Rosette Strain Gages have three measuring grids arranged at an angle of 0°/45°/90° or 0°/60°/120°.
M Series strain gauges have been specially developed for high resistance to alternating loads at increased strain levels and high temperatures up to 300°C (572°F). They are foil strain gauges with measuring grids made of a special nickel-chromium alloy. OMEGA/HBM offer this special strain gauge with various geometries, measuring grid lengths and temperature response matching.
New materials offering high strength such as fiber composites pose a major challenge for strain gauges used for measurements specifically when pushing components to their mechanical limit of performance. Situations may arise where a strain gauge subjected to alternating loads at increased load levels is weakened and fails earlier than the component under test. The M Series has been specially developed for high resistance to alternating loads and allows for testing of materials featuring high strength.
All M Series strain gauge types are available with different measuring grid lengths: • 1.5 mm: where space is a constraint or when highly selective measurement results are required • 3 mm: for inhomogeneous materials and where space is a requirement or not • 6 mm: for inhomogeneous materials and where space is not a requirement
The right measuring grid length: The measuring grid length depends on the aim of measurement, since the result of a measurement with strain gauges will be determined as the average of strains. In general, measuring grid lengths of 3 to 6 mm (0.06 to 0.24') generates a better result.
Long measuring grids are recommended where there is an inhomogeneous material such as concrete or wood. A long strain gauge will bridge the inhomogeneity of the work piece and return the strain underneath the measuring grid as the measurement result.
Short measuring grids are suitable for detecting a local strain state. Therefore, they are suitable for determining strain gradients, the maximum point of notch stresses and similar stresses.
Specifications Strain Gage Construction–Foil Strain Gauge Carrier: Material: Glass fiber reinforced phenolic Thickness: 35 ±10 µm Grid Foil: Material: CrNi Thickness: 5 µm Encapsulation: Material: Polyimide film Thickness: 25 ±5 µm Connections: Solder pads with strain relief Resistance: 350 and 1000 Ω Resistance Tolerance: ±0.3%(1) Gage Factor: Approximate 2.2 (specified on each package) Gage Factor Tolerance: ±1.5% (for grid length <3 mm) ±0.7% (for grid length ≥3 mm) Temperature Coefficient of the Gauge Factor: Specified on each package Transverse Sensitivity: Specified on each package Operating Temperature Range: -200 to 300°C (-328 to 662°F) Temperature Response (Ferrite Steel): 10.8 ppm/K (6.0 ppm/°F) Maximum Elongation: Positive Direction: 10,000 µm (1%) Negative Direction: 15,000 µm (-1.5%) Minimum Bending Radius: 5 mm (0.20') for linear gauges 10 mm (0.39') for stacked rosettes Bonding Material that Can Be Used: Z70 or EP310S Fatigue Life (Test to Failure): 107 cycles at 2000 µm/m 106 cycles at 2200 µm/m 104 cycles at 3100 µm/m