbar

Intellimotion browser

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User Interface

Pull down menu

Intellimotion builder

Motion toolbar

Intellimotion browser

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 1

Governor Mechanism

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Lesson 1: Topics

Introduction to the COSMOSMotion Feature Manager

Understand basic capabilities of COSMOSMotion

Run a Simulation

Create a result plot

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Lesson 1: Defining and Simulating a Mechanism

Parts

– Moving Parts

– Ground Parts

Constraints

– Joints

– Joint Primitives

– Cam Constraints

Forces

– Applied Forces

– Flexible Connectors

– Gravity

Results

Translational Distance

Collar and Slider.

Initial Distance : 345 mm

Slider Distance: 323 mm

Minumium Distance : 22 mm

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 2

Crankslider Mechanism

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Lesson 2: Topics

Create moving and ground parts

Review basic joint types in COSMOSMotion

Understand Automatic Constraint mapping

Apply motion to a joint

Create a result plot

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Lesson 2: Constraint Mapping Concept

1 Coincident and 1 concentric mates becomes a revolute joint

1 Concentric mate becomes a cylindrical joint

A point on a point coincident mate becomes a spherical joint

A point on an axis coincident mate becomes an Inline Joint

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Lesson 2: Results

Collar-1 not only translates along collar_shaft-1 but also rotates.

The rotation needs to be prevented

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Lesson 2: Motion on Joints

Joint Types Type of motion allowed Available options

under Motion On

list

Cylindrical Rotation and translation in one

direction

Rotate Z

Translate Z

Revolute Only Rotation in one direction Rotate Z

Translational Only Translation in one direction Translate Z

Spherical Rotations in all directions, No

translation

Rotate X

Rotate Y

Rotate Z

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Lesson 2: Results

Power Consumption in Mechanism

Why is Power Consumption negative

in some places?

Conversion:

Pound_force foot/sec to Watt

Pound_force foot/sec to HP

1 Pound_force foot/sec = 1.3558 W

1 Pound_force foot/sec = 0.00134 HP

1 ft = 12 in

4 pound_force foot/sec = 0.451933 W

4 pound_force foot/sec = 0.000447 HP

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 3

Piston Crankshaft Mechanism

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Lesson 3 Topics

Review basic joint types in COSMOSMotion

Create Mechanical Joints

Apply motion to a joint

Create and review results

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Lesson 3: Basic Joint Types

Joints used to constrain the relative motion of a pair of rigid bodies by physically connecting them.

Joint Primitives used to enforce standard geometric constraints

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Lesson 3: Joint definition

Location

Direction

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Lesson 3 Results

Torque required to drive the mechanism

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 4

Coupler

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Lesson 4 Topics

Simulate motion of gears using joint couplers

Joint coupler to associate the movement of one joint with another

Modeling gear-mate from SolidWorks model

Conversion

Convert RPM to deg/s

1 RPM = 360 degree

1 min = 60 s

100 RPM = 600 deg/s

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Lesson 4: Couplers

Any one of the following joint combinations will create

a coupler:

– Revolute-Revolute

– Revolute-Translational

– Revolute-Cylindrical

– Translational-Cylindrical

– Translational-Translational

– Cylindrical-Cylindrical

Only motion transfer. No load transfer

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Lesson 4: Coupler Definition

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Simulate Couplers using Gear Mate in SolidWorks

Lesson 4: Gear Mate in SolidWorks

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 5

Door Mechanism

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Lesson 5 Topics

Create springs and damper entities in COSMOSMotion

Attach different parts together to move them as a single entity

Constrain the motion of a cylindrical joint to achieve correct mechanism behavior

Modify springs and dampers to achieve desired design goals

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Lesson 5 Attaching Parts

Physically attach one part to another

Two parts will be welded or rigidly connected to one

another.

No relative motion between the two parts

Initial orientation between the two parts will be locked and

will be maintained throughout the simulation

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Lesson 5: Springs

Translational Spring Force = -k (X - X0)n + F0

Where:

k = Spring stiffness coefficient (always > 0)

X = Current distance between the spring connection points

X0 = Reference length of the spring (Free length)

n = Exponent defining spring characteristic

F0 = Reference force of the spring (preload)

Positive force repels the two parts.

Negative force attracts the two parts.

Similar force expression applies to Torsional Springs

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Lesson 5: Dampers

Translational Damper Force = c*vn

Where:

c - Translational damping coefficient

v - Current relative velocity between parts at the attachment points

n - Exponent.

Similar force expression applies to Torsional Dampers

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Lesson 5: Results

gas_piston-1 not only translates along gas_cylinder-1 but also rotates.

The rotation needs to be prevented

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Lesson 5: Results

Velocity goal is satisfied

Door does not stop in 30 seconds

Should we increase or decrease spring stiffness?

Spring stiffness: 1 N/mm

Damper Co-efficient: 5 N (sec/mm)

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Lesson 5: Results

Velocity goal is satisfied

Door stops in 30 seconds

Spring stiffness: 2 N/mm

Damper Co-efficient: 10 N (sec/mm)

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 6

Hatchback Mechanism

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Lesson 6 Topics

Create an Action Only force to simulate an

Change the mass properties of a part

Use Impact forces to control two parts from interfering each other

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Affect the dynamic behavior of a mechanism

Do not prohibit or prescribe motion and so do not add or remove degrees-of-freedom from your model.

