Formula Used:
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Hoop stress is the circumferential stress that develops in a thin-walled spherical shell when subjected to internal or external pressure. It represents the tensile stress acting tangentially to the circumference of the shell.
The calculator uses the formula:
Where:
Explanation: This formula calculates the hoop stress in a thin spherical shell based on the strain measurement in any one direction, accounting for material properties through Poisson's ratio and modulus of elasticity.
Details: Accurate hoop stress calculation is crucial for designing pressure vessels, storage tanks, and other spherical containers to ensure structural integrity and prevent failure under pressure loads.
Tips: Enter strain (unitless), Poisson's ratio (between 0-0.5), and modulus of elasticity in Pascal. All values must be valid (strain ≠ 0, Poisson's ratio 0-0.5, modulus > 0).
Q1: What is the typical range for Poisson's ratio?
A: For most metals and alloys, Poisson's ratio ranges between 0.1 and 0.5. Rubber-like materials can have values close to 0.5.
Q2: Why is this formula specific to thin spherical shells?
A: Thin shell theory assumes uniform stress distribution through the thickness, which simplifies the stress-strain relationship for spherical geometries.
Q3: How does hoop stress differ in cylindrical vs spherical shells?
A: In spherical shells, hoop stress is uniform in all directions, while in cylindrical shells, circumferential hoop stress differs from longitudinal stress.
Q4: What are the limitations of thin shell theory?
A: Thin shell theory becomes less accurate for thick-walled vessels or when the radius-to-thickness ratio is small (typically < 10).
Q5: How does internal pressure affect hoop stress?
A: Internal pressure creates tensile hoop stress, while external pressure creates compressive hoop stress in the spherical shell.