Composites Analysis

MSC Software Confidential

Composites Analysis In Summa Ultimate Innovation Day 2012

Presented By: Andrew Main

October 8, 2012


INTRODUCTION Composite trends

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MSC Software Confidential 10/8/2012 3

Composite Trends

Boeing 787 Airbus A350

Bombardier C Series


Composite Trends

McLaren F1 Hypercar Launched 1992 Cost $970K

Mercedes-Benz SLR Sports car Market Launch 2003 500 units p.a. for 7 years Carbon fibre bodywork & monocoque Price c. $450K

McLaren MP4-12C Launched 2010 $229k

Mass Production Methods Bumpers, panels…? Lower temperature

thermoplastic resins Press forming (e.g. Hexcel

HexMC ® )


Composite Trends

● Wind Turbine Blade

● Up to 60 80 m long

● (and still growing)

● Cost reduction


Composite Trends

● Tennis rackets

● Bicycle frames and wheels

● Prosthetic limbs

● Golf clubs

● Kayaks

MSC Software Confidential 10/8/2012 7

MSC Composite Product Overview

CATIA CPD

Fibersim

“Pre and Post Processing”

“Solvers”

Patran/

Laminate Modeler

SimXpert

MSC Marc

MSC Dytran

Nastran

Sol 700

Sol 400

C

A

D

…And our

latest arrival


Classical Analysis Solutions

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MSC.Patran

• Open Architecture – Imports from most standard CAD

systems • IGES, STEP, ACIS, PRO/E,

CATIA, STL, PARASOLID, UNIGRAPHICS

– Exports to most common FE solvers • MSC.Nastran, MSC.Marc,

MSC.Dytran, MSC.Actran, LS-DYNA, ABAQUS, ANSYS, SAMCEF, PAMCRASH

• Fully featured pre and Post-Processing

• Customisable via Patran Command Language (PCL)

• Creation of composite properties

• Post-processing composite results

• Support for shell and solid composite elements.


• Advanced Composites modelling tool, plug-in for Patran.

• Draping • Interfaces to Design and

Manufacture

• Model Checking tools

– What is the local layup?

• Advanced post-processing

– What is reserve factor or margin of safety of structure?

– What is the failure mode?

– Which ply is failing?

Laminate Modeler

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Laminate

Modeler

DESIGN

MANUF-

ACTURE

ANALYSIS


• Simulation of placing

material onto mould

• Material forms on mould by

shearing.

– Excessive shear shows in red.

This shows a manufacturing

problem

– Splits can be introduced to

reduce shear

• Flat patterns can be exported

to cutting machines

• Draped patterns can be

exported to Virtek Laser-

edge projection system

Laminate Modeler Draping

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Laminate Modeler Model creation

• Create list of plies in

order of manufacture

• Laminate Modeler

converts this into

properties

• Each element has

properties according to

draping of individual

plies on that element

• Creates higher quality

models capturing reality

more accurately

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SimXpert

• Pre-post processor with strong process automation capability

– Graphical programming interface

– Programmable using Python

– Interfaces through Python to Microsoft Excel

• Composite property editor

• Composite verification

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• FiberSIM/SimXpert interoperability

– SimXpert used for FEM model definition (mesh,properties, LBC, analysis setup)

– FiberSIM creates composite layup using various methods • Zones

• Plies

• Connection of programs needed to map element properties from SimXpert to FiberSIM and to import detailed layup definitions from FiberSIM to SimXpert

SimXpert - FiberSim Bi-directional Transfer

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SimXpert


Solvers

• Nastran

– SOL <=200

• Solutions based on classical laminate theory

• Fast

• Statics, dynamics, optimisation

• Shell elements only

– SOL 400

• Advanced composites based on full integration of layers

• Not as fast

• Shells, solids and “solid shells”

• Advanced failure modelling

– SOL 700

• Explicit solver

• Composite impact modelling

• Marc

– More non-linear options

– Coupled thermal, structural,

chemical spring-back modelling

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Shell

element

Solid

element

Solid Shell

element

Layered

Composite

definition


E-Xstream digimat

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• Prediction of properties of

a composite material from

its constituent parts

– Stress/strain

relationships

– Failure prediction at

microscopic level

– Failure prediction using

standard theories

• Prediction of sandwich

panel properties and

failure prediction

• Prediction of composite

SN fatigue curves


Going Beyond First Ply Failure

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• Disastrous failure of several De

Havilland Comet airliners in 1950’s

due to progressive fatigue crack

growth.

– Lack of appreciation of problem

• Composite materials do not fail in

same manner as a metal.

– We need to understand progressive

failure to ensure we have no

composite Comets!

– First ply failure may not be enough.

This does not allow analysis of

existing flaws or damage.

Why?

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• Standard failure models used to predict ply failure

• If a ply fails

– the modulus of the ply is multiplied by 0.01 (Default) to “disable”

the ply. (Immediate failure)

– Stiffness is reduced so that Failure Index = 1.0 (Gradual failure)

• Choice of immediate or gradual depends on material

Progressive Failure Analysis (PFA)

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• Select a failure criterion

– Maximum stress

– Maximum strain

– Hill

– Hoffman

– Tsai-Wu

– Hashin

– Hashin-Fabric

– Hashin-Tape

– Puck

– User defined

Progressive Failure Analysis (PFA)

• Puck distinguishes between fiber and

matrix failure

– 5 failure modes

• 2 fiber and 3 matrix

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Going Beyond First Ply Failure

• Answer basic questions about the design

– What lies beyond FPF?

– Is FPF associated with abrupt failure?

– How is the stress re-distributed over adjacent plies and/or adjacent elements after a ply

failure?

– How far is FPF from Last Ply Failure?

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Total damage at 50% applied displacement Total damage at 60% applied displacement Total damage at 70% applied displacement Total damage at 80% applied displacement Total damage at 90% applied displacement Total damage at 30% applied displacement Total damage at 40% applied displacement

FPF

30%

40%

50%

60%

70%

80% 90%

Tip Displacement

Tip

Forc

e


Gradual Versus Immediate Degradation

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MSC Software Confidential 23

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VCCT CZM

Modelling Delamination


• In linear fracture mechanics, a crack starts to grow

when

– Total G > Gc

– G is the energy release rate

– Gc is the fracture toughness

• VCCT is one of the methods used to compute the

energy release rate.

VCCT

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Energy release rate:

G = Fu/2a


VCCT

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line crack – 2D or shell face crack – shell to shell face crack – 3D solid

line crack – shell edge to solid or shell face crack – shell to solid

• Supported in both Marc and Nastran

• Supported crack types are shown below


• All three modes of crack extension are supported

Modes of Crack Extension

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Mode I:

Opening

Mode II:

Sliding

Mode III:

Tearing


VCCT Example – Buckling Delamination

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F

F

• 4-Ply Composite

modeled with 2

layers of solid

elements

• Defect between

3rd and 4th ply

• Glue parts

together, except

at defect

Circular defect

Compressive loading


VCCT Example – Buckling Delamination

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VCCT Example – Buckling delamination

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Top view

Arrows show

local x

direction of

crack tips


Cohesive Zone Modeling (CZM)

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• Why?

• VCCT gives a brittle failure

• Most resins behave in a visco-elastic way

• The implementation of CZM is based on:

• Library of special interface elements

• Material model to characterize the interface behavior

Interface Element


Cohesive Zone Modeling (CZM)

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• Material models

• Bilinear

• Exponential

• Linear-exponential

• Material behavior

• Initially reversible

• Irreversible if v > vc

bottom face

1

2

3

4

5

6

7

8 top face

s

n

t top and bottom

face may coincide (zero thickness)


CZM – Example

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• Finite element model:

– Mesh plates and adhesive layer independently using

higher order elements

– Utilize the contact option to glue the adhesive layer

to the plates


CZM – Example

33


Even Further Beyond...

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VCCT Example – Crack Bifurcation

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• Growth through composite skin with stiffeners


VCCT Example

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Delamination with CZM

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• Automatic insertion of cohesive elements


A Practical Example In Collaboration with

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http://www.dlr.de/en/


Motivation For Analysis and Test

Problem Description

Stress in Thickness

Direction lead to early

failure



Analytical Calculation ASTM D 6415-06a STM for Measuring the Curved Beam Strength of a FRPMC

Solution developed by Lekhnitskii

i

o

r

r

r

E

E

2 2

1 12 2

2 2

1 11

2 1 1 1 1g

MM

rori

srst

rm

w

MCBS

1 11 1

1

2 2 2

1 11

1 1

m or

o o m

r rCBS

r g r r

s



Automated Modeling

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Test Results

(±452f / 02 / 90)s

Shear Failure

(02 / ±452f / 90)s

Unfolding

(±456f)

Unfolding



Example Correlation From Analysis To Test

• Red Line is analytical result

• Other lines are test results

• Dotted lines show scatter from test

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Analytical Results From Nastran

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Frame from analysis showing full

loading on angle section with

delaminations in corner



Conclusions

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• What is the future of composites?

– We don’t know

– We may correctly predict trends

– There may be new innovations we do not predict

• What can we do?

– Partner with organisations doing practical research

• UK National Composites Centre

• DLR

– Keep innovating

The Future…

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Composites Analysis

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