Reliability optimization allocation method for multifunction systems based on goal oriented methodology

This paper proposes a new reliability optimization allocation for multifunction systems based on GO methodology. First, two constraints functions are proposed, which are unit reliability constraint function and system reliability constraint function, respectively. The unit reliability constraint function consists of allocated reliability index of unit and the range of reliability index for unit. And the system reliability constraint function consists of the target reliability index of system, and the predicted reliability index of system obtained by using GO method and allocated reliability index of unit. Then, the objective function of optimization allocation problem is established to describe the system cost minimization taking into consideration costs of unit redesigned and unit selected versions. Based on above, the mathematic model of reliability optimization allocation problem for complex multifunction systems is established. In addition, an improved genetic algorithm is presented to solve this mathematic model. Furthermore, the process of the new reliability optimization allocation method for complex multifunction systems is formulated. Finally, the new method is applied in reliability optimization allocation of Power-shift Steering Transmission whose goal is to minimize the system cost. The results analysis shows that the system costs for different operation times turn to a relatively stable value, and the allocated reliability indexes of unit are satisfied with engineering requirements. All in all, this new optimization allocation method can not only obtain the reasonable allocation results quickly and effectively, but it also can overcome the disadvantages of existing reliability optimization allocation methods for complex multifunction systems efficiently. In addition, the analysis process shows that the reliability optimization allocation method based on GO method can provide a new approach for the reliability optimization allocation of multifunction systems.