Young's Modulus of Elasticity
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/cm2. This 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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