Specifications

Rosette Measurements
This program makes a rectangular rosette measurement on channels 0, 1,
and 2 of multiplexer card number 1.
!Dimension a computer variable to store the strain measurements.
DIM Strn_rdgs(1:3)
!Clear and reset the multimeter.
CLEAR 70903
OUTPUT 70903;"*RST"
!Specify the gage factor for each channel measured.
OUTPUT 70903;"STR:GFAC 2.075E-6,(100,102);:GFAC 2.11E-6,(@101)"
!Measure the unstrained reference for each channel.
OUTPUT 70903;"CAL:STR (@100:102)"
DISP "Add tension to the specimen; then press ’Continue’"
PAUSE
DISP ""
!Measure the strain on the specified channels. Enter and display the readings.
OUTPUT 70903;"MEAS:STR:QUAR? (@100:102)"
ENTER 70903;Strn_rdgs(*)
E1=Strn_rdgs(1)
E2=Strn_rdgs(2)
E3=Strn_rdgs(3)
Epsilon=.5*(E1+E3+((E1-E3)^2+(2*E2-E1-E3)^2)^.5)
Sigma=(10.4/2)*((E1+E3)/(1-.32)+1/(1+.32)*((E1-E3)^2+(2*E2-E1-E3)^2)^.5)
Theta=.5*ATN((2*E2-E1-E3)/(E1-E3))
PRINT Epsilon
PRINT Sigma
PRINT Theta
END
Comments • The wiring diagram used for this example is on page 28.
• A gage factor must be specified, and an unstrained reference must be
measured for each channel.
• A rosette measurement is a series of three
1
⁄
4
bridge measurements
(channels 100 - 102). Each measurement is substituted into the
applicable equation.
• The rosette equations used in this program are listed in Appendix B.
For this program, a poisson ratio (ν) of 0.32 and modulus of
elasticity (
E) of 10.4 are assumed.
Chapter 3 Making Strain Gage Measurements 39
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com