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Stress and strain gauge ( strain gauge) What is that?
Stress strain gauge Strain gauge (sometimes called a stress gauge) is a sensor whose resistance changes with the force applied; it converts force, pressure, strain, weight, etc. into a change in resistance that can then be measured. When an external force is applied to a stationary object, stress and strain are the results. Stress is defined as the internal resistance of the object and strain is defined as the displacement and deformation that occurs.
Stress gauges are one of the most important sensors in electrical measurement techniques used to measure mechanical quantities. As their name suggests, they are used to measure strain. In technical terms, “strain” includes tensile strain and compressive strain, which are distinguished by positive or negative signs. Therefore, stress gauges can be used to detect expansion as well as contraction. Typical metal foil stress gauge Deformation of an object is always caused by external or internal impact. Deformation can be caused by force, pressure, moment, heat, structural changes of the material, etc. If certain conditions are met, the quantity or value of the influencing quantity can be deduced from the measured strain value. In experimental stress analysis, this feature is widely used. Experimental stress analysis uses strain values measured on the surface of a specimen or structural member to indicate the stresses in a material and also to predict the safety and durability of the material. Special transducers can be designed to measure force or other derived quantities, such as torque, pressure, acceleration, displacement, vibration, and others. The transducer typically contains a pressure-sensitive diaphragm with stress gauges attached.
KYOWA manufactures stress gages for a wide range of purposes, from static strain measurement to dynamic strain and impact strain measurement at frequencies of several hundred kHz.
Their wide range of applications makes them convenient for use on structures of various materials and shapes.
Principle of stress gauge
Metals change their resistance when they are deformed. Stress gauges take advantage of this property.
The amount of resistance of a metal is inversely proportional to its cross-sectional area and directly proportional to its length.
The elongation or contraction of a metal and the changes in resistance are proportional to a particular constant.
Elongation, stress and Poisson's ratio
When a tensile force P is applied to a material, the material will have a stress σ corresponding to the applied force. Proportional to the stress, the cross-section shrinks and the length expands ⊿L compared to the length L that the material had before being subjected to the tensile force.
Select a stress gauge
Select the stress gauge most suitable for the measurement purpose, given the measurement object and conditions under consideration. Select the conductor cable and adhesive to meet the measurement environment.
Also, consider the various accessories available to protect against harsh environments and save on labor.
General Purpose Precision Strain Gauges
General Purpose Precision Stress Gauges are packaged constantan foil stress gauges that come in a variety of styles for scientific, industrial, and test stress analysis. These precision stress gauges can be used for monitoring industrial equipment test stress analysis or a variety of scientific applications. In the general purpose stress gauge section, you will find the stress gauge styles next to the part number so you can see the shape of the stress gauge. Gauge dimensions are also provided in SI (Metric, mm) and US Customary Units (Inches). General purpose precision stress gauges are available in linear, double parallel grid, T-shaped (0/90°), rectangular or triangular (45° or 60°), stacked or flat, and cutout styles.
Aluminum foil stress tester for printed circuit boards (PCB)
Model: KFRS 120Ω Single axis, KFRS 120Ω Bi-axis, 0°/90°, KFRS 120Ω Tri-axis, 0°/90°/45° PCB plane arrangement used for a variety of products including mobile phones, car navigation systems and digital cameras. These meters are temperature compensated meters (SELCOM meters) to evaluate them
KYOWA Strain gages KFGS Series
How to measure strain with strain gauges?
Now that the strain measurement procedure has been established, the next step in using a strain gauge is to collect useful data. The strain gauge must be connected to a circuit that can respond accurately to small changes in resistance associated with strain. Multiple strain gauges can be used in a divider bridge circuit to measure small changes in resistance. This is known as a Wheatstone bridge. In the Wheatstone bridge configuration, an excitation voltage is applied across the circuit and the output voltage is measured across two points in the middle of the bridge. With no load applied to the load cell, the Wheatstone bridge is in balance and has no output voltage. Any small change in the material underneath the strain gauge will result in a change in the resistance of the strain gauge as it deforms with the material. This throws the bridge out of balance, resulting in a change in the output voltage. As mentioned earlier, the change in resistance is very small, which means that signal amplification is often required to accurately identify the changes. Amplification enhances the changes in the distortion signal; however, it also results in the detection of more unwanted noise in the signal. Signal filtering removes the excess noise, ensuring that the data is accurate and easy to understand.
SEMIKI's long experience in consulting and distributing strain gauges means we can apply strain gauge technology to many different types of materials. SEMIKI can meet customers' requirements for applying strain gauges to different designs and materials such as aluminum, steel and stainless steel.
Conclude
The stress gauge has a structure in which a thin metal film with a thickness of a few microns is bonded to a thin insulating sheet (such as polyimide, polyester, etc.).
This film is photo-etched to the shape of the stress gauge which can be created using the negative film mask of the stress gauge samples.
These photo etched stress gauge samples are trimmed to standard resistance values to meet the requirements as stress gauges.
Strain gages are used to measure stress and deformation in many different manufacturing industries from electronics, steel, gas, medical...
Please contact SEMIKI for advice on choosing strain gages that suit your needs
CONTACT:
SEMIKI Measuring Equipment Company Limited
Email: sales@semiki.com
Phone: +84 9797 61016