Nondestructive Evaluation of Tensile Stress-loaded GFRPs Using the Magnetic Recording Method

Area of Science:

• Materials Science and Engineering
• Non-Destructive Testing
• Composite Materials

Background:

• The Magnetic Recording Method (MRM) is traditionally limited to ferromagnetic materials.
• Inspecting non-magnetic composites like glass fiber-reinforced polymer (GFRP) under stress requires adapted NDT techniques.
• Existing methods may lack the precision needed for accurate load assessment in composite structures.

Purpose of the Study:

• To adapt the Magnetic Recording Method (MRM) for evaluating tensile stress in non-magnetic GFRP composites.
• To assess the feasibility and accuracy of the modified MRM for non-destructive stress monitoring.
• To establish a quantitative relationship between applied load and magnetic pattern changes in GFRP.

Main Methods:

• A modified MRM involved bonding ferromagnetic steel strips (DC01) to GFRP samples using epoxy adhesive.
• A sinusoidal magnetic pattern was imprinted onto the steel strips using an array of permanent magnets.
• Residual magnetization was measured before and after applying static tensile stress, with statistical analysis of RMS values.

Main Results:

• Applied tensile stress induced measurable changes in the amplitude of the sinusoidal magnetization pattern.
• Frequency variations were minimal and not used for evaluation in GFRP samples.
• Statistical analysis of RMS values provided unequivocal and exact information on the applied load for strains up to 0.6%.

Conclusions:

• The modified MRM is a feasible and accurate technique for monitoring tensile stress in non-magnetic GFRP composites.
• The method offers a reliable way to assess applied load non-destructively.
• This adaptation expands the application of MRM to a broader range of composite materials.