No abstract

This paper looks at sizing optimization results, and attempts to show the practical implications of using a novel constraint. Most truss structural optimization problems, which consider sizing in order to minimize weight, do not consider the number of different crosssections that the optimal solution can have. It was observed that all, or almost all, crosssections were different when conducting the sizing optimization. In practice, truss structures have a small, manageable number of different cross-sections. The constraint of the number of different cross-sections, proposed here, drastically increases the complexity of solving the problem. In this paper, the number of different cross-sections is limited, and optimization is done for four different sizing optimization problems. This is done for every number of different cross-section profiles which is smaller than the number of cross-sections in the optimal solution, and for a few numbers greater than that number. All examples are optimized using dynamic constraints for Euler buckling and discrete sets of cross-section variables. Results are compared to the optimal solution without a constrained number of different crosssections and to an optimal model with just a single cross-section for all elements. The results show a small difference between optimal solutions and the optimal solutions with a limited number of different profiles which are more readily applicable in practice.

In this paper the effects of adding buckling constraints to truss

No abstract

The use of continuous variables for cross-sectional dimensions in truss structural optimization gives solutions with a large number of different cross sections with specific dimensions which in practice would be expensive, or impossible to create. Even slight variations from optimal sizes can result in unstable structures which do not meet constraint criteria. This paper shows the influence of the use of discrete cross section sizes in optimization and compares results to continuous variable counterparts. In order to achieve the most practically applicable design solutions, Euler buckling dynamic constraints are added to all models. A typical space truss model from literature, which use continuous variables, is compared to the discrete variable models under the same conditions. The example model is optimized for minimal weight using sizing and all possible combinations of shape and topology optimizations with sizing.

A new generation of planetary speed reducers has a lot of various reducer concepts. One of the new type are cycloid drives. A massive appearance of cycloid drive reducers is related to the second half of the 20 th century. This type of reducers represent a very interesting and attractive mechanical power transmission research field. The main reason for research interest is that cycloid reducers has a large potential in practice usage and they have very similar price related to conventional, planetary and other reducer types.Efficiency analysis of new two-stage cycloid drive concept is presented in this paper. The efficiency is determined based on losses due to friction in the bearing eccentric shaft surface, on the central gear rollers and the output rollers. New two-stage cycloid drive concept efficiency is done for 8 standard power values from 0.25kW to 15kW, with various input RPM and various transmission ratios. In order to evaluate the efficiency of new twostage cycloid drive concept, the comparison with existing solutions in practice has been made. At the end of the paper are given conclusions with possible directions of research continuation.

No abstract

The actual cycloidal speed reducer elements differ from their theoretical ideal due to existing tolerances; therefore, the cycloid disc behaves like a corrected one. This study is oriented towards determining contacts in corrected cycloid speed reducer profiles from the aspect of geometry. Based on this geometry, an objective function was developed for the optimization with some limitations. Heuristic optimization was used to determine the position of the cycloidal drive elements when a contact was established and, consequently, to determine clearances in other places. Some limitations were set so that the model could reflect a real contact. In this study, a TLBO algorithm was used for the optimization of a cycloidal speed reducer. Clearances were analysed for different correction values of the cycloid disc profile of an actual cycloidal drive and the optimization procedure was presented. The results provide a real picture of the contact in the presence of inevitable machining tolerances.