Resource-constrained scheduling of design changes based on simulation of change propagation process in the complex engineering design

Abstract

When resource constraints are taken into consideration in the deployment of engineering changes, assignments of resources and changes to design entities and selection of change propagation paths make the scheduling problem difficult to solve. Due to complicated dependency relations between engineering entities in the complex engineering design process making it difficult to build an explicit objective function to evaluate different change propagation paths, an integrated simulation and optimization approach is adopted in this research to identify the optimal change scheduling plans for renewable resource-constrained change propagations. First, a digraph model is built to represent the product structure or design process connected with input and output logical relations; second, mathematic formulations of change scheduling problems in two kinds of resource usage schemes are presented; third, a forward-propagate-later-rollback strategy is adopted to develop the resource-constrained change propagation simulation algorithms; fourth, simulation results are used to evaluate individuals in genetic algorithm (GA) during the optimization of propagation likelihood for each involved design dependency. Two case studies are conducted to demonstrate the effectiveness of the models and methods developed in this research. Results for both resource usage schemes are compared, and it can be found that: (1) shorter-duration change propagation plans can be found in the dedicated resource usage scheme than in the flexible scheme; (2) the flexible resource usage scheme can produce a fairer workload allocation between design resources than the dedicated scheme; and (3) the tradeoff between change duration and cost should be determined by design delivery urgency and cost budget in addition to choosing an optimal change propagation plan.