Download - SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Transcript
Page 1: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR
Page 2: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Predicting Stress Relaxation Behavior of Fabric Composites Using Finite Element Based Micromechanics Model

Anand Vijay KaruppiahGraduate Research AssistantMentor: Dr. Suresh Keshavanarayana Raju Wichita State University

Page 3: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

ContentsIntroduction

Literature Review

Finite Element Based Micromechanics Approach

Results & Discussion

Conclusion

Page 4: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Introduction• What is Viscoelasticity ? E.g. Polymers, Fiber Reinforced Composite

• What is stress Relaxation?

• Woven Fabric Composite: E.g. Plain Weave, Satin Weave…etc.• Aerospace Structural Applications:

1. http://www.aerooptimal.com/industries/composite-structures

Stress Relaxation

Page 5: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Problems Faced in Experiments• Stress distribution is Inhomogeneous and unknown• Slippage• Out-of-plane Bending Deformation (Buckling)

Before Loading After Loading

Micro view

Macro view

Uniaxial loading

3-Point Bending (Flexural Loading)

Page 6: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Finite Element based Micromechanics Model Approach

Page 7: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Literature ReviewPlain Weave Architecture2001(Shrotriya ,P et al.)

2012 (Kawai Kwok)

1. “Three-dimensional viscoelastic simulation of woven composite substrates for multilayer circuit boards” by Shrotriya .P et al.2. “Micromechanical modeling of deployment and shape recovery of thin-walled viscoelastic composite space structures” by Kawai Kwok

Page 8: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Assumption

The Unit cell model is idealized to contain a linearly viscoelastic matrix and orthogonally interlaced unidirectional (UD) composite tows (fiber bundles) with waviness and straight regions.

Both fill and warp tows are assumed to contain equal fiber volume fraction.

Cross section of tows are assumed to be a flattened lenticular shape.

Woven Fabric Type: 8-Harness satin Weave

Page 9: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Procedure followedStep 1:Calculating the Design Parameters

• Waviness (Crimp) angle• Aspect ratio of tow cross section• Fiber Volume fraction of Tow• Length of the Unit cell

Microscopic Image of 5320-8HS cross section

Filaments with Resin

Laminate

Tow cross section

Page 10: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Method: Subcell Modeling Approach• The model is assumed to contain

repeating pattern of binary subcells within the unit cell itself.

Software's Used: CATIA V5, Hypermesh v10 and FORTRAN 90.

Step 2: Modeling the Unit cell of 8-Harness Satin Weave

1. Rao .M.P,Pantiuk .M, ”Modeling the Geometry of Satin Weave Fabric Composites”. Journal of Composite Material, Vol. 43, No. 1/2009.

8-Harness Satin Weave

Page 11: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Step 1:Continue

Design Parameters

αhfhW

gwaias ai as

hmh

w

L

h

w

L

LT

Page 12: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Assembly of Binary Subcells for 8-Harness Satin Weave Architecture

Page 13: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Step 2: (Contact Bodies) ContinuedFill Tows Warp Tows

Neat Resin

FEA Software Used: MSC Marc v2014Commercial software

Contact Method followed:Segment-Segment

1.MSC Marc 2011 r1 Reference Manual Vol. B: Element Library, MSC. Software Corporation, Santa Ana, CA, 2011, pp 611.2.MSC Marc 2011 r1 Reference Manual Vol. A: Theory and User Information, MSC. Software Corporation, Santa Ana, CA, 2011, pp 611.

Page 14: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Fiber Bundle/Tows Weave Architecture of 8-Harness Satin

Unit Cell (RVE) of 5320-8HS Woven fabric (Vf=0.56)

Page 15: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Constituents Properties

Page 16: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Material and Sample Fabrication

Material Used: Cytec Cycom 5320-8 HS (Harness Satin) weave fabric prepreg and 5320-1 Pure Epoxy Resin

• Out-of-autoclave material• Dimension: 36mm x 5mm x 0.51mm• Nominal cure temperature: 250F for 1hr• Recommended post-cure temperature:

350F for 2hrs

Stacking Sequence for 5320-8HS• [0/90/90/0]• [+45/-45/-45/+45]

Method used: Stress Relaxation

5320-8HS Prepreg Material

5320-1 Resin

Silicon Mold

Molded 5320-1 Resin Specimen

Page 17: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Material and Sample Fabrication Cont.

