Part Definitions Chapter 3

Training Manual March 15, 2001 Inventory # Chapter Objectives Upon completion of this chapter, students will be able to define and utilize Parts within the ANSYS/LS-DYNA Program –1. Define what a Part is in an Explicit Dynamic Analysis –2. Describe how Parts are used in ANSYS/LS-DYNA –3. Define how to create a Part and Part Assembly in ANSYS/LS-DYNA –4. Describe how Parts are listed and updated –5. Given step-by-step guidance, a contact analysis will be performed using Part definitions

Training Manual March 15, 2001 Inventory # PART 1: BALL Mat 1: Si 3 N 4 Ceramic Real 1 Type 1: Solid 164 P PART 2: PLATE Mat 2: Steel Real 2 Type 2: Solid 164 Part – Definition A Part is a group of elements that have the same combination of Element Type, Real Constant Set, and Material ID Numbers. Typically, a Part is a specific ‘entity’ within a model. This entity is then given a reference number, called a Part ID, that can be used in subsequent ANSYS/LS-DYNA commands. To demonstrate how Parts are defined in a finite element analysis, consider the problem of a sphere in normal contact with a plate. As depicted, the model consists of two distinct parts, one for the sphere and one for the plate.

Training Manual March 15, 2001 Inventory # Example: How Parts Are Used In ANSYS/LS-DYNA The definition of a Part in an Explicit Dynamic Analysis is very important because many ANSYS/LS-DYNA commands refer directly to Part IDs. The following are some tasks that incorporate Part IDs: –1. Defining or deleting contact between two entities (EDCGEN and EDDC commands) –2. Defining rigid body loads, constraints, properties, or assemblies (EDLOAD, EDCRB, EDIPART, and EDASMP commands) –3. Reading Time History material data (EDREAD command) –4. Applying Damping to a component within a model (EDDAMP command)

Training Manual March 15, 2001 Inventory # Creating, Listing, and Updating Parts Parts are created, updated, and listed using the EDPART command. The menu paths are: –Preprocessor: LS-DYNA Options > Parts Options To create parts within a model, simply select the OK button. Part IDs will be automatically generated from a sequential list of the selected elements. If any Element Type, Real Constant Set, or Material number changes in the element list, a new Part ID will be assigned to that group of elements.

Training Manual March 15, 2001 Inventory # Listing Part IDs After new Parts have been created, they will be automatically listed to the screen. They can also be listed using the EDPART command: A typical listing of Part Ids is shown:

Training Manual March 15, 2001 Inventory # (continued) Listing Part IDs In a Part listing, Part ID numbers are given in the PART column with the corresponding MAT, TYPE, and REAL numbers. As shown in the previous listing, Part numbers have a status of either USED (1) or UNUSED (0) An UNUSED Part ID is any combination of MAT, TYPE, and REAL that is not referred to by any currently selected elements. UNUSED Parts typically occur when elements are deleted from a model. If a Part listing shows that there are unused Parts in a model, these Parts can be eliminated by recreating the Part list (EDPART, CREATE). Recreating the list will compress the Unused Part numbers so that the total number of Parts in the model will be reduced. However,...

Training Manual March 15, 2001 Inventory # Updating a Part List If Parts are repeatedly created using the EDPART, CREATE command, the PART list is continuously overwritten. This may cause problems for previously defined commands (e.g., for contact) that reference a particular Part number that has now changed. In order to eliminate such a problem, the part list can be Updated (rather than recreated) to obtain the current Part list. Updating the Part list extends the existing Part definitions without changing their order and allows elements to be added to an existing Part of the same TYPE, REAL and MAT. To Update the Part list, issue the EDPART, UPDATE command:

Training Manual March 15, 2001 Inventory # Recommended Procedure For Using Parts 1. Build the model until a part number is required to be input by a Part-specific command. 2. Create a Part list (EDPART, CREATE) and list it (EDPART, LIST). 3. Use the appropriate Part number from the listing. 4. During subsequent modeling, Update (EDPART, UPDATE) and List (EDPART, LIST) the current Parts before another Part- related command is issued. 5. Repeat step 4 for all repeated Part-specific commands. Note: The Part list is updated and remains permanent upon issuing the SOLVE command. If a command references a Part ID that is not defined, the solution will be terminated.

Training Manual March 15, 2001 Inventory # Selecting Parts PARTSEL command brings select logic to parts. Element components _part1, _part2, etc. are automatically created Selected Parts can be plotted to clarify Part ID input for part- related commands PARTSEL, Type, PMIN, PMAX, PINC –Type = ‘S’, ‘R’, ‘A’, ‘U’, ‘ALL’, ‘NONE’, ‘INVE’, and ‘PLOT’ –single quotes required due to macro status of command –PMIN, PMAX, PINC = minimum, maximum, and increment #

Training Manual March 15, 2001 Inventory # Selecting Parts UTILITY MENU: Select > Parts...

Training Manual March 15, 2001 Inventory # Plotting Parts Parts selected from the PARTSEL command can be automatically plotted using the PARTSEL, ’Plot’ Option Note: that the PARTSEL,’Plot’ Option not only plots the selected parts, but also makes them the currently selected element set. UTILITY MENU: Plot > Parts...

Training Manual March 15, 2001 Inventory # Part Assemblies In ANSYS/LS-DYNA it is also possible to group a set of Parts into assembly using the EDASMP command. EDASMP,,ASMID,PART1, PART2, …,PART16 –Up to 16 Parts can be grouped into an assembly –ASMID = part assembly no. ( must be greater than highest part no.) Part assemblies are most commonly used when defining contact (Cont and Targ fields of the EDCGEN command) Preprocessor: LS-DYNA Options > Assembly Options….

Training Manual March 15, 2001 Inventory # Part Assemblies To create a part assembly, simply define the group of parts Part Assemblies can also be listed or deleted.

Training Manual March 15, 2001 Inventory # Part Creation and Use Exercise The exercise for this chapter begins on page E3-1 of Volume II. Creation and use of parts are demonstrated in a simple example of a box impacting a thin cantilever beam.