The following applies here:
εs Apparent strain of the strain gauge
αr Temperature coefficient of the electrical resistance
αb Thermal expansion coefficient of the measurement object
αm Thermal expansion coefficient of the measuring grid material
k K factor of the strain gauge
Δϑ Temperature difference that triggers the apparent strain
εa Strain indicated at the amplifier
εm The strain triggered by the mechanical load
αDMS Thermal coefficient of linear expansion as per the strain gauge pack
In a practical test, four HBM strain gauges of the LG11-6/350 type, adapted to steel (α=10.8 10-6/K), were installed on an aluminum workpiece. A four-wire circuit was used to eliminate cable influences. According to the data supplied by the manufacturer for the material, α=23.00 *10-6/K for T= 0 … 100°C.
Tab. 1 Measurement results for a strain gauge adapted for ferrit. steel, installed on aluminum
During this measurement, the strain gauge creep is an undesirable effect. So in the interest of maximum accuracy, it is advisable to use HBM series K strain gauges, which have three different creep adjustments as standard and of these, use the strain gauge with the greatest end loop length.
Also, when the measuring temperatures are over 60 °C, it is advisable to use hot curing adhesives for installation.
Note: Subject to modifications. All product descriptions are for general information only. They are not to be understood as a guarantee of quality or durability.