Pre-processing for crashing tubes analysis

In this chapter using HperMesh

? Create *ORIENTATION system

? Create contact between shell elements

? Create *AMPLITUDE and apply to time varying load

Hands-on exercises encompass setting up an analysis for the dynamic response of two tubes with a time varying velocity on one tube and the other tube fully constrained. Creating the ABAQUS input file for this analysis using HyperMesh is broken down into two sections:

Complete the model data

Open a HyperMesh file containing some model and history data.

Create *ORIENTATION

Create *SURFACE, *SURFACE INTERACTION, *CONTACT PAIR

Complete the history data

Create *BOUNDARY, TYPE = VELOCITY, AMPLITUDE = curve

Create *STEP

Comments: Units used in this model are as follows:

Length

Millimeters (mm)

Force

Kilonewtons (kN)

Mass

Kilogram (kg)

Time

Miliseconds (ms)

Section 1: Complete the model data

Exercise 1.1: Load ABAQUS Explicit user profile

1. Enter the user prof… panel in the Tool page.

2. Select the Abaqus profile and click OK.

3. Select the Explicit template and click OK.

Exercise 1.2: Retrieve pre-defined data

From the files panel, hm file sub-panel, retrieve the file CrashTubes_Start.hm6.

The model contains the following ABAQUS model and history data:

· Two ELSETs named FixTube and MovTube. Both have a *SHELL SECTION property. In HyperMesh, this translates to two component collectors named FixTube and MovTube.

· One *MATERIAL named STEEL_ELAS_PLAS associated to the two *SHELL SECTION properties

· Type S4R elements for both ELSETs

· *BOUNDARY constraints

· A HyperMesh system

Overview of ABAQUS *ORIENTATION

*ORIENTATION specifies a local system defining local material directions for elements.

In ABAQUS, shell and membrane elements have default local directions. They are not the global system directions. The default local 1-direction is the projection of the global x axis direction onto the shell surface. If the global x axis is normal to the shell surface, the local 1-direction is the projection of the global z axis onto the shell surface. The local 2-direction is perpendicular to the local 1-direction in the surface of the shell. Refer to the figure below.

Default local shell directions

Define *ORIENTATION in HyperMesh as follows:

Create a systems collector and a HyperMesh system.

1. Using the collectors panel, create a systems collector with no card image.

The *ORIENTATION name is automatically derived from the name of the systems collector containing the *ORIENTATION. Because of this, place each *ORIENTATION in its own systems collector.

2. From the Geom page use the systems panel to create a HM system.

From the HyperMesh system create the *ORIENTATION.

1. In the card panel, select the HM system and click edit.

In the pop-up card image, there is “*SYSTEM”. This is incorrect. It should read “HM system”. This does not affect the *ORIENTATION definition. A *SYSTEM is not written to the ABAQUS input file.

2. In the menu area, activate the ORIENTATION option to create the *ORIENTATION keyword.

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