Lecture 3: Fibre architecture

1 / 20

# Lecture 3: Fibre architecture - PowerPoint PPT Presentation

Lecture 3: Fibre architecture. At the end of this lecture you will have an understanding of: Distribution of fibres Packing arrangements of fibres Orientation of fibres Length of fibres Defects. Lecture 3: Fibre architecture.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Lecture 3: Fibre architecture' - duante

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Lecture 3: Fibre architecture
• At the end of this lecture you will have an understanding of:
• Distribution of fibres
• Packing arrangements of fibres
• Orientation of fibres
• Length of fibres
• Defects

Lecture 3: Fibre architecture

• Composites properties are strongly dependant on the arrangement and the distribution of fibres:
• Diameter and length
• Volume fraction
• Alignment
• Packing arrangement (distribution)

Lecture 3: Fibre architecture

• Volume fraction and weight fraction:
• Depending on the property we want to discuss, we need to consider either type of description
• Volume fraction is used for most physical properties (strength …)
• Weight fraction is used for properties such as density

Lecture 3: Fibre architecture

• Volume fraction and weight fraction:
• Vf = (wf/ρf)/(wf/ρf+wm/ρm)
• wf= vfρf/(vfρf+ vmρm)
• With Vf , Vm, wf, wm, ρf, ρm, volume fraction, weight fraction, and density of fibre and matrix

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• In unidirectional lamina, fibres are aligned
• Two ideal models Hexagonal and square packing

2R

2R

2r

2r

h

h

Lecture 3: Fibre architecture

• Fibre packing arrangements:

2R

2R

2r

2r

h

h

h

h

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• these ideal arrangement do not occur usually and there is usually clustering of fibres.
• Properties are then affected because Vf is lower
• For a resin to penetrate a dense pack of fibres is difficult which leads to defects (voids) and lower properties

Lecture 3: Fibre architecture

• Fibre packing arrangements:

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• Laminates:
• Set of plies stacked together
• Good properties within the plane of the plies
• Plies can be arranged in a stack to make the properties isotrope

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• Laminates:

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• Laminates are described by their stacking sequence

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• Woven arrays of fibres:

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• Knitted arrays of fibres:

Lecture 3: Fibre architecture

• Fibre packing arrangements:
• Braided arrays of fibres:

Lecture 3: Fibre architecture

• Orientation of fibres:
• Occurs often during processing
• Easier with short fibres
• Dependant on strain, viscosity of matrix and fibre length

Lecture 3: Fibre architecture

• Short fibre arrangements:
• Orientation is statistically measured by the texture of the composite (distribution of orientations)

Lecture 3: Fibre architecture

• Orientation of fibres:

Lecture 3: Fibre architecture

• Short fibre arrangements:
• Length is also a distribution

Lecture 3: Fibre architecture

• Short fibre arrangements:
• Length is also a distribution and often described by 2 averages:
• Length number average: Ln=ΣNiLi/ΣNi
• Length weight average: Lw=ΣWiLi/ΣWi

Lecture 3: Fibre architecture

• Voids:
• Appear during manufacturing process, or
• due to improper impregnation of the resin, or
• appear during deformation of the composite
• Measured either by direct observations, or by density measurements