Surface-to-Surface Simulation Workshop 11 Node-to-Node Elements Surface-to-Surface Simulation REFERENCE: Training Manual Node-to-Node Elements (7-12)

11. Node-to-Node Elements Surface-to-Surface Simulation Purpose Demonstrate using the node-to-node contact elements to simulate surface-to-surface contact Goal Create 3D node-to-node contact elements and solve the small deflection contact analysis Model Description Applied pressure load 1/2 symmetry applied pressure load 1/2 symmetry 5500 psi 0 psi Beam #1 Beam #2 contact zone E = 10E6 PSI October 15, 2001 Inventory # 001568 W11-2

11. Node-to-Node Elements …Surface-to-Surface Simulation STEPS TO FOLLOW: 1. Start an ANSYS Interactive session in the working directory specified by the instructor using “node-to-node” as the jobname 2. Resume the NODE-TO-NODE database Utility Menu > File > Resume from Select “node-to-node.db1” [OK] OR enter the following command: RESUME, node-to-node, db1 NOTE: The node-to-node.db1 database contains the completed geometry, material, boundary condition, and loading definitions for this finite element model. October 15, 2001 Inventory # 001568 W11-3

11. Node-to-Node Elements …Surface-to-Surface Simulation 3. Add 3D node-to-node contact element type Main Menu > Preprocessor > Element Type > Add/Edit/Delete [Add…] Contact 3D nd-to-nd 178 Element type reference number = 3 [OK] [Close] OR enter the following commands: /PREP7 ET, 3, CONTA178 October 15, 2001 Inventory # 001568 W11-4

11. Node-to-Node Elements …Surface-to-Surface Simulation 4. Define the real constant for the contact element Main Menu > Preprocessor > Real Constants > Add/Edit/Delete… [Add…] Type 3 CONTA178 [OK] Real Constant Set No. = 1 [Close] OR enter the following command: R, 1 NOTE: This will define the REAL constant and use the default values. October 15, 2001 Inventory # 001568 W11-5

11. Node-to-Node Elements …Surface-to-Surface Simulation 5. Set the element attributes Main Menu > Preprocessor > Create > Elements > Elem Attributes … Element type number = 3 CONTA178 Material number = 1 Real constant set number = 1 [OK] OR enter the following commands: TYPE, 3 MAT, 1 REAL, 1 NOTE: The graphics window title bar contains the current element attribute settings. October 15, 2001 Inventory # 001568 W11-6

11. Node-to-Node Elements …Surface-to-Surface Simulation 6. Create the node-to-node contact elements at the coincident nodes Main Menu > Preprocessor > Create > Elements > At Coincid Nd… Tolerance of coincidence = 0.0001 Nodal number ordering “Low to high” [OK] [Pick All] OR enter the following command: EINTF, 0.0001 7. Solve the contact analysis Main Menu > Solution > Current LS OR enter the following commands: /SOLUTION SOLVE NOTE: If the CONTA178 nodes are coincident, you must specify the gap direction by means of real constants NX, NY, and NZ (the global Cartesian X, Y, and Z components of the gap direction vector). For this model, the contact normal is parallel with the global Y axis. Therefore, the vector coordinates are: < NX, NY, NZ > = < 0, 1, 0 > October 15, 2001 Inventory # 001568 W11-7

11. Node-to-Node Elements …Surface-to-Surface Simulation 8. Specify the contact normal direction vector Main Menu > Preprocessor > Real Constants > Add/Edit/Delete… Select “Set 1” [Edit…] Type 3 CONTA178 [OK] Defined gap normal - X comp. NX = 0 Defined gap normal - Y comp. NY = 1 Defined gap normal - Z comp. NZ = 0 [Close] OR enter the following command: RMODIF, 1, 6, 0, 1, 0 October 15, 2001 Inventory # 001568 W11-8

11. Node-to-Node Elements …Surface-to-Surface Simulation 9. Solve the small displacement contact analysis Main Menu > Solution > Current LS [OK] OR enter the following commands: /SOLUTION SOLVE 10. Select the solid elements for post-processing Utility Menu > Select > Entities Elements By Elem Name Element name = SOLID185 Choose “From Full” ESEL, S, ENAME, , SOLID185 NOTE: CONTA178 elements do not support large deflection. (The element maintains its original orientation in either a small or a large deflection analysis). October 15, 2001 Inventory # 001568 W11-9

11. Node-to-Node Elements …Surface-to-Surface Simulation 11. Plot the von Mises stress Main Menu > General Postproc > Plot Results > Nodal Solu Stress von Mises SEQV [OK] OR enter the following command: /POST1 PLNSOL, S, EQV October 15, 2001 Inventory # 001568 W11-10

11. Node-to-Node Elements …Surface-to-Surface Simulation 12. Select the contact elements for post-processing Utility Menu > Select > Entities Elements By Elem Name Element name = CONTA178 Choose “From Full” [OK] OR enter the following command: ESEL, S, ENAME, , CONTA178 13. Define an element table (ETABLE) for the contact normal force (FN) and for the gap size (USEP). Element Output Name Item Sequence Number Name Item E FN SMISC 1 FSY 2 FSZ 3 STAT NMISC OLDST USEP ALPHA 4 BETA 5 UTY 6 UTZ 7 MU 8 ANGLE 9 KN 10 KS 11 TOLN 12 FTOL 13 SLTOL 14 NOTE: When you are defining ETABLEs you need to know the item and sequence number for the element output to be defined. Each element description in the ANSYS Elements Reference has an "Element Output Definitions" table like the one shown here for CONTA178. October 15, 2001 Inventory # 001568 W11-11

11. Node-to-Node Elements …Surface-to-Surface Simulation 13. (… ETABLE definition continued) Main Menu > General Postproc > Element Table > Define Table [Add] User label for item = FN By sequence num SMISC Enter 1 in selection box [Apply] User label for item = GAP NMISC, 3 [OK] [Close] OR enter the following command: ETABLE, FN, SMISC, 1 ETABLE, GAP, NMISC, 3 October 15, 2001 Inventory # 001568 W11-12

11. Node-to-Node Elements …Surface-to-Surface Simulation 14. Select all nodes attached to selected elements Utility Menu > Select > Entities Nodes Attached to Elements Choose “From Full” [Apply] [Plot] …to plot the nodes OR enter the following command: NSLE NPLOT 15. Turn on numeric contour labeling Utility Menu > PlotCtrls > Numbering SVAL Numeric contour values = On [OK] /PNUM, SVAL, 1 October 15, 2001 Inventory # 001568 W11-13

11. Node-to-Node Elements …Surface-to-Surface Simulation 16. Plot the contact normal forces Main Menu > General Postproc > Element Table > Plot Elem Table Item to be plotted = FN Average at common nodes? = Yes – average [OK] OR enter the following command: PLETAB, FN, AVG October 15, 2001 Inventory # 001568 W11-14

11. Node-to-Node Elements …Surface-to-Surface Simulation 17. List the contact normal forces together with the gap size. Main Menu > General Postproc > Element Table > List Elem Table Item to be listed = FN [OK] OR enter the following command: PRETAB, FN, GAP NOTE: Review the extreme values for GAP. The negative values indicate an interference and a closed gap, where the maximum amount of penetration is virtually zero. October 15, 2001 Inventory # 001568 W11-15