1
4.34. Make a copy of the beam section of Figure P4.17 and use the ‘least squares
fit’ method to estimate the location of the principal axes. Label the stiff and
flexible axes ‘1’ and ‘2’ respectively.
Estimates for the location of the principal axes are shown in Figure P4.34.1.
x
y
O
.
a
a
a
a
2
a
2
a
2
a
2
a
1. stiff
2. flexible
Figure P4.34.1

1
4.38. A beam with the S-section of Figure P4.19 is loaded by a bending moment
about the
x
-axis. Show on the figure your best estimate of (i) the location of the
principal axes, (ii) the location of the neutral axis and (iii) the point
P
where the
maximum tensile stress will occur.