Debulking SchemeDebulk time: 20 minutes Manufacture Recommended Cure Profile

Stress Relaxation Recorded

Dis

plac

emen

t, Te

mpe

ratu

re

0 t0 t1 t

Time (min)

Thermomechanical loading

s

tress

0 t0 t1 t

Time (min)

Displacement

Temperature

Test Procedure:

Page 18: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Step 3: Experimental determination of Viscoelastic properties of 5320-1 Epoxy Resin

Dynamic Mechanical Analyzer (DMA) Test setup for 5320-1 Pure Epoxy Resin

5320-1 Resin

3-Point Bending Tension

Page 19: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Master curve Formulation

1

2

( )log

( )o

To

C T Ta

C T T

( / )

1

( ) i

nt

ii

E t E E e

Prony Series

William Landel Ferry (WLF) Equation

Step:1 Step:2

Step:3

Page 20: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

1.Cytec. CYCOM 5320-1 Epoxy Resin System. Accessed on [12/18/2015]; Available from http;//www.cemselectorguid.com/pdf/CYCOM_5320-1_031912.pdf.2.Cytec. CYCOM T650-35K Carbon Fiber. Accessed on [12/21/2015]; Available from: http://cytec.com/sites/default/files/datasheets/THORNEL_T650-35_052112.pdf

Table 1. Elastic and thermal properties of the fiber and neat resin

i Ei (MPa) (s)1 2.56E+02 2.75E+02

2 2.33E+02 5.41E+03

3 2.35E+02 9.41E+04

4 2.59E+02 1.47E+06

5 3.73E+02 1.38E+07

6 5.86E+02 9.67E+07

7 4.79E+02 8.05E+08

8 3.70E+02 5.58E+09

9 4.72E+02 3.34E+10

i

Table 2. Relaxation times and coefficients of the Prony series for 5320-1 Epoxy Resin

Page 21: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Step 4: Estimating the Material Properties of Viscoelastic Tows/Fiber Bundles

Hexagonal Array of 5320-UD

( / )( ) ( )

1

( ) M

nt

ijkl ijkl ijkl MM

C t C C e

Stiffness matrix:

(Vf 0.77)

a) σ11 Stress contour under 140 C at 2000s

b) σ23 Stress contour under 140 C at 2000s

c) σ12 Stress contour under 140 C at 2000s

e) σ22 Stress contour under 140 C at 2000s

Page 22: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Step 5: Verification of Model Prediction

Homogenized solid model under flexural loading

(FEA Model)

Experimentation of 5320-8HS

5320-8HS

Page 23: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Overall View of Finite Element Analysis

[+-90] & [+-45] Homogenized laminate model

5320-8HS unit cell (RVE) model

Hexagonal array (Vf 0.77)

Fill Tows

Warp Tows

8 Harness interlaced satin weave architecture

Stress Relaxation Behavior of Woven

Fabric

2. Defining the Contact Body for 5320-8HS Unit cell model (Segment-Segment Contact Algorithm)

1. Estimating the Viscoelastic Properties of Fiber Bundle with Known fiber and Resin Properties under different Load cases

3. Verification of Unit cell Model Prediction

3. Applying Kinematic conditions of Periodic Symmetryand analyzing under different load cases

Page 24: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Accuracy of Micromechanical Model(Elastic Behavior)

5320-8HS System EXPERIMENT FEA (Unit Cell) % ERROR

E11 (Msi) 10.1000 10.6938 5.8789

E22 (Msi) 10.2000 10.7015 4.9163

E33 (Msi) -- 1.8019 --

0.0480 0.0448 6.6693

-- 0.4855 --

-- 0.4851 --

G12(Msi) 0.7550 0.7304 3.2532

G23(Msi) -- 0.5723 --

G31(Msi) -- 0.5727 --

23

12

13

Page 25: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Results and Discussion

Page 26: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Experimental Results

Experimental comparison of Effective Stress relaxation of 5320-8HS and 5320-1 at 140 °C

Page 27: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Numerical Results

Stress Relaxation Behavior of 5320-8HS Unit cell under different load cases at 140 °C

Page 28: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Comparison of Experimental and Numerical Results

(a) (b)

Flexural viscoelastic Behavior of 5320-8HS at 140 °C a) [+-45°] plies b) [+-90°] plies

Page 29: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Stress contours for normal load along the warp direction at time of 2000 s a) Fill Tows b) Warp Tows c) 5320-8HS Unit Cell

a) b)

c)

Observation

Page 30: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Stress contours for normal load along the Fill direction at time of 60s, 500s, 1000s,1500s, 2000s

a) Fill Tow#2 b) Warp Tow#2

a) b)

Page 31: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Stress contours of Neat Resin region around Fill tow#2 at time of 60s, 500s, 1000s,1500s, 2000s

Page 32: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Observation: (Contin.)

(a) (b)

a) Distribution of σ31 in 5320-8HS Laminate model at 2000 s b) Variation of σ31 in 5320-8HS Laminate model along the width of the Specimen at 2000 s, 1500 s, 1000 s, 500s,

100 s, 6 s

Page 33: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Conclusion

• Developed Micromechanical model predictions are in good agreement with experimental results.

