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For the thin-walled assumption to be valid, the vessel must have a wall thickness of no more than about one-tenth (often cited as Diameter / t > 20) of its radius. [4] This allows for treating the wall as a surface, and subsequently using the Young–Laplace equation for estimating the hoop stress created by an internal pressure on a thin-walled cylindrical pressure vessel:
Barlow's formula (called "Kesselformel" [1] in German) relates the internal pressure that a pipe [2] can withstand to its dimensions and the strength of its material. This approximate formula is named after Peter Barlow , an English mathematician .
This equation defines the yield surface as a circular cylinder (See Figure) whose yield curve, or intersection with the deviatoric plane, is a circle with radius , or . This implies that the yield condition is independent of hydrostatic stresses.
On the surface of the cylinder, or r = R, pressure varies from a maximum of 1 (shown in the diagram in red) at the stagnation points at θ = 0 and θ = π to a minimum of −3 (shown in blue) on the sides of the cylinder, at θ = π / 2 and θ = 3π / 2 . Likewise, V varies from V = 0 at the stagnation points to V = 2U on the ...
For cylindrical pressure vessels, the normal loads on a wall element are longitudinal stress, circumferential (hoop) stress and radial stress. The radial stress for a thick-walled cylinder is equal and opposite to the gauge pressure on the inside surface, and zero on the outside surface. The circumferential stress and longitudinal stresses are ...
Hertzian contact stress refers to the localized stresses that develop as two curved surfaces come in contact and deform slightly under the imposed loads. This amount of deformation is dependent on the modulus of elasticity of the material in contact. It gives the contact stress as a function of the normal contact force, the radii of curvature ...
This type of stress may be called (simple) normal stress or uniaxial stress; specifically, (uniaxial, simple, etc.) tensile stress. [13] If the load is compression on the bar, rather than stretching it, the analysis is the same except that the force F and the stress σ {\displaystyle \sigma } change sign, and the stress is called compressive ...
A specialized case of hydrostatic stress contains isotropic compressive stress, which changes only in volume, but not in shape. [1] Pure hydrostatic stress can be experienced by a point in a fluid such as water. It is often used interchangeably with "mechanical pressure" and is also known as confining stress, particularly in the field of ...