Mecanica de Materiales

1. A propeller shaft subjected to combined torsion and
axial thrust is designed to resist a shear stress of 56
MPa and a compressive stress of 85 MPa (see figure).
(a) Determine the principal stresses and show them
on a sketch of a properly oriented element.
(b) Determine the maximum shear stresses and
associated normal stresses and show them on a
sketch of a properly oriented element.
Problem 1
Tutoria semana 15 página 1

2. A simple beam of rectangular cross section (width
4 in., height 10 in.) carries a uniform load of 1200
lb/ft on a span of 12 ft (see figure). Find the principal
stresses σ1 and σ2 and the maximum shear stress
τmax at a cross section 2 ft from the left-hand
support at each of the following locations:
(a) the neutral axis,
(b) 2 in. above the neutral axis and
Problem 2
Tutoria semana 15 página 2

3. An arm ABC lying in a horizontal plane and supported at A
(see figure) is made of two identical solid steel bars AB and BC
welded together at a right angle. Each bar is 20 in. long.
Knowing that the maximum tensile stress (principal stress)
at the top of the bar at support A due solely to the weights of
the bars is 932 psi, determine the diameter d of the bars.
z
Problem 3
Tutoria semana 15 página 3