scholarly journals Towards the design of monolithic decoupled XYZ compliant parallel mechanisms for multi-function applications

2013 ◽  
Vol 4 (2) ◽  
pp. 291-302 ◽  
Author(s):  
G. Hao
Keyword(s):  
Natural Frequency ◽  
Dynamic Modelling ◽  
Performance Characteristics ◽  
Geometrical Parameters ◽  
Parallel Mechanisms ◽  
Redundant Design ◽  
Acceleration Sensors ◽  
Characteristics Analysis ◽  
Motion Range ◽  
Energy Harvesting Devices

Abstract. This paper deals with the monolithic decoupled XYZ compliant parallel mechanisms (CPMs) for multi-function applications, which can be fabricated monolithically without assembly and has the capability of kinetostatic decoupling. At first, the conceptual design of monolithic decoupled XYZ CPMs is presented using identical spatial compliant multi-beam modules based on a decoupled 3-PPPR parallel kinematic mechanism. Three types of applications: motion/positioning stages, force/acceleration sensors and energy harvesting devices are described in principle. The kinetostatic and dynamic modelling is then conducted to capture the displacements of any stage under loads acting at any stage and the natural frequency with the comparisons with FEA results. Finally, performance characteristics analysis for motion stage applications is detailed investigated to show how the change of the geometrical parameters can affect the performance characteristics, which provides initial optimal estimations. Results show that the smaller thickness of beams and larger dimension of cubic stages can improve the performance characteristics excluding natural frequency under allowable conditions. In order to improve the natural frequency characteristic, a monolithic decoupled configuration that is achieved through employing more beams in the spatial modules or reducing the mass of each cubic stage mass can be adopted. In addition, an isotropic variation with different motion range along each axis and same payload in each leg is proposed. The redundant design for monolithic fabrication is introduced in this paper, which can overcome the drawback of monolithic fabrication that the failed compliant beam is difficult to replace, and extend the CPM's life.

Modeling Heat and Mass Transfer Correlations for Flow Through Micro Channels in Monolith Honeycomb Catalytic Combustor

2009 ◽  
Author(s):  
Juan Yin ◽  
Yi-wu Weng
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Catalytic Combustion ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Predicting Performance ◽  
Micro Channels ◽  
Characteristics Analysis ◽  
Flow Through ◽  
Catalytic Combustor

This paper investigated performance characteristics analysis of catalytic combustion by utilizing 1-D models incorporated heat and mass transfer correlations. The 1-D numerical results were compared with 2-D models studies and experimental data. The performance characteristics were mainly the effects of operating conditions on methane conversion rate. The comparable analysis confirmed that 1-D model can success in predicting performance of catalytic combustion when empiric inter-phase heat and mass transfer correlations are used and appropriate operating conditions are chosen.

On the Optimum Groove Geometry for Herringbone Grooved Journal Bearings

2006 ◽  
Vol 128 (3) ◽  
pp. 585-593 ◽  
Author(s):  
A. M. Gad ◽  
M. M. Nemat-Alla ◽  
A. A. Khalil ◽  
A. M. Nasr
Keyword(s):  
Groove Depth ◽  
Radial Force ◽  
Journal Bearings ◽  
Friction Torque ◽  
Performance Characteristics ◽  
Width Ratio ◽  
Geometrical Parameters ◽  
Thrust Bearings ◽  
Circular Groove ◽  
Groove Profile

Recently, herringbone-grooved journal bearings have had important applications in miniature rotating machines. The scribed grooves, on either the rotating or stationary member of the bearing, can pump the lubricant inward, which generates supporting stiffness and improves the dynamic stability, especially for concentric operation. Most of the previous investigations that dealt with herringbone grooved journal bearings and grooved thrust bearings were theoretical. Few experimental attempts for the investigation of the performance characteristics of herringbone grooved journal bearings (HGJBs) and grooved thrust bearings have been done. All these investigations concentrated on rectangular and circular groove profiles of HGJBs. In order to improve the performance characteristics of HGJBs, a new design of the groove profile, the beveled-step groove profile, is introduced. The introduced groove profile is capable of increasing the pressure recovery at the divergence of the flow over the step. In addition, it increases the amount of oil pumped inward over the circular groove profile. Optimization processes were carried out experimentally, in order to obtain the optimal geometry of the introduced groove profile. The optimum geometrical parameters of the groove (groove angle α, groove width ratio β, and groove depth ratio Γ) are 29deg, 0.5, and 2.0, respectively, which give maximum radial force and maximum radial stiffness of the beveled-step HGJB. In order to check the effectiveness of the introduced beveled-step groove profile, the obtained results were compared with that for rectangular groove profile. The comparison shows that the introduced beveled-step HGJBs have higher radial force, higher load carrying capacity, and lower friction torque than the rectangular HGJBs.

