A Compliance-Based Parameterization Approach for Type Synthesis of Flexure Mechanisms

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
M. Jia ◽  
R. P. Jia ◽  
J. J. Yu
Keyword(s):  
Finite Element ◽  
Degree Of Freedom ◽  
Analytical Models ◽  
Fe Modeling ◽  
Type Synthesis ◽  
Geometric Properties ◽  
Final Goal ◽  
Compliance Matrices ◽  
Serial Chains

This paper presents an approach based on parameterized compliance for type synthesis of flexure mechanisms with serial, parallel, or hybrid topologies. The parameterized compliance matrices have been derived for commonly used flexure elements, which are significantly influenced by flexure parameters including material and geometric properties. Different parameters of flexure elements generate different degree of freedom (DOF) characteristic of types. Enlightened by the compliance analysis of flexure elements, a parameterization approach with detailed processes and steps is introduced in this paper to help analyze and synthesize flexure mechanisms with the case study as serial chains, parallel chains, and combination hybrid chains. For a hybrid flexure, the results of finite element (FE) modeling simulations are compared to analytical compliance elements characteristic. Under linear deformations, the maximum compliance errors of analytical models are less than 6% compared with the FE models. The final goal of this work is to provide a parameterized approach for type synthesis of flexure mechanisms, which is used to configure and change the parameters of flexure mechanisms to achieve the desired DOF requirements of types initially.

A Parameterization Approach for Compliance Analysis and Synthesis of Flexure Mechanisms

2014 ◽  
Author(s):  
M. Jia ◽  
R. P. Jia ◽  
J. J. Yu
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Degree Of Freedom ◽  
Analytical Models ◽  
Type Synthesis ◽  
Geometric Properties ◽  
Element Modeling ◽  
Analysis And Synthesis ◽  
Serial Chains

This paper presents an approach based on parameterized compliance for type synthesis of flexure mechanisms with serial, parallel, or hybrid topologies. The parameterized compliance matrixes have been derived for commonly used flexure elements which are significantly influenced by flexure parameters including material and geometric properties. Different parameters of flexure elements generate different degree of freedom (DOF) characteristic of types. Enlightened by the compliance analysis of flexure elements, a parameterization approach with detailed processes and steps is introduced in this paper to help analyze and synthesize flexure mechanisms in the case study as serial chains, parallel chains, and combination hybrid chains. For a hybrid flexure, finite element modeling simulations results are compared to analytical compliance elements characters. Within linear deformations, the maximum compliance errors of analytical models are less than 6% compared with FE models. The final goal of this work is to provide a parameterized approach for type synthesis of flexure mechanisms that can be used to configure and change the parameters of flexure mechanisms to achieve desired DOF requirements of types initially.

Accurate Evaluation of Bolt and Clamped Members Stiffnesses Of Bolted Joints

2021 ◽  
Author(s):  
Rashique Iftekhar Rousseau ◽  
Abdel-Hakim Bouzid ◽  
Zijian Zhao
Keyword(s):  
Finite Element ◽  
Joint Stiffness ◽  
Element Model ◽  
Fe Analysis ◽  
Bolted Joints ◽  
Analytical Models ◽  
Fe Modeling ◽  
Bolted Joint ◽  
A New Technique ◽  
External Loads

Abstract The axial stiffnesses of the bolt and clamped members of bolted joints are of great importance when considering their integrity and capacity to withstand external loads and resist relaxation due to creep. There are many techniques to calculate the stiffnesses of the joint elements using finite element (FE) modeling, but most of them are based on the displacement of nodes that are selected arbitrarily; therefore, leading to inaccurate values of joint stiffness. This work suggests a new method to estimate the stiffnesses of the bolt and clamped members using FE analysis and compares the results with the FE methods developed earlier and also with the existing analytical models. A new methodology including an axisymmetric finite element model of the bolted joint is proposed in which the bolts of different sizes ranging from M6 to M36 are considered for the analysis to generalize the proposed approach. The equivalent bolt length that includes the contribution of the thickness of the bolt head and the bolt nominal diameter to the bolt stiffness is carefully investigated. An equivalent bolt length that accounts for the flexibility of the bolt head is proposed in the calculation of the bolt stiffness and a new technique to accurately determine the stiffness of clamped members are detailed.

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.

Potential anti-vibration pavements with damping layer: Finite element (FE) modeling, validation, and parametrical studies

2021 ◽  
Vol 281 ◽  
pp. 122550
Author(s):  
Jiandong Huang ◽  
Massimo Losa ◽  
Pietro Leandri ◽  
Shiva G. Kumar ◽  
Junfei Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Fe Modeling

scholarly journals Stability charts based on the finite element method for underground cavities in soft carbonate rocks: validation through case-study applications

2019 ◽  
Vol 19 (10) ◽  
pp. 2079-2095 ◽  
Author(s):  
Michele Perrotti ◽  
Piernicola Lollino ◽  
Nunzio Luciano Fazio ◽  
Mario Parise
Keyword(s):  
Finite Element ◽  
Safety Margin ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Geometrical Features ◽  
Overall Stability ◽  
Underground Cavities ◽  
The Stability ◽  
Rock Mechanical Properties

Abstract. The stability of man-made underground cavities in soft rocks interacting with overlying structures and infrastructures represents a challenging problem to be faced. Based upon the results of a large number of parametric two-dimensional (2-D) finite-element analyses of ideal cases of underground cavities, accounting for the variability both cave geometrical features and rock mechanical properties, specific charts have been recently proposed in the literature to assess at a preliminary stage the stability of the cavities. The purpose of the present paper is to validate the efficacy of the stability charