introduction to radioss for composites

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Chapter 2: Orienting & Stacking Plies in a Laminate

Introduction to RADIOSS for Composites

© 2016 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

Agenda

1. Composites Overview

2. Properties: Orienting & stacking plies to make laminatea. Orthotropic Solid, /PROP/TYPE6 (SOL_ORTH)b. Composite Thick Shell, /PROP/TYPE22 (TSH_COMP)c. Sandwich Shell, /PROP/TYPE11 (SH_SANDW)d. Plies and Stack Shell, /PROP/TYPE19 (PLY) and /PROP/TYPE17 (STACK)e. Exercise 2.1 – Bird Impact on Honeycomb Sandwich Panelf. Exercise 2.2 – Defining Orientation and Stacking of Plies in HyperMesh 14.0

3. Materials: Defining types of ply materials

4. Determining composite material properties (Law 25)

5. Failure: Options for modeling material failure

6. Post-processing composite results in HyperView 14.0

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Composite Laminate Modeling Techniques

• Each ply with at least one solidLarge model, long CPU time

Advance Mass Scaling to increase simulation speed

High accuracy

• Mixed approach (middle layer thick)Shells for top and bottom ply

Solid, thick shell or cohesive for middle layer

Medium size model, significant CPU time

• Shell & Thick ShellOne shell element through the thickness

Multiple plies, with different materials

“Standard size “ model

Solids

Shells

Solids

Shell Sandwich


Summary of Composite Properties in RADIOSS

Type Description Type # Law Name Comment

Solids Orthotropic 6 SOL_ORTH For honeycomb & concrete

ThickShells

Orthotropic 21 TSH_ORTH Thick shell

Composite 22 TSH_COMP Thick shell

Shells

Orthotropic 9 SH_ORTH Orthotropic shell

Sandwich 11 SH_SANDW Most often used for shells

Fabric 16 SH_FABR Typically for safety airbags

Ply 17 PLY For ply based modeling

Stack 19 STACK For ply based modeling

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Orthotropic Solid: /PROP/TYPE6 (SOL_ORTH)

• For 8-node hex elements, 4 and 10-node tetras/BRICK, /TETRA4, /TETRA10

• Defines fiber plane for composite materials:Orthotropic Composite LAW 12 (3D_COMP)Concrete LAW24 (CONC)Honeycomb LAW28 (HONEYCOMB), LAW68 (COSSER)

• Solid element isoparametric frame:r : center of (1, 2, 6, 5) to center of (4, 3, 7, 8)s : center of (1, 2, 3, 4) to center of (5, 6, 7, 8)t : center of (1, 4, 8, 5) to center of (2, 3, 7, 6)

Orthogonalization of theisoparametric system


Example: Honeycomb Composite Sandwich

• Honeycomb often part of composite sandwich:• Composite shells for skin• Solid elements for the honeycomb

• Represent meso-scale behavior of honeycomb with macro-material model

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/PROP/TYPE6 (SOL_ORTH) – Key Parameters

Isolid Select element formulation for 8-noded solid (hex)

Ismstr Specify small or large strain formulation

Vx Vy Vz Components of Vector that defines material orthotropy

skew_ID Option for defining material orthotropy

Ip Defines how reference plane is specified


Orthotropic Solid Element Formulations, Isolid

• Typically, Isolid = 1 for standard 8-node hex, 4 and 10-node tetra with one integration point

• If hourglassing is an issue, then use fully integrated element, Isolid = 17

• For honeycomb and orthotropic foams, Ismstr = 1, which indicates that engineering stress vs engineering strain functions will be given

/PROP/SOL_ORTH/6honeycomb# Isolid Ismstr Icpre Inpts Iframe dn

1 1 0 0 0 0# q_a q_b h

0 0 0# Vx Vy Vz Iskew Ip Iorth

0 0 0 1 0 0# Ortho_angle

0# dt_min

0

ElementFormulation

Engr Stress-Strain

Options for defining material orientation

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/PROP/SOL_ORTH – Options for Defining Material Directions

• By default, material orthotropic directions will line up with the global system

• If skew_ID is given, then material axes (m1, m2, m3) will be the local system

• Best option if parts are flat


1 1 0 0 0 0# q_a q_b h


0 0 0 1 0 0

Prop ID 6

skew_ID 2

m1

m2m1 m2

Prop ID 7

skew_ID 1


/PROP/SOL_ORTH – Options for Defining Material Directions

• If material directions change as in a curved panel, then set flag, Ip, to line up material axes with element coordinate system

• In the example below, the honeycomb material axis 1 can be specified to line up with the element s-axis by setting Ip =2


1 1 0 0 0 0# q_a q_b h


0 0 0 0 2 0

ts

t

sr

ElementSystem Element

System

Caution! RADIOSS solid element coordinate system is not the same as OptiStruct

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Composite Thick Shell: /PROP/TYPE22 (TSH_COMP)

• Composite thick shells modeled as solid elements (one through the thickness)

• N layers with: Up to 200 orthotropic layersDifferent orientation of each layerVariable layer thicknessDifferent materials for layers

• Advantages:Delamination (element level only) modelingChange of thickness better representedBetter for thick composite partDirect connection with solid part

• Timestep similar to shell


/PROP/TYPE22 (TSH_COMP) – Key Parameters

Isolid Select element formulation for 8-noded solid (hex)


Icstr Constant stress formulation flag (Isolid = 14 only)

Vx Vy Vz Components of Vector that defines material orthotropy

skew_ID Option for defining material orthotropy

Φ i Angle for layer i

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/PROP/TYPE22 (TSH_COMP) – Example #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|/PROP/TYPE22/1epeq2p44# Isolid Ismstr Icstr Inpts Iint dn

14 0 010 282 0 0# q_a q_b h

0 0 0# Vx Vy Vz Skew_ID Iorth Ipos

1.0 0.0 0.0 0 0 0# Ashear

0# Phi Thick Z m

0 .125 0 1 45 .125 0 1 90 .125 0 1

-45 .125 0 1 -45 .125 0 1 90 .125 0 1 45 .125 0 1 0 .125 0 1

#dtmin0

Fully integrated element with 8 layers

Number of integration points (layers) in r (2), s (8), and t (2)


List of layers’ orientation, thickness,

and material


Sandwich Shell: /PROP/TYPE11 (SH_SANDW)

• 4 and 3 node sandwich shell elements• N layers with

Up to 100 layersDifferent orientation of each layerVariable layer thicknessLayer position can be directly prescribedDifferent materials for layers

• Material law can be:Law 25 (composite shell)Law 27 (brittle elastic plastic)Law 36 or 60 (tabulated piecewise non linear elastic-plastic)User laws

• Must use same material law type for the property layers

Most Complete Option for

Shells

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/PROP/TYPE11 (SH_SANDW) – Key Parameters

Ishell , Ish3n Select element formulation for 4-noded & 3-noded shells


N Define number of layers (plies)

Vx Vy Vz Components of Vector that defines material direction 1

skew_ID Option for defining material direction1, X-axis replaces vector, V

Φi ti Zimat_IDi

Defines orientation, thickness, position and material of each ply

Iorth Defines how element deformation affects orthotropy angle

Ipos Layer positioning flag


/PROP/TYPE11 (SH_SANDW) – Example

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|/PROP/SH_SANDW/45 layers# Ishell Ismstr Ish3n Idril

12 0 0 0# hm hf hr dm dn

0 0 0 0 0# N Istrain Thick Ashear Ithick Iplas

5 1 1.5 0 1 1# Vx Vy Vz Skew_ID Iorth Ipos

0 0 1 0 0 0# Phi t Z mat_ID

0 .3 0 1 45 .3 0 1 90 .3 0 1 45 .3 0 1 0 .3 0 1

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Element Formulation

Number of Layers (Plies)

Used to adjust total thickness of laminate


List of layers’ orientation, thickness,

and material

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Shell Formulations for Composites, Ishell, Ish3n

IshellHourglass

Control Element Description Comments Relative cost

4 Penalty method

Q4 Belytshko & Tsay(Default)

Control warpage, careful about hourglassing 1.0

12 n/a QBAT Fully integrated Composite, high accuracy analysis 2.0

24 Physical stabilization QEPH Improved under-

integratedAdvanced hourglass

control 1.2

2(Ish3n) n/a C0 Improved behavior for

large rotation (Default) For triangle shell ---


Defining Material Direction 1 for each Layer (Ply)

Global vector, , (or the X-axis of Local Skew) is projected onto the shell

Direction 1 of the material orthotropy is defined by angle Phi, , relative to the projection of on the shell

V

1

n

V

V

/PROP/SH_SANDW/45 layers# Ishell Ismstr Ish3n Idril




0 0 1 0 0 0# Phi t Z mat_ID

0 0.5 0 1 90 0.5 0 1 0 0.5 0 1

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Material Orientation Update Option, Iorth

• No update (Iorth = 0)

• Updated due to deformation (Iorth = 1)

F F

FF ’


Simulation: Comparison of Iorth = 1 and Iorth = 0

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/PROP/SH_SANDW/45 layers# Ishell Ismstr Ish3n Idril




0 0 1 0 0 0# Phi t Z mat_ID

0 .3 0 1 90 .3 0 1 0 .3 0 1

Stacking Layers (Plies)