Frequency Characteristics Analysis of Micro-Displacement Structure with Parallel Flexure Hinges

2016 ◽  
Vol 693 ◽  
pp. 141-145
Author(s):  
Jie Qiong Lin ◽  
Ming Ming Lu ◽  
Xiao Qin Zhou ◽  
Qiang Liu
Keyword(s):  
Natural Frequency ◽  
Structure Design ◽  
Frequency Characteristics ◽  
Test Results ◽  
Structure Parameter ◽  
Dynamics Modeling ◽  
Displacement Structure ◽  
Flexure Hinges ◽  
Modeling Analysis ◽  
Characteristics Analysis

Flexure hinges based micro-displacement structure has been widely used for micro-precision machinery, and the natural frequency characteristics analysis is one of the most important elements in the structure design. In this paper, natural frequency characteristics analysis of a micro-displacement structure with parallel flexible hinges is presented. The effects of each structure parameter to the natural frequency of the micro-displacement structure are simulation by dynamics modeling. The parameters can be divided into three categories, namely, parallel flexure hinges parameter, micro-displacement structure parameter and material parameter. Two micro-displacement structures using common materials are machined for frequency test. The test results of two micro-displacement structure verified the modeling analysis, and the natural frequency characteristics analysis in this paper can be referenced in micro-displacement structure design.

Characteristics Analysis of the Automobile with Negative Stiffness Suspension

2013 ◽  
Vol 456 ◽  
pp. 189-192 ◽  
Author(s):  
Xiao Zhen Qu ◽  
Guang Quan Hou ◽  
Hao Liu ◽  
Hui He
Keyword(s):  
Natural Frequency ◽  
Ride Comfort ◽  
Vertical Direction ◽  
Negative Stiffness ◽  
Vehicle Model ◽  
Vehicle Handling ◽  
Characteristics Analysis ◽  
Vibration Transmissibility ◽  
Simulation Results

One new negative stiffness suspension is introduced in this paper. The vehicle with negative stiffness suspension has good ride comfort and handling stability. The natural frequency of system could be reduced in vertical direction by applying negative stiffness suspension. The vehicle model with negative stiffness suspension or not is built in ADAMS. The comparison of simulation results show that the vehicle with negative stiffness suspension could reduce the natural frequency of system and vibration transmissibility, and also improve the vehicle ride comfort and vehicle handling stability.

Optimal Design of the Three-Degree-of-Freedom Parallel Manipulator in a Spray-Painting Equipment

Robotica ◽  
2019 ◽  
Vol 38 (6) ◽  
pp. 1064-1081
Author(s):  
Guang Yu ◽  
Jun Wu ◽  
Liping Wang ◽  
Ying Gao
Keyword(s):  
Optimal Design ◽  
Parallel Manipulator ◽  
Optimization Design ◽  
Virtual Work ◽  
Kinematic Model ◽  
Geometrical Parameters ◽  
Parallel Mechanisms ◽  
Spray Painting ◽  
Conditioning Performance ◽  
Accuracy Performance

SUMMARYSpray-painting equipments are important for the automatic spraying of long conical objects such as rocket fairing. This paper proposes a spray-painting equipment that consists of a feed worktable, a gantry frame and two serial–parallel mechanisms and investigates the optimal design of PRR–PRR parallel manipulator in serial–parallel mechanisms. Based on the kinematic model of the parallel manipulator, the conditioning performance, workspace and accuracy performance indices are defined. The dynamic model is derived using virtual work principle and dynamic evaluation index is defined. The conditioning performance, workspace, accuracy performance and dynamic performance are involved in multi-objective optimization design to determine the optimal geometrical parameters of the parallel manipulator. Furthermore, the geometrical parameters of the gantry frame are optimized. An example is given to show how to determine these parameters by taking a long object with conical surface as painted object.

The Vibration Characteristics Analysis of Ship Foundation Based on the Arrangement of Isolators

2011 ◽  
Vol 55-57 ◽  
pp. 2202-2205
Author(s):  
Yu Wang ◽  
Xing Lin Chen ◽  
Guang Min Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Frequency ◽  
Vibration Characteristics ◽  
Force Characteristic ◽  
The Finite Element Method ◽  
Foundation Vibration ◽  
Characteristics Analysis ◽  
Excitation Force ◽  
General Connection

Contrary to the general connection style, the vibration characteristics of the ship foundation vibration is researched under the arrangement style of isolators acted on it. And the influence of the parameters of rigidity and damp to the excitation force characteristic is studied too. Based on the real ship data and the finite element method, the study is shown that the excitation force from the device to the foundation is not only related to the rigidity, damp of isolators and the natural frequency of device-isolator-foundation system but also the related to arrangement style of isolator. When the excited frequency is lower it had little effect on the vibration characteristics relatively. However that the frequency is higher, it had significant effect on the vibration.

