SECTION OF SOLIDS || ENGLISH @manaspatnaikofficial @btechplus
11 videos • 1,325,430 views • by Manas Patnaik Invisible features of an object are shown by dotted lines in their projected views. But when such features are too many, these lines make the views more complicated and difficult to interpret. In such cases, it is customary to imagine the object as being cut through or sectioned by planes. The part of the object between the cutting plane and the observer is assumed to be removed and the view is then shown in section. The imaginary plane is called a section plane or a cutting plane. The surface produced by cutting the object by the section plane is called the section. It is indicated by thin section lines uniformly spaced and inclined at 45°. The projection of the section along with the remaining portion of the object is called a sectional view. Sometimes, only the word section is also used to denote a sectional view. (1) Section: Section planes are generally perpendicular planes. They may be perpendicular to one of the reference planes and either perpendicular, parallel or inclined to the other plane. They are usually described by their traces. It is important to remember that the projection of a section plane, on the plane to which it is perpendicular, is a straight line. This line will be parallel, perpendicular or inclined to xy, depending upon the section plane being parallel, perpendicular or inclined respectively to the other reference plane. As per latest 8.1.S. convention (SP: 46-2003), the cutting-plane line should be drawn as Chain thin (narrow) with thick (wide) at the ends and at changing of position. (2) Sections: The projection of the section on the reference plane to which the section plane is perpendicular, will be a straight-line coinciding with the trace of the section plane on it. Its projection on the other plane to which it is inclined is called apparent section. This is obtained by (i) projecting on the other plane, the points at which the trace of the section plane intersects the edges of the solid and (ii) drawing lines joining these points in proper sequence. (3) True shape of a section: The projection of the section on a plane parallel to the section plane will show the true shape of the section. Thus, when the section plane is parallel to the H.P. or the ground, the true shape of the section will be seen in sectional top view. When it is parallel to the V.P., the true shape will be visible in the sectional front view. But when the section plane is inclined, the section has to be projected on an auxiliary plane parallel to the section plane, to obtain its true shape. When the section plane is perpendicular to both the reference planes, the sectional side view will show the true shape of the section. In this chapter Video lectures on sections of different solids are demonstrated in stages by means of typical problems as follows: 1. Sections of prisms 2. Sections of pyramids 3. Sections of cylinders 4. Sections of cones 5. Sections of spheres. Download the App: https://cwcll.on-app.in/app/home?orgC...