Tensile Properties of Fibres

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Textile Testing MA Wilding

• Tensile Properties of Fibres Yarns (A)
• Terminology
• Definition of Quantities
• Example Methods
• Typical Results

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Suggested Reading Material

• JE Booth
• "Principles of Textile Testing (1983)
• Chapter 8
• BP Saville
• Physical Testing of Textiles (1999)
• Chapters 4 5

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The Basics of a Tensile Test

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The Basics of a Tensile Test

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The Inputs Outputs of a Test (useful to
think of test as a black box)
Example Inputs ...
Extension/Displacement/Elongation Units mm, cm,
etc
Strain (normalised extension) Extension divided
by original length Units NONE (but often use )

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The Inputs Outputs of a Test (useful to
think of test as a black box)
Example Outputs ...
Force (Load) - eg Tension SI Unit newton
Stress (normalised load) Conventional (eg newton
m-2) - used in engineering Specific (eg newton
tex-1) - used for textiles

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Does Tension-1 Tension-2?
Yes but the stresses differ
Higher stress
Lower stress

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Tensile Tests
Inputs outputs can be interchanged depending
on the type of test
They are not material properties But the outputs
are determined from the inputs by the properties

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Load-Elongation Stress-Strain Curves

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Properties from Load/Elongation Stress/strain
Curves

• Strength - breaking load (N, cN )
• Tenacity - breaking stress (cN/tex )
• Initial Modulus - slope at origin (cN/tex )
• Extensibility - breaking strain (, say)
• Yield Point - limit of elasticity
• Work of Rupture (WOR) - energy to break
• Specific WOR - WOR per unit mass

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Two Different Types of Tensile Modulus

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Tensile Properties of Fibres
There is a wide range of property values across
the entire spectrum of fibres
The order of ranking of different fibres depends
on the property being considered

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Examples of Fibre Stress-Strain Curves

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Which Property is Most Important?
It depends on the application
Some examples

• Yarn for a conveyor belt
• - initial modulus
• Neck of a sweater
• - yield strain
• Webbing for a car seat-belt climbing rope
• - work of rupture
• Rope (hoist)
• - strength (or tenacity)

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Comparison of Different Fibres

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Comparison of Different Fibres

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Comparison of Different Fibres

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Comparison of Different Fibres

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Comparison of Different Fibres