Lecture 23
Example Problem
Stress/Area Relationship
Given:
a 1000 lb load suspended from a ceiling by a 1"x 1" member.
Determine:
a. the stress in the member
b. the stress if the size of the member is increased to 2" x 2".
Solution:
a. The internal force in that member is 1000# tension and the tension stress (intensity of the force per unit of area) is 1000 pounds divided by the area of 1 square inch. This is a stress of 1000 psi.
b. The 1000# load is now distributed evenly across an area of 4 square inches; thus, 1000# divided by 4 in^2 is a stress of 250 psi. This clearly demonstrates the inverse relationship between stress and area.
It becomes obvious that one way to reduce the total stress on a member is to increase its cross section. The other way would be to reduce the load.
Copyright © 1995 by Chris H. Luebkeman and Donald Peting