Shell middle surface

Shell Normal

Z = 0

Z = t/2

First layer

Last layer

Z = -t/2Layers are stacked from bottom to top

First layer

Last layer


Ply Drop-off : Use Ipos = 1 for user defined layer stacking

# N Istrain Thick Ashear Ithick Iplas1 0 .1 0 1 1

# Vx Vy Vz Skew Iorth Ipos0 0 1 0 0 1

# Phi Thick Z m0 .1 -.15 1



# Phi Thick Z m0 .1 -.15 1 0 .1 0.0 1



# Phi Thick Z m0 .1 1 0 .1 1 0 .1 1

/PROP/SH_SANDW/1 /PROP/SH_SANDW/2 /PROP/SH_SANDW/3

Shell Normal

Layer positions calculated automatically when Ipos = 0

Z-location is middle of ply from shell mid-surface when Ipos = 1

-.15

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Composite Modeling in HyperWorks for Shell Elements

• Zone-based composite modeling• Traditional composites modeling method (SH_SANDW)• Each unique laminate zone has its own property definition• Has limitations…

• Ply-based composite modeling• Modern composites modeling method (PLY & STACK)• Plies are defined using element sets• Stack keyword defines how plies are oriented and stacked• Resolves many of the zone-based limitations…

Zone based modeling

Ply based model(visualized in HyperMesh)


Ply-based Shell: /PROP/TYPE19 (PLY) and /PROP/TYPE17 (STACK)

• 4 and 3 node sandwich shell elements

• Ply layers defined by: /PROP/TYPE19 (PLY)

Elements belonging to ply defined inelement group (/GRSHEL and /GRSH3N)

Definition of layer thickness

Material Law 25, 27, 36 or 60

Incremental orientation of each layer, Δϕ

• Stack of plies given by: /PROP/TYPE17 (STACK)

Stack = a “stack of plies”

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Advantages of Ply and Stack Definition

• More structured and more physical input—similar to how composites are manufactured

• The ply/stack structure can be created in HyperMesh 14.0 directly

• Better suited for optimization

• Creates potential of future enhancement to have inter-ply information transfer for modeling rupture and delamination (PLYXFEM)

Standard Kinematic shell

Modified Kinematic shellAdditional variable are added on each node/ply


Composites Technology – Ply Based Modeling

• A Composite Part is made up of “n” Plies and One Laminate• Direct Relationship to the Manufacturing Process• Ply Based Modeling Process

Define Ply Shapes and Related Ply DataDefine Stacking Sequences

• Design Change Requires only 1 Update

P1 45P2 90P3 -45P4 0

P6 90P5 -45

P7 45

Stack Table

Ply Mat Thk Theta

P7 M1 0.01 45

P6 M1 0.01 90

P5 M1 0.01 -45

P4 M1 0.01 0

P3 M1 0.01 -45

P2 M1 0.01 90

P1 M1 0.01 45

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Ply & Stack Visualizations in HyperMesh 14.0

• Live 3D Representation of Traditional 2D Representation for visual verification

• Visualize Composites Layers (Plies) with or without Fiber Direction

• Set Individual Plies Display State On/Off

• Color “by Thickness”

Traditional Representation

3D Representation with Composite Layers


/PROP/TYPE17 (STACK) & /PROP/TYPE19 (PLY): Example

8 0 0

/PROP/PLY/8Ply Example# mat_ID_i t delta_phi id_grsh4n id_grsh3n

1 0.5 0 11 0#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|/PROP/STACK/9Stack Example# Ishell Ismstr Ish3n Idrill Z0

12 0 0 0 0# hm hf hr dm dn


3 0 1.5 0 1 1# VX VY VZ skew_ID Iorth Ipos

0 0 1 0 0 0# Pply_IDi PHIi Zi

8 0 0

# Pply_IDi PHIi Zi8 90 0

# Pply_IDi PHIi Zi8 0 0

Ply Definition

Stack Definition

Elements belonging to a ply defined by a set

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Example: Hail Strike on Composite Plate

• Element Size: 6 x 6 mm

• Orthotropic, multilayered

• Composite plate modeled in threedifferent ways:

Shells:• 8 Layers • 1936 elements

Thick shells:• 8 Layers • 1936 elements

Solid elements:• 8 elements in the thickness• 15488 elements


Displacement Results: Hail Behavior on Thick Shell

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Results: Reaction Force for the Various Formulations


Exercise 2.1 and 2.2

SPH Bird

Honeycomb Sandwich

Exercise 2.1: Bird Strike on Honeycomb Sandwich Panel

Exercise 2.2: Material Orientation Definition

8-ply Laminate

6-ply Laminate

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End of Chapter 2

introduction to radioss for composites

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