A 2-legged XY parallel flexure motion stage with minimised parasitic rotation

2014 ◽  
Vol 228 (17) ◽  
pp. 3156-3169 ◽  
Author(s):  
Guangbo Hao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Design Approach ◽  
Analytical Models ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Motion Range ◽  
Cross Axis

XY compliant parallel manipulators (aka XY parallel flexure motion stages) have been used as diverse applications such as atomic force microscope scanners due to their proved advantages such as eliminated backlash, reduced friction, reduced number of parts and monolithic configuration. This paper presents an innovative stiffness centre based approach to design a decoupled 2-legged XY compliant parallel manipulator in order to better minimise the inherent parasitic rotation and have a more compact configuration. This innovative design approach makes all of the stiffness centres, associated with the passive prismatic (P) modules, overlap at a point that all of the applied input forces can go through. A monolithic compact and decoupled XY compliant parallel manipulator with minimised parasitic rotation is then proposed using the proposed design approach based on a 2-PP kinematically decoupled translational parallel manipulator. Its load–displacement and motion range equations are derived, and geometrical parameters are determined for a specified motion range. Finite element analysis comparisons are also implemented to verify the analytical models with analysis of the performance characteristics including primary stiffness, cross-axis coupling, parasitic rotation, input and output motion difference and actuator nonisolation effect. Compared with the existing XY compliant parallel manipulators obtained using 4-legged mirror-symmetric constraint arrangement, the proposed XY compliant parallel manipulators based on stiffness centre approach mainly benefits from fewer legs resulting in reduced size, simpler modelling as well as smaller lost motion. Compared with existing 2-legged designs with the conventional arrangement, the present design has smaller parasitic rotation, which has been proved from the finite element analysis results.

Vibration Characteristics Analysis of Large Dismountable Out-Moving Jaw Crusher

2014 ◽  
Vol 472 ◽  
pp. 27-30
Author(s):  
Yong Jiang
Keyword(s):  
Natural Frequency ◽  
Experimental Analysis ◽  
Vibration Analysis ◽  
Large Scale ◽  
Vibration Characteristics ◽  
Vibration System ◽  
Working Process ◽  
Jaw Crusher ◽  
Characteristics Analysis ◽  
Working Frequency

The working process of the out-moving jaw crusher is complex vibration system with multeity freedoms, it is vibration Characteristics directly affect the performance of the machine. The thesis put PWD120150 as research target, experimental analysis was conduct to the typical vibration Characteristics, the natural frequency and the working frequency of the machine and key components was obtained, which provided references for the design of avoiding mechanical resonance, and provided technical reference to the vibration analysis of the large scale equipment.

Dynamic Modelling of an Off-Road Vehicle for the Design of a Semi-Active, Hydropneumatic Spring-Damper System

2015 ◽  
Author(s):  
Giuseppe Panetta ◽  
Francesco Mancarella ◽  
Massimo Borghi ◽  
Barbara Zardin ◽  
Francesco Pintore
Keyword(s):  
Dynamic Behaviour ◽  
Dynamic Test ◽  
Dynamic Modelling ◽  
Hydraulic Model ◽  
Front Axle ◽  
Geometrical Parameters ◽  
Vehicle Dynamic ◽  
Hydraulic Actuator ◽  
Damping Force ◽  
Multibody Model

In this paper a tool integrating a multibody full car model of a tractor and the hydraulic model of the suspension system is presented as a virtual tool able to help the designer and also the control tuning of the system. The full car approach is chosen in order to be able to describe all the vehicles movements (roll, yaw, pitch) while the detailed lumped parameters model of the hydraulic suspensions allows to consider the role of the electrohydraulic valves, accumulator, hydraulic actuator on the vehicle dynamic behaviour. The hydraulic model and the multibody model exchange forces and displacements at the joint points: one between actuator and sprung mass (chassis) and the other one between actuator and unsprung mass (front axle and wheels). Experimental test have been performed (suspension leveling maneuvers, tests on ISO 50008 track, bump tests) and the results of the numerical model have been compared with the experimental data, allowing the understanding of the influence of the numerous design and control parameters involved in the determination of the vehicle dynamic behaviour. The influence of mechanical and geometrical parameters on the damping force hysteresis measured during levelling test are shown and described. Finally, the dynamic behavior of the suspension is analyzed making reference to a dynamic test over a bump.

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