Introduction to ADAMS/View ME 451
VIRTUAL PROTOTYPING PROCESS Build Test Review Improve • Build a model of your design using: • Bodies • Forces • Contacts • Joints • Motion generators
VIRTUAL PROTOTYPING PROCESS Build Test Review Improve • Test your design using: • Measures • Simulations • Animations • Plots • Validate your model by: • Importing test data • Superimposing test data
VIRTUAL PROTOTYPING PROCESS Build Test Review Improve • Review your model by adding: • Friction • Forcing functions • Flexible parts • Control systems • Iterate your design through variations using: • Parametrics • Design Variables
VIRTUAL PROTOTYPING PROCESS Build Test Review Improve • Improve your design using: • DOEs • Optimization • Automate your design process using: • Custom menus • Macros • Custom dialog boxes
Coordinate Systems • Definition of a coordinate system (CS) • A coordinate system is essentially a measuring stick to define kinematic and dynamic quantities.
Coordinate Systems • Types of coordinate systems • Global coordinate system (GCS): • Rigidly attaches to the ground part. • Defines the absolute point (0,0,0) of your model and provides a set of axes that is referenced when creating local coordinate systems. • Local coordinate systems (LCS): • Part coordinate systems (PCS) • Markers
Part Coordinate Systems • Definition of part coordinate systems (PCS) • They are created automatically for every part. • Only one exists per part. • Location and orientation is specified by providing its location and orientation with respect to the GCS. • When created, each part’s PCS has the same location and orientation as the GCS.
Markers • Definition of a marker • It attaches to a part and moves with the part. • Several can exist per part. • Its location and orientation can be specified by providing its location and orientation with respect to GCS or PCS.
Markers • Definition of a marker (cont.) • It is used wherever a unique location needs to be defined. For example: • The location of a part’s center of mass. • The reference point for defining where graphical entities are anchored. • It is used wherever a unique direction needs to be defined. For example: • The axes about which part mass moments of inertia are specified. • Directions for constraints. • Directions for force application. • By default, in ADAMS/View, all marker locations and orientations are expressed in GCS.
Difference between part and geometry • Parts • Define bodies (rigid or flexible) that can move relative to other bodies and have the following properties: • Mass • Inertia • Initial location and orientation (PCS) • Initial velocities • Geometry • Is used to add graphics to enhance the visualization of a part using properties such as: • Length • Radius • Width • Is not necessary for most simulations. • Simulations that involve contacts do require the part geometry to define when the contact force.
Difference between part and geometry Center of Mass Marker
mar_2 cyl sph cm mar_1 Difference between part and geometry • Dependencies in ADAMS/View
Creating some parts • Link • Box • Sphere • Extrusion • Importing a geometry from CAD package…. Parasolid…
Constraints • Definition of a constraint • Restricts relative movement between parts. • Represents idealized connections. • Removes rotational and/or translational DOF from a system. • Joints • Revolute • Translational • Fixed • Other…… ________________________
HMMWV Vehicle Model • High Mobility Multipurpose Wheeled Vehicle (HMMWV) modeled in ADAMS/Car
Let’s create some mechanisms • Simple pendulum • Parallelogram mechanism
Starting ADAMS/View • Start ADAMS/View • Type “aview” hit enter • Type “ru-standard” hit enter • Type “i” hit enter • In the Welcome dialog box • Under the heading, How would you like to proceed, select Create a new model. • Set some working directory. • Name the model missilelauncher. • Verify that Gravity is set to Earth Normal (-Global Y). • Verify that Units are set to MMKS - mm, Kg, N, s, deg. • Select OK.
The missile launcher model • You will • construct a very simple parallelogram mechanism used in a missile launcher by importing a simple geometry and creating rigid bodies and joints in ADAMS/View • Simulate the mechanism • Create measure and add sensor • Refine the model and simulate again • PostProcess the results • This will give you a rough idea about what goes on in the world of virtual prototyping
Importing Geometry • Import a rough geometry for missile’s barrel • Go to File import • Select “Parasolid” as the file format. • Right click in the box next to “File to Read” select “Browse” and point to barrel.x_t • Right click in the box next to Model name and select “missilelauncher” • Click OK • Right click the barrel point to Part:PART2 Rename • Rename the part to .missilelauncher.barrel
Setting up working grid • Setting up the working grid • Note: Use “z” “r” and “t” keys to Zoom, Rotate and Pan • Go to Settings Working Grid • Select “Pick” option from the drop down menu for “Set Location” • Select the Center of lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction. • See the figure on next slide
Creating rigid body: Links • Go to View Coordinate Window (F4) • Right click on Rigid Body Button in the “Main Toolbox” • Select Rigid Body: Link • Click the origin of the grid to specify one end of the Link and Click at location (550, -150, 0) to specify the other end of link • Note: The coordinates of the locations can be seen in the coordinate window • Right click the link, point to Part:PART_3 Rename • Rename the part as .missilelauncher.arm1
Creating rigid body: Links • Right click the link, point to Part:arm1 Copy • This will create another Rigid Body of type “link” at the same position as Part:arm1 • The name of this newly created part will be arm1_2 • Right click the part, select Part:arm1_2 Rename • Change the name to .missilelauncher.arm2 • We want to move this newly created part from the center of lower left cylindrical hole to the center of upper right cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction.
