5.2
Cylindrical or spherical pressure vessels (e.g., hydraulic cylinders, gun barrels,
pipes, boilers and tanks) are commonly used in industry to carry both liquid s and gases
under pressure. When the pressure vessel is exposed to this pressure, the material
comprising the vessel is subjected to pressure loading, and hence stresses, from all
directions. The normal stresses resulting from this pressure are functions of the radius of
the element under consideration, the shape of the pressure vessel (i.e., open ended
cylinder, closed end cylinder, or sphere) as well as the applied pressure.
Two types of analysis are commonly applied to pressure vessels. The most
common method is based on a simple mechanics approach and is applicable to “thin
wall” pressure vessels which by definition have a ratio of inner radius, r, to wall thickness,
t, of r/t=10. The second method is based on elasticity solution and is always applicable
regardless of the r/t ratio and can be referred to as the solution for “thick wall” pressure
vessels. Both types of analysis are discussed here, although for most engineering
applications, the thin wall pressure vessel can be used.
Thin-Walled Pressure Vessels
Several assumptions are made in this method.
1) Plane sections remain plane
2) r/t = 10 with t being uniform and constant
3) The applied pressure, p, is the gage pressure (note that p is the
difference between the absolute pressure and the atmospheric pressure)
4) Material is linear-elastic, isotropic and homogeneous.
5) Stress distributions throughout the wall thickness will not vary
6) Element of interest is remote from the end of the cylinder and other
geometric discontinuities.
7) Working fluid has negligible weight
Cylindrical Vessels: A cylindrical pressure with wall thickness, t, and inner radius,
r, is considered, (see Figure 12.1). A gauge pressure , p, exists within the vessel by the
working fluid (gas or liquid). For an element sufficiently removed from the ends of the
cylinder and oriented as shown in Figure 12.1, two types of normal stresses are
generated: hoop, s h , and axial, s a , that both exhibit tension of the material.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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