scholarly journals Robot trajectory optimization control of braiding for three-dimensional complex preforms

2021 ◽  
Vol 16 ◽  
pp. 155892502110432
Author(s):  
Xinfu Chi ◽  
Qiyang Li ◽  
Hongxia Yan ◽  
Sun Yize

The quality of composite preform has great influence on its mechanical properties. Aiming at the problems of difficulty in robot teaching and unstable braiding angle in the process of braiding three-dimensional complex component, a control method of robot is proposed. Firstly, the mandrel is discretized to ensure that the axis of each discrete mandrel is perpendicular to the braiding point plane, and the orientation and direction of the tool center are calculated. Then, the take-up speed of the robot is calculated, so that the self-adjustment of the braiding angle can be realized in the braiding process. The experimental results show that the control method can effectively reduce the braiding angle error of variable cross-section mandrel within 2°, and can improve the quality of composite products in actual production.

2015 ◽  
Vol 744-746 ◽  
pp. 821-826 ◽  
Author(s):  
Yi Xiang Fu

The distribution of the temperature gradient and temperature change of the pre-stressed concrete box girder are extremely complicated because of the multiplex environment. Temperature load has attached great importance in the field of engineering, and it has a great influence on the bridge’s structure, especially the box structure. The engineering background of this paper is a typical three-dimensional pre-stressed concrete continuous box girder bridge with variable cross section, comprising five spans in one continuous unit. Experiment on it and research the change rules of the temperature distribution, as well as the influence of the structure’s internal force resulted by temperature. Finite element software-Midas/FEA is used to model and calculate the bridge in order to analyze the temperature influence on structure’s stress in contrast to the measured data from the experiments


2012 ◽  
Vol 9 (1) ◽  
pp. 94-97
Author(s):  
Yu.A. Itkulova

In the present work creeping three-dimensional flows of a viscous liquid in a cylindrical tube and a channel of variable cross-section are studied. A qualitative triangulation of the surface of a cylindrical tube, a smoothed and experimental channel of a variable cross section is constructed. The problem is solved numerically using boundary element method in several modifications for a periodic and non-periodic flows. The obtained numerical results are compared with the analytical solution for the Poiseuille flow.


2014 ◽  
Vol 217-218 ◽  
pp. 201-207
Author(s):  
Chun Fang Wang ◽  
Kai Kun Wang ◽  
Zhe Luo

Flexible thixo-extrusion, as an innovative near-net-shape forming method, has huge advantages in processing the components with complex geometry. However, it should keep in mind that conventional liquid casting still represents the dominant mean of aluminum alloys production. One of the obstacles the thixo-extrusion has to overcome is lack of proof that can live up to the claim that thixo-extruded components have better mechanical properties. The main aim of this paper is to simulate the flexible thixo-extrusion process of aluminum alloy A356 and investigate the control method of materials flow front. An isothermal compression test of aluminum alloy A356 is first conducted to obtain the true stress-strain curves at different temperatures and strain rates. A constitutive equation describing the relationship of stress, strain, strain rate and temperature is fitted by Origin and then imported to the DEFORM-3D simulation software. The results show that the quality of final component is enormously influenced by the radius of the arcs and the flexible thixo-extruded components has less defects compared with the conventional extruded ones.


1997 ◽  
Vol 11 (23) ◽  
pp. 2777-2790 ◽  
Author(s):  
M. Razavy

The problem of a quantum wire connected smoothly on both sides to leads of variable cross section is studied. A method for solving this problem in terms of a set of nonlinear first order matrix differential equations for the variable reflection amplitude is discussed. The reflection coefficient obtained in this way is directly related to the conductivity, and is calculated as a function of the energy of the ballistic electrons. This formulation can be applied to three-dimensional as well as two dimensional quantum wires. For two specific cases the reflection coefficient is obtained as a function of the wave number of the incident electron, and the contribution of quantum tunneling to the transmission in each case is demonstrated. Also a model with a dissipative force is introduced and its effect on the transmission of the electrons is investigated.


2011 ◽  
Vol 103 ◽  
pp. 399-403
Author(s):  
Ying Dao Li ◽  
Wei Hong Zhong ◽  
Hong Wei Guan ◽  
Xiu Shui Ma

Negative pressure is the main control variable in scrap copper smelting process, the control of negative pressure is not only closely related with producing safely, but also produces a direct impact on the quality of the anode plate, it is also a key breakthrough in energy saving. This paper first analyses the characteristics of negative pressure control in scrap copper smelting process, aims to larger overshoot and longer regulation under conventional PID control method, and then utilizes fuzzy control to correct the PID parameters online, to achieve the optimization control of negative pressure. Simulation result shows that the adjustment process of optimized control of negative pressure is steady and rapid, usually no or slightly overshoot, and the settling time is also reduced significantly.


2015 ◽  
Vol 809-810 ◽  
pp. 604-609
Author(s):  
Andrzej Buchacz

Studying the diagrams of characteristics of complex subsystem of mechatronic one it has been determined that in case of approximate method the resonance frequencies cover with those which have been determined with exact method. However the values of the characteristic in other areas are different. Therefore there is the mistake of approximate method, which in case of studying the single systems does not have any influence because in resonance areas the characteristic values of the system approach to the infinity. However the difference in values of flexibility within two methods has the great influence on the result of complex systems. The main subject of deliberation was to determine the flexibility of the complex system with constant cross section using the exact and approximate that means Galerkin's method. The mechanical and/or mechatronic system composed from many mechanical subsystems having the same length and variable cross section, loaded by the focused moment was analysed. One case of attachment the complex system that means free torsional vibrating bar were examined. That why it was necessary to correct the results of approximate method. The problems presented in this paper, that means the analysis of subsystem of mechatronic and mechanical complex systems is however the introduction to the synthesis of torsional vibrating mechatronic systems with assumed frequency spectrum.


1977 ◽  
Vol 99 (2) ◽  
pp. 367-373 ◽  
Author(s):  
B. H. Walker ◽  
M. B. Friedman

A mathematical model of an oil field drill string which includes the effect of torque has been developed. The drill string can include arbitrary members with known mechanical properties. The solution gives the three-dimensional deflection curve, forces on the borehole wall, the magnitude and direction of the resultant force and slope of the deflection curve at the bit.


Author(s):  
А.Н. Синько ◽  
Т.Ю. Никонова ◽  
В.В. Юрченко ◽  
А.К. Матешов ◽  
И.А. Марченко

В статье авторами проведено математическое моделирование процесса точения с использованием волнового воздействия на режущий инструмент. Установлены зависимости между видом образующейся стружки и качеством обработанной поверхности от интенсивности вводимых в зону резания колебаний, а также численные данные параметров режима резания. Авторами установлено, что существует определенный оптимальный уровень колебаний, при котором наблюдается максимальная стойкость инструмента, повышение производительности и улучшение качества обработанной поверхности. Данные зависимости позволяют разработать структурную схему и последовательность проектирования операций с применением вибрационного точения. Для данного процесса авторами установлен оптимальный уровень интенсивности колебаний применительно к инструментам, оснащенным твердым сплавом, при обработке конструкционных и высоколегированных материалов. Практической значимостью работы является получение математических моделей о процессе точения с использованием вибрационного воздействия на режущий инструмент, на основании которых были получены данные и созданы прототипы режущих инструментов для применения в аппаратах вибрационного точения. Основной методикой получения математических данных о вибрационном воздействии на режущий инструмент является обобщение многочисленных экспериментальных данных, а также проведение исследования с помощью программ твердотельного проектирования. В результате исследований получены параметрические уравнения, позволяющие на стадии проектирования прогнозировать и описывать траекторию движения режущей кромки резца при вибрационном воздействии на режущий инструмент. Получены графические схемы траектории перемещения режущей кромки инструмента, демонстрирующие переменное сечение срезаемого слоя при вибрационном воздействии на режущий инструмент. The purpose of this work is to obtain mathematical data about the turning process using vibration effects on the cutting tool. The main method for obtaining mathematical data on the vibration effect on the cutting tool is to generalize numerous experimental data, as well as conducting research using solid-state design programs. In the course of the work, mathematical modeling of the turning process was carried out using the wave effect on the cutting tool. The dependences between the type of chips formed and the quality of the treated surface on the intensity of vibrations introduced into the cutting zone, as well as numerical data on the parameters of the cutting mode, are established. It has been established that there is a certain optimal level of oscillation at which the maximum tool life, increased productivity and improved quality of the treated surface are observed. These dependencies allow you to develop a block diagram and design sequence for the vibration turning operation. For vibration turning, the optimal level of vibration intensity is set for tools equipped with a hard alloy when processing structural and high-alloy materials. The obtained parametric equations make it possible to predict and describe the trajectory of the cutting edge of the cutter at the design stage when the cutting tool is vibrated. Graphic diagrams of the trajectory of the cutting edge of the cutting tool are obtained, showing a variable cross-section of the cut layer under vibration action on the cutting tool. In this work, the regularities of vibration turning during turning are shown. On the basis of which practical data were obtained and prototypes of cutting tools for use in vibration turning devices were created.


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