Force Entities

– Translational and Torsional Springs

– Translational and Torsional Dampers

– Action-Only Forces/Moments

– Action-Reaction Forces/Moments

– Impact Forces

– Flexible Connectors

– Gravity

Lesson 6: Forces

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Lesson 6: Force Definition

Force Type – Whether the loading is a force or

a moment.

Location

Direction – Along an axis defined by an

edge, plane or cylindrical surface.

– Along the line-of-sight between two points

Magnitude – Enter a pre-defined function

expression (step, harmonic, spline).

– Enter an equation directly into the Function Expression field using the library of built-in COSMOSMotion functions.

Cylinder Component

Bore Diameter: 0.49 in

Bore Radius : 0.245 in

Area: 0.19 sq. in

Pressure : 500 Psi

Force: 94.30 Lbs

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Lesson 6: Action Only Force

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Lesson 6: Material Properties

Adding Materials Modifying Material Properties

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Lesson 6: Results

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Lesson 6: Impact Forces

Intermittent force that is dependent on relative distance between two components).

Impact forces are used to simulate the collision between two parts.

As two parts approach within a specified distance, the impact force becomes active, and a force specified by the impact parameters is applied to both of the colliding parts.

The collision is dependent on the materials and geometry of the bodies colliding.

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Impact Force = Spring Force + Damping Force

Stiffness: Depends on material properties and curvature of interacting surfaces

Exponent: Determines impact force characteristic

Max Damping: Simulates energy loss in collision

Penetration: Depth at which maximum damping occurs.

Length: distance at which the impact force is activated (parts contact)

Lesson 6: Impact Parameters

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Lesson 6: Impact Parameters

Good numbers for impact parameters:

Stiffness: 10000 lb/in 10000 N/mm

Exponent: 1.1-1.3 1.1-1.3

Damping: 0.1-100 lb-s/in 1-100

Penetration: 0.0001 in 0.01 mm

d cannot be specified as 0

Height of Piston: 0.95 in

Impact Distance Clearance Distance

1 in 0.05 in

0.95 in 0 in

0.9 in -0.05 in Components interfere

0.85 in -0.15 in

1.3 in 0.35 in

This values are linearly proportionaly due to the exponent input.

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Lesson 6: Results

Translational displacement of the concentric joint between the piston and cylinder parts

Notice that the displacement is held at 8 inches

which means that the impact force does not

allow further translation between the parts

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Lesson 6: Results

Magnitude of the impact force applied

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 7

Contacts

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Lesson 7 Topics

Apply Point to curve contact

Apply Curve to curve contact

Apply 3D Contact

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Point-curve - Restricts a point on one rigid body to lie on a curve on a second rigid body.

Curve-curve - Constrains one curve to remain in contact with a second curve.

Intermittent curve-curve - Applies a force to prevent curves from penetrating each other. Only active if the parts are touching

3D Contact – Applies a force to prevent bodies from penetrating each other. Only active if the parts are touching

Lesson 7: Understanding Contacts

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Contact is similar to an impact force in that the material properties of the parts are used to define the contact parameters.

Contact differs from an impact force since any point along a curve or geometry is used in the contact

Contact simulates friction forces between parts.

Lesson 7: Impact Forces Vs Contacts

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Lesson 7: 3D Contact

Surface Representation of parts:

– Tessellated Geometry

Faster but less accurate in certain contact situations like point to surface or multiple contacts

– Precise Geometry

Longer simulation time but produces accurate results

Contact Containers

Page 54: Cosmos work  motion essential

Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 8

Railcar Mechanism

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Lesson 8: Topics

Apply Gravity force to the mechanism

Create an Action-Reaction force to accelerate the railcar

Learn some advanced plotting techniques in COSMOSMotion

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Lesson 8: Action Reaction Force

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Lesson 8: Results

Probing translational velocity plot of body-1

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Lesson 8: Results

Plotting multiple plots in the same XY graph

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Lesson 8: Results

Replacing X axis time scale with a desired results

quantity

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Image courtesy of National Optical Astronomy Observatory, operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Lesson 9

Floor Jack Mechanism

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61 © 2007 SolidWorks Corp. Confidential.

Lesson 9 Topics

Apply motion to a part

Use different types of motion functions

Make a design change and study mechanical advantage

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Lesson 9: Part Motion

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Lesson 9: Function Types

Constant

Step Function

d0 = Initial value of displacement

d1 = Final value of displacement

t0 = Start step time

t1 = Final step time

Harmonic

Amplitude; Frequency; Time Offset; Phase Shift; Average

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Lesson 9: Function Types

Spline

–You can use your own motion data to control your mechanism by importing data points.

–To import data points, they must be in a .TXT or .CSV file format.

–You may import an unlimited number of data points.

-20

0

20

40

60

80

100

0 1 2 3 4

Overshoot

0

20

40

60

80

100

0 1 2 3 4

Data Points

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Lesson 9: Results

Translational Displacement of the

cylinder joint connecting the

piston and cylinder

Force on handle

Force to move the piston. A very

small force is required to push the

handle. This gets amplified

internally at the piston cylinder

area