Why Do Stress Levels Vary Between Two Gauges on a Thin-Walled Pressure Vessel?

In summary, the conversation is about an experiment conducted on a thin-walled pressure vessel with certain dimensions and two gauge measurements. The experiment data shows that the actual principle stresses of the two gauges are higher than the theoretical values, which raises the question of why one gauge has significantly higher stress than the other and the theoretical values. Further discussion mentions a possible error due to the ratio of radius to thickness of the vessel.
  • #1
imnotadmin
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pls help-- thin-walled pressure vessel

Hi, all. I have done an experiment of “thin-walled pressure vessel”. The vessel: length 200mm, outside radius 526mm, inner radius 47.6mm. There were two rectangle rosettes gauge in the vessel surface. Based on the experiment data (100 psi), the actual principle stresses of the two gauges are calculated: 1) 72 Gpa (hoop) and 37 Gpa (axial). 2) 66 Gpa (hoop) and 32 Gpa (axial). And the theoretical principles are: 62 Gpa (hoop) and 31 Gpa (axial).

I am wondering why the stresses of gauge one are mush bigger than the gauge 2. Can somebody tell me why?


Thank you very much!
 
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  • #2


Sorry I put a wrong data in the first thread. The diameter of the vessel is 100mm and the thickness is 0.55 mm. The r/t = 90. I have checked a textbook and it mentioned " when r/t =10, the results of a thin-wall analysis will predict a stress that is approximately 4%. For larger r/t, this error will be even smaller."

So I don't understand why the stress of rosettes 1 is so much than rosettes 2 and the theoretical values.
 

FAQ: Why Do Stress Levels Vary Between Two Gauges on a Thin-Walled Pressure Vessel?

1. What is a thin-walled pressure vessel?

A thin-walled pressure vessel is a container or structure that is designed to hold a fluid or gas under pressure, with a wall thickness that is significantly smaller than the vessel's radius. This type of vessel is commonly used in industries such as oil and gas, chemical processing, and aerospace.

2. What are the main factors that affect the strength of a thin-walled pressure vessel?

The strength of a thin-walled pressure vessel is influenced by several factors, including the material used, the thickness of the wall, the shape and size of the vessel, and the type of loading it is subjected to. Other factors such as temperature, corrosion, and manufacturing defects can also impact the vessel's strength.

3. How do you calculate the stress and strain in a thin-walled pressure vessel?

The stress and strain in a thin-walled pressure vessel can be calculated using equations derived from the principles of mechanics and material science. These equations take into account the vessel's dimensions, material properties, and applied loads to determine the stress and strain at different points along the vessel's wall.

4. What are the main failure modes of a thin-walled pressure vessel?

The main failure modes of a thin-walled pressure vessel include plastic deformation, buckling, and bursting. Plastic deformation occurs when the vessel's material permanently deforms under excessive stress. Buckling is a failure mode in which the vessel's walls buckle and collapse under compressive loads. Bursting is the most catastrophic failure mode, in which the vessel's walls rupture and release the pressurized fluid or gas inside.

5. How can the safety of a thin-walled pressure vessel be ensured?

The safety of a thin-walled pressure vessel can be ensured through proper design, material selection, and testing. Engineers use mathematical models and simulation software to design vessels that can withstand expected loads and conditions. The vessel's materials should also be carefully selected based on their strength, corrosion resistance, and other properties. Regular inspection and maintenance can also help identify and address any potential issues before they lead to failure.

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