Feed direction dependent milling dynamics of an asymmetric flexible machining system

2021 ◽  
pp. 1-13
Author(s):  
Xing Zhang ◽  
Kunhong Chen ◽  
Zengguang Wang ◽  
Wanhua Zhao
Keyword(s):  
High Performance ◽  
Machining Accuracy ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Vibration Displacement ◽  
Feed Direction ◽  
Machining System ◽  
General Dynamics ◽  
Dynamics Response ◽  
Milling Dynamics

Abstract Asymmetric flexible machining system has been widely used in NC machining. In traditional milling dynamics model, the cutter feed direction is usually defined as parallel to its vibration DOF, while the nonparallel condition and its induced milling dynamics response are not deeply considered. This paper presents a general dynamics modeling method for asymmetric flexible machining systems. Firstly, to the best of the author's knowledge, a new dimension named feed direction is proposed, which is used to establish the generalized coupling relationship between the vibration displacement and the regenerative milling force, thus improve the applicability of the milling dynamics model and reduce the experimental workload compared with the traditional modeling. Secondly, through the theoretical and experimental research, it is shown that the asymmetric flexible machining system has a significant feed direction dependent characteristics, and implied the existence of high performance machining region with higher stability and low SLE by contrast with the symmetrical milling system and the traditional model. Finally, by controlling the feed direction angle, the milling parameters in roughing and finishing operation are optimized, and the machining efficiency has been greatly improved on the premise of stable cutting and machining accuracy at last.

Molecular Dynamics Modeling the Nano-Identation of Titanium

2021 ◽  
Author(s):  
Peiqiang Yang ◽  
Xueping Zhang ◽  
Zhenqiang Yao ◽  
Rajiv Shivpuri
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Titanium Alloys ◽  
Large Scale ◽  
Mechanical Response ◽  
Pure Titanium ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Nano Indentation ◽  
Molecular Dynamics Modeling

Abstract Titanium alloys’ excellent mechanical and physical properties make it the most popular material widely used in aerospace, medical, nuclear and other significant industries. The study of titanium alloys mainly focused on the macroscopic mechanical mechanism. However, very few researches addressed the nanostructure of titanium alloys and its mechanical response in Nano-machining due to the difficulty to perform and characterize nano-machining experiment. Compared with nano-machining, nano-indentation is easier to characterize the microscopic plasticity of titanium alloys. This research presents a nano-indentation molecular dynamics model in titanium to address its microstructure alteration, plastic deformation and other mechanical response at the atomistic scale. Based on the molecular dynamics model, a complete nano-indentation cycle, including the loading and unloading stages, is performed by applying Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The plastic deformation mechanism of nano-indentation of titanium with a rigid diamond ball tip was studied under different indentation velocities. At the same time, the influence of different environment temperatures on the nano-plastic deformation of titanium is analyzed under the condition of constant indentation velocity. The simulation results show that the Young’s modulus of pure titanium calculated based on nano-indentation is about 110GPa, which is very close to the experimental results. The results also show that the mechanical behavior of titanium can be divided into three stages: elastic stage, yield stage and plastic stage during the nano-indentation process. In addition, indentation speed has influence on phase transitions and nucleation of dislocations in the range of 0.1–1.0 Å/ps.

scholarly journals Estimation of Super High-Rise Pumping Pressure for High-Performance Concrete Based on Computational Fluid Dynamics Modeling and Situation Measurement

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Weijiu Cui ◽  
Chuankai Zhao ◽  
Sheng Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Calculation Method ◽  
Pressure Loss ◽  
High Performance ◽  
High Performance Concrete ◽  
Accurate Method ◽  
Dynamics Modeling ◽  
High Rise ◽  
Pipe Line

Traditional methods fail to predict the pumping pressure loss of high-performance concrete properly in super high-rise pumping situations due to complex changes of concrete properties. Therefore, it is imperative to propose a relative accurate method for pumping pressure estimation in super high-rise buildings. This paper builds the simplified pressure calculation method “pressure induced by the gravity plus pressure along the pipe line.” The later one is gained by establishing topology optimized model based on computational fluid dynamics and considering the lubrication layer formation. The effect of rheological properties and flow rate is analyzed based on this model in detail. Furthermore, the developed calculation method is verified by the measured pumping pressure during the super high-rise building construction of the Shanghai Tower (the tallest building in China recently). The relative differences between the calculation results and the measured data in situ are less than 6%, indicating the applicability of this method for predicting the pressure loss of the super high-rise pumping.

