The simulated annealing algorithm is become one of the important tools for solving complex nonlinear optimization problems

because of its parallelism

be suitable for parallel and solving complex nonlinear optimization problems and global search ability.Considering contact strength

bending strength and boundary constraints

the optimizationmodel of automobile planetary transmission is set up which is to minimize the volume and weight of final drive.The objective function with penalty terms is built by penalty strategy with addition type

so as to transform the constrained optimization into the unconstrained optimization.Then the simulated annealing algorithm based on penalty strategy is adopted to optimize final drive of vehicle.Using the global search ability of simulated annealing algorithmto conduct heuristic search and parallel computing

its search efficiency and accuracy are very high

so that the global optimal solution is ensured reliably.