Nonlinear Analysis of Spur Gear Pair with Time-varying Mesh Stiffness T. V. V. L. N. Rao, M. Awang, M. R. Lias and A. M. A. Rani MATEC Web of Conferences, 13 (2014) 04032 Published online: 17 July 2014 DOI: 10.1051/matecconf/20141304032