scholarly journals Force Analysis of the Overconstrained Mechanisms Based on Equivalent Stiffness Considering Limb Axial Deformation

2021 ◽  
Author(s):  
Jinwei Guo ◽  
Yongsheng Zhao ◽  
Bo Chen ◽  
Guoxing Zhang ◽  
Yundou Xu ◽  
...  
Keyword(s):  
External Force ◽  
Stiffness Matrix ◽  
Force Balance ◽  
Analytical Relationship ◽  
Equivalent Stiffness ◽  
Axial Deformation ◽  
Force Analysis ◽  
Limb Stiffness ◽  
Overconstrained Mechanisms ◽  
The Relationship

Abstract Considering the limb axial deformation, taking typical 2SS + P and 7-SS passive overconstrained mechanisms, 2SPS + P and 7-SPS active overconstrained mechanisms, and 2SPS + P and 7-SPS passive-input overconstrained mechanisms as examples, a new force analysis method based on the idea of equivalent stiffness is proposed. The equivalent stiffness matrix of passive overconstrained mechanism is derived by combining the force balance and deformation compatibility equations with consideration of axial elastic limb deformations. The relationship between the constraint wrench magnitudes and the external force, limb stiffness is established. The equivalent stiffness matrix of active overconstrained mechanism is derived by combining the force balance and displacement compatibility equations. Here, the relationship between the magnitudes of the actuated wrenches and the external force, limb stiffness is investigated. Combining with the equivalent stiffness of the passive overconstrained mechanism, an analytical relationship between the actuated forces of passive-input overconstrained mechanism and the output displacement, limb stiffness is explored. Finally, adaptability of the equivalent stiffness to overconstrained mechanisms is discussed, and the effect of the limb stiffness on overconstrained mechanisms force distribution is revealed.

Mechanical Model of Pelletization in the Impressing Roller System

2013 ◽  
Vol 732-733 ◽  
pp. 348-351
Author(s):  
Xiao Peng Huang ◽  
Fang Xin Wan ◽  
Jing Feng Wu
Keyword(s):  
Research Result ◽  
Reference Value ◽  
Force Balance ◽  
Total Force ◽  
Force Analysis ◽  
Forming Mechanism ◽  
Material Layer ◽  
Work Area ◽  
Function Relationship ◽  
Roller System

By the force analysis of alfalfa grass powder material layer in work area of circular mould pelletizing system, grass pellet briquetting mechanism when alfalfa grass powder pass work area was explained, function relationship between the thickness of material layer and the circular mould angle was established, force balance equation of material layer differentiation unit under the general conditions was deduced, and the total force of material layer applied by circular mould was obtained. Research result has practical meaning for guiding the process test of grass pellet product and optimizing product structure, and has a certain theoretical reference value for in-depth revealing granulating forming mechanism of hoop standard granulator.

Effect of links deformation on motion precision of parallel manipulator based on flexible dynamics

2017 ◽  
Vol 44 (6) ◽  
pp. 776-787 ◽  
Author(s):  
Chunxia Zhu ◽  
Jay Katupitiya ◽  
Jing Wang
Keyword(s):  
Parallel Manipulator ◽  
High Speed ◽  
Beam Theory ◽  
Parallel Manipulators ◽  
Dynamic Responses ◽  
Axial Deformation ◽  
Content Type ◽  
High Performing ◽  
Coupling Equations ◽  
The Relationship

Purpose Manipulator motion accuracy is a fundamental requirement for precision manufacturing equipment. Light weight manipulators in high speed motions are vulnerable to deformations. The purpose of this work is to analyze the effect of link deformation on the motion precision of parallel manipulators. Design/methodology/approach The flexible dynamics model of the links is first established by applying the Euler–Bernoulli beam theory and the assumed modal method. The rigid-flexible coupling equations of the parallel mechanism are further derived by using the Lagrange multiplier approach. The elastic energy resulting from spiral motion and link deformations are computed and analyzed. Motion errors of the 3-link torque-prismatic-torque parallel manipulator are then evaluated based on its inverse kinematics. The validation experiments are also conducted to verify the numerical results. Findings The lateral deformation and axial deformation are largest at the middle of the driven links. The axial deformation at the middle of the driven link is approximately one-tenth of the transversal deformation. However, the elastic potential energy of the transversal deformation is much smaller than the elastic force generated from axial deformation. Practical implications Knowledge on the relationship between link deformation and motion precision is useful in the design of parallel manipulators for high performing dynamic responses. Originality/value This work establishes the relationship between motion precision and the amount of link deformation in parallel manipulators.

scholarly journals Rotation-joint stiffness modeling for industrial robots considering contacts

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879306 ◽  
Author(s):  
Zhifeng Liu ◽  
Jingjing Xu ◽  
Qiang Cheng ◽  
Yongsheng Zhao ◽  
Yanhu Pei
Keyword(s):  
Fractal Theory ◽  
Joint Stiffness ◽  
Industrial Robots ◽  
Torsional Stiffness ◽  
Equivalent Stiffness ◽  
Force Analysis ◽  
Joint System ◽  
End Effector ◽  
Stiffness Modeling ◽  
High Speeds

Joint flexibility has a major impact on the motion accuracy of a robotic end effector, particularly at high speeds. This work proposes a technique of precisely modeling the torsional stiffness of the rotational joints for the industrial robots. This technique considers the contacts that exist in the joint system, which can have a significant effect on the overall joint stiffness. The torsional stiffness of the connections that commonly exist in the rotational joints, such as the belt connection, the connections using key, bolts, and pins, were modeled by combining the force analysis and the fractal theory. Through modeling the equivalent stiffness for the springs in serial and in parallel, the torsional stiffness of all joints for the ER3A-C60 robot were calculated and analyzed. The results show that the estimated stiffness based on the proposed technique is closer to the actual values than that based on the previous model without considering the contacts. The analysis is useful for controlling the dynamic characteristic of the industrial robots with the rotational joints while planning the trajectory for the end effector.

Strength prediction of woven composite rings using progressive damage modeling

2020 ◽  
Vol 29 (6) ◽  
pp. 851-873
Author(s):  
H Khayyam Rayeni ◽  
AH Mazaheri ◽  
F Taheri-Behrooz
Keyword(s):  
Representative Volume Element ◽  
Stiffness Matrix ◽  
Volume Element ◽  
Progressive Damage ◽  
Equivalent Stiffness ◽  
Woven Composite ◽  
Damage Initiation ◽  
Plain Weave ◽  
Representative Volume ◽  
Composite Pipe

The ultimate failure of the woven composite pipes has been investigated using progressive damage modeling. The composite pipe specimens were made of (E) glass plain weave fabrics according to the ASTM D2290 standard. The hoop strength of these specimens has been obtained from the tensile tests. The damage initiation and propagation of composite pipe have been predicted by a numerical multi-scale method. For this purpose, the damage of the yarns and resin of the plain weave laminate was investigated by modeling a representative volume element. Then, the macroscopic stresses and strains of the representative volume element were calculated to obtain the equivalent stiffness matrix using suitable boundary conditions. Then, the mechanical properties of the laminate and material properties degradation coefficients were derived by this equivalent stiffness matrix. Hashin and Von Mises failure criteria were utilized in USDLFD subroutine to predict the damage initiation of the yarn and resin in the representative volume element, respectively. The sudden degradation method has been used to investigate the damage propagation in these constituents. Then, the woven composite ring was modeled in ABAQUS software and its ultimate strength was predicted by UMAT subroutine using obtained degradation coefficients of the representative volume element from the previous step. Finally, the numerical results were compared with the experimental data which show good agreement between the results.

Design and Damping Force Analysis for Turbine Composite Regenerative Damper

2012 ◽  
Vol 446-449 ◽  
pp. 1360-1365
Author(s):  
Yong Qiang Gao ◽  
Jin Qiu Zhang ◽  
Jie Yue ◽  
Zhi Zhao Peng
Keyword(s):  
Basic Principle ◽  
Electromotive Force ◽  
Load Resistance ◽  
Force Analysis ◽  
Damping Force ◽  
Piston Velocity ◽  
Axial Turbine ◽  
New Type ◽  
The Relationship

Turbine composite regenerative damper is one of new type damper which can regenerate the energy of vibration. The component and principle of generator and regenerate energy for turbine composite regenerative damper is introduce, and based on hydrodynamics and axial turbine basic principle, the relationship between induced electromotive force and piston velocity ,load resistance is induced. At last, the relationship between damping force and piston velocity, load resistance is induced too. The method is meaningful to understand and instruct the design of turbine composite regenerative damper.

Friction Force Analysis on Diaomond Lapping of Sapphire Wafers

2013 ◽  
Vol 797 ◽  
pp. 461-468 ◽  
Author(s):  
Chao Chang Arthur Chen ◽  
Ching Hsiang Tseng ◽  
Wei Kang Tu
Keyword(s):  
Aluminum Oxide ◽  
Copper Plate ◽  
Endpoint Detection ◽  
Critical Factors ◽  
Force Analysis ◽  
Transient Region ◽  
Test Parameters ◽  
The Coefficient Of Friction ◽  
Relationship Of ◽  
The Relationship

This paper is to design and developing a friction sensor system (FSS) for prediction of endpoint detection (EPD) on diamond lapping of sapphire or mono-crystalline aluminum oxide wafers. The endpoint detection usually includes start region, lapping region, transient region and endpoint region to control the planarization procedure by diamond lapping with variant plate of copper, resin copper, or tin materials. Experiments have been performed with 9 tests composed by three kinds of viscosity of slurry lapping with three kinds of lap plates. The coefficient of friction (CoF) has been obtained by the designed FSS and then compared with different test parameters. The as-lapped sapphire wafers have also measured by coherence surface interferometer, CCI-Lite (Taylor Hobson, UK). Experimental results show that the hardness of plate and viscosity of slurry are critical factors for as-lapped wafer quality. The EPD of diamond lapping with resin copper plate can be determined by the CoF data and that can be used for justifying the appropriate lapping time of sapphire wafers. Future study can focus on the relationship of sub-surface crack caused by the diamond lapping process.

