SOLUTION

Load Cell

• Load cells can measure tension, compression, or shear.
• Load cells cannot measure Temperature.
• Tension cells are used for the measurement of a straight-line force ‘pulling apart’ along a single axis; typically annotated as the positive force.
• Compression tension cells are used for the measurement of a straight-line force ‘pushing together’ along a single axis; typically annotated as the negative force.
• Shear is induced by tension or compression along offset axes. Most load cells actually measure the displacement of a structural element to determine force.
• The force is associated with a deflection as a result of calibration.
• There are many form factors or packages to choose from—S-beam, pancake, donut or washer, plate or platform, bolt, link, miniature, cantilever, canister, load pin, rod end, and tank weighing.
• Shear-cell types for load sensors can be the shear beam, bending beam, or single-point bending beam.
• The most common sensor technologies are piezoelectric and strain gauges.
• For piezoelectric devices, a piezoelectric material is compressed and generates a charge that is conditioned by a charge amplifier.
• For strain gauge devices, strain gauges (strain-sensitive variable resistors) are bonded to parts of the structure that deform when making the measurement.
• These strain gauges are typically used as elements in a Wheatstone bridge circuit, which is used to make the measurement.
• Strain gauges typically require an excitation voltage and provide output sensitivity proportional to that excitation.