Flexible strain sensor based on a frequency selective surface.

Area of Science:

• Electromagnetics
• Materials Science
• Mechanical Engineering

Background:

• Frequency Selective Surfaces (FSSs) are advanced artificial materials with significant potential in various engineering fields due to their precise frequency selection capabilities.
• Existing methods for strain detection may lack the conformability and real-time monitoring required for complex structures.

Purpose of the Study:

• To develop and validate a flexible strain sensor based on FSS reflection characteristics for real-time strain monitoring.
• To investigate the correlation between FSS structural changes, frequency shifts, and mechanical deformation.

Main Methods:

• Design of an FSS sensor operating at 31.4 GHz with -35 dB amplitude and a quality factor of 16.2.
• Application of the sensor for strain detection on a rocket engine case using static and electromagnetic simulations.
• Experimental validation through uniaxial tensile testing of the FSS sensor.

Main Results:

• The FSS sensor exhibited a frequency shift of approximately 200 MHz for a 1.64% radial expansion of the engine case.
• A clear linear relationship was observed between frequency shift and deformation under various loads.
• Experimental tests showed a sensor sensitivity of 1.28 GHz/mm during uniaxial stretching.

Conclusions:

• The developed FSS strain sensor possesses high sensitivity, strong mechanical properties, and a linear response, confirming its practical applicability.
• The FSS sensor technology offers a promising avenue for accurate, real-time strain detection in demanding engineering environments.