global-local analysis of composite structures using the ...gl/mul2_gl_sept19-1.pdfglobal-local...

Global-local analysis of composite

structures using the MUL2@GL tool

Erasmo Carrera, Alberto G. de Miguel, Matteo Filippi, Ibrahim Kaleel, Alfonso

Pagani, Marco Petrolo & Enrico Zappino

Turin (Italy), September 27, 2019

Politecnico di Torino

1

Mul2 Research Group - DIMEAS

Mul2 Group www.mul2.polito.com

MUL2 research group @ PoliTO

2

Aeroelasticity

Composites

Computational Mechanics

In NUMBERs:• 6 Academic Staff• 4 Post-Doc• 6 PhD Students• Many visiting…

PROJECTs:H2020, FP7, ESA, INDUSTRIAL PROJECTs, CLEAN-SKY

Bio-Mechanics

PARTNERs:EMBRAER, PURDUE, ENSAM, CALTECH, NASA…

Rotor Dynamics

Failure

MultifieldFinite

Elements


The challenge of composite simulation

3

Macro Structur

e

Structuralcomponent

Lamina

& Layer

Matrix & Fibre

Macro-scale101 m

Macro-scale100 m

Meso-scale10-2 m

Micro-scale10-6 m

Classical FEM Models

Matrix\Fiber FailureCrack propagation

Micro-bucklingEtc

Delamination/ debond

Failure Indexes• Max Stresses\Strains• Tsai-Wo, Tsai-Hill• …Delamination Analysis• Cohesive elements• …

Refined 3D modelsCrack propagation…

PeridynamicsHomogenizationFailure Indexes• Puck • Hashin• LaRC03• LaRC04• LaRC05

Free-edge effects

Structuralresponse

Interlaminar stresses


Available models for composite analysis

4

• Appropriate models for composite laminates are:

- beam/plate/shell models based on higher-order

kinematics;

- layer-wise approximations;

- zig-zag models;

- mixed formulations (e.g., RMVT);

- all are particular cases of CUF.

• By using commercial tools (i.e., Nastran, ABQ, etc.), users

shall employ 3D brick elements (4/5 per layer).

• This is still possible for small parts (coupon size), but

unfeasible for full-scale real life structures.

• As a consequence, in the industrial practice we use simplified

laminated plate models, “magic” failure indexes, and

invariants, which seriously alter the safety margins and shrink

the design space!

Allix, O. “Virtual delamination testing through non-linear multi-

scale computational methods: some recent progress”, Computers,

Materials and Continua 2013


Scope

5

• What if we have the capability to integrate advanced modelling techniques for the accurate analysis of composites

into current analysis/design tools and without changing the formalism of already available FEM models?

• What if we have the capability to cheaply (online) measure and assess stress/strain distributions and 3D failure

indexes (LaRC, 3D Hashin, etc.) in individual critical components or zones of our FEM model?

• We can then move towards disrupting our current approaches, e.g.:

- Design/optimize the structure taking into account the real stress states and margins.

- Reveal unfeasible design solutions already in the preliminary phase and save time for the subsequent detail

analysis process.


Theory: global-local method

6

C. Collier et al. “An approach to preliminary design and

analysis”, In 48th AIAA/ASME/ASCE/AHS/ASC Structures,

Structural Dynamics, and Materials Conference, 2007

• One-way coupling: displacements & rotations from global FEM model to

local model

• The critical elements are chosen as local models

Our method:

a a

c ca

m ma ic g a i

ig i i ca m

i ac m


Why?

7

E11 = 40 GPa, E22 = E33 = 4.0 GPa, ν12 = ν13 = ν23 = 0.25, G12 = G13 = G23 = 1.0 GPa

Ply properties:

Geometry:

L = 2 m, b = 0.1 m, t = 3 mm

1

[0 45 −45 90 45 −45 ]

LW model

ESL model

Up to 30%

error


Why?

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E11 = 40 GPa, E22 = E33 = 4.0 GPa, ν12 = ν13 = ν23 = 0.25, G12 = G13 = G23 = 1.0 GPa

Ply properties:

Geometry:

L = 2 m, b = 0.1 m, t = 3 mm

1

[0 45 −45 90 45 −45 ]

LW model

ESL model

Up to 30%

error

LaRC5 Matrix Failure:


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MUL2@GL tool


MUL2@GL tool

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Standalone package ‘MUL2@Global- ca ’


MUL2@GL tool

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Standalone package ‘MUL2@Global- ca ’

Installation in FEM softwares

• : C ‘ ba - ca ’ into ‘a i’

• Abaqus: C ‘ ba - ca ’ into ‘abaqus_plugins’

Inputs

Nastran

- Input file (bdf)

- Ouput file (op2)

- Material allowables

Abaqus

- Output file (odb)

- Material allowables

Outputs

3D strains, 3D stresses and failure indexes

- Coordinate systems: local, global and lamina

- Stress failure index: Hoffman, Hashin 3D, LaRC5

- Instantaneous visualization

- Stored data files: csv, dat and post in Femap &

Abaqus


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Aeronautic showcase

• Material: similar to IM7

• Lay-up: min 28 layers, max 62 layers

FEMAP model Deformed


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Aeronautic showcasePly Thickness Angle

1 0.183 45

2 0.183 -45

3 0.183 0

4 0.183 45

5 0.183 0

6 0.183 90

7 0.183 0

8 0.183 45

9 0.183 45

10 0.183 0

11 0.183 0

12 0.183 45

13 0.183 0

14 0.183 -45

15 0.183 45

16 0.183 0

17 0.183 0

18 0.183 0

19 0.183 90

20 0.183 90

21 0.183 -45

22 0.183 -45

23 0.183 0

24 0.183 -45

25 0.183 0

26 0.183 -45

27 0.183 0

28 0.183 0

29 0.183 0

30 0.183 90

31 0.183 0

32 0.183 0

33 0.183 90

34 0.183 0

35 0.183 0

36 0.183 0

37 0.183 -45

38 0.183 0

39 0.183 -45

40 0.183 0

41 0.183 -45

42 0.183 -45

43 0.183 90

44 0.183 90

45 0.183 0

46 0.183 0

47 0.183 0

48 0.183 45

49 0.183 -45

50 0.183 0

51 0.183 45

52 0.183 0

53 0.183 0

54 0.183 45

55 0.183 45

56 0.183 0

57 0.183 90

58 0.183 0

59 0.183 45

60 0.183 0

61 0.183 -45

62 0.183 45

3D stress solutionsLocal element


Tutorial example

Sym

Sym

Fixed

Rigid conn

Force

Reinforced composite panel

• Material: IM7/8552, ht=0.2 mm

• Lay-up: [0/90/45/-45/02]S


Tutorial example



• Lay-up: [0/90/45/-45/02]S


Tutorial example



• Lay-up: [0/90/45/-45/02]S

Max Hoffman FI = 0.2739


Tutorial example

Running MUL2@GL as a standalone

Selection of input model

Selection of Nastran results

Destination folder for stored outputs

Input critical elements for local analysis

Choice of failure criteria

Input material strengths

Direct comparison with Nastran shell

results


Tutorial example

Outputs


Tutorial example

Outputs

• Comma-separated values (csv) for Excel

• Data table (dat)

• Folder with postprocessing files for FEMAP


Documentation

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Publications Detailed tutorial


MUL2@GL available soon …

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Free-edge analysis

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Free-edge concentrations

C MITTELSTEDT AND W BECKER. “’Interlaminar Stress

Concentrations in Layered Structures: Part I – A Selective

Literature Survey on the Free-Edge Effect since 1967”, Journal

of COMPOSITE MATERIALS, Vol. 38, No. 12/2004

Extension

09

0

900

Bending

09

0

900

Mul2 assessment


Free-edge analysis

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Tensile test – composite coupon


Free-edge analysis

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Selection of a local element in the free edge of the coupon

Activation of free-

edge analysis


Free-edge analysis

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Definition of the free-edge side of the selected local element thourgh the node ids


Free-edge analysis

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Visualization of the free-edge strains and stresses

• All the outputs are also saved in dat and csv format


Free-edge analysis

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Comparison with literature semi-analytical solutions

T LORRIOT, G MARION, R HARRY, H WARGNIER. “Onset

of free-edge delamination in composite laminates under tensile

loading”, Composites Part B: Engineering, Vol. 34, No. 5, 2003

Ref:

Thank you for the attention

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global-local analysis of composite structures using the ...gl/mul2_gl_sept19-1.pdfglobal-local...

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