A new design of a two-stage cycloidal speed reducer is presented in this paper. A traditional two-stage cycloidal speed reducer is obtained by the simple combination of single-stage cycloidal speed reducers. A single-stage reducer engages two identical cycloid discs in order to balance dynamical loads and to obtain uniform load distribution. Consequently, the traditional two-stage reducer has four cycloid discs, in total. The newly designed two-stage cycloidal speed reducer, presented in this paper, has one cycloid disc for each stage, that is, two cycloid discs in total, which means that it is rather compact. Due to its specific concept, this reducer is characterized by good load distribution and dynamic balance, and this is described in the paper. Stress state analysis of cycloidal speed reducer elements was also realized, using the finite elements method (FEM), for the most critical cases of conjugate gear action (one, two, or three pairs of teeth in contact). The results showed that cycloid discs are rather uniformly loaded, justifying the design solution presented here. Experimental analysis of the stress state for cycloid discs was realized, using the strain gauges method. It is easy to conclude, based on the obtained results, that even for the most critical case (one pair of teeth in contact) stresses on cycloid discs are in the allowed limits, thus providing normal functioning of the reducer for its anticipated lifetime.
This paper describes validation process of numerical model of combined collision kinetic energy absorber of rail vehicles based on results of experimental investigations. Combined absorber works on the principle of extrusionsplitting the seamless tube. With the aim to choose the most appropriate tube geometry, the tubes of the different geometry of cross section were made and tested. Key geometry parts have the shape and length of the grooves along the inner tube wall. During the second phase of deformation comes to controlled splitting of the tube wall along these grooves. Experimental and numerical investigations were realized on the scaled samples. Using this type of absorber energy absorption occurs by friction between absorption elements and elastic-plastic deformation of the tube.Combining of two deformation processes gives a higher absorption power as well as compact dimensions of absorber which can be installed in a very limited space in the front part of the vehicle structure. Creating of the numerical model and numerical simulations of extrusion-splitting processes were realized using SolidWorks and ANSYS LS Dyna software packages. Results of experimental investigations and numerical simulations show very good agreement which verifies developed numerical model for use in further investigations in this field.
The problem of internal forces that occur on the cycloid disc during the cycloid speed reducer operation so far has not been considered in a way that reflects its actual workloads and stresses in the cycloid disc itself. This paper presents a dynamic analysis of the stress-strain state of a cycloid disc by using experimental and numerical methods. The following cases of meshing are presented in the paper: a single-tooth, double-tooth, and triple-tooth meshing of the cycloid disc and the ring gear. The cycloid disc was chosen for this study because it is one of the main elements and the most critical element of the cycloid speed reducer. An experimental physical model of the cycloid disc and the meshing elements of the cycloid speed reducer was made based on a previously performed 3D CAD model. The numerical analysis of the stress-strain state of the cycloid disc was performed with the identically defined external load using the transient stress method. The paper presents a comparative analysis of the experimental and numerical results, which gives a solid insight into what is happening in the cycloid disc during the cycloid speed reducer operation. The experimental and simulation results both give the results with a deviation between 3% and 15%. After the detailed analyses, it is shown that the most critical element of cycloid speed reducer are output rollers, which need further study.
The aim of this research work is investigations of absorption characteristics of a circular seamless tube collision absorber filled by rigid polyurethane (PU) foam under axial load. Shrinking of circular tube passing through cone bushing starts after absorber is activated at the moment of collision. The energy absorption realises in three ways: elastic-plastic deformation of the tube wall, friction between absorption elements and compression the rigid PU foam inside the tube. Using rigid PU foam, as the seamless tube filler, in the process of collision energy absorption increases absorption power in comparing to with only empty tube, as well as gives gradual increases of deformation resistance during deformation process. Experimental research was prepared and realized in the laboratory using the scaled samples. The effect of rigid PU foam, configuration of absorber filled by PU foam on the absorption power and manufacturing technology of the samples, are considered and discussed in this paper. The results indicate that the shrinking foam filled tube absorber has for about 18% bigger absorption power than the empty one. Formation of numerical model and numerical analyses of shrinking foam filled tube absorber were realized using ANSYS software package. Force vs. stroke (F(s)) diagrams obtained by tests and numerical analyses are in a good correlation which confirms formed numerical model as a suitable for further quasi-static analyses and for dimensioning the similar types of absorber.
This paper presents comparative experimental and numerical strength analysis of wagon for transporting bulk material according to the TSI standard and norm EN 12663:2000. The aim of this analysis is to show that results of stresses obtained by measuring with strain gauges and stresses obtained by FEM calculation gives good agreement. Based on the results and their good match, it can be concluded that the numerical FEM analysis can be reliably used for structural analysis. According to this fact, FEM analysis can reduce number of the testing new products. This leads to great savings in the design of new prototypes, in order to immediately start the process of mass production. This would lead to significantly less cost of products.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.