Full resolution (JPEG) - On this page / på denna sida - Strength of Materials - Square beams exposed to torsional stress - Torsional deflection - Formula for torsional deflection in hollow round shafts
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
STRENGTH OF MATERIALS. 27 I
take the side instead of the diameter. The formula for tor-
sional strength in a square beam will be :
p_ (Side)3
X 1.2 X c
Length of leverage.
c = Constant (same as for a round beam).
P = Load in pounds.
Side is measured in inches.
Length of leverage is measured in feet.
Torsional Deflection.
The torsional deflection in degrees will increase directly
with the length of the shaft and the twisting load, and inversely
as the fourth power of the diameter of the shaft ; therefore, the
formula for torsional deflection is :
r_cXmXLXP
S
&
S = Deflection in degrees for the length of the shaft.
m = Length of lever in feet.
L = Length of shaft in feet.
P = Load in pounds.
D — Diameter of shaft in inches.
c = Constant obtained from experiments for different
kinds of material, and is the deflection in degrees for a shaft
one inch in diameter and one foot long, when loaded with one
pound on the end of a lever one foot long.
The author of this book has made experiments on tor-
sional deflection in wrought iron shafts two inches in diameter.
The average deflection was lj£ degrees in 10 feet of length,
when a load of 50 pounds was applied on a lever h% feet long.
Constant c, as calculated from these experiments, will be 0.00914.
Using this constant, the formula for torsional deflection for
wrought iron will be :
C _Z X m X P X 0.00914
* -^
Machinery steel and wrought iron will deflect about the
same. Cast-iron will deflect twice as much as wrought iron. A
square bar will deflect 0.589 times as much as a round bar when
side and diameter are alike.
Formula for Torsional Deflection in Hollow Round Shafts.
S_ L XwX PXc
D = Outside diameter in inches.
d = Inside diameter in inches.
All the other letters have the same meaning as explained
under formulas for solid shafts.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