Analyses of Full-Scale Tank Car Shell Impact Tests

2007 ◽  
Author(s):  
Y. H. Tang ◽  
H. Yu ◽  
J. E. Gordon ◽  
M. Priante ◽  
D. Y. Jeong ◽  
...  
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Three Dimensional ◽  
Full Scale ◽  
Collision Dynamics ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Closed Form Solutions

This paper describes analyses of a railroad tank car impacted at its side by a ram car with a rigid punch. This generalized collision, referred to as a shell impact, is examined using nonlinear (i.e., elastic-plastic) finite element analysis (FEA) and three-dimensional (3-D) collision dynamics modeling. Moreover, the analysis results are compared to full-scale test data to validate the models. Commercial software packages are used to carry out the nonlinear FEA (ABAQUS and LS-DYNA) and the 3-D collision dynamics analysis (ADAMS). Model results from the two finite element codes are compared to verify the analysis methodology. Results from static, nonlinear FEA are compared to closed-form solutions based on rigid-plastic collapse for additional verification of the analysis. Results from dynamic, nonlinear FEA are compared to data obtained from full-scale tests to validate the analysis. The collision dynamics model is calibrated using test data. While the nonlinear FEA requires high computational times, the collision dynamics model calculates gross behavior of the colliding cars in times that are several orders of magnitude less than the FEA models.

Effect of Self-Interstitial Diffusion Anisotropy in Electron-Irradiated Zirconium. A Cluster Dynamics Modeling

2005 ◽  
Vol 237-240 ◽  
pp. 659-664
Author(s):  
Frédéric Christien ◽  
Alain Barbu
Keyword(s):  
Point Defects ◽  
Thin Foil ◽  
Elastic Interaction ◽  
Dislocation Loops ◽  
Considerable Influence ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Diffusion Anisotropy ◽  
Vacancy Loops ◽  
Transmission Electron

Irradiation of metals leads to the formation of point-defects (vacancies and selfinterstitials) that usually agglomerate in the form of dislocation loops. Due to the elastic interaction between SIA (self-interstitial atoms) and dislocations, the loops absorb in most cases more SIA than vacancies. That is why the loops observed by transmission electron microscopy are almost always interstitial in nature. Nevertheless, vacancy loops have been observed in zirconium following electron or neutron irradiation (see for example [1]). Some authors proposed that this unexpected behavior could be accounted for by SIA diffusion anisotropy [2]. Following the approach proposed by Woo [2], the cluster dynamics model presented in [3] that describes point defect agglomeration was extended to the case where SIA diffusion is anisotropic. The model was then applied to the loop microstructure evolution of a zirconium thin foil irradiated with electrons in a high-voltage microscope. The main result is that, due to anisotropic SIA diffusion, the crystallographic orientation of the foil has considerable influence on the nature (vacancy or interstitial) of the loops that form during irradiation.

Systems dynamics model of a transition firm

2005 ◽  
Vol 31 (3) ◽  
pp. 67-80
Author(s):  
David L. Olson ◽  
Paraskeva Dimitrova‐Davidova ◽  
Ivan Stoykov
Keyword(s):  
System Dynamics ◽  
Multiple Criteria ◽  
Dynamics Simulation ◽  
Economic Systems ◽  
Eastern European ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Pedagogical Tool ◽  
Modeling Process ◽  
Eastern European Countries

Eastern European countries are undergoing a transition from centralized economic planning to more open economic systems. A team of Bulgarian and U.S. researchers have collaborated to study this problem, using a real Bulgarian winery as the focus of their research. System dynamics modeling was selected as a tool to provide better understanding of management issues. A framework for future objective research, and as a pedagogical tool. This system dynamics model generates output on a number of measures. This paper presents initial output from the model, reporting profit ability, risk, and market share measures. These multiple measures create the need for multiple criteria analysis. Three multiple criteria techniques are demonstrated, and their value in the system dynamics simulation modeling process is discussed.

Robustness and Controllability Analysis for Autonomous Navigation of Two-Wheeled Mobile Robots

2007 ◽  
Author(s):  
Alessio Salerno ◽  
Jorge Angeles
Keyword(s):  
Mobile Robots ◽  
Autonomous Navigation ◽  
Autonomous Robots ◽  
Upper Bounds ◽  
Small Time ◽  
Dynamics Model ◽  
Wheeled Mobile Robots ◽  
Rank Condition ◽  
Dynamics Response ◽  
Kalman Rank Condition

This work deals with the robustness and controllability analysis for autonomous navigation of two-wheeled mobile robots. The analysis of controllability of the systems at hand is conducted using both the Kalman rank condition for controllability and the Lie Algebra rank condition. We show that the robots targeted in this work can be controlled using a model for autonomous navigation by means of their dynamics model: kinematics will not be sufficient to completely control these underactuated systems. After having proven that these autonomous robots are small-time locally controllable from every equilibrium point and locally accessible from the remaining points, the uncertainty is modeled resorting to a multiplicative approach. The dynamics response of these robots is analyzed in the frequency domain. Upper bounds for the complex uncertainty are established.

