**Introduction**

##### Young΄s modulus E, is a measure of stiffness of an isotropic elastic material. Its the numerical evaluation of Hooke΄s law. It is defined as the ratio of stress (force per unit area) to corresponding strain (deformation) in a material under tension or compression.

##### The higher the value of Young’s modulus, the stiffer the material.

**Papercete΄s Young΄s Modulus **

##### Papercrete΄s Young΄s modulus has not been established. To make the acoustic calculations I need to define an approximate value.

I studied the values of different materials with similar microstructure (fibrous lightweight concrete, mdf) to make an estimation. Paper and mdf are made from woo

##### d pulp and have similar densities and directional variation in Young’s modulus. Paper because of stiff cellulose micro-fibres can provide stiffness at relatively low weight.

##### Until I determine experimentally the Young΄s modulus 1 I w

##### ill use an approximate value of E=8 GPa.

Many applications require stiff materials, (lie at the top of the chart). Stiff lightweight materials are hard to find – composites appear to offer a good compromise, but they are usually quite expensive

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