• Although the fiber reinforcement improves the mechanical properties of resin, it does not always improve its viscoelastic properties.

• Also, developed micromechanical model can be used to predict the viscoelastic behavior for different various fiber volume fraction.

• Therefore, this in turn reduces a lot of material testing cost and labor.

• Similar procedure can be followed for all woven fabric system

Page 34: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Future Study

• In our current research, we are focusing to validate the master curve generated from the elevated temperatures with micromechanical prediction.

• Also, we are focusing to enhance our computation using Parallel Processing Technique.

Page 35: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

References Karami, G., “Finite Element Micromechanics for Stiffness and Strength of Wavy Fiber Composites”. Journal of Composite

Material, Vol. 38, No. 4/2004. Shrotriya, P., Sottos, N., “Viscoelastic response of woven composite substrates”. Composite Science and Technology, Vol.

65, 2005, pp. 621–634. Zhu, Q., Shrotriya, P., Geubelle, P., Sottos, N., “Viscoelastic response of a woven composite substrate for multilayer circuit

board applications”. Composite Science and Technology, Vol. 46, 2003, pp. 394–402. Kawai, K., “Mechanical modeling of deployment and shape recovery of thin-walled viscoelastic composite space structures”.

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2012. Abadi, M.T., “Micromechanical analysis of stress relaxation response of fiber-reinforced polymers”. Composites Science and

Technology 69 (2009): p.1286–1292. MSC Marc 2011 r1 Reference Manual Vol. B: Element Library, MSC. Software Corporation, Santa Ana, CA, 2011, pp 611. MSC Marc 2011 r1 Reference Manual Vol. A: Theory and User Information, MSC. Software Corporation, Santa Ana, CA,

2011, pp 611. Cytec. CYCOM 5320-1 Epoxy Resin System. Accessed on [12/18/2015]; Available from

http;//www.cemselectorguid.com/pdf/CYCOM_5320-1_031912.pdf. Anandvijay, K.R, Suresh, K.R., Kevontrez, K.J., Abhiruchika, S., “An Experimental and Numerical Study of Flexural

Viscoelastic Response of Woven Composite” AIAA, Region V Technical Conference 2016, Ames, IA. Cytec. CYCOM T650-35K Carbon Fiber. Accessed on [12/21/2015]; Available from:

http://cytec.com/sites/default/files/datasheets/THORNEL_T650-35_052112.pdf Kumosa, M., “Micro and Meso-mechanics of 8-HS satin woven fabric composites: part I-Evaluation of elastic behavior”.

Elsevier science Ltd., 2001. Rafic, Y., Hallal, A., et al., Comparative review study on elastic properties Modeling for Unidirectional Composite materials,

Textbook, Chapter 17. INTECH Open Access Publisher, 2012, ISBN: 9535107119. Aliabadi, M.H., “Woven composites”. Computational and Experimental methods in structures-vol.6. London, UK: Imperial

College Press, 2015, ISBN-9781783266173. Rao .M.P,Pantiuk .M, ”Modeling the Geometry of Satin Weave Fabric Composites”. Journal of Composite Material, Vol. 43,

No. 1/2009.

Page 36: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Questions ?

Page 37: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Backup slides

Unit Cell Design Parameters

Mesh Details

Tow Fill warp Resin Total

No. of Elements 864 13824 13824 62472 90120

Element type: Hexahedral, Pentahedral, Tetrahedral

Tow Thickness,g (mm) 0.175

Gap b/w tows, g (mm) 0.04Waviness length, ai (mm) 0.768

Tow cross section Flatness, as (mm) 0.512Unit Cell Length,LT (mm) 10.56

Resin Thickness, hm (mm) 0.002

Unit Cell Thickness, h (mm) 0.352

Crimp angle (deg) α 12

Page 38: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Backup slides  X faces Y faces Z faces

Properties X- X+ Y- Y+ Z- Z+

E11 U=0,V and W free

U=cons, V and W free

V=0, U and W free 

V=cons, U and W free

W=0, U and V free

W=Wo, U and V free

E22 ,E33 U=0, V and W free

U=cons, V and W free

V=0, U and W free

V=Vo, U and W free

W=0, U and V free

W=cons, U and V free

G12 V=W=0 V=0,W= Wo V=0 V=0 U=V=0 U=V=0

G23 V=W=0 V=Vo ,W= 0 U=W=0 U=W=0 W=0 W=0

Loading and boundary conditions of 8-Harness unit cell in a) XY-Plane and b) XZ-Plane

Boundary Conditions

Page 39: SAMPE 2016_PREDICTING STRESS RELAXATION BEHAVIOR

Backup slidesViscoelastic behavior of tows