ME 212 Lecture Notes - Lecture 5: Neutral Axis
Document Summary
Flexural stress varies directly linearly with distance from the neutral axis. Thus for a symmetrical section such as wide flange, the compressive and tensile stresses will be the same. This will be desirable if the material is both equally strong in tension and compression. However, there are materials, such as cast iron, which are strong in compression than in tension. It is therefore desirable to use a beam with unsymmetrical cross section giving more area in the compression part making the stronger fiber located at a greater distance from the neutral axis than the weaker fiber. In this section, the following notation will be use: fbt = flexure stress of fiber in tension fbc = flexure stress of fiber in compression. = neutral axis yt = distance of fiber in tension from n. a. yc = distance of fiber in compression from n. a. The inverted t section of a 4-m simply supported beam has the properties shown in fig.
to the vertical by a rod BCof a circular cross-section, forming an angle of 
with the beam.
=400MPa and the safety factor S.F.= 2 ;
