The Young's modulus and its basic physical meaning

The modulus of longitudinal elasticity of a structural material, or the Young's modulus, is a physical quantity that characterizes the property of materials that provides their resistance to deformations acting in the longitudinal direction.

The parameter characterizes the degree of rigidity of a particular material.

The name of the module corresponds to the name of Thomas Young - a famous English physicist and scientist, who studied the processes of compression and stretching for solid materials. This physical quantity is denoted by the Latin letter E. The Young's modulus in Pascals is measured.

The parameter Young's modulus, or the modulus of longitudinal elasticity, is used for various calculations when testing materials for the degree of deformation under tension-compression, and also for bending.

It should be noted that most of the structural materials used are characterized by Young's modulus of sufficiently large values, which, as a rule, are of the order of 10 ⁹ Pa. Therefore, for convenience of calculations and recording, a multiple prefix "giga" (GPa) is used.

Below are the characteristics of the Young's modulus for some structural materials, which are often used for various practical purposes. It is on their strength properties that the durability of building structures and other objects depends.

According to the table above, the maximum index of the module belongs to steel, and the minimum value to the tree.

A graphical definition of the Young's modulus is possible with the help of a special stress diagram, which shows a curve obtained by repeated testing of the same material for strength.

In this case, the physical meaning of the Young's modulus is to find the mathematical relation of normal stresses to the corresponding deformation indices in a certain section of the diagram to a specific predetermined proportionality limit σ _pc.

In the form of a mathematical expression Young's modulus looks like this: E = σ / ε = tgα

It should also be said that the Young's modulus is also a proportionality coefficient in the mathematical description of Hooke's law, which looks like this: σ = Eε

Therefore, the direct relationship of the longitudinal elastic modulus with the measured characteristics of the material cross-sections involved in the rigidity tests is expressed by means of indicators such as EA and E1.
EA is an index of the tensile-compression rigidity of a material in its cross-section, where A is the value of the cross-sectional area of the rod.

E1 is an index of rigidity when bending a material in its cross-section, where 1 is the value of the axial moment of inertia that arises in the section of the material being tested.

Thus, the Young's modulus is a universal indicator that allows characterizing the strength properties of a material from several sides.