Development of a composite seat for a WRC racing car 2013 European Altair Technology Conference

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Marcel Zeisberg / Dirk Bordiehn (co-author)

Development of a composite seat for a WRC racing car 2013 European Altair Technology Conference

2013-04-24

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Table of content

• The Volkswagen Motorsport GmbH…........................................ 3 • Motivation for building an own seat..……………………………... 4 • Material models……................................................................... 5 • Finding a suitable geometry........................................................ 11 • Optimization process for the layup………………………………… 16 • Final FE calculation of the seat……………………………………. 20 • Conclusion…………………………………………………………… 21

2013-04-24 Development of a composite seat for a WRC racing car - Marcel Zeisberg 2

- Public Version -

Material information of this document are property of the Volkswagen Motorsport GmbH. The permission for the use of information can be assigned only through the Volkswagen Motorsport GmbH. Violation of the copyright will be prosecuted under civil and criminal law and places inter alia an obligation of compensation for damage on the responsible party.

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The Volkswagen Motorsport GmbH

History: - founded in 1966; started with Formel V - 1976: Scirocco-Cup (first one-make cup) - 1977: Golf GTI at the German Rally Championship - 1979-1994 engine manufacturer of the Formel 3 - 1980: Winner of the Rally Dakar (Race Iltis) - 1998: Class winner 24H of Nürburgring (VW Scirocco GT24) - 1998: Lupo Cup begins, later the ADAC Volkswagen Polo Cup - 2003-2011: Rally Dakar with Volkswagen Race Touareg (Winner 2009-2011) - since 2007: Formel 3 Euro Series - since 2013: World Rally Championship

Company: - 180 employees at the factory in Hannover - 100% subsidiary of the Volkswagen AG


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Motivation for building an own seat

The main reasons why a seat development is necessary: - improvement of the ergonomics by designing a seat for driver and co-driver

- reduction of rotational inertia around all axis and decrease COG`s height by

realize a better packaging

- mass reduction (minimum weight for WRC cars=1200kg empty with spare wheel)

- improvement of passive safety


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Material models


The way to generate a FE material model

material tests with sandwich pieces for validation

make clear what values you need

simulation of the material tests

material tests

define material cards in HyperMesh (CFRP and core separate)

optimize the material cards

1st v

alid

atio

n lo

op

simulation of sandwich test pieces

material model finished

2nd

valid

atio

n lo

op

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Material models


make clear what values you need

- material cards which were used for the development process: MAT1: foam core for 2D and 3D elements (ROHACELL® etc.) MAT2: honeycomb core for 2D elements (aluminum and aramid) MAT9: core for 3D elements MAT8: fiber reinforced plastic (CFRP and AFRP)

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Material models


define material cards in HyperMesh (CFRP and core separate)

Attention! before entering this values use the HW help; order does not fit with established literature

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Material models


- all values which are not provided by the manufacturer have to be determined by physical tests

material tests simulation of the material tests

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Material models


- define a layup you want to validate, for example zone-based with HyperLaminate - check all times material orientation and element normals (2D->composites/)


Attention! orientation of 3D elements is not mapped by the 2D elements (faces); orientation have to be defined by assign coordinate system at the property (tick PSOLIDX, assign CORDM)

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- it is very important to define the right material orientation for the core (3D elements)

- influence of wrong material orientation at 3D elements:

Material models



Source: (1) WHZ Racing Team; UAS Zwickau

(1)

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Finding a suitable geometry


1. Comparison of different side cut contours and edge designs

- use of isotropic imaginary materials for composite shell in combination with known material models for the core

- evaluation matrix with relation number for a qualitative comparison (e.g. stiffness per surface content)

„Before you make it complicated, make it useful!“ CR

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2. Topology-Optimization by using the SKO method

- to get an idea for a possible design, especially for the core, Topology-Optimization making sense

- use less constraints and a maximum of design space for the first optimizations - all load cases have to be included; for weighting factors pre simulations are useful - include adjacent components for realistic deformation behavior

symmetry constraint only

draw direction and min.

member size constraints

added

You will not receive satisfactory results by the first run. Modify constraints step by step!

