Measured Variable
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Measuring variable
A measured variable is a physical quantity that is determined by a measurement process. Typical physical measured variables include force, length, mass, temperature, time, etc.
The value of the measured variable obtained from a measuring device is referred to as the measured value; it is formed from a numerical value and the physical unit.
Characteristic measured variables in technical fracture mechanics are, for example, the impact load (force) determined by strain gauges in the instrumented Charpy impact test (ICIT) or the deflection determined by a photo-optical displacement measuring device. When determining characteristic values in quasi-static fracture mechanics tests, CT test specimens are used to measure not only the fracture load but also the displacement of the point of application of the load in the line of action of the load and the notch widening (see crack opening), which are often measured using laser optical device systems.
The measured variable does not have to be the direct subject of the measurement. It can also be determined using physically defined mathematical relationships between variables that are subject to direct measurement, e.g. velocity. The aim of every measurement is to determine the true value of the measured variable. A distinction is made between dimensioned and dimensionless measured variables:
- Dimensional measured variables: load (force) in newtons, time in seconds, mass in kilograms
- Dimensionless measured variables: angle, index of refraction
- DIN 1319: Fundamentals of Metrology
- Part 1 (1995-01): Basic Terminology
- Part 2 (2005-10): Terminology related to Measuring Equipment
- Part 3 (1996-05): Evaluation of Measurements of a Single Measurand, Measurement Uncertainty
- Part 4 (1999-02): Evaluation of Measurements – Uncertainty of Measurement
See also