ASC ANTEC 2001 September 11, 2001

University of Minnesota

Filament Winding Impregnation Study

David Cohen Susan C. Mantell

Toray Composites Department of Mechanical Engineering

University of Minnesota

ASC ANTEC, September 2001

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Problem Statement: What is Wet Winding?

Cylinder constructed by wrapping continuous fibers around a mandrel

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Impregnation Process during Winding

Fibers pass through a resin bath before winding

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Approach

2. Experiment Design

4. Interpret Results

1. Identify Key Variables resin flow front

w h

h f

Winding variables Tow properties

Which models are relevant? Which variables have significant effects?

3. Wind Samples

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Identify Key Variables

Lateral Flow Axial Flow

h

resin flow front

c

h f

Pressure Time Viscosity Porosity Permeability Tow height

Surface Tension Time Viscosity Permeability/ Channel width Tow height

c

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Experiment Design

Winding Speed -> Time Winding Tension -> Pressure, Tow height, Channel width Resin Temperature -> Viscosity Fiber Sizing Level -> Surface Tension Resin Content 3 Levels for Each Variable

28 Tests Total

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Quality Measures

Inner Tow Fiber Volume Fraction Void Volume Fraction

Between Band

Void Volume Fraction

Overall

Fiber Volume Fraction Void Volume Fraction

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Wind Samples

ω

54 in square mandrel (no compaction forces)

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Results: Void Fraction within the Band

Should be approximated by lateral flow model: Dimensionless parameters:

Winding speed Winding speed-Winding tension Resin Temperature

Significant effects

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Results: Void Fraction between Bands

Should be approximated by axial flow model: Dimensionless parameters:

Resin Temperature-Size Level Winding speed-Winding tension Winding tension

Significant effects

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Results: Deviation in Fiber Volume Fraction

Combination of slow winding speed, high winding tension and high resin content

Vf closest to desired value

ASC ANTEC 2001 September 11, 2001

University of Minnesota

Conclusions and Future Work

Conclusions ü  DOE results indicate both axial and lateral flow occur

ü  Significant effects Winding Speed Winding Tension Bath Temperature

Future Work

Models Tow dimensions Prepregging during wet winding h h f