How do you deal with temperature, humidity, and noise effects on strain gauge and rosette performance?

1 Temperature effects

Temperature changes can cause thermal expansion or contraction of both the strain gauge and the test material, resulting in apparent strain readings that do not reflect the actual mechanical deformation. To avoid this, you need to use a temperature compensation technique, such as using a dummy gauge, a bridge circuit, or a temperature sensor. A dummy gauge is a strain gauge that is mounted on an unstressed material with the same thermal properties as the test material, and connected in the opposite arm of a Wheatstone bridge circuit. A bridge circuit is a configuration of four resistors that produces a voltage output proportional to the difference in resistance between two pairs of resistors. A temperature sensor is a device that measures the ambient temperature and provides a correction factor for the strain gauge output.

2 Humidity effects

Humidity can affect the strain gauge performance by causing moisture absorption, swelling, or corrosion of the gauge or the adhesive. Moisture can also alter the electrical properties of the gauge or the lead wires, resulting in changes in resistance or capacitance. To prevent these effects, you need to use a moisture-resistant strain gauge, such as one with a polyimide or epoxy coating, and a suitable adhesive, such as a cyanoacrylate or epoxy resin. You also need to seal the gauge and the lead wires with a protective coating, such as a silicone rubber or a polyurethane varnish.

3 Noise effects

Noise is any unwanted signal that interferes with the strain gauge output, such as electromagnetic interference, mechanical vibration, or electrical noise. Noise can reduce the signal-to-noise ratio and distort the strain measurement. To reduce noise, you need to use a shielded cable, a low-noise amplifier, a filter, or a signal averaging technique. A shielded cable is a cable that has a metal layer around the conductors that blocks external electromagnetic fields. A low-noise amplifier is a device that amplifies the strain gauge signal without introducing significant noise. A filter is a device that removes unwanted frequencies from the strain gauge signal, such as a low-pass filter or a high-pass filter. A signal averaging technique is a method that combines multiple samples of the strain gauge signal and calculates the mean value, which reduces the random noise.

4 Here’s what else to consider

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