adams 动力学分析软件教程 6.pptx

General Design of Mechanical EngineeringLEE, Chul-Hee Department of Mechanical Engineering INHA UniversityCopyright © 2010, Chul-Hee LEEBasic knowledge about Geometry, motion, function and joint primitives. The lift mechanism modeling, simulation and analysis.Lecture Structure It must belong to a part and moves with the part.It is used to add graphics to enhance the visualization of a part.It is not necessary for performing simulations.Locations and orientations are defined indirectly by parts using anchor markers.Property of GeometryConstruction geometryØ Includes objects that have no mass (spline, arc, and so on).Ø Is used to define other geometry.Solid geometryØ Includes objects with mass (box, link, and so on).Ø Can be based on construction geometry.Ø Is used to automatically calculate mass properties for the parent part.Property of Geometry Anchor marker, which is itself Parent: part Orientation and location No anchor marker Parent: part LocationProperty of GeometryThe object being moved (or copied). And:Ø Either, a point on the object, and the location to which the selected point will be moved.Ø Or, a vector and a distance along the vector.Move objectsThere are two types:Ø Translational: applied to translational or cylindrical joints (removes 1 DOF).Ø Rotational: applied to revolute or cylindrical joints (removes 1 DOF).You define the joint to which motion is applied.ADAMS automatically uses the joint’s I and J markers, bodies, and single DOF.You define function for magnitude.Joint Motion (JM)The I and J markers (and, therefore, the parts to which they belong) referenced in the joint move with respect to each other as follows:The I and J markers overlap when motion θt = 0.During simulation, the z-axes of both markers are aligned.You can define motion magnitude as a:Ø DisplacementØ VelocityØ Acceleration function of timeMarker Usage in JMYou use functions to define magnitudes of input vectors used in: Motion drivers Applied forces Functions can depend on time or other system states, such as displacement, velocity and reaction forces. Every function evaluates to a single value at each particular point in time. Motion drivers can only be a function of time: M = f(time) Functions defining motion driver magnitudes can be: Displacement (time) Velocity (time) Acceleration (time)Function in ADAMSJoint PrimitiveI marker: Parent part: Bucket Its xy-plane is coplanar to the ground plane. J marker: Parent part: ground Its z-axis is perpendicular to the z-axis of the I marker. When constrained, the z-axes of the I and J markers are always perpendicular during simulation. Use the construction method 2 Bodies - 2 Locations.Joint PrimitiveProblem statementProblem statementProblem statementStart ADAMS/View:Ø Set the directory to exercise_dir/mod_08_lift_mech_1.Ø Create a new model named lift_mech, with Gravity set to Earth Normal (-Global Y), andØUnits set to MKS - m, kg, N, s, deg.Set up the working environment: Ø Adjust the grid to (A 20 m x 20 m grid, with 1 m spacing in each direction should be good.)Ø Because the grid spacing is much greater than the default, you’ll have to zoom out to see the grid on your screen.ProcessProcessBuild the parts:Ø Build the base part.üTip: Note the orientation of the block with respect to the xy plane.Ø Be default, the screen icons are set for models in millimeters. Because your model is in meters, you should adjust the icon sizes so you can see the icons. To adjust the icons, from the Settings menu, select Icons, and then set New Size to 1.Ø Build the main feature of the mount part by creating a block.ProcessØ Inspect your model. Note that the mount must be centered on the base. If necessary, use the vector option of the Point-to-Point tool (also known as the Position: Move- Translate tool) on the Move toolstack to slide the mount along the base, in the global z direction, by 2.25 m.Ø Before building the shoulder, set the working grid to cut through the center of the block:Settings Æ Working Grid Æ Set Location Æ Pick, and then select the cm marker of the block.ProcessØ Change the size of the working grid to .5 m. If you do not change the size, you will notice that when you try to create the shoulder part, ADAMS/View snaps to the nearest grid point, thus building the shoulder in a position that is not parallel to the base part.Ø Use the Cylinder tool to build the shoulder part.Ø Build the boom part.Ø Use the Location Event, as you did in Build the pendulum link, on page 103, to start the cylinder 2 meters over from the center-of-mass (cm) marker of the mount part.ProcessØ Apply fillets to the mount part using the Fillet tool :u In both the Radius and End Radius text boxes, enter 1.5 m.u Left-click each vertex, and then right-click to create. Refer to the next figure to see the vertices you should select.ProcessBuild the bucket:Ø Build a block with the la。