1.Metal Foil Strain Gauges: These are the most widely used strain gauges. They consist of a thin metal foil, typically made of materials like constantan or karma, bonded to a flexible backing material. When subjected to strain, the foil undergoes a change in resistance, which is measured to determine the applied force or deformation.
2.Semiconductor Strain Gauges: Semiconductor strain gauges are based on piezoresistive materials, such as silicon or germanium. These materials exhibit changes in resistance when subjected to mechanical strain. Semiconductor strain gauges offer advantages like high sensitivity, small size, and resistance to temperature changes, making them suitable for certain specialized applications.
3.Bonded Resistance Strain Gauges: These strain gauges consist of a thin wire or filament, typically made of materials like platinum or tungsten, bonded to the surface of the material being tested. Changes in the length or shape of the material cause the bonded wire to undergo resistance changes, which are measured to determine strain.
4.Diffused Semiconductor Strain Gauges: In this type, the piezoresistive material is diffused into a semiconductor substrate, such as silicon. These strain gauges offer high sensitivity and stability, making them suitable for demanding applications where precision is critical.
5.Photomechanical Strain Gauges: Photomechanical strain gauges utilize optical principles to measure strain. They typically involve applying a pattern of lines or dots to the surface of the material. As the material deforms, the pattern undergoes changes in shape or size, which can be measured optically to determine strain.
6.Vibrating Wire Strain Gauges: In vibrating wire strain gauges, a wire or filament is tensioned between two points and set into vibration. Changes in tension due to strain cause changes in the wire's natural frequency, which can be measured to determine strain.
Each type of strain gauge has its advantages and limitations, and selecting the appropriate type depends on factors such as the application requirements, environmental conditions, and desired measurement accuracy.