Bending of a Pipe by a Punch Workshop 8

Workshop Supplement March 15, 2001 Inventory # WS8-2 Utility Menu > File > Read Input from … > pipe.inp > OK Exercise Bending of a Pipe by a Punch 1. Read in the input file “pipe.inp” The input pipe.inp creates a model of two concentric pipes with rigid connecting plates at both ends to form a straight beam. A rigid cylindrical punch is defined in the perpendicular direction directly above the beam center. An initial downward velocity is applied to the punch in order to make contact with the outer pipe. Due to symmetry, only one quarter of the structure is modeled, but results for the entire structure will be displayed. The material properties, loading conditions, and contact specifications need to be defined. The beam will first bend and then collapse under the loading. After the problem is solved, both general and time history postprocessing will be performed.

Workshop Supplement March 15, 2001 Inventory # WS8-3 Step 2. Define bilinear kinematic plasticity models for both pipes. –Preprocessor: Material Props –> Define MAT Model … > Add … –> Plasticity > Bilinear Kinemat > OK Next enter the data shown at the right for the outer pipe. Then Press OK. Since the inner pipe has the same material properties, repeat this procedure for MAT 2. –Preprocessor: Material Props –> Define MAT Model … > Add … –> Plasticity > Bilinear Kinemat > OK Although the same material model could have been used for both pipes, using duplicate materials facilitates element selection, etc. (e.g., ESEL,S,MAT,, 2 ! inner pipe elements)

Workshop Supplement March 15, 2001 Inventory # WS8-4 Step 3. Define rigid body properties for the plate and punch. Materials 3 and 4 are used to define the plate and punch, respectively. The elastic properties are identical, but the translational and rotational constraints are different. Reasonable values must be used for the elastic properties, since the contact algorithms use this data to determine the penalty stiffness. –Preprocessor: Material Props –> Define MAT Model > Add … –> Other > Rigid > OK Enter the plate data (top right) > OK –Preprocessor: Material Props –> Define MAT Model > Add … –> Other > Rigid > OK Enter the punch data (bottom right) > OK

Workshop Supplement March 15, 2001 Inventory # WS8-5 Step 4. Specify material properties for the point mass (MAT 5). A mass element is used to represent the portion of the rigid punch that is not modeled. It is located on the Y-axis of the punch. The actual mass has already been defined with a real constant, but the corresponding material properties need to be defined to complete the description. Use elastic isotropic properties for MAT 5 as shown below. Without this mass element, the punch could bounce off of the pipes instead of bending them! –Preprocessor: Material Props –> Define MAT Model > Add … –> Linear Elastic > Elastic After entering the data –> OK > Close

Workshop Supplement March 15, 2001 Inventory # WS8-6 Step 5. Specify type 5 hourglass control to minimize zero energy modes. Only the two pipes (MAT 1 and MAT 2) need to have hourglass control, since the rigid bodies (MAT 3 and MAT 4) are not susceptible to zero energy modes. –Preprocessor: Material Props –> Hourglass Ctrls> Local > 1 > 5 –Preprocessor: Material Props –> Hourglass Ctrls > 2 > 5 Keep the remaining default values and select OK for each hourglass GUI box. Hourglass control types 4 and 5 are the same for shells, but type 5 is also valid for solids, so using type 5 is recommended.

Workshop Supplement March 15, 2001 Inventory # WS8-7 Step 6. Define the initial velocity of the punch of –13.9 in the VY Direction. –Utility Menu > Select > Entities … > Elements > By Attributes > Material num > 4 > From Full > OK –Utility Menu > Select > Entities … > Nodes > Attached to > Elements > From Full > OK –Utility Menu > Select > Comp/Assembly Create Component > punch > Nodes > OK –Preprocessor: LS-DYNA Options > Initial Velocity > w/ Nodal Rotate …>PUNCH > 0 > > OK

Workshop Supplement March 15, 2001 Inventory # WS8-8 Part 1 = Outer Pipe Part 2 = Inner Pipe Part 3 = End Plate Part 4 = Punch Part 5 = Mass Element Step 7. Select everything in the model before creating the part list. –Utility Menu > Select > Everything Create and list the Parts to be used in the contact specifications. –Preprocessor: LS-DYNA Options > Parts Options...> Create > OK Step 8.

