The treatment of mechanical design as a constraint management problem has long been related to equality constraints. Work involving inequality constraints has been generally restricted to optimization and symbolic computation. This paper presents a methodology for handling inequality constraints in an interactive mechanical design process. The presented method is similar to the basis interchange algorithm used in the Generalized Reduced Gradient (GRG) method for constrained nonlinear optimization. The main difference is that our method relies on user guidance to select which specification has to be changed in order to satisfy the violated inequality constraint. Also, the specification is only adjusted; unlike the procedure in the GRG method where the basis is changed. An inequality constraint violation is detected whenever the corresponding slack variable becomes negative. An occurrence-matrix formulation is used to represent both the equality and inequality constraints that govern the design. The work is illustrated for the classical weldment design problem.

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