Comparison of three methods for measuring the bending stiffness of ultrafine metal wires

Abstract

Ultrafine metal wires have been widely used as structural constituents of metal meshes for electromagnetic interference shielding. To investigate the bending property of metal wires during the knitting process, the three-point bending, cantilever bending, and pure horizontal bending methods were carried out and compared. The relationships among the bending property, the twist pitch and the number of twisted wire strings were also analyzed. The specific dependence of the bending stiffness on twist pitch resulted from the internal frictional constraints, and a twist pitch of 4.5 mm was chosen as the optimized twisted parameter. The bending properties evaluated by the three methods were equally sensitive to the twist pitch, and a similar linear trend of bending stiffness with the number of twisted wire strings was found. The values of bending stiffness from the three methods were significantly different, and the descending order was the three-point bending, the cantilever bending, and the pure horizontal bending method. The correlation coefficient of the three methods was higher than 0.935, which is a strong positive correlation. From the investigation came a conclusion that the three-point bending method is more useful in realistic conditions because of its diversity and universality for various bending deformations.