Generally speaking, the sensors that need to test the impact force of different products will be different, but many people don't know what kind of sensor to choose. Therefore, this paper introduces several sensors for measuring impact force for your reference.

At present, when measuring dynamic force, impact force sensor mainly includes strain impact force sensor and pressure impact force sensor. How to choose the actual impact force measurement process?

The strain impact force sensor converts the elastic deformation in the impact process into the change of strain resistance, and converts the change into a signal recognizable by the measuring circuit through the wheatbridge circuit.

Positive and negative charges are generated on the crystal surface of the pressure material during the impact process, which is directly proportional to the impact force. The charge is converted into the voltage recognized by the back-end acquisition circuit through the external charge amplification circuit. The pressure impact force sensor is designed according to the pressure effect.

Pressure impact force sensor: due to the use of pressure ceramics and pressure quartz materials, the pressure impact force sensor has large stiffness, small structure and high natural frequency, which is suitable for dynamic measurement. When the pressure sensor is used for measurement, the pressure material generates an electrical signal, but there is little displacement. The sensitivity of the pressure sensor does not depend on the size and structure of the pressure material, but on the type and geometry of the pressure material used.

Select actual application process

In the process of force loading, the deformation of the pressure sensor is very small and the stiffness is very high, which leads to high resonance frequency, which is very suitable for dynamic testing. However, a complete measurement chain is very important for dynamic characteristics. Therefore, the components installed with sensors need to have greater mass and have a great impact on the overall mass and cut-off frequency of the system, so as to avoid the changes of structural vibration and impact form caused by additional mass. In addition, the bandwidth of the charge amplifier depends on the charge, so the high charge caused in large force measurement will in turn limit the bandwidth.

When the rated resistance is large, the cut-off frequency of the strain sensor is high. The elastomer of the small range force sensor is soft, the structural stiffness is small, and the resonant frequency is low. However, when testing a small range of force quickly, the pressure current sensor is the first choice. For a large force, the sensor based on strain principle should be selected.

The amplifier connected to the strain sensor can compensate various errors, including temperature compensation for sensitivity and zero, as well as linearity and bending moment errors. Therefore, the strain sensor is very suitable for high-precision static calibration, and higher repeatability can be achieved through elastomer structure. Therefore, for mechanical calibration, the sensor based on strain principle is the only choice, and the high-pressure force sensor is installed with bolts in the installation process. When the actual impact force occurs, the bolt will divert the impact force. The user cannot use the appearance parameters provided by the sensor manufacturer in actual use, but should be calibrated with the structural components as a whole. Generally, shock acceleration method and strain equivalent shock method are used for calibration.

High initial load

In the process of power application, if necessary, the charge generated by the pressure sensor may be short circuited, and the input state of the charge amplifier can be displayed as zero. Therefore, the input range of the charge amplifier is not affected by the high initial load. Therefore, the pressure sensor can maintain high accuracy under high initial load.

Some strain force sensors have IP68 protection level, and the tightly sealed shell protects the sensitive strain gauge, which makes it possible to use in harsh environments. The cable of the pressure sensor can be connected through special protection to ensure its safe operation.

High precision measurement

The accuracy of modern force sensor is high, the error of strain sensor is only 200ppm, and the linear error of pressure sensor is slightly higher, generally 0.5% of the full range. Its limitation mainly comes from drift. Higher accuracy can be obtained by calibrating the whole range.

Limited space

The structure of pressure sensor is very compact. For example, the height of CLP series is only 4mm. Therefore, it is very suitable for integration into existing systems. Although the accuracy of pressure sensor is low, it should be the first choice for applications with high space requirements.