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Finite Element Modeling of the Filament Winding Process

Liyang Zhao, Reed McPeak, Susan C. Mantell

Department of Mechanical Engineering University of Minnesota

David Cohen Toray Composites America

Sponsored by Alliant Techsystem

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Overview

  Background

  Objective

  Theoretical Model

  Material Characterization

  FEA Approach

  Validation

  Summary

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Background on Filament Winding

  The oldest manufacturing process in composite industry (since 1940’s)

  Applications: rocket nozzles, motor cases, jet engine components...

  Structure geometry: cylindrical, spherical, and others

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Schematic of Filament Winding

Main Process Variables •  Tow Tension •  Lay-up •  Temperature •  Winding time/speed

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Material Properties

Fibers: High strength to weight ratio glass fibers; organic fibers; carbon and graphite fibers;

Resin System: Low-temperature cure Long pot life High flexibility Low toxicity

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Objective

Geometry

Material Properties

Processing Conditions (Time, Temp, Pressure)

Product Quality

Final dimensions Fiber/matrix volume fractions Final degree of cure Stress state

1. Material Characterization 2. Finite Element Simulation 3. Experimental Validation

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Problem Statement

T o

T i

<Thermochemical> temperature, cure, viscosity

pressure

Fiber Tension

<Fiber Motion> fiber position, fiber volume fraction <Resin Mixing>

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Thermochemical Model

α < αgel

•  Degree of Cure

•  Viscosity

•  Heat generation

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Fiber Motion Model

•  Fiber bed stiffness

•  Layer stiffness

for for

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Resin Mixing Model

•  Uncured resin from previously wound layers can be squeezed into the new layer

•  Evaluate the effective viscosity by rule of mixture

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Material Characterization

•  Resin Characterization • Cure kinetics

• Viscosity

• Resin mixing

•  Fiber Characterization

Nonlinear Stiffness

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Cure kinetics for HBRF-55A resin

•  DSC test (Differential Scanning Calorimeter)

•  Isothermal scan at 100, 115, 130, 145, and 160°C

•  Dynamic scan at rate of 20°C/min

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Viscosity of HBRF-55A resin

•  Rheology test (Dynamic Stress Rheometer)

•  Dynamic scan at rate of 0.5, 1, and 2°C/min

•  Room temp. test

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Resin Mixing

•  Two resin samples (m1=77.9 Pa.s, m2=1.42 Pa.s)

•  Mixture ratio: 1:3, 1:1 and 3:1

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Fiber Characterization

  Fiber compaction test

  IM7 graphite fiber R sized, W sized

  Va = 0.857 (R size) Va = 0.891 (W size)

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Finite Element Approach

Why Finite Element? •  Complex geometry (domes, joint region) •  Viscoelastic materials •  Commercial support/documentation •  Import existing files

Approach •  ABAQUS software •  Standard elements •  User defined subroutines

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FEM Implementation

Model Input

Load History Input

Result

node definition element definition material definition

Wind/hold times Step 1: Layer #1 Winding Step 2: Layer #1 Holding ............. Step n: Last Layer holding Cure cycle

data file (temp, stress, cure, ...) restart file (post processing)

Heat generation Nonlinear Material

User defined subroutines ABAQUS Solver

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Model Proof Run

Proof Run:

- 28 Layers - Initial Wind Stress = 50MPa

- All Hoop Winds - Constant Layer Wind Time = 1 Hr

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Model Proof Run

Proof Run:

- 28 Layers - Initial Wind Stress = 50MPa

- All Hoop Winds - Constant Layer Wind Time = 1 Hr

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Model Proof Run

Proof Run:

- 28 Layers - Initial Fiber Volume Fraction = 0.56

- All Hoop Winds - Constant Layer Wind Time = 1 Hr

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Experimental Validations (1)

Cylinder: Delta3 (CT1)

Fiber: Hexcel IM7

Resin: HBRF-55A

Num. of Layers: 15

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Experimental Validations (2)

Cylinder: Delta2 (CT5)

Fiber: Hexcel IM7

Resin: HBRF-55A

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Experimental Validations (3)

Cylinder: Titan B-4C

Fiber: Hexcel IM7

Resin: HBRF-55A

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Summary

Completed •  Thermochemical •  Fiber motion •  Resin Mixing

Temperature Viscosity Degree of Cure Fiber Volume fraction

FEM