Timothy A. Philpot - Mechanics of materials _ an integrated learning system-John Wiley (2017)

The 28,800 lb · ft bending moment about the z axis creates bending stresses at the section
of interest. Point H, however, is located on the neutral axis for this bending moment, and
thus, the bending stress at H is zero.
12,853 psi
28,800 lb·ft
H
K
z
x
Combined Stresses at H
The normal and shear stresses acting at point H can be summarized on a stress element.
Notice that the torsion shear stress acts in the −x direction on the +y face of the element.
After the proper shear stress direction has been established on one face, the shear stress
directions on the other three faces are known.
Torsion shear
5,355.4 psi
y
Bending stress
13,611.5 psi
y
14,578 psi
5,355 psi
H
x
H
x
Axial stress
966.2 psi
Stress transformation Results at H
The principal stresses and the maximum shear stress at H can be determined from the
stress transformation equations and procedures detailed in Chapter 12. The results of
these calculations are shown in the accompanying figure.
14,578 psi
H
y
x
5,355 psi
18.2°
9,050 psi
7,290 psi
1,756 psi
16,330 psi
y
12,900 lb
Stresses at K
The equivalent forces and moments acting at the section of interest will again be evaluated,
this time to determine the type, magnitude, and direction of any stresses created at K.
The 12,900 lb axial force creates compressive normal stress, which acts in the
y direction:
H
K
966 psi
Fy
12,900 lb
s y = = = 966 psi ( C)
2
A 13.352 in.
z
x
645