In design theory, optimal problems are formulated in the form of deterministic (clear) models of mathematical programming. It is of interest to consider such tasks of optimal designing of structures, which would take into account the information situation in relation to the initial data, conditions of consolidation, behavior of the environment, goals and other factors of the uncertain nature. For the formulation and solution of such problems, an appropriate mathematical apparatus is needed that would a priori include the possibility of taking into account this situation. The concept of uncertainty is intuitive for every person. However, its formalization causes some difficulties. Simulation of random uncertainty is carried out in the boundaries of probability theory. Here a priori are assumed to be known and reliable functions of distribution and density of random variables, their numerical characteristics. This information is obtained on the basis of processing a large statistical sample. For a long time it was believed that all the necessary work for uncertainty gives the theory of probabilities. But over time, due to a change in human perception of the environment, the adequacy of this approach began to cause doubts. In this paper we consider the problems of optimal design of a hinge-rod system, which is imposed a restriction on rigidity, strength and stability under conditions of fuzzy and fuzzy-random information. The application of one of the modern methods of "soft" computing - the theory of fuzzy sets to problems of weight optimization is shown. The implementation of the problem is accomplished using the method of dynamic programming. The algorithm of implementation of the set optimization models is developed. The stages of fuzzy simulation are formulated and described: fuzzification, optimization and analysis, defuzzification. The analysis of the choice of load safety factor coefficient is carried out using the proposed methodology. The results of the influence of the form and character of the membership function in the case of fuzzy data information about Young's modulus on optimal solutions are given. According to the defuzzificated volume of hinge-rod system we can propose corresponding determined Young's modulus as recommendation. Numerical examples for various load combinations are given and results of all numerical experiments show how the mechanical system reacts to the inaccurate description of the given load. The problem of designing, when the information of the load is uncertain as the fuzzy-random description is presented.