TOPOLOGY OPTIMIZATION OF CONTINUUM STRUCTURE WITH GLOBALIZATION OF STRESS CONSTRAINTS BY ICM METHOD

Stress constraints are associated with each element.Therefore,a large number of constraints must be considered;and the sensitivity analyses associated with stress constraints is too expensive to be acceptable.Structure may also be subjected to multiple loading combinations,which increases the number of constraints and computation costs.Based on the von Mises strength theory,overall elements' stress constraints are transformed into a structural energy constraint,namely,a global constraint substituting for many local constraints.ICM method is adopted to formulate and solve the problem of the topology optimization of continuum structure subjected to the global strain energy constraint.The process of optimization is divided into three steps:(a)the maximal structural energy subjected to a weight constraint is minimized to converge to minimum;(b)according to the minimum energy,a formula based on numerical experience is obtained to determine the allowable structural energy under each load combination;(c)an optimization model with the weight function subjected to all allowable structural energies is established and solved to search for the optimum topological structure.The allowable structural energy given by the formula in the second step can handle the cases of large load-differenceor morbid loadings.Several numerical examples show that the path of load transfer can be obtained using the global constraints of stresses,convenient for multiple loading combinations.