Strain Gauge Material Properties

Determination of material properties of standardized test samples.

Strain gauge material properties. A strain gauge also spelled strain gage is a device used to measure strain on an object. Simmons and arthur c. A conductive material is bonded to a thin backing. Mechanical properties are essential in describing the behaviour of a material when a load is applied.

Specialized semiconductor strain gauges based on silicon have gauge factors of 50 to 200 but these devices are nonlinear making them more difficult. In equation 5 13 the metal strain gage behavior is explained by 1 2υ parcel the dimensional effect but to semiconductor strain gages the piezoresistive parcel πe predominates the change in resistivity has a greater effect on the value of the resistance than the change in geometry. The material construction of the wire directly affects the sensitivity of the strain gage. Further discussion on sensitivity can be found in the strain gage sensitivity page.

Determination of durability parameters of components structures in the test bench or in the field. Metal strain gauges have a gauge factor of about 2. As the object is deformed the foil is. Applications are mainly static or quasi static strains.

The types of construction for these include thin film foil and semiconductor strain gauges. Variation in expansion coefficients between the gage and base materials may cause dimensional changes in the sensor element. And in gauge lengths of 0 125 inches 3 2 mm and longer can be strained to 20. The gauge is attached to the object by a suitable adhesive such as cyanoacrylate.

The sensitivity of metal strain gauges can be 10 6 strain. Because of this. It should be borne in mind however that under high cyclic strains the p alloy will exhibit some permanent resistivity change with each cycle and cause a corresponding zero shift in the strain gauge. Invented by edward e.

Ruge in 1938 the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. Select constantan advance copel alloy wire if. Constantan in this form is very ductile. Many tests such as tension compression impact bending shear torsion and hardness tests are developed in order to observe the response of a material to an applied external force these properties are important in order for engineering designers to select appropriate materials for.

One of the most popular materials used for the strain gauges is the. The metals can be easily cut into the zigzag foils for the formation of the strain gauges. Although semiconductor materials exhibit substantial nonlinear behavior and are temperature sensitive. Strain in the material is a critical factor determining damage effect and durability.

Earlier wire types of strain gauges were used commonly which are now being replaced by the metal foil types of gauges as shown in the figure below. Materials used for the strain gauges. Strain gauge sensors use the strain gauge element as the underlying mechanism.