Application Cases

Experiment Name: Application of Power Amplifier in the Study of Quantitative Detection Characteristics of Stress-Induced Magnetic Anisotropy in Ferromagnetic Steel Materials

Experiment Objective:
This experiment investigates the physical manifestation of stress-induced magnetic anisotropy and its quantitative stress detection characteristics. An experimental system was designed and built, and a ferromagnetic Q195 steel plate specimen was fabricated. Under uniaxial elastic stress loading, the stress-induced magnetic anisotropy characteristics of the ferromagnetic material were explored by varying the direction of the applied external magnetic field.

Experimental Equipment:
Signal generator, power amplifier ATA-4014, excitation coil, TMR probe, oscilloscope, test specimen, etc.

Experimental Procedure:
The U-shaped iron core is made of easily magnetized soft magnetic alloy silicon steel, with a coil wound around it and a magnetic flux path length of 200 mm, used to generate the excitation magnetic field. The TMR probe is a leakage magnetic field sensor used to collect magnetic induction intensity (B) signals. Channel 1 of the oscilloscope is used to collect the current signal of the magnetic field intensity (H), and Channel 2 is connected to the voltage output across the TMR probe to collect the magnetic induction intensity (B) signal. The experimental signal is generated by the signal generator, amplified by the power amplifier, and then sent to the excitation coil. The excitation coil generates a magnetic field, and after the U-shaped iron core is magnetized, a magnetic circuit is formed between the U-shaped iron core and the specimen. The TMR probe detects the leakage magnetic field signal outside the magnetic circuit.

In this experiment, the frequency is set to 300 Hz. The larger the excitation voltage, the stronger the magnetic field excited in the U-shaped coil. However, excessive voltage will cause the leakage magnetic field intensity generated by the excitation to exceed the linear operating range of the TMR probe and will also generate excessive current, leading to coil overheating. Since the resistance of the excitation coil in this experiment is 5.5 Ω and the rated current of the coil copper wire is 0.5 A, the excitation voltage is selected as 0.3 V. The current through the excitation coil is approximately 0.055 A, far below the rated current, allowing the experiment to be conducted safely, and the generated leakage magnetic field intensity remains within the linear operating range of the TMR probe.

Experimental Results:
The research results show that stress causes ferromagnetic Q195 steel to exhibit magnetic anisotropy characteristics. The magnetic characteristic parameters of stress-induced magnetic anisotropy increase approximately linearly with increasing stress. The corresponding stress can be obtained by extracting the corresponding parameters. The research findings provide a valuable reference for systematically investigating the quantitative characteristics of stress-induced magnetic anisotropy in ferromagnetic materials.

Specifications of the High-Voltage Amplifier ATA-4014C Used in the Experiment: