Youngs Modulus is a Measure of Stiffness
YOUNG'S MODULUS also called Modulus of Elasticity
measures the stiffness of an elastic material. The Stiffness of Carbon Fiber can be compared using its Young's Modulus
It is one of the important characteristic of a material. Being able to compare and quantify stiffness is fundamental to Engineering and construction. Young Modulus is how stiffness is expressed for engineering types.
Anyone doing research on materials used to make masts and in particular carbon fiber, will run into youngs modulus sooner or later.
Defining a few words we already know!
-
An Elastic Material:
- is a material that is able to resume its normal shape after a load is removed. In other words if you bend or stretch something and it springs back to its original shape, with no damage, it's an elastic material.
- A Stiff material
- Is a material that needs a large force applied to it to change its shape.
- a Flexible material
- is one that only requires a small force to change its shape.
- Stress
- is a measure of force
- Strain
- is a measure of deformation (amount of bend or stretch)
Young's modulus predicts how much a material bends or extends under tension or shortens under compression.
It is expressed as a ratio of stress over strain.
Young Modulus=Stress/Strain
Unit: 10 9 N/m2 Or Gpa (GigaPascal)
Young's modulus is not always the same in all orientations of a material.
Most metals and ceramics, along with many other materials, are isotropic, their mechanical properties are the same in all orientations.
Some materials can be modified or physically treated to modify their structure and make it directional. These materials then become anisotropic, and Young's modulus will be different depending on the direction of the force. Anisotropy can be seen in many composites. Carbon fiber has much higher Young's modulus (is much stiffer) when force is parallel to the fibers (along the grain). Other anisotropic materials include wood and reinforced concrete.
Young's modulus can vary due to differences in sample composition and test method.
These values are offered for comparison only. Units are GPascal
| Rubber (small strain) | 0.01–0.1 |
| PTFE (Teflon) | 0.5 |
| Low density polyethylene | 0.2 |
| Polypropylene | 1.5-2 |
| Nylon | 2–4 |
| Pine wood (along grain) | 8.963 |
| Oak wood (along grain) | 11 |
| High-strength concrete (under compression) | 30 |
| Magnesium metal (Mg) | 45 |
| Aluminium | 69 |
| Aramid (such as Kevlar) | 70.5–112.4 |
| Brass and bronze | 100–125 |
| Copper (Cu) | 117 |
| Glass-reinforced plastic (70/30 by weight fibre/matrix, unidirectional, along grain) | 40–45 |
| Carbon fiber reinforced plastic (70/30 fibre/matrix, unidirectional, along grain) | 181 |
| Steel | 200 |
| Silicon carbide (SiC) | 450 |
| Tungsten carbide | 450–650 |
| Single-walled carbon nanotube | 1,000+ |
The units of measure are not so terribly important for the amateur mast maker, what is more to the point is the comparison of materials. Its interesting to compare Carbon Fiber with Glass Fibre and Aluminium. Carbon Fibre stiffness is about 4 times that of fiberglass and over twice the stiffness of Aluminium.
email: Christine
|
