Experimental fabrication and nondestructive testing of carbon fiber beams for delaminations using embedded Terfenol-D particles

The experimental results for damage sensing using embedded magnetostrictive particles as sensors in carbon fiber–reinforced polymer laminates are presented. Laminates constructed of varying counts of pre-impregnated plies (Hexcel AS4/3501-6) are embedded with Terfenol-D particles and a delamination to observe changes in the sensing signal in and around the damage region. The testing apparatus consists of a primary circuit to generate a magnetic flux excitation and a secondary circuit to sense voltage induced into a pickup coil. In addition, three groups of test results were generated to observe the effect of fabrication on sensing. The experimental results from the three groups reveal that the particle distribution has a significant effect on the sensing signal. The sensing signal is dominated by changes in local particle distribution, and the effect of the delamination and ply variation did not have a discernible effect on the sensing signal for this setup.