influence of element order in various aspect of evolutionary structural optimization

in recent year, the evolutionary structural optimization (eso) method, has been applied as an effective tool for structures design. the concept of eso method is to use the finite element  results in each iteration of process and removal of inefficient material based on these results. in this method there are several experimental parameters such as rejection rate and evolutionary rate that are effective in results. this paper studies the influence of elements according to orders and in this regard has been applied eight node element and in addition to that it compares whit four node element results, is investigated influence in stress value, volume reduction, other parameters such as evolutionary rate and rejection rate. the results show that some parameters for low order elements are not suitable in high order elements problems and there for, has represented adequate value parameters. several examples are provided whit various boundary condition.