Creating rigid body: Links • Right click the position stack and select the translate tool as shown in the picture • Note: The software will tell you what you need to do next on the information bar at the bottom of the main window • Select the object to move: Right click the two parts (which are on top of each other) • This will give you option to select the part. Select arm2 • The next prompt will be “select a point to move from”: here, select the center of lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction • The next prompt will be “select the point to move to”: here select the center of upper right cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction.
Creating Joints • Create 4 revolute joints at locations shown
Creating Joints • Right click the joints stack in Main Toolbox and select Revolute Joint • Select following options • 2 Body 1 Location • Normal to Grid • First body: Pick Body • Second Body: Pick body
Creating Joints • Joint 1: Revolute Joint between Ground and Arm1 • Select Ground as the first body and Arm1 as the second body • Select the marker at the location (550, -150, 0) as the location for the joint • Joint 2: Revolute Joint between Ground and Arm2 • Select Ground as the first body and Arm2 as the second body • Select the marker on Arm2 corresponding to the previously selected marker on Arm1 as the location for the joint
Creating Joints • Joint 3: Revolute Joint between Arm1 and barrel • Select Arm1 as the first body and barrel as the second body • Select the marker at the location of the center of lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction • Joint 4: Revolute Joint between Arm2 and barrel • Select Arm2 as the first body and barrel as the second body • Select the marker at the location of the center of upper right cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction
Applying motion to Joint • Applying Motion to Joint 1 • Select Rotational Joint Motion tool as shown in the figure • Click on Joint 1 • This will add a rotational motion to the joint
Applying motion to Joint • Right click on the motion and point to Motion:MOTION_1 Modify • This will launch modify motion box as shown • Enter -30.0d * time as the Function of time (note the –ve sign)
Running initial simulation • Click on “Interactive Simulation controls” • Enter 5.0 sec for End Time and enter 500 for number of Steps (see the figure) • Select the play tool • This will run a simulation and the mechanism will turn through 150 degrees and will stop (why 150 degrees?)
Need for Measures and Sensor • We want the mechanism to stop when the Arms are vertical and the barrel is at maximum height • To achieve this we will create a “Sensor” which will stop the simulation as soon as the links are vertical • The Sensor needs to keep track of some value/measurement, so that it can stop the simulation when this measure reaches some particular value • So there are 2 steps • Create a Measure • Create a Sensor based on this measure
Measure We will create a measure to track the Horizontal Distance between these two points We know that the arms will be vertical when this distance will become zero (this is exactly what the sensor will look for)
Measure • Go to Build Measure Point-to-Point New
Measure • Give the measure name .missilelauncher.for_vertical_sensor • Right click in the box next to “To Point” and select arm1.Marker_1 (the marker at the location of the center of lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction) • Right click in the box next to “From Point” and select arm1.Marker_2 (the marker at the location (550, -150, 0)) • Select “Translational Displacement” as characteristic • Component : X • Select “Create Strip Chart” and hit OK
Sensor • Building a Sensor • Go to Simulate Sensor New • Name the Sensor .missilelauncher.vertical_sensor • Select Run-Time expression for Event Definition • Click next to the Expression box • This will launch Function Builder
Sensor Delete anything that is seen here Select “Measures” for Getting Object Data Right Click in the box and point to Runtime Measures Guess for_vertical_sensor Then hit Insert object name and click OK
Sensor • Now will be back to Create Sensor dialog box • Set event evaluation to None • Select Non-Angular Values • Select Equal • Enter value as “0” • Set the Error Tolerance as 1.0E-05 • Check Terminate current simulation step and... • Check Stop • Hit OK
Sensor • Now again run the simulation for 5 seconds with 500 steps and verify that the simulation stops when the arms are vertical
Refining the model • Adjust the barrel mass • Right click the barrel • Point to Part:barrel Modify • Select Define Mass by “User input” • Enter 100kg next to Mass • Hit OK
Final Simulation and PostProcessing • Run the simulation for 5 seconds with 500 steps and post process the results • To launch the post Processor • Go to Review PostProcessing (F8) • Select Objects as source and review the results
Applications • Application of this virtual prototyping • One can review forces coming on joints, and hence select appropriate bearings • Torques acting at the joints can be found and hence an appropriate motor can be selected based on the operating speed and torque requirements • A controls module can be added and tested • All mass properties, geometries, operating speeds etc can be changed and their effects can be evaluated