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Tensile testing process.

Tensile test :-


Introduce:-Tensile test property often are measure during development of new material and process , tensile property often are used to predict the behavior of a Material under forms of loading other than uniaxial tention.

1)-Tensile specimen and test machines.
2)- stress -strain curve , elastic versus plastic deformation.
3)-yield point , Ductility
4)-test methodology and analysis
5)-True stress and strain.


Test methodology and data analysis:-

1.sample selection.
2.sample preparation. 
3.Test setup.
4.Test procedure. 
5.Data recording and analysis.
6.Reporting.



Yield Strength

y * a = s

Take the minimum yield in psi of the ASTM grade (see our Strength Requirements by Grade Chart for this value), multiplied by the stress area of the specific diameter (see our Thread Pitch Chart). This formula will give you the ultimate yield strength of that size and grade of bolt.


Shear Strength :-

First, find the ultimate tensile strength using the formula above. Take that value and multiply it by 60% (0.60). It is important to understand that this value is only an estimate. Unlike tensile and yield strengths.36,000 psi * 0.334 in^2 = 12,024 lbs


Ultimate Tensile Strength

y * a = s

Take the minimum tensile strength in psi of the ASTM grade, multiplied by the stress area of the diameter. This formula will give you the ultimate tensile strength of that size and grade of bolt.

58,000 psi * 0.334 in^2 = 19,372 lbs



Young's modulus:-

Young's modulus (E or Y) is a measure of a stiffness or resistance to elastic deformation under load. It relates stress (force per unit area) to strain (proportional deformation) along an axis or line. The basic principle is that a material undergoes elastic deformation when it is compressed or extended, returning to its original shape when the load is removed. More deformation occurs in a flexible material compared to that of a stiff material.


Equation and Units

The equation for Young's modulus is:

E = σ / ε = (F/A) / (ΔL/L0) = FL0 / AΔL

Where:

  • E is Young's modulus, usually expressed in Pascal (Pa)
  • σ is the uniaxial stress
  • ε is the strain
  • F is the force of compression or extension
  • A is the cross-sectional surface area or the cross-section perpendicular to the applied force
  • Δ L is the change in length (negative under compression; positive when stretched)
  • L0 is the original length

While the SI unit for Young's modulus is Pa, values are most often expressed in terms of megapascal (MPa), Newtons per square millimeter (N/mm2), gigapascals (GPa), 

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