Dynamics modeling and analysis of a four-wheel independent motor-drive virtual-track train

2020 ◽  
pp. 146441932096401
Author(s):  
Zhonghui Yin ◽  
Jiye Zhang ◽  
Haiying Lu ◽  
Weihua Zhang
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Spatial Dynamics ◽  
Dynamic Responses ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Coupling Effects ◽  
Dynamic Interactions ◽  
Modeling And Analysis

Due to urbanisation and the economic challenges of traffic, it is urgently necessary to develop an environmentally friendly virtual-track train with suitable speed, high load capacity and low construction cost in China. To guide the design and evaluate this train’s dynamic behaviour, a spatial-dynamics model has been developed based on the dynamics theory and tyre-road interaction. The proposed dynamics model comprises mechanical vehicle systems, traction and braking characteristics and tyre-road dynamic interactions. The coupling effects amongst those systems of virtual track train are derived theoretically for the first time. The nonlinear characteristics of the tyre are modelled by the transit tyre-magic formula with consideration of road irregularities. Based on a designed PID controller and the comprehensive dynamics model, the dynamic performance of the system can be revealed considering motion coupling effects and complicated excitations, especially under traction and braking conditions. The dynamic responses of whole virtual track train can be obtained by numerical integration under different conditions. The vibration characteristics of such train are assessed under running at a constant speed and during the traction/braking process. The results show that the vibrations of the vehicle system are significantly influenced by road irregularities, especially at high speed ranges. The motions and vibrations of different components are intensive coupled, which should not to be neglected in the dynamics assessment of the virtual track train. Besides, the dynamics model can also be applied to dynamics-related assessment (fatigue, strength and some damage conditions, et al.) and parameter optimisation of the virtual-track train.

Design and its Experiments of Micro Electrochemical Machining System

2010 ◽  
Vol 97-101 ◽  
pp. 2505-2508 ◽  
Author(s):  
Yuan Bo Li ◽  
Yong Jun Zhang ◽  
Zhong Ning Guo
Keyword(s):  
High Resolution ◽  
Power Supply ◽  
Pulse Width ◽  
Short Pulse ◽  
Electrochemical Machining ◽  
Pulse Frequency ◽  
Machining Accuracy ◽  
Micro Ecm ◽  
Machining System ◽  
Short Pulse Width

A micro Electrochemical Machining (ECM) system has been developed, and macro/micro complex feed mechanism has been presented in order to achieve high-resolution. A nanosecond pulse power supply for micro-ECM has been developed, and the minimum pulse width can reach 50 ns. Complementary chopper circuit has been designed to avoid waveform distortion, which can achieve higher pulse frequency. A series of ECM experiments using the machining system have been carried out, and results of tests have proved that high-resolution spindle, and high frequency, short pulse width power supply help to achieve better quality surface, higher machining accuracy.

Synchronous Adjustment of Milling Tool Path Based on the Relative Deviation

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Xiao-Jin Wan ◽  
Cai-Hua Xiong ◽  
Lin Hua
Keyword(s):  
Tool Path ◽  
Cutting Tool ◽  
Cnc Machining ◽  
Numerical Control ◽  
Machining Process ◽  
Machining Accuracy ◽  
Source File ◽  
Modern Computer ◽  
Adjustment Strategy ◽  
Machining System

In machining process, machining accuracy of part mainly depends on the position and orientation of the cutting tool with respect to the workpiece which is influenced by errors of machine tools and cutter-workpiece-fixture system. A systematic modeling method is presented to integrate the two types of error sources into the deviation of the cutting tool relative to the workpiece which determines the accuracy of the machining system. For the purpose of minimizing the machining error, an adjustment strategy of tool path is proposed on the basis of the generation principle of the cutter location source file (CLSF) in modern computer aided manufacturing (CAM) system by means of the prediction deviation, namely, the deviation of the cutting tool relative to the workpiece in computer numerical control (CNC) machining operation. The resulting errors are introduced as adjustment values to adjust the nominal tool path points from cutter location source file from commercial CAM system prior to machining. Finally, this paper demonstrates the effectiveness of the prediction model and the adjustment technique by two study cases.

The Research on General Modeling Methods of the Complicated Transmission Based on Hypergraph Theory

2011 ◽  
Vol 86 ◽  
pp. 704-708 ◽  
Author(s):  
Chang Le Xiang ◽  
Ying Ying Zhang ◽  
Hui Liu ◽  
Meng Cui
Keyword(s):  
Planetary Gear ◽  
Automatic Generation ◽  
Gear Transmission ◽  
Dynamics Model ◽  
Modeling Methods ◽  
General Dynamics ◽  
Fixed Axis ◽  
Hypergraph Theory ◽  
Complex Transmission ◽  
Conversion Rules

In order to be adapt to the increasingly large complex transmission modeling, this paper propose methods of building generalized modeling through applying hypergraph theory to the complex fixed axis transmission, the planetary gear transmission and the integrated transmission. The author established conversion rules between the real transmission to hypergraph, and found feasibility algorithm for relay route auto search. Hypergraph theory can be further used to realize automatic generation of general dynamics model.

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