Reliability Optimization Design On Axle Gearbox Of A New Repairing Vehicle For Overhead Contact Line Equipment

An axle gearbox of a new repairing vehicle for overhead contact line equipment isdesigned in this thesis. To ensure good performance, low cost and high reliability, a newdesign method combining reliability design and optimization design, reliability optimizationdesign method is used. It can make up the defect that optimization design cannot reflect thetrue operating conditions, and solve the problem reliability design is often not the optimalsolution.Due to the expected reliability will affect the feasible region size of optimal solution, itshould be carefully designed based on system performance and cost, which is quite difficult inthe actual project. In order to avoid that the lack of experience causes the improper value,bi-objective reliability optimization model, that is, using reliability as both constraints andobjective function, and taking the minimum volume of gearbox as an objective function, isselected in the thesis. Compared with the optimal solutions with reliability optimizationmodels using reliability as constraints and as objective function, respectively, it is verifiedthat the selected model can reflect the design concept of the axle gearbox better, that is,reliability as high as possible with high performance and low cost.The key elements affecting reliability and volume of axle gearbox are the gears. So whenthe reliability optimization mathematical model is created in this thesis, the reliability andvolume of gears are used as the objective function, that of instead of the gearbox. And thegear parameters are taken as the design variables. The constraint conditions include boundaryconditions and reliability constraints. To simplify the calculation, the bi-objective function istreated as a single-objective function by introducing weight coefficients. The establishedmathematical model is a nonlinear constrained minimization problem of multivariate function.To solve it, sequential quadratic programming algorithm is better than the penalty functionmethod. This algorithm can converge fast, and be efficient and reliable. In addition, theprogramming can be simple by calling fmincon function directly in MATLAB.The design is completed following4steps. First, according to the design requirements,complete the preliminary design of the axle gearbox, and finish its three-dimensionalmodeling and simulation based on SolidWorks2013. Secondly, verify that the design meetsthe requirements, complete the traditional design of the gearbox by checking the strength andreliability. Then, carry out the reliability optimization design by taking the gearbox oftraditional design as the initial value, and modify traditional design with optimal solution toobtain the optimal design of the axle gearbox. Finally, finish reliability analysis of theoptimized axle gearbox and modal analysis of the box, calculate the input speed whenresonance occurs, for avoiding the speed to reduce noise and improve life of gearbox. The comparison shows that: the gearbox volume designed by reliability optimizationmethod is reduced9.13%than by traditional method, reliability is improved2.2171%withinone year of the life cycle. This indicates that the traditional design is too conservative and thevalue of each parameter is not optimal. Therefore, it is necessary to design the axle gearboxwith reliability optimization method.