A strain gauge is a device used to measure strain (deformation) in an object subjected to an external force. It operates on the principle that when an object is subjected to a force, it undergoes deformation or strain, which can be quantified by changes in its electrical resistance. Strain gauges are commonly used in various applications, including force and weight measurement. Here's how they function in these contexts:
Force Measurement:
In force measurement, a strain gauge is typically attached to a load-bearing element, such as a beam or a structure, that experiences deformation when subjected to a force. As the force is applied to the object, it undergoes strain, causing the strain gauge to also deform. This deformation changes the electrical resistance of the strain gauge material.
Strain gauges are typically made from a conductive material, such as metal, that has a predictable change in resistance when strained. The most common type of strain gauge is the bonded metallic foil strain gauge. When the object is strained, the strain gauge's resistance changes proportionally to the amount of strain experienced by the object.
By measuring the change in resistance of the strain gauge, the applied force can be indirectly calculated using the relationship between strain and force. This measurement can then be used to determine various parameters such as tension, compression, or torque.
Weight Measurement:
Weight measurement is a specific application of force measurement, where the force being measured is the weight of an object due to gravity. Strain gauges can be used in load cells, which are devices designed to measure weight or force. Load cells are commonly used in scales, industrial weighing systems, and other applications where weight needs to be accurately determined.
In a load cell, strain gauges are arranged in a specific pattern on a structural element, often forming a Wheatstone bridge configuration. When weight is applied to the load cell, the strain gauges experience deformation, causing changes in their resistances. The Wheatstone bridge circuit is designed to detect these changes in resistance and convert them into an electrical signal, which can then be further processed to provide an accurate weight measurement.
In summary, the function of a strain gauge in force and weight measurement is to convert the mechanical deformation (strain) of an object into an electrical signal (change in resistance), which can be measured and used to determine the force or weight applied to the object.