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speci�cations:

Strain gage dimensions

The specied active measuring grid length a is the net length of the grid without theend loops (transverse bridges). If the following facts are taken into account, it is possi- ble to cut the carrier foil: Cutting the foil in parallel to the measuring grid has only minor effects. Shortening the carrier foil perpendicular to the direction of the measu- ring grid will inuence the way the strain is introduced, thereby also changing essenti- al characteristics of the strain gage. Therefore we recommend leaving a minimum distance of 1mm between the measuring grid end and the end of the carrier foil.
aactive measuring grid length Schematic diagram of a strain gage

Strain gage resistance

The electric resistance between the two metal leads, solder tabs or cable ends for con- necting the measuring cable is called the resistance of a strain gage.
(1) Please notethat the nominal resistance for strain gages with connection cables* is specied without the cable.The HBM product range comprises strain gages with nominal resistances of 120 Ω ,350 Ω , 700 Ω , and 1000 Ω . The nominal resistance is stated on each strain gage package including the resistance tolerance per package. The resistance of each single strain gage from HBM has been checked.

Gage factor (strain sensitivity)

The strain sensitivity k of a strain gage is the proportionality factor between the relative change in resistance ∆ R/R
and the strain to be measured: ∆ R/R
= k ε The strain sensitivity yields a dimensionless number and is designated as gage factor. This gage factor is determined for each production batch by measuring and is specied on each strain gage package as a nominal value complete with tolerance. The gage factors vary between the production batches by just a few thousandths.

Temperature coefficient of the gage factor

The specied gage factor applies at room temperature. This factor changes as the tem- perature changes; however, with an excellent approximation, this correlation is linear. In the case of constantan measuring grids (V, G, K, Y series) the gage factor is propor- tional to temperature; in the case of chromium/nickel measuring grids (C series) the gage factor is inversely proportional to temperature. The temperature coefficient of the gage factor and its tolerance are stated on each strain gage package.
(1) Strain gages of the V series, LE11* see page 42 et sqq Strain Gages and Accessories13