Research On Regular Nesting Optimization Design Method Of Ship Sheet

Ship sheet nesting deals with sheet parts of different sizes and various shapes,which involves pretty heavy workloads.Proper sheet nesting proposal directly influences economical consumption of production.Therefore,ship sheet nesting optimization design(SSNOD)is conducted for rectangle and right triangle sheet parts to achieve high use ratio of ship sheet.Right triangles can be assembled to rectangles.Thus,SSNOD in this paper is to arrange ship sheet parts of different sizes and various shapes for maximum use ratio under certain constraints.In term of SSNOD,based on researches on relevant rectangle nesting projects and their nesting algorithms,this paper proposes maximum residual rectangle algorithm(MRRA)for rectangle nesting.Based on the frame of MRRA,this paper introduces five different heuristic strategies for nesting guide.Then proper test sample is experimented and the results are satisfying.Because of the incapability of global search of MPPA,based on intelligent algorithms,this paper introduces genetic algorithm(GA).Firstly,the overall algorithm frame of first heuristic search and then genetic algorithm optimization is determined,called MRRA-GA.Then,paraments of genetic algorithm is set.Ten nesting models based on the sample above is tested for both MRRA and MRRA-GA.By comparing these ten models results,MRRA-GA is proved to have better performance by producing nesting proposals with higher use ratios.The efficiency of MRRA-GA is further improved by improving algorithm of GA parts.According to three fundamental process of GA,this paper introduces the niche genetic strategy in selection process and self-adaption genetic strategy in both crossover process and mutation process.By testing the same test models in the above chapter,the improved MRRA-GA shows better global search capability,while maintaining high use ratio of ship sheet.Based on the test results,the improved MRRA-GA proposed in this paper has higher efficiency when dealing with SSNOD.Therefore,it saves lots of labor force on nesting process,in certain degree,and the use ratio of ship sheets is maintained on the high level.