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3. Topology-Optimization with 2D elements only

- main flux of force recognizable (helpful for UD-layer definition) - results not as important for seat shape design as 3D optimization results

symmetry constraint only

increased min. member size

? ?

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4. Topography-Optimization / Shape-Optimization

- core = 3D elements with MAT1 and MAT9 cards; surface = 2D elements - design component = outer shell; automatically morphing of the core structure - giving an idea where constant core thickness is makes sense - adequate results to the Topology-Optimization

no non design areas; no edge

non design area and edge

added; increased min. width and draw

height

Results should be used for Gauge-Optimization process which coming next.

? ?

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5. Core and shell thickness Free-Size-, Size- and Gauge-Optimization

The first calculations should be Free-Size-Optimizations with appropriate constraints.

- 2D elements combined with final material models, quasi isotropic composite layup and core defined with HyperLaminate

- alternately Gauge- and Free-Size-Optimization of the different design areas

- refining of the design areas after every optimization - with the Gauge-Optimization choice of core material can be done

? ? ? ?

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Optimization process for the layup


- by using the Size-Optimization results the final seat was generated with a CAD tool - final model for all calculations and optimizations consist of a 3D element core and

2D faces

Free-Size-Optimization

Composite-Size-Optimization

Composite-Shuffle-Optimization

creates a thickness distribution for each ply

calculates the number of plies for each ply contour you reimport with the FSTOSZ results

giving you the best stacking order for the plies

?

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- ply based layup definition by using the PCOMPP property - OptiStruct is not able to increase ply thickness; because of that “super plies” with a

maximum material thickness have to be created

- input manufacturing constraints at the Free Size Desvar (type: Stack); e.g.:

Free-Size-Optimization with super plies

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Composite-Size-Optimization

- Variant 1: - activate control card FSTOSZ before starting the Free-Size-Optimization - import Modelname_sizingXX.fem-input deck (a Free-Size output file)

- Variant 2:

- generate own plies, Size-Optimization will also work (perfect if you are designing the composite part in CAD parallel to the CAE work)

- activate control card SZTOSH before running Size-Optimization

- set manufacturing constraints (e.g. same as Free Size Desvar plus stress bounds)

Hint If you are interested in composite optimization methods visit www.altairuniversity.com/structural/optimization/composites/

enter prepreg thickness

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Composite-Shuffle-Optimization

- Variant 1: - import Modelname_shuffling.XX.fem-input deck (a comp.-size output file)

- Variant 2:

- use the own plies, Size-Optimization is not necessary before running a Composite-Shuffle-Optimization

- set manufacturing constraints

number of

successive plies

orientation of cover ply

-0.9mm deflection

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Final FE calculation of the seat


- with the results of the optimization process for the layup a final model of the seat was created (inclusive UD tapes)

- focus on producibility of the plies, composite failure index and observing of the design targets regarding compliance (FIA tests)

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Conclusion


• What has the biggest influence on the optimization results for composite parts?

• Which process gives me a satisfying result if the inner or outer shell of a composite part is given by the design dept.? (e.g. monocoques)

• When I start to design a composite layup according to the load?

material models, model quality (material orientation, element normals), adjacent parts, design constraints

“quick and dirty:” Free-Size-, Size- / Gauge-Optimization of a 2D element model with zone based plies and core defined at HyperLaminate

going more in detail: Topography-Optimization of a sandwich model (3D core and faces) combined with Free-Size-, Composite-Size-, and Composite-Shuffle-Optimization (ply based layup)

geometry investigation, material choice and core design have to be finished before you start the layup optimization; otherwise you will waste a lot of time because of the big number of variables

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Thank you for your attention!

Development of a composite seat for a WRC racing car 2013 European Altair Technology Conference

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