In order to avoid stress concentration,the shape boundary must be properly designed via shape optimization.Traditional shape optimization approach eliminates the stress concentration effect by using free-form curve to present the design boundaries without taking the machinability into consideration.In most numerical control(NC)machines,linear as well as circular interpolations are used to generate the tool path.Non-circular curves,such as nonuniform rotational B-spline(NURBS),need other more advanced interpolation functions to formulate the tool path Forming the circular tool path by approximating the optimal free curve boundary with arcs or biarcs is another option.However,these two approaches are both at a cost of sharp expansion of program code and long machining time consequently.Motivated by the success of recent researches on biarcs,a reliable shape optimization approach is proposed in this work to directly optimize the shape boundaries with biarcs while the efficiency and precision of traditional method are preserved.Finally,the approach is validated by several illustrative examples.
