· Using Dynamic Simulation to Simulate a Cam and Valve Assembly

· Simulate a cam, valve, and spring mechanism

· We determine

· Contact forces between cam and valve

· Forces in spring

· Torque required to drive cam

· View simulation results in Output Grapher

· Export simulation data to Microsoft Excel

· For better comprehension first complete Introduction to Dynamic Simulation tutorial (page 1)

· Open Assembly

· Active project: tutorial_files

· Open: cam_valve.iam

· Save As: cam_valve_tutorial (page 2)

· Activate Dynamic Simulation

· Main Menu

· Select Applications > Dynamic Simulation

· Assembly tools are replaced by Dynamic Simulation tools

· Message: Do you want to start the Dynamic Simulation now?

· Click No

· We will specify joints and forces needed to create a simulation next (page 3)

· Convert constraints

· Click Dynamic Simulation Settings

· Check to enable Automatically Update Translated Joints

· Click OK

· If already enabled

· Click Cancel

· Revolution joint is created between cam and support

· Prismatic joint is created between valve and support (page 4)

· Define Gravity

· In Browser

· External Loads node

· Gravity node

· Right-click

· Select Define Gravity

· Or Double-click Gravity node

· Establish gravity vector

· Select a vertical edge of support

· If direction points up

· Click Invert Normal button to flip arrow

· Simulation Panel in browser

· Click Run

· Valve responds to force of gravity and drops away from mechanism

· Click Construction Mode button (page 5)

· Insert a Spring

· Adjust mechanism first

· Right-click prismatic joint

· Select Properties

· Click dof 1 (T) tab

· Position field: 8 mm

· Press Tab key to update assembly

· Valve moves so that two reference frame origins are separated by 8 mmClick OK

· Click Insert Joint tool

· Select Spring/Damper/Jack from pull-down menu

· This joint requires two selections

· Select circular edge on support

· Select circular edge on valve

· Click OK

· Spring is created (page 6)

· Define the spring

· Spring is active by default

· In Browser

· Right-click spring joint

· Select Properties

· Stiffness field: 1 N/mm

· Free Length field: 50 mm

· Note: Double-click in input fields to select entire string

· Click More button (>>)

· Radius field: 12 mm

· Note: These values only affect the appearance of spring, not its physical properties

· Click OK (page 7)

· Run the Simulation

· Simulation Panel

· Click Run

· Valve oscillates slightly due to gravity and spring preload

· Return to Construction Mode (page 8)

· Insert a Contact Joint

· Drag valve down to reveal pending selection to insert joint

· Click Insert Joint tool

· Select 2D Contact from drop-down menu

· Select sketch loop on cam lobe

· Select sketch loop on the top of valve stem

· (remember we are making a 2D contact)

· We must select sketches and not surrounding geometry

· Click OK

· Contact joint is created and added to newly-added Contact Joints group in browser (page 9)

· Edit the joint properties

· Click the Look At tool

· Select front face of cam

· In Browser

· Right-click 2D Contact and select Properties

· Must: Z axis for both triads must point out and away from part (cam or valve)

· Expand properties dialog

· Select Normal check box

· Normal scale: 0.003

· Select Tangential check box

· Tangential scale: 0.01

· Click OK (page 10)

· Add Imposed Motion

· Add an imposed motion to specify required rotation of cam

· In Browser

· Right-click revolution joint

· Select Properties

· Click dof 1 (R) tab

· Click Edit Imposed Motion button

· Select Enable Imposed Motion check box

· In Driving field: Velocity must be selected

· Click velocity input box arrow

· Select Constant Value

· Change value to 360 deg/s

· Click OK (page 11)

· View the Simulation Results

· Click Run on Simulation Panel

· Allow simulation to run

· Click Output Grapher tool

· Output Grapher dialog box

· Output Grapher browser

· Contact joint

· Force folder

· Select frc[4.1]

· Spring/Damper/Jack joint

· Force folder

· Select frs[3] (page 12)

· View the Simulation Results

· View results in graph

· Arrange Output Grapher and model to view both simultaneously

· Double-click in graph

· Vertical black line appears

· Keep focus on Output Grapher

· Press left and right keys and view results in graph and model (cool!) (page 13)

· Export the Data

· On Output Grapher toolbar

· Click Export Data to Excel

· Click OK to accept default selection in dialog

· View chart and data in Microsoft Excel

· Close Microsoft Excel

· We do not need to save file

· On Output Grapher toolbar

· Click Deselect All

· In Dynamic Simulation - Output Grapher dialog

· Under Revolution joint

· Driving force folder

· Select Ukin[1.1]

· Torque to drive the cam appears (in graph)

· Close Output Grapher

· Close assembly without saving (page 14)

· Summary

· There was an overview of

· How to link a cam and valve

· How to create a spring device

· How to use Output Grapher to view simulation results

· We also learned how to

· Create a spring

· Create a 2D Contact joint

· Impose a motion

· Simulate dynamic motion

· View the simulation results

· Export the simulation results to Excel

· Must: Apply what we learned to models we create (page 15)

· Other: Right click and Continue occurs in Insert Joint, after first selection