MR8740T_user_manual_eng_20191016H.pdf - 第229页

224 Information for Reference Purposes Mechanical properties of industrial materials Material Modulus of longitudinal elasticity (Y oung’ s modulus) Poisson’ s ratio E (GPa) ν Carbon steel (Carbon content: 0.1% to 0.25%)…

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223
Information for Reference Purposes
Scaling method for strain gauges
This section describes how to determine the scaling conversion ratio when measurement is
performed with strain gauges and Model U8969 Strain Unit.
The appropriate conversion equation into stress varies depending on how the strain gauges are
used.
Three methods are available: the 1-gauge (for a gauge), 2-gauge (for two gauges), and 4-gauge
methods (for four gauges). The 2-gauge method is used for strain measurement involving
temperature compensation.
E: Young’s modulus,
ν
: Poisson’s ratio,
e
: Measured strain value
Measuring tensile and compressive stress: Stress (
σ
) = E ×
e
When 2- or 4-gauge method measurement is performed involving temperature compensation,
position the gauges perpendicularly to each other.
The stress (
σ
) is multiplied by 1 / (1 +
ν
) for the 2-gauge method, and 1 / [2 (1 +
ν
)] for the 4-gauge
method.
Measuring bending stress: Stress (
σ
) = E ×
e
When 2- or 4-gauge measurement is performed involving temperature compensation, the stress (
σ
)
is multiplied by 1/2 or 1/4, respectively.
Measuring torsional stress: Stress (
σ
) = E / [2 (1 +
ν
)] ×
e
(2-gauge method)
When the 4-gauge method is used, the stress is halved.
Refer to the instruction manual of the strain gauge for how to combine strain gauges for each
measurement.
Example: Measuring compressive stress
Using the 1-gauge method, material of measured object: aluminum, Young’s modulus: 73 (GPa)
(Refer to the table below.)
σ
= 73 × 10
9
× (Measured value) × 10
−6
(unit of measured value:
me
)
= 73 × (Measured value) (unit: kPa)
= 7.44* × (Measured value) (unit: gf/mm
2
)
*: 1 Pa = 1.01971621 × 10
−7
kgf/mm
2
= 1 N/m
2
Conversion ratio: 7.44, unit: gf/mm
2
Enter this value as the scaling conversion ratio.
13
Appendix
224
Information for Reference Purposes
Mechanical properties of industrial materials
Material
Modulus of longitudinal
elasticity (Young’s
modulus)
Poisson’s ratio
E (GPa)
ν
Carbon steel (Carbon
content: 0.1% to 0.25%)
205 0.28 to 0.3
Carbon steel (Carbon
content: 0.25% or more)
206 0.28 to 0.3
Spring steel (Quenched) 206 to 211 0.28 to 0.3
Nickel steel 205 0.28 to 0.3
Cast iron 98 0.2 to 0.29
Brass (Cast) 78 0.34
Phosphor bronze 118 0.38
Aluminum 73 0.34
Concrete 20 to 29 0.1
Refer to “Converting Input Values (Scaling Function)” (p. 38).
225
Information for Reference Purposes
Example of a waveform text le
The waveform text le consists of a header and data.
The header includes the following information:
(1) Title comment
(2) Recording length, sampling rate, trigger time
(3) Channel number, module type, measurement range, LPF, channel comment, scaling (setting,
conversion ratio, offset), invert
Saves data.
"Title comment"...............................................................................................................(1)
"Rec length","Sampling","Trigger Time"
"2500 sample","1MS/s","17/09/20 16:42:07.044" ...........................................................(2)
"Channel","Mode","Range(f.s.)","L.P.F.","Comment","Scaling","Ratio","Offset","Invert"
"CH1-1","VOLTAGE","10V","OFF","Analog 1-1","OFF","-","-","OFF" ..............................(3)
"CH1-2","VOLTAGE","100mV","OFF","Analog 1-2","OFF","-","-","OFF"
"CH2-1","K","200^cC","---","Temperature 1","ON(SCI)","2.1568E+00","4.9874E+00","OFF"
"CH2-2","K","200^cC","---","Temperature 2","OFF","-","-","ON"
"CH3-1","VOLTAGE","10V","---","Digital Voltmeter Unit 3-1","ON(ENG)","2.4178E+00","1.0254E+01","OFF"
"CH3-2","VOLTAGE","10V","---","Digital Voltmeter Unit 3-2","OFF","-","-","ON"
"L4 A1","-","-","-","4LA1","-","-","-","-"
"L4 A2","-","-","-","4LA2","-","-","-","-"
"L4 A3","-","-","-","4LA3","-","-","-","-"
"L4 A4","-","-","-","4LA4","-","-","-","-"
"Time[s]","CH1-1[V]","CH1-2[V]","CH2-1[^cC]","CH2-2[^cC]","CH3-1[V]","CH3-2[V]","L4A1","L4A2","L4A3","L4A4"
+0.000000000E+00,+1.510000E+00,-3.000000E-04,+3.997600E+02,+3.997600E+02,-9.997559E-03,-9.340576E-02,1,1,1,1
+1.000000000E-06,+1.510000E+00,-2.500000E-04,+3.997600E+02,+3.997600E+02,-9.997559E-03,-9.340576E-02,1,1,1,1
0.000000000E-06,+1.510000E+00,-3.000000E-04,+3.997600E+02,+3.997600E+02,-9.997559E-03,-9.340576E-02,1,1,1,1
+3.000000000E-06,+1.440000E+00,+3.500000E-04,+3.997600E+02,+3.997600E+02,-9.997559E-03,-9.340576E-02,1,1,1,1
+4.000000000E-06,+1.430000E+00,+2.000000E-04,+3.997600E+02,+3.997600E+02,-9.997559E-03,-9.340576E-02,1,1,1,1
13
Appendix