Workshop Supplement March 15, 2001 Inventory # WS As in implicit ANSYS, it is usually best to make the flexible, finer mesh the contact surface (e.g., the outer pipe) and to make the rigid, coarser mesh the target surface (e.g., the punch). Step Define the contact between the punch and the outer pipe. –Preprocessor: LS-DYNA Options > Contact > Define Contact –> Auto Nodes-Surf > 1 > 4 > 0.1 > OK (use the remaining defaults)

Workshop Supplement March 15, 2001 Inventory # WS8-10 Step 10. Define contact between the inner and outer pipes. Create the component “pipes” (all pipe nodes) to use with automatic single surface contact. The pipes will be able to contact themselves and each other. –Utility Menu > Select > Entities > Elements > By Attributes > Material num > 1,2,1 > From Full > OK –Utility Menu > Select > Entities > Nodes > Attached to > Elements > From Full > OK –Utility Menu > Select > Comp/Assembly > Create Component > pipes > Nodes > OK –Preprocessor: LS-DYNA Options > Contact > Define Contact > Auto Single Surf > 0.1 > OK >OK

Workshop Supplement March 15, 2001 Inventory # WS8-11 Steps 11, 12, & 13. Step 11: Enter Solution and specify the solution control options Specify a solution time of 50 ms and write 100 sets of data to both.RST and.HIS –Solution: Time Controls –> Solution Time > 50 >OK –Solution: Output Controls > File Output Freq> 100 > 100>OK Step 12: Write out global statistic data. –Solution: Output Controls > ASCII Output > Global data Step 13. Select everything, save the model, and solve the analysis. –Utility Menu > Select > Everything –ANSYS Toolbar > SAVE_DB –Solution: SOLVE > OK

Workshop Supplement March 15, 2001 Inventory # WS8-12 Only a symmetric quarter of the structure was actually modeled, but results for the full model may be seen... Step 14. Enter the General Postprocessor and view the final deformed shape. –General Postproc: - Read Results - Last Set –Utility Menu > Plot Ctrls > Style > Displacement Scaling > 1.0 (true scale) –General Postproc: Plot Results –> Deformed Shape > Def + undef edge > OK

Workshop Supplement March 15, 2001 Inventory # WS8-13 Step 15. Reflect the results about the YZ plane, and then the XY plane. –Utility Menu > Plot Ctrls > Style > Symmetry Expansion –> Periodic/Cyclic Symmetry > Reflect about YZ > OK –Utility Menu > Plot Ctrls > Style > Symmetry Expansion –> Periodic/Cyclic Symmetry > Reflect about XY > OK

Workshop Supplement March 15, 2001 Inventory # WS8-14 Variables 2 through 14 are now filled with data from the glstat file. Step 16. Enter the Time History Postprocessor (POST26) and plot the global information written to the LS-DYNA ASCII results file GLSTAT. First specify the number of variables for data storage and flag the history file PIPE.HIS to read the time information from. –TimeHist Postpro: Settings > File > 30 > pipe.his > OK Now flag the GLSTAT file to read the global data from starting with variable 2 (variable 1 = time data). –TimeHist Postpro: Read LS-DYNA Data > GLSTAT file … > 2 > OK

Workshop Supplement March 15, 2001 Inventory # WS8-15 TimeHist Postpro: Graph Variables … > 3, 4, 7, 8, 9, 14 > OK Kinetic Energy Internal Energy Sliding Energy External Work Total Energy Hourglass Energy Finally, store the data and plot the desired variables. –TimeHist Postpro: Store Data … > –Merge w/existing > OK Review ANSYS output window... (continued) Step 16.

Workshop Supplement March 15, 2001 Inventory # WS8-16