External magnetic field assisted high-strain-rate low-temperature-rise electromagnetic expanding ring technique

Area of Science:

• Materials Science
• Mechanical Engineering
• Electromagnetism

Background:

• Conventional electromagnetic expanding ring tests face limitations due to Joule heating at high strain rates.
• Elevated temperatures compromise the accuracy of dynamic mechanical property measurements.

Purpose of the Study:

• To introduce and validate a novel electromagnetic expanding ring technique modulated by an external magnetic field.
• To achieve high strain rate loading with significantly reduced specimen temperature rise.

Main Methods:

• Theoretical analysis, numerical simulations, and experimental validation were employed.
• An external steady-state magnetic field was applied to modulate the electromagnetic driving force.
• The dynamic response of the expanding ring specimen under the influence of the external field was investigated.

Main Results:

• The external magnetic field modulation successfully increased specimen strain rates without increasing induced eddy currents.
• A 5.2 T external magnetic field doubled the strain rate compared to conventional methods.
• Specimen temperature at a strain of 0.1 decreased from 770°C to 240°C, demonstrating effective mitigation of Joule heating.

Conclusions:

• The proposed technique reliably achieves high strain rate loading with low temperature rise.
• This method is effective for investigating the dynamic mechanical behavior of materials.
• The technique offers improved accuracy for materials testing under extreme conditions.