A family of novel compliant linear-motion mechanisms based on compliant rolling-contact element pivot

Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering that COmpliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for applications of heavy load. These mechanisms are achieved by replacing four rigid pivots in a parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, structures of CORE pivot are introduced and five extended arrangements for bearing heavy load are presented. Meanwhile, motion for the CORE pivot is analyzed and preconditions for achieving a pure roll are discussed. Then, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained, and kinematics of the mechanisms is analyzed and parametric design condition for rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations and experiment tests are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.

Experimental research of mass transfer in a stabilized foam layer

The object of research: mass transfer processes on a combined contact element in a column apparatus. Investigated problem: determination of the regularities of process parameters in the processing of gas-liquid systems in a foam layer, as well as to interpret the obtained experimental data. The problem of processing industrial gas flows is solved by conducting the process in an intensive mode. The main scientific results: as a result of the study, the regularities of ammonia absorption were revealed depending on the main parameters of the experiment: gas velocity in the column cross-section, ammonia concentration, free cross-section of the combined contact element, and liquid loads. The process of mass transfer in the gas phase is significantly influenced by hydrodynamic parameters – the gas velocity in the apparatus and the specific load on the liquid, which indirectly affect the height of the liquid layer on the plate and the gas content of the layer. The area of practical use of the research results: sorption processes for processing gases and liquids in technological processes, absorption of harmful substances in the treatment of gas emissions. Innovative technological product: new block poppet-nozzle contact device that operates in a stabilized hydrodynamic mode; new ball-shaped weighted nozzle for three-phase foam layer. Scope of application the innovative technological product: technological processes in the treatment of gas emissions or technological gases.

Simulation of Deformation Transfer Coefficient of Pipe Bend Buried Based on Shaking Table Test and Goodman Contact Element

Due to the large difference of stiffness between pipe and soil, the movement of the two can not be coordinated under seismic. Therefore, the deformation transfer between pipe and soil is a very important research content in the study of pipe failure. At present, scholars have done less research on the pipe-soil deformation transfer of elbow. In this paper, the fitting formula of deformation transfer coefficient of buried elbow under seismic action was obtained by scale shaking table test of pipe bend and 3D finite element model based on Goodman contact element. Then, the test results are compared with the calculation results of the fitting formula and the simulation results of the finite element method to verify the rationality of the fitting formula and analyze the change law of the deformation transfer coefficient at the elbow of the pipe, including the influence of different pipe diameters, buried depth, wall thickness, soil properties, and elbow angles. It is confirmed that these factors have a great influence on the deformation transfer between the pipe and soil, which indicates that the fitting formula of the deformation transfer coefficient at the elbow is of huge significance to the earthquake resisting design of pipe.

A Family of Novel Compliant Linear-Motion Mechanisms Based on Compliant Rolling-Contact Element Pivot

Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering Compliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for heavy load applications. These mechanisms are achieved by replacing four rigid pivots in parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, the CORE pivot is introduced and five extended arrangements for bearing heavy load are given. Meanwhile, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained. In addition, kinematics of the mechanisms is analyzed and parametric design condition for achieving rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.

Mathematical model and characteristics analysis of crossed-axis helical gear drive with small angle based on curve contact element

To improve load capacity and transmission characteristics of crossed-axis helical gear drive, a generation approach of the gear pair with small-angle based on the curve contact element is proposed. Contact principle based on spatial curve meshing relationships is introduced and geometric models of tooth profiles are developed according to a pair of mated conjugate curves. Furthermore, a mathematical model of crossed-axis helical gear drive with small-angle is established. Numerical examples are illustrated for this research using the 10° shaft angle, and the computerized simulation is also developed based on the solid models. According to gear geometry and finite element method, general characteristics including undercutting conditions, sliding ratios and contact stress for tooth profiles are analyzed. Comparisons with crossed-axis involute gears are also carried out. Finally, the gear prototype is processed using the gear milling method and a basic performance test is conducted. Analysis results show that the new gear pair has well contact characteristics. Further studies on the dynamic analysis and precision manufacturing method will be carried out.

Contact element use peculiarities in the numerical model construction of the reinforcing bar force interaction with an anchoring field

The application experience of non-metallic composite materials is quite wide in foreign countries, as well as systematized and assembled into a single database. In Russia, since the necessary computing resources have become more relevant and accessible for design organizations, independent researchers, and graduate students of higher educational institutions, this question resurfaced only in the last decade. As well as benefits, non-metallic composite reinforcement has its disadvantages, which prevent it from wide usage in structures, including a relatively low elastic module, as well as the inability to bend during installation. To improve the reinforced structures with stressed reinforcement calculation and possible prestressing force loss prediction, the finite element model production has been discussed. This model would allow us to evaluate the damaging shear stresses in the reinforcement region. The bracing formation process in the scope of this model was presented in this article, with the purpose of simulation the contact layer stress-strain state between reinforcement and concrete. The calculation is performed in a linear setting. Model development of a T-section decking component reinforced with a composite reinforcement beam produced via LIRA SAPR software. Exert a force on shank ends that is equivalent to the clamping force when the prestressed reinforcement is released. The authors proposed a selection option of the junction stiffness by stem contact with the anchoring field. The stiffness is assumed to be constant along the entire length of the contact layer. Elastic coefficient variation of the contact layer was performed here. The contact layer is highlighted conditionally as a separate material. A model for three types of materials was discussed. The shear stresses patterns in the contact element region were obtained. The patterns of abutting end reinforcement bars motion are obtained. To create a span element with a pre-tensioned reinforcement, a full-scale experiment was performed, as well as reinforcement abatement. Upon abatement, the retraction was recorded. The retraction results of the shank ends were measured, the values of which are comparable to the numerical motion.