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# Young's Modulus of Elasticity

## Teräksen kimmokerroin

Elastic modulus, modulus of linear deformation, coefficient of elasticity, modulus of elasticity

The Young's modulus (of elasticity) E describes the amount of deflection under load. The modulus of elasticity is placed in the deflection formula as divider => the higher the modulus of elasticity value, the less the material bends.

A common modulus of elasticity of steel is 21 000 kN/cm2. The modulus of elasticity  has in literature two used values of 20 600 and 21 000 kN/cm2This calculation and tables use the lower value that gives 1% higher deflection. Both values ​​are sufficiently accurate, but we are planning for a safer side, where the calculation is used for the design.

Young's modulus

When designing the deflection, it is determined by the profile cross-sectional shape. This means the same deflection to different grade of steels. The strength of steel has the importance when achieving a lightweight structure. This is achieved by allowing greater local stresses => the higher deflection. Calculation is based on the steel manufacturer's guaranteed yield strength for special steel and when standard steel for the tabulated values​​. Practical grades of steel are the S235 and S355, which have a wide range of dimensions. Steel product catalogs act as guides for the selection of steel. The elastic limit of steel is between the range of the yield strength and proportionality limit. The limit of proportionality is the first part of a load-elongation curve. The elongation increases in proportion to an increase in tension. When tension reaches the yield limit, elongation continues from here on more than the increase in tension. Above the elastic limit, it will remain a permanent deformation.

kN/cm2                                 N/mm2                       GPa

Aluminium                                 7000                               70 000                      70

Concrete                                1 000 - 4 000                 10 000 -40 000            10 - 40

Duralumin                                7 400                              74 000                      74

Silver                                        8000                               80 000                       80

Invar                                        14 600                            146 000                    146

Iridium                                     15 600                            156 000                    156

Ice - 4o  C                                 1 000                               10 000                      10

Cadmium                                  5 100                               51 000                      51

Copper                                   12 000                             120 000                    120

Glass                                      7 200                                72 000                       72

Natural rubber (caoutchouc)        5                                     50                         0,05

Brass and Bronze             10 300 -   12 400               103 00 - 124 00           100

Nylon                                     200  -   400                     2 000 - 4 000              2 - 4

Steel                                         21 000                            210 000                    211

Titanium                            10 500 - 12 000            105 000 -  120 000       105 - 120

Diamond                          105 000 - 120 000       1 050 000 - 1 200 000     1050 - 1200

Oak along the grains                  1 100                              11 000                     11

Tungsten                                   40 000                             400 000                   400

Tungsten carbide              45 000 -  65 000           450 000 - 650 000         450 - 650

1 Pa = N / m2

## Finally

- Of stronger material manufactured part can be loaded with a greater force.

- Strength does not have stiffness => another increase, also another grows. As a result of this analysis has a mathematical possibility, while maintaining the proportionality of load conditions, and comparable materials.

- The modulus of elasticity is a divisor in the formula => to reduce the deflection, must choose the larger cross-section of the same material or a material change to a higher elastic modulus.

25.5.2015*23:50 (868 - 12)
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