HBM-M-Shear

Supported Applications

The Omega/HBM M Series encapsulated foil strain gages are engineered for high resistance to alternating loads and operation at elevated temperatures up to 300°C (572°F). These sensors utilize a special nickel-chromium alloy foil construction, making them suitable for testing high-strength materials such as fiber composites. The series supports various measurement geometries including linear strain determination, tension/compression analysis via T rosettes and stacked T rosettes, shear stress determination using V-shaped configurations, and biaxial stress state evaluation with rectangular or stacked rosette arrangements.

Operating Conditions & Performance

The M Series operates within a temperature range of -200 to 300°C (-328 to 662°F). The carrier material is glass fiber reinforced phenolic with a thickness of 35 ±10 μm, while the grid foil consists of CrNi (nickel-chromium) at 5 μm thick. Encapsulation utilizes polyimide film measuring 25 ±5 μm in thickness. Electrical connections are provided via solder pads with strain relief.

Performance specifications include a gage factor of approximately 2.2, specified on each package. Gage factor tolerance is ±1.5% for grid lengths less than 3 mm and ±0.7% for grid lengths greater than or equal to 3 mm. The series supports maximum elongation in the positive direction up to 10,000 μm (1%) and negative direction up to 15,000 μm (-1.5%). Minimum bending radius is 5 mm (0.20") for linear gages and 10 mm (0.39") for stacked rosettes.

Fatigue life data indicates performance of 10⁷ cycles at 2000 μm/m, 10⁶ cycles at 2200 μm/m, and 10⁴ cycles at 3100 μm/m. Temperature response on ferrite steel is documented as 10.8 ppm/K (6.0 ppm/°F). Resistance tolerance is ±0.3%.

Configuration Options

The series offers configurable geometries, grid lengths, and resistance values to accommodate specific measurement requirements:

• Geometries: LM1 (Linear), TM1 (T rosette), TM9 (Stacked T rosette), XM4 (V-shaped for shear stresses), RM8 (Rectangular rosette), and RM9 (Stacked rosette).
• Measuring Grid Lengths: 1.5 mm (0.06"), 3 mm (0.12"), and 6 mm (0.24").
• Nominal Resistance: Available in 350 Ω configurations; the series documentation also lists 1000 Ω as a supported resistance value.
• Excitation Voltage: Maximum permitted effective excitation voltage varies by model, ranging from 7 V to 22 V depending on geometry and grid length. For stacked rosettes, this limit is specified at 5% of the standard maximum for steel material applications.

Bonding materials compatible with the series include Z70 (rapid adhesive) or EP310S (high temperature two-component epoxy resin). Accessories such as accelerators and cleaning solvents are available to support installation on vertical surfaces or overhead working conditions.

Key Product Differences

The M Series distinguishes itself through specific geometric configurations tailored for different stress states. The LM1 geometry provides a single measurement grid for linear strain in one direction. TM1 and TM9 geometries utilize two grids offset by 90° to measure tension and compression, with the TM9 offering a stacked configuration. For shear stress determination, the XM4 V-shaped gage arranges two grids at ±45° to the axis.

Biaxial stress states with unknown principal stress directions are addressed using RM8 (rectangular) or RM9 (stacked) rosettes, which feature three measurement grids oriented at 0°, 45°, and 90°. Model numbers follow a structured format: 1--/GE, such as 1-XM41-1.5/350GE.

Packaging varies by geometry; most models are sold in 5-packs, while the LM1 series is packaged in sets of ten.