What is the maximum shear stress in a thin walled pressurized sphere?
A pressure vessel is assumed to be a thin walled pressure vessel when the thickness of the vessel is less than 1/20 of its radius….List of Equations:
| Parameter | Formula |
|---|---|
| Maximum out-plane shear stress (τmax(out plane)) | (pgr)/(2t) |
| Spherical pressure vessel | |
| Hoop stress (σ1) | (pgr)/(2t) |
| Longitudinal stress ( σ2) | (pgr)/(2t) |
What happens if a thin pressure vessel is subjected to external pressure?
When a pressure vessel is subjected to external pressure, the above formulas are still valid. However, the stresses are now negative since the wall is now in compression instead of tension. The hoop stress is twice as much as the longitudinal stress for the cylindrical pressure vessel.
What is the usual value of FOS for thin pressure vessel?
Typical overall Factors of Safety
| Equipment | Factor of Safety – FOS – |
|---|---|
| Heavy duty shafting | 10 – 12 |
| Lifting equipment – hooks .. | 8 – 9 |
| Pressure vessels | 3.5 – 6 |
| Turbine components – static | 6 – 8 |
What is meant by pressure vessel?
Pressure Vessels are containers which are designed to hold liquids, vapors, or gases at high pressures, usually above 15 psig. Examples of common pressure vessels used in the petroleum refining and chemical processing industries include, but are not limited to, storage tanks, boilers, and heat exchangers.
Which stress is constant in a thick shell?
From equations 2 and 3 above we can see that the sum of the radial and tangential stresses is constant, regardless of radius: Hence the longitudinal strain is also constant since: constant.
What is the variation of stress in thick cylinder across thickness?
Hoop stress in thick cylinders also varies with thickness. r is the inside radius of the cylinder. is the hoop stress. When the vessel has closed ends the internal pressure acts on them to develop a force along the axis of the cylinder.
What are principal stresses?
principal stresses are the maximum and minimum (extremum) extensional (norma) stresses. in a stress state at a point. The principal directions are the corresponding directions.
How do you get principal stresses?
In 2-D, the principal stress orientation, θP , can be computed by setting τ′xy=0 τ ′ x y = 0 in the above shear equation and solving for θ to get θP , the principal stress angle. Inserting this value for θP back into the equations for the normal stresses gives the principal values.
What is the difference between von Mises stress and principal stress?
Von Mises is a theoretical measure of stress used to estimate yield failure criteria in ductile materials and is also popular in fatigue strength calculations (where it is signed positive or negative according to the dominant Principal stress), whilst Principal stress is a more “real” and directly measurable stress.