MEC2403 Pracs Week 5
P 5.1
Determine the maximum tensile stress σt and maximum compressive stress σc due to the load P acting on the simple beam AB (see figure).
Data are as follows:
P = 5.4 kN, L = 3.0 m, d = 1.2 m, b = 75 mm, t = 25 mm, h = 100 mm, and h1 = 75 mm.
P 5.2
A cantilever beam AB of triangular cross section has length L = 0.8 m, width b = 80 mm, and height h = 120 mm (see figure). The beam is made of brass weighing 85 kN/m3.
(a) Determine the maximum tensile stress σt and maximum compressive stress σc due to the beam’s own weight.
(b) If the width b is doubled, what happens to the stresses?
(c) If the height h is doubled, what happens to the stresses?
Hints:
- The neutral axis lies h/3 below the top surface if the beam
- For the setup shown, the moment of inertia of the beam (about an axis which is parallel to its width) is given by bh3/36
P 5.3
A cantilever beam AB with a rectangular cross section has a longitudinal hole drilled throughout its length (see figure).
The beam supports a load P = 600 N. The cross section is 25 mm wide and 50 mm high, and the hole has a diameter of 10 mm.
Find the bending stresses at the top of the beam, at the top of the hole, and at the bottom of the beam.
P5.4.
A bending couple M is applied to a beam with a rectangular cross section b x d that is to be extruded from a cylindrical section shown in the figure. Determine the ratio d/b for which the maximum stress will be as small as possible