Conceptual Design of 2-DOF Flexure-Based Sensing Mechanisms for Superconductor Gravity Gradient

2015 ◽  
Author(s):  
M. Jia ◽  
R. P. Jia ◽  
J. J. Yu
Keyword(s):  
Finite Elements ◽  
Conceptual Design ◽  
Screw Theory ◽  
Analytical Models ◽  
Gravity Gradient ◽  
Type Synthesis ◽  
Finite Elements Analysis ◽  
Compact Structure ◽  
Sensing Mechanism ◽  
Analysis Models

By employing screw theory and the freedom and constraint topology (FACT), the type synthesis for 2-DOF flexure-based sensing mechanism of superconductor gravity gradient was produced with the parameterized compliance approach. Six types of mechanism with 1R1T DOF were deduced with freedom and constraint pattern in parallel topologies. Based on the compliance analysis, one type was selected as preferred sensing mechanism with the comparison of freedom, main direction compliance, parasitic errors, precision and complexity. For reducing the parasitic and coupling errors, optimization was produced with the parameterized compliance approach. Then specific geometric properties were presented with compact structure for the measurement application. The simulations showed the results of analytical models were close to that of FEA (finite elements analysis) models and the maximum errors of compliance parameters were less than 6%. The conceptual design of 2-DOF flexure-based sensing mechanisms could reach the required functions.

scholarly journals Type Synthesis Principle and Practice of Flexure Systems in the Framework of Screw Theory: Part I—General Methodology

2010 ◽  
Author(s):  
J. J. Yu ◽  
S. Z. Li ◽  
X. Pei ◽  
Hai-jun Su ◽  
J. B. Hopkins ◽  
...  
Keyword(s):  
System Theory ◽  
Conceptual Design ◽  
Building Block ◽  
High Performance ◽  
Screw Theory ◽  
Physical Entity ◽  
Type Synthesis ◽  
General Methodology ◽  
Synthesis Procedure ◽  
Systematic Formulation

The systematic methodologies involved in type synthesis of flexure systems are no doubt helpful to generate one and more high-performance precision machine designs at the stage of conceptual design with a rapid and effective way. This paper provides a systematic formulation of the type synthesis of parallel, serial, and hybrid flexure systems via a mapping from a geometric concept to physical entity. The whole type synthesis principle is built upon screw system theory and the geometric Freedom and Constraint Topology (FACT) approach, also combining with other concepts and methods including equivalent compliance mapping, building block etc, which enables the type synthesis of flexure systems deterministic, simple and practical. After that, Type synthesis procedure for various flexure systems are elaborated with examples. As a result, as many specified-DOF (Degree of Freedom) flexure systems as possible can be found and therefore pave the way for obtaining an optimal configuration.

scholarly journals Type Synthesis of 2T1R Decoupled Parallel Mechanisms Based on Lie Groups and Screw Theory

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Shuwei Qu ◽  
Ruiqin Li ◽  
Shaoping Bai
Keyword(s):  
Lie Groups ◽  
Lie Group ◽  
Screw Theory ◽  
New Method ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Compact Structure ◽  
Selection Of

Decoupled parallel mechanisms (DPMs) have the characteristics of compact structure and simple control with wide applications. This paper presents a new method of type synthesis for DPMs by virtue of Lie groups and screw theory. The method consists of synthesis at limb level and configuration level. At limb level, Lie group is used to synthesize the limbs with required DOFs. At configuration level, screw theory is adopted to determine configuration with synthesized limbs that satisfy the type synthesis criteria of DPMs. The type synthesis criteria including limb decoupling and selection of the driving pairs are presented. Upon the formulation, the procedure of type synthesis of DPMs is developed. Type synthesis is conducted with the proposed method, which leads to new spatial and planar fully decoupled 2T1R mechanisms.

A SPLINES BASED METHOD FOR MODELING THE HUMAN HEAD FOR USE IN FINITE ELEMENTS ANALYSIS

2017 ◽  
Author(s):  
Daniel Ponce ◽  
Eduardo Szpoganicz ◽  
Leonardo Mejia Rincon ◽  
Ernesto Ponce Lopez
Keyword(s):  
Finite Elements ◽  
Human Head ◽  
Finite Elements Analysis

scholarly journals A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Yongquan Li ◽  
Yang Zhang ◽  
Lijie Zhang
Keyword(s):  
Closed Loop ◽  
Screw Theory ◽  
Line Graph ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Allocation Criteria ◽  
Grassmann Line Geometry ◽  
Moving Platform ◽  
Atlas Method

Abstract The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms, or using screw theory to perform multiple getting intersection and union to complete type synthesis. The number of redundant parallel mechanisms obtained by these two methods is limited. In this paper, based on Grassmann line geometry and Atlas method, a novel and effective method for type synthesis of redundant actuated parallel mechanisms (PMs) with closed-loop units is proposed. Firstly, the degree of freedom (DOF) and constraint line graph of the moving platform are determined successively, and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph, and a branch constraint allocation scheme is formulated based on the allocation criteria. Secondly, a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units. Finally, the branch chains that meet the requirements of branch chains configuration criteria and F&C (degree of freedom & constraint) line graph are assembled. In this paper, two types of 2 rotational and 1 translational (2R1T) redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational (2T1R) redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples, and 238, 92 and 15 new configurations were synthesized. All the mechanisms contain closed-loop units, and the mechanisms and the actuators both have good symmetry. Therefore, all the mechanisms have excellent comprehensive performance, in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled. The instantaneous analysis shows that all mechanisms are not instantaneous, which proves the feasibility and practicability of the method.

An Evolutionary Multi-Objective Optimization Approach to the Topology Optimization of Auxetic Structures

2002 ◽  
Author(s):  
Ashraf O. Nassef
Keyword(s):  
Topology Optimization ◽  
Elastic Modulus ◽  
Finite Elements ◽  
Multiobjective Optimization ◽  
Poisson Ratio ◽  
Optimization Approach ◽  
Multi Objective Optimization ◽  
Finite Elements Analysis ◽  
Multi Objective ◽  
Auxetic Structures

Auxetic structures are ones, which exhibit an in-plane negative Poisson ratio behavior. Such structures can be obtained by specially designed honeycombs or by specially designed composites. The design of such honeycombs and composites has been tackled using a combination of optimization and finite elements analysis. Since, there is a tradeoff between the Poisson ratio of such structures and their elastic modulus, it might not be possible to attain a desired value for both properties simultaneously. The presented work approaches the problem using evolutionary multiobjective optimization to produce several designs rather than one. The algorithm provides the designs that lie on the tradeoff frontier between both properties.

scholarly journals Prediction of Cyclic Fatigue Life of Nickel-Titanium Rotary Files by Virtual Modeling and Finite Elements Analysis

2015 ◽  
Vol 41 (11) ◽  
pp. 1867-1870 ◽  
Author(s):  
Alessandro Scattina ◽  
Mario Alovisi ◽  
Davide Salvatore Paolino ◽  
Damiano Pasqualini ◽  
Nicola Scotti ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Finite Elements ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Finite Elements Analysis ◽  
Virtual Modeling
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