The Study of FEM for Internal Force Analysis of the Sluice Structure

2011 ◽  
Vol 71-78 ◽  
pp. 3275-3279
Author(s):  
Xiao Na Li ◽  
Tong Chun Li ◽  
Yuan Ding
Keyword(s):  
Cross Section ◽  
Bending Moment ◽  
Internal Force ◽  
Force Balance ◽  
Shearing Force ◽  
Force Analysis ◽  
Reconstruction Project ◽  
Unit Stress ◽  
Reinforcement Design

This paper takes a sluice reconstruction project as an example. The constraint internal force, the related axis force, bending moment, and shearing force at the corresponding section are solved according to the unit stress and internal force balance. Furthermore, technology of mesh auto-generation in cross-section is utilized to plot the internal force graph of the structure directly, which will provide reference for reinforcement design and make it more convenient.

scholarly journals Thermal and Microstructure Study of the Chip Formation During Turning of Ti64 β Lamellar Titanium Structure

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Vincent Wagner ◽  
Floran Barelli ◽  
Gilles Dessein ◽  
Raynald Laheurte ◽  
Phillipe Darnis ◽  
...  
Keyword(s):  
Chip Formation ◽  
Chip Morphology ◽  
Cutting Condition ◽  
Shear Direction ◽  
Temperature Model ◽  
Force Analysis ◽  
Single Chip ◽  
Band Formation ◽  
Titanium Structure ◽  
The Relationship

In recent years, many titanium alloys have emerged, each of them associated with a range of different heat treatments. Thus, several microstructures have been studied to varying degrees. For example, the Ti64 titanium alloy, mostly known for its α + β structure, can display a different state: the structure, inducing nonstandard mechanical behavior. This work presents chip formation in this specific microstructure where a strong heterogeneity is observed and where the shear band formation is a function of the relationship between the shear direction and the microstructure orientation. From these reasons, major differences are found in the chip morphology, within the same cutting condition, in comparison to the bimodal structure where a single chip morphology is obtained for each cutting condition. A section of this paper is devoted to the presentation of the β microstructure where different configurations can be seen within the same chip. Next, the influence of cutting conditions on the chip formation is studied. To highlight the specific chip formation process, a temperature model has been developed and combined with cutting force analysis to understand clearly the specificity of the chip formation for this structure. Finally, the discussion explains the different chip formation scenarios according to the workpiece microstructure to be cut.

Force Analysis and Modeling of Carbon Nanowires Operation in SEM

2011 ◽  
Vol 183-185 ◽  
pp. 1901-1906
Author(s):  
Wei Bin Rong ◽  
Dong Jie Li ◽  
Li Ning Sun ◽  
Jin Yu Wang
Keyword(s):  
Size Effect ◽  
Experimental System ◽  
Force Analysis ◽  
Simplified Models ◽  
Relationship Of ◽  
Influence Degree ◽  
The Relationship ◽  
Carbon Nanowires

Due to influence of size effect, the force properties in nanoscale are greatly different from those in macroscale and the traditional models of operation are becoming difficult to meet the development of nanoscale manipulation. To provide guiding theory for practical nano-manipulation, the nanoscale forces of contact and non-contact operation of nanowires are analyzed for nano-manipulation in SEM. The Vander Waals models among the probe, nanowire and substrate are modeled according to the force properties in nanoscale, and then the simplified models are simulated with MATLAB. The influence degree of various factors and the relationship of them during the operation are obtained. At last, experimental system is established to verify the correctness of the proposed models.

FE Approach: Electro-Mechanical-Fluid Interaction of Jet Pipe Electrohydraulic Flow Control Servovalve

2003 ◽  
Author(s):  
Somashekhar S. Hiremath ◽  
M. Singaperumal ◽  
R. Krishna Kumar
Keyword(s):  
Steady State ◽  
Force Balance ◽  
Fe Model ◽  
Volume Changes ◽  
New Approach ◽  
Turbine Engine ◽  
Steady State Operation ◽  
Actual Flow ◽  
The Relationship ◽  
Fluid Interaction

Jet pipe electrohydraulic servovalve finds main application in feedback control system working on jet engine and fighter aircrafts. The analyzed jet pipe electrohydraulic servovalve is used in precise fuel control applications in gas turbine engine. This paper gives a new approach for servovalve modeling with the hydrostatic fluid elements in achieve steady state operation. The actual flow required to achieve the force balance is presented analytically. FE model gives the relationship between the spool and jet pipe position in achieving the steady state operation. The spool end cavity volume changes are presented.

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