Strain gages A strain gauge (or strain sensor) is a device used to measure the deformation of an object under the influence of external forces. By converting mechanical deformation into an electrical signal (through a change in resistance), it allows engineers to calculate stress, force, pressure, and many other parameters.
The way a strain gauge works is based on the change in electrical resistance of a conductor when it is mechanically deformed. This principle is known as strain gauge. piezoresistive effect.
Here are the specific steps involved in the operation of a strain gauge:
1. Basic principles of physics: Resistance (The R) of a conductor depends on its length (L) and cross-sectional area (A) according to the formula: R=𝜌⋅(L/A).
When stretched: The string became longer and thinner. → Resistance increase.
When compressed: The wire gets shorter and thicker. → Resistance decrease.
2. The process of strain transmission Strain gauges are typically constructed from an extremely thin metal mesh (metal foil) bonded to a flexible, insulating base.
The sensor is securely attached to the surface of the object to be measured using specialized adhesive.
When an object is subjected to force and deformation, the adhesive layer will transmit that deformation directly to the metal mesh of the sensor.
3Signal conversion (Wheatstone bridge circuit):Because the change in resistance of a strain gauge is extremely small (typically measured in micro-ohms), it cannot be measured directly with conventional meters. Instead, the sensor is connected to a... Wheatstone bridge circuit:
This circuit converts small changes in resistance into changes in voltage.Vout).
This voltage is then amplified and processed to display as a distorted value.𝜖) or specific unit of force.
The main practical applications of strain gauges:
1. Stress analysis and material testing
Durability test: Determine the load-bearing capacity of a material (metal, plastic, composite) before it fractures.
Design optimization: It helps engineers adjust the shape and materials of products (such as car frames, airplane wings) to ensure safety while saving materials.
2. Structural Health Monitoring (SHM)
Construction project: Attached to critical structures such as bridges, hydroelectric dams, and high-rise buildings to monitor stability and detect early signs of danger.
Tunnels and geotechnical engineering: Measure the deformation of the tunnel lining, retaining walls, or the movement of soil and rock to prevent landslides.
3. Manufacturing other types of sensors
Strain gauges are the core component (the heart) inside many common measuring devices:
Load cell: Used in various types of electronic scales, from precision scales to vehicle scales.
Pressure sensor: Measure the pressure of liquids or gases in industrial pipelines.
Torque Sensor: Measure the torque on the rotating shafts of engines or machinery.
4. Applications in transportation and machinery
Aerospace: Monitor the bending of the aircraft's wings and the spacecraft's body during flight.
Automotive industry: Inspect for collisions, measure braking force, and check for vibrations of mechanical components.
Shipping: Measuring the stress on the hull of a ship when subjected to the impact of ocean waves.
5. Biomedical and Robotics
Medical: Attached to prosthetics or surgical robots, the device responds to touch, allowing it to function with the precision of a human hand.
Bone research: Measuring the forces acting on bones and joints in movement studies.
KyowaKyowa (Japan) is a world-leading manufacturer of measuring instruments, renowned for introducing the first strain gages in Japan in 1949. Kyowa's products are highly regarded for their reliability and versatility, meeting the needs of everything from basic research to demanding industrial applications.
Strain Gages Introduction【KYOWA】
Popular Strain Gage models:Kyowa offers a wide range of models suitable for various materials and environmental conditions:
KFGS Series (Standard): This is a standard line using a flexible polyimide resin base (~14 μm thick), offering excellent moisture resistance and temperature self-compensation.
KC series (For concrete): Strain gauges are long, wire-like devices specifically designed to measure the average strain of concrete or materials with coarse aggregates.
KFGT series (Temperature Combination): The integration of a temperature sensor (T-type thermocouple) allows for simultaneous measurement of strain and temperature, resulting in more accurate error compensation.
KFEM (Super Deformable) Series: Used for measuring extremely large elongation (up to 20-30%), suitable for studies of plastic deformation of metals.
Other special lines: This includes waterproof strain gauges, solderable types, hydrogen-filled (KFV) types, and types specifically designed for printed circuit boards (PCBs).
Key technical features
Material: Commonly used alloys are Cu-Ni (Constantan) or Ni-Cr for resistor elements, ensuring high stability.
Temperature compensation: Most modern models incorporate a self-temperature compensation feature for target materials such as steel or aluminum.
Quality standards: Complies with stringent international standards such as NAS 942 and VDI/VDE 2635.
Response frequency: Capable of measuring both static and dynamic deformation at frequencies above 100 kHz.
Kyowa strain gauges are not only used for stress measurement but are also a core component in other sensors:
Structural measurement: Testing the structural integrity of bridges, roads, tunnels, hydroelectric dams, and high-rise buildings.
Transportation industry: Stress testing on automobiles, ships, and aircraft.
Sensor manufacturing: They are used as sensing elements in transducers to measure force (load cells), pressure, acceleration, and torque.
Video: Installation process for strain gauge connections
Contact SEMIKI Measuring Equipment Co., Ltd. Buying strain gauges (especially those from the Japanese manufacturer Kyowa) offers several important benefits in terms of quality, technical specifications, and after-sales service.
Official distributor: SEMIKI is the official distributor of measuring equipment from Japan, including product lines from KyowaThis ensures you receive a genuine 100% product, avoiding the risk of counterfeit or low-quality goods.
Diverse product range: SEMIKI offers a full range of popular Kyowa strain gauges such as KFGS (general) KFRS (for PCB circuit boards), and specialized 2-axis and 3-axis sensors.
In-depth technical support: Our team of engineers specializes in the measurement of material stress and strain, and is ready to advise you on choosing the right model for your specific material (steel, aluminum, concrete) and environmental conditions.
After-sales service and maintenance: SEMIKI has its own service and repair center in Ho Chi Minh City, supporting customers with calibration, testing, and troubleshooting of measuring equipment.
Video: Instructions on how to mount a KFRS miniature strain gauge sensor onto a printed circuit board (PCB).
Contact Semiki:
Website: You can find out more details and send a consultation request via Semiki.com.
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