Investigation of strain sensing properties of polyester/magnetite composite materials

摘要

The aim of this work is to investigate the strain sensing properties of polyester/magnetite composite materials of different contents 5, 10, 15, 20% w/w. Specifically, we manufactured magnetic composite materials with a polyester matrix (thermosetting polymer) and nanoparticles of magnetite (Fe_3O_4) as additives, processed by "molding technique". For these composites we used two different magnetite powders of grain sizes a) 20-30nm (premade from Alfa Aesar) and b) ＜1 urn (powder made by the co-precipitation method in our laboratory). The specimens were subjected into tensile stress in order to observe the alternation of "Reluctance" induced by strain. The sensing probe is consisted of an electromagnet and a Hall sensor (magnetic flux density sensor). The electromagnet's coil is supplied by direct current (DC) causing magnetic flux to circulate the core of the specimen. The results from the tensile stress experiments show that the magnetic flux density B decreases analogous to the Strain.