# A Program To Calculate Principal Stresses, - HP 49g+ User Manual

Graphing calculator.

To find the principal normal values press š until the cursor returns to the
intersection of the circle with the positive section of the σ-axis. The values
found at that point are
1.40). Now, we expected the value of τ'
axes. What happens is that, because we have limited the resolution on the
independent variable to be
stresses become zero.
o
, τ'
= 58
, and (σ'
) = (1.06E2,5.51E-1) = (106, 0.551).
xx
xy
information tell us is that somewhere between
stress, τ'
, becomes zero.
xy
To find the actual value of n, press \$. Then type the list corresponding to
the values {σx σy τxy}, for this case, it will be
Then, press @CC&r.
The last result in the output, 58.2825255885
actual value of n.
A program to calculate principal stresses
The procedure followed above to calculate
follows:
Program PRNST:
«
INDAT
CC&r
" n"
TAG
3 ROLLD
R C DUP
C R + "σPx"
TAG
SWAP C R - "σPy"
TAG
"
To run the program use:
J@PRNST
25˜
75˜
50`
o
, τ'
φ
= 59
, and (σ'
) = (1.06E2,-1.40E0) = (106, -
xx
xy
= 0 at the location of the principal
xy
o
= 1
, we miss the actual point where the shear
If you press š once more, you find values of are
φ
{ 25
Start program PRNST (PRiNcipal STresses)
Enter data as in program MOHRCIRC
Calculate σc, r, and fn, as in MOHRCIRC
Tag angle for principal stresses
Move tagged angle to level 3
Convert σc and r to (σc, r), duplicate
Calculate principal stress σPx, tag it
Swap,calculate stress σPy, tag it.
End program PRNST
Start program PRNST
Enter σx = 25
Enter σy = 75
Enter τxy = 50, and finish data entry.
What this
o
o
= 58
and
φ
= 59
, the shear
75
50 } [ENTER]
o
, is the
n, can be programmed as
Page 22-38
φ  