Lecture 39
Example Problem
Shear Stress
Given:
the beam consisting of two 2" x 6" pieces of plastic glued together subjected to the loading shown (downward forces from left to right are 5k, 3k and 2k).
Determine:
a. the maximum horizontal shearing force in the beam at max V
b. the magnitude of the shearing stress the glue must develop
Solution:
First plot the shear diagram for the beam.
a. From the shear diagram, the maximum shear force occurs at 14 ft from the left end and is equal to -5.5 k.
b. the shearing stress in the glue
fv = VA'y / Ib
V = max shear force = 5.5k
A' = area above glueline = (6in)(2in) = 12 in^2
y = distance from NA to centroid of A' = 2 in
I = moment of inertia = 136 in^4
b = width of glueline = 2 in
f = (5.5k)(12 in^2)(2in) / (136 in^4)(2in) = .48 ksi
Copyright © 1995 by Chris Luebkeman and Donald Peting