MethodWhat is calculated?
A gauge also responds to strain transverse to its measuring direction; the ratio of sensitivities is the transverse sensitivity q (Keil eq. 2.16). Because the manufacturer calibrates k on a beam with ν₀ = 0.285, the gauge only reads without error in exactly that uniaxial field. For two perpendicular gauges, eq. 2.25 can be solved for both true strains.
Equations
ε′ = (εₗ + q·εq)/(1 − ν₀·q) (Keil Gl. 2.25)
εₐ = (1 − ν₀q)(ε′ₐ − q·ε′ᵦ)/(1 − q²)
εᵦ = (1 − ν₀q)(ε′ᵦ − q·ε′ₐ)/(1 − q²)
f = q(ν₀ + εq/εₗ)/(1 − qν₀) (Keil Gl. 2.26)
ProcedureStep by step
- Record both indicated strains with the same gauge factor set on the amplifier.
- Take q and ν₀ from the gauge manufacturer's datasheet.
- Use the corrected strains for stress calculation and the error values to judge whether the correction matters.
Typical mistake
Using the percentage value of q as an absolute number, or ignoring the sign of q (can be negative for long grids).
PracticeApplication and limits
Stress analysis with T rosettes or two single gauges, especially when one gauge lies transverse to the principal strain: Keil's example with q = 1 % and εq/εₗ = −3.33 gives an error of −3.1 %.
Valid for two exactly perpendicular gauges with equal q. For three-element rosettes apply the equations pairwise; q itself varies with temperature and production lot.
SourceTechnical basis
Keil, Dehnungsmessstreifen, 2nd ed. 2017, sec. 2.3 transverse sensitivity, eqs. (2.16), (2.20)–(2.27).
The source supports the equation structure and worked examples; this calculator does not replace calibration of the measuring chain.
FAQFrequently asked questions
When can I skip the correction?
In uniaxial loading along the gauge with ν ≈ 0.285 the error is zero; Keil's rule of thumb 2.27 gives f ≈ q·εq/εₗ.
Why does ν₀ = 0.285 appear?
Because the transverse component present during calibration is already contained in the stated gauge factor (eq. 2.23).
Does it apply to 45° rosette grids?
For the 45° grid the transverse strain must be derived from the other two grids; the correction is then done iteratively or with the manufacturer's rosette formulas.
In the same cluster
All strain-gauge calculators