Carbon fiberPoisson ratio

Anyone doing research on materials used to make masts and in particular carbon fiber, will run into youngs modulus sooner or later.

When testing composites like carbon fibre or fiberglass, it is tricky to prepare samples that are exactly comparable and a great deal of attention needs to be paid to the sample preparation, matrix and density of fibres and weave. In any research paper I have read, a significant amount of detail goes into describing the way the samples are made. Because materials like aluminium or copper are more uniform the preparation is not as critical. If there are crystal orientations then these have to be matched and noted.

Carbon fiber modulus of elasticitygraph

Young's modulus predicts how much a material bends or extends under tension or shortens under compression. The higher the young's modulus, the stiffer the material.

The units of measure are not so terribly important for the amateur boat and mast maker, what is more to the point is the comparison of materials. It's 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. Carbon fibre is also about twice as stiff as Kevlar.

There are several different tests such as the 3 point test, or a stretch test. Essentially a sample is prepared and a force is applied to it. The deflection or stretch is measured.

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.

Carbon fiber modulus of elasticityvs steel

Carbon fiber modulus of elasticityformula

It is expressed as a ratio of stress over strain. In other words, how much something bends (strain) under a given load (the stress).

Measuring the bending of a carbon fibre tube. They are not testing to destruction. This is a 3 point test. The material to be tested is placed on 2 supports and a third point comes down and applies a force. The machine then measures how much deflection there is for a given force. The higher the Young's modulus, the lower the deflection before the piece breaks.

Most metals and ceramics, along with many other materials, are isotropic, their mechanical properties are the same in all orientations.

It's important to stress that stiff is not equivalent to strong. A stiff material might not deflect much under load but may break at a lower stress (force) than another less stiff material.

N = Newton, m = Meter. A Newton is equal to the force that would give a mass of one kilogram an acceleration of one meter per second per second. A Pascal is equal to one newton per square meter.

Some materials are made or can be modified or physically treated to modify their structure and make it directional. These materials are or 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.