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Cross Section Creator Manual

CSC – Main View

Main Toolbar

Solution Explorer window

Properties window

Output window

Editors windows

CSC – Import procedures

Import FE (Ls-Dyna *.k and *.key file format)

Import RADIOSS file

Import *.stl file format

CSC – Create Cross Sections from FE Parts

Create Cross Section – import from *.k or *.key file format

Create Cross Section – import from RADIOSS

Create Cross Section – import from *.stl file format

New Cross Section in CCC (Crash Cad Calculate)

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Cross Section Creator – Main View

In the Cross Section Creator (CSC) main view you will see:

1) 3D main view

2) Main toolbar

3) 3D view toolbar

4) Solution Explorer window

5) Properties window

6) Output window

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On the Main Toolbar you will find icons which will enable you to import FE data and

open CSC tools. You can also easily save the current Solution, and /or open a new or

previously created Solution.

In the Solution Explorer window you will find the Solution Explorer tree.

The Solution Explorer tree includes folders and list of each and every object of the

currently opened Solution (FE Parts, imported Materials and Characteristics, newly

created Cross Sections)

In the Properties window you will find the properties for the currently selected object.

In the Output window you will find additional information about the current status of

any selected tool. This window also includes basic help information for the selected tool

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After importing a Material or creating a new Cross Section, you can open an Editor

window.

Cross Section Editor, Material Editor or Characteristic Editor window can be moved freely

on the screen.

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In the Editor windows you will be able to view the Cross Section extracted from the FE

geometry.

IMPORTANT

Edition and calculations are not available in CSC.

Edition and calculation features are available in CCC (Crash Cad Calculate) in which you

can easily open all cross sections created in CSC.

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CSC Import Procedures

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In Cross Section Creator (CSC) you will find several import possibilities.

All import features are easily accessible through the Main Toolbar.

CSC provides the possibility to import mesh models in the following file format: .rad, .k;

.key; .stl)

The detailed description of each import procedure is available in the later sections of this

manual.

Import FE (Ls-Dyna *.k file)

CSC gives the possibility to

import data from FE parts

model saved in *.k or *.key

file format.

The “FE Part” import

procedure will be described on

an example of a mesh model

of a B-pillar visible on the

right hand side.

To start the import procedure click on the

“Import FE (LS-Dyna *.k file)” icon

available in the CSC Main Toolbar.

Cross Section Creator provides the possibility to set the required units when importing a

FE model.

After selecting the Import option a new window “Import and Units Conversion

Utility” will appear on the screen.

In this window you can set the required units of the imported model (length, mass,

mass density, pressure / stress, strain).

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You can also save your

setting as default settings by pressing the “set as default”

button in the Import and Units Conversion Utility window.

Once the units and scaling

are defined you can select

the Import Data file. After

that click on the Import

button.

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A new window Available Parts will appear

on the screen. In this window you can select as many elements as you wish to import. In case of the given example all elements of

the B-pillar model were selected.

After selecting the required FE parts click on the Import button, as illustrated in the picture on the right.

When import is finished the message box will

appear on the screen. Click OK.

The Import procedure is now finished.

All imported elements can be easily found in the Solution Explorer Window, in the

Imported Objects folder. They will be also displayed in the 3D view window.

Note that along with the geometry, all information about the Material of the FE elements

as well shell thickness data will be automatically imported into CSC.

Moreover the import tool creates simultaneously Material basing on

FE data. The Material Properties such as

Material Constants, Stress – Strain

- Characteristics and the Strain –

Rate Effects parameters are visible

in material definition.

Note that CSC allows importing

both 2D Array and 3D Array.

The 2D Array is used to define the

Stress-Strain property of the Material.

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VCS imports also characteristics based on original FE file of curves definitions that describe the Stress-Strain relation including Strain Rate Effect. The CSC counterpart of this material property is the 3D array.

Additionally CSC has importing possibility for material which stress strain relation was

defined in simplified way by entering the values of first effective plastic strain[EPS1],

second effective plastic strain [EPS2], etc. and corresponding yield stress values [ES1],

[ES2].

IMPORTANT NOTE:

The Material is imported only in case when it is assigned to the geometrical component in FE keyword file.

Due to number of formats of LS Dyna keyword file the properties of imported objects in CSC might have wrong values or the import of properties can be neglected.

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Import from RADIOSS

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CSC provides the possibility of easy

import of FE Parts from RADIOSS

file.

The import procedure is similar to the one described in the previous chapter of this

manual.

To start the import procedure click on the “Import RADIOSS file” icon available in the

CSC Main Toolbar.

In the “Import and Units Conversion Utility” window select the Import Data file. After

that click on the Import button.

A new window Available Parts will appear on the screen. In this window you can select as many elements as you wish to import.

In case of Radioss file import Following objects are imported:

Nodes defined in one block

4 nodes shells defined by the /SHELL/part_id keywords Johnson-Cook materials used in above parts - /MAT/PLAS_JOHNS (law2)

The selected parts are imported in the following order:

First the /PART/part_id block is read in order to get the ID’s of part properties

(prop_id) and material (mat_id). If the /PART/part_id block does not exist the import procedure is abandoned and part is not imported.

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The prop_id (/PROP/SHELL/prop_id) is used to retrieve the thickness of all shells defined in given part and corresponding material. If /PROP/SHELL/prop_id block is not defined the part has default thickness 0

and null material. The interface imports material defined in FE file as /MAT/PLAS_JOHNS (law2). If other material is defined the empty material is

created in CSC with the name corresponding to the ID defined in properties block.

In the last step of import routine the FE nodes and shell elements are

imported. The interface imports the 4 nodes elements and corresponding FE nodes only.

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Import *.stl file

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Additionally Cross Section Creator enables import of

mesh models saved in *.stl file format.

To start the import procedure click on the “Import STL

file” icon available in the CSC Main Toolbar.

In the “Import and Units

Conversion Utility” window

select the Import Data file.

After that click on the Import

button.

A mesh model will be now

visible in the main 3D view.

It will be also automatically

added to the “Imported

Objects” branch of the Solution

Explorer three.

Please note that in case of a *.stl file import, import of materials is not available.

Moreover, information about shell thickness will be also inaccessible.

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Create Cross Section from FE Part

CSC provides a special Create Cross Section from FE Part tool dedicated to enable

the user to build even complex cross section geometry from previously imported mesh

models for further calculations and edition in the CCC software.

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With the usage of Create Cross Sections

from FE Part tool extraction of cross section

is possible after a 3-click procedure.

The User has the possibility to easily work

on number of cross sections extracted from

most crucial parts of the analysed

structure.

Create Cross Section - *.k file format import

Cross Sections are created on the basis of FE model in following steps:

STEP 1

After importing the required FE

model hide or delete all

expendable elements

(functionality available in the

object’s Properties window)

There is no limitation on the

number of parts contributing to

a single Cross Section.

In the following example a

cross section created from 4 FE

parts will be presented.

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Important notice:

The Create Cross Section from FE Part tool automatically extracts Cross Sections from

ALL FE PARTS VISIBLE IN THE 3D VIEW.

Please make sure that in your 3D view window only the required FE Parts are displayed.

At the same time check whether all necessary FE Parts are visible before you start to

create your Cross Sections.

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STEP 2

After selecting the Create Cross Section from FE Part tool select one part as a Master

FE part.

Once the part is selected by the tool program displays FE nodes (white) used for the

definition of quadrilateral FE elements.

Useful tip :

It is recommended to adjust the

size of points visible after selecting

the FE Part (edition of the points

can be done in FE Part’s properties

window). This facilitates the

selection of desired points when

creating Super Beam.

By default the nodes size is set to

1, which is optimal in majority of

cases.

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STEP 3

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Select two FE nodes in order to define the reference axis.

The selected nodes will change from

white to red. The node can be deselected

by pressing CTRL + right mouse button

click.

The reference axis is a line segment

defined on one of the side faces. The

axis is used as a reference to make a

cross section through the FE part(s) in

the plane perpendicular to the

reference axis.

Useful tip :

Remember to select first two points located on the same edge a FE Part, as illustrated in

the picture above.

STEP 4

The cross section through the FE parts

is made following selection of one of

the FE elements. The selected (gray)

FE element marks position of the

cutting plane perpendicular to the

reference axis on the FE part.

The trace of the extracted cross

section is shown on the 3D view as

thick white line. The cross section

selection is removed by pressing

CTRL + right mouse button click.

Useful tip :

Remember to select a field from a possibly most flat surface of the original FE beam.

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STEP 5

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Once the cross section is positioned in

the desired location on the FE part

the ‘C’ key should be pressed.

This creates the new Thin Walled

Cross Section which is automatically

added to the Solution Explorer tree.

At the same time the trace of the

cross section is removed from the 3D

view.

STEP 6

The Thin Walled Cross Section created automatically by the Create Cross Section from

FE Part tool represents the “best fit” to the expected final shape of the cross section

calculated following the Cross Section discretization rules

constant with the Macro Element

theory (proper central angles, lengths of the side

faces etc.)

Please note that in the Solution explorer three you will be

able to find automatically created Points, Plates and Segments of the newly created Cross Section, as illustrated in the picture below.

In case of elementary Cross Sections the automatic fit is almost complete. In case of more complex Cross Sections the user interaction is necessary to complete the Cross

Section according to the Macro Element discretization requirements. Please note that any edition of the newly created Cross Section can be done after opening it in the Crash

Cad Calculate (CCC) software.

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Create Cross Section – RADIOSS import

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Following a similar procedure as the one described in the previous chapter, it is possible

to extract Cross Sections from earlier imported RADIOSS mesh model.

Extraction of Cross Section from a RADIOSS model will be presented on the example of

a bumper assembly visible in the picture below.

Before selecting the Create

Cross Section fromFE Prt

tool make sure that in your

3D view window only the

required FE Parts are

displayed.

At the same time check

whether all necessary FE

Parts are visible before you

start to create your Cross

Sections.

In the presented example Cross Section of only one crashbox is to be created.

Therefore one expendable crashbax needs to be removed from the 3D view. In the

selected elements Properties window swich the “Visibility” flag to “False”, as illustrated in

the picture above

In the first step of the extraction

procedure select two FE points in

order to define the reference axis.

The selected points will change from

white to red. A point can be

deselected by pressing CTRL + right

mouse button click.

Remember to select first two points

located on the same edge a FE Part,

as illustrated in the picture on the

left

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In following step of the procedure,

cross section through the FE parts is

made following selection of one of

the FE elements.

The selected (gray) FE element

marks position of the cutting plane

perpendicular to the reference axis

on the FE part.

Remember to select a field from a

possibly most flat surface of the

original FE beam.

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The trace of the extracted cross section is shown

on the 3D view as thick white line.

Once the cross section is positioned in the desired

location on the FE part the ‘C’ key should be

pressed

A newly created Cross Section for this beam can

be found in Solution Explorer window.

It can be also viewed in the Cross Section Editor

window (shown in the picture on the left).

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Create Cross Section - *.stl file format import

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Simillarly as described in previous chapters, a Cross Section can be sreated basing on an

earlyer imported *.stl model.

The following examle presents the cross section extraction procedure from a single STL

element.

After selecting the Create Cross

Section from FE Part tool select

one part as a Master part.

Once the part is selected by the tool

program displays nodes (white) used

for the definition of mesh elements.

Please note that in case of a *.stl

model it can be benefficial to increase

the default size of ndoes to facilitate

the selection process.

In the first step of the extraction

procedure select two FE points in

order to define the reference axis.

The selected points will change from

white to red. A point can be

deselected by pressing CTRL + right

mouse button click.

Remember to select first two points

located on the same edge a FE Part, as

illustrated in the picture on the right

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In following step of the procedure,

cross section through the mesh part

is made following selection of one of

the triangular elements.

The selected (gray) triangular mesh

element marks position of the cutting

plane perpendicular to the reference

axis.

Remember to select a field from a

possibly most flat surface of the

original beam.

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The trace of the extracted cross section is shown on the 3D view as thick white line.

Once the cross section is positioned in

the desired location on the FE part the

‘C’ key should be pressed

As a result a thinn waled Cross Section

will be created.

It will be automatically added to the

Solution Explorer three, and it can be

viewd afted opening the Cross Section

Editor window, as ilustrated in the

picture on the left.

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New Cross Section in CCC

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Cross Section Creator which enriches the functionalities and capabilities of Crash Cad

Calculate, provides the possibility of fast and easy extraction of Cross Sections from a

mesh model and consequently closes the optimization and design loop.

CSC offers a user friendly 3D environment which allows import of a FE model and

creation of Cross Sections after a simple, 3-click operation. Such cross sections can be

than transferred into the Crash Cad Calculate 2D environment, where further

calculations and optimization routines can be done.

Edition, modifications, optimization and calculations of Cross Sections created from z

mesh model are available after opening a CSC file in the CCC software

After opening CCC go to the

Main Toolbar and select the

“Open” icon.

Afterwards select a previously

saved CSC file, as illustrated

in the picture on the right.

Automatically all Cross

Sections created in CSC, as

well as all Materials imported

from the original mesh model

will be added to the CCC

solution.

As it was mentioned earlier, the cross section geometry created automatically by CSC is

already divided into Points, Plates and Segments, which can be found in the Solution

Explorer window.

However in case of more complex Cross Sections the user interaction is necessary to

complete the Cross Section according to the Macro Element discretization requirements.

HINT: In the case of complex cross-sections composed of several FE parts it is recommended

to assign different colors to 2D points. This would significantly simplify the correction process.

Once all the corrections are introduced the unused nodes on the 2D view must be

removed in order to calculate the crushing response. When the calculation process in the

Cross Section Editor is successfully finished

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Thinn Walled Cross Section in Macro Element Approach –

discretization into Super Folding Elements

Accordingly to the Macro Element Method

the CCC software enables the creation of a

simplified cross section model build of

plates and segments based on Points.

In the picture on the right you can see an

example of a Cross Section modelled in

CCC. Please note that each segment has

been marked in different colour.

A Macro Element model is a simplified

model, where details of the cross sectional

geometry should be neglected.

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The simplicity of cross section

modelling by means of macro

elements (in comparison to a

FE model) is illustrated in the

picture on the left.

The problem of radius modelling at the

Cross Section level is related to the definition

of SuperFolding Element (SFE) and

corresponding modelling methodology (quite

different then in FE programs).

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Please note that SFE models crushing behaviour of the

entire corner area in a prismatic member. Consequently,

the cross-section details smaller then dimensions (a, b)

of the SFE cannot be effectively modelled using this

methodology.

In particular the small corner radii, r, are found to have

negligible impact onto energy absorption of the cross

section and are neglected in Crash Cad Calculate

calculations.

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The energy absorption in corner area can be significantly increased only for radii that

guarantee development of full plastic folds like in the case of circular or hexagonal

column.

In the case of very small Super Folding Elements – dense discretization at Cross

Sectional level, CCC signals the modelling/design error.