Contact Analysis. Learn how to: define surface contact solve a contact analysis display contact results. I-DEAS Tutorials: Simulation Projects

Transcription

1 Contact Analysis I-DEAS Tutorials: Simulation Projects This tutorial shows how to analyze surface contact. The electrical flash contacts in a 35mm camera will be modeled to calculate the contact forces. Learn how to: define surface contact solve a contact analysis display contact results

2 Before you begin... Prerequisite tutorials: Introducing the I-DEAS Interface Quick Tips to Using I-DEAS and Creating Parts Extruding and Revolving Features Introduction to Simulation Free Meshing Boundary Condition Sets Boundary Condition Surface Loads Boundary Condition Symmetry Displaying Results 2

3 Setup of 4 If you didn t start I-DEAS with a new (empty) model file, open a new one now and give it a unique name. File Open Open Model File form Model File name: any unique name OK Make sure you re in the following application and task: Simulation Master Modeler Set your units to mm. Options Units mm (milli newton) 3

4 Setup 2 of 4 What: Sketch and dimension the shape shown. Horizontal (for some dimension text) What: Extrude 2mm. 2 2 (deselect edge) 4

5 Setup 3 of 4 What: Set the material sides of the surfaces. How: Things to notice The arrows indicate the top of each surface. You set the material side to define the direction of the element normal for meshing. 2 Repeat the process for the other surface. 2 5

6 Setup 4 of 4 What: Name the part. Name: Contacts What: Create an FE model. Boundary Conditions Geometry Based Analysis Only Save your model file. File Save Warning! If you are prompted by I-DEAS to save your model file, respond: No Save only when the tutorial instructions tell you to not when I-DEAS prompts for a save. Why: If you make a mistake at any time between saves and can t recover, you can reopen your model file to the last save and start over from that point. To reopen your model file to the previous save, press Control-Z. 6

7 Define surface contact of 8 What: Define a contact set for the surfaces anticipated to contact. How: Contact Set form Contact Set: Electrical Contact Global Search (off) Regions... Contact Region form Contact Region: Moving Contact Add to Region Create Don t dismiss the Contact Region form yet... 7

8 Define surface contact 2 of 8 Contact Region form Contact Region: Stationary Contact Add to Region Create Dismiss Don t dismiss the Contact Set form yet... 8

9 Define surface contact 3 of 8 What: Define the pair of surfaces to contact. How: Contact Set form Pairs... Things to notice The arrows indicate the side the software identifies as the top (material side) of each surface. In the illustration below, the bottom surface of the moving contact will touch the bottom surface of the stationary contact. (Your surfaces may be different.) Contact Pair form Hitting Contact Region: Moving Contact Bottom (if arrow is pointing up) Top (if arrow is pointing down) Target Contact Region: Stationary Contact Bottom (if arrow is pointing down) Top (if arrow is pointing up) Search Dist. Between: 0 and 3 Create Dismiss 9

10 Define surface contact 4 of 8 Contact Set form OK What: Restrain the right two edges of both contacts. 2 2 shift-pick OK 0

11 Define surface contact 5 of 8 What: Restrain the edge shown of the moving contact to displace downward in the Y direction a specified distance. Y Translation: 3 Y Translation: constant (all other directions: free) OK

12 Define surface contact 6 of 8 What: Mesh the surfaces with thin shell elements. Meshing Thicknesses:.5 All Element Length: Keep Mesh 2

13 Define surface contact 7 of 8 What: Preview the contact elements. Boundary Conditions Contact Set form Preview OK Contact elements can be previewed only after the mesh is generated. Warning! If you do not see the contact preview as shown, open your model file to the last save (Control-Z) and create the contact elements again, starting on page 6. 3

14 Define surface contact 8 of 8 What: Create a boundary condition set containing the contact set. Boundary Condition Set Management form Restraint Set Contact Set Warning! Make sure the contact set is toggled on, and that the correct contact set is listed (ELECTRICAL CONTACT). OK Recovery Point File Save 4

15 Solve a contact analysis of 2 What: Create a solution set and solve the model. Why: Reaction forces are stored by default to display the force required to deflect the contacts. Element forces will display the contact force between the contacts. How: Model Solution Manage Solution Sets form Create... Name: Contact Analysis Type of Solution: Linear Statics Output Selection... Output Selection form Constraint Forces (scroll down) Store/List: Store OK Continued on the next page... 5

16 Solve a contact analysis 2 of 2 Solution Set form Options... Solution Options form Contact Control... Contact Control form Things to notice The value of the normal penalty factor controls the stiffness of the contact. For some problems, you may have to adjust this value higher. OK or Dismiss (all forms) Recovery Point File Save 6

17 Display contact results of 5 What: Display the stress and displacement in the contacts. To properly display the contact, set the displacement scale factor to.0. Create Display form OK Deformed/Undeformed Options form Scale Factor OK Continued on the next page... 7

18 Display contact results 2 of 5 Things to notice The shell displayed elements should not actually contact, since they re separated by the thickness defined for the elements. In some cases, there will be penetration at corner nodes. Warning! If both contacts don t bend down as shown, you either did not define the contact regions and pair properly, or forgot to include the contact set in the boundary condition set. 8

19 Display contact results 3 of 5 What: Display the contact stress. Select Results form Display Contact Stress OK 9

20 Display contact results 4 of 5 Since you don t see stress values, display the stresses on the bottom layer instead of the top of the elements. Things to notice Contact stresses only exist on the side of the element (top or bottom) that contacts. 20

21 Display contact results 5 of 5 What: Display an arrow plot of the reaction forces. Display: Reaction Force Things to notice The sum of the nodal reaction forces on the displaced edge is the force required to deflect both contacts. Reaction forces are available for display only if you request reaction forces as stored output in the solution set. 2

22 Display contact results 5 of 5 What: Display an arrow plot of the contact forces on the element faces. Display: Contact Forces Arrow Options form OK Contact forces are available for display only if you request constraint forces as stored output in the solution set. 22

23 Tutorial wrap-up You have completed the Contact Analysis tutorial. You can delete or put away the FE model and the part. This part is not used in any other tutorials. What s next? Other tutorials introduce different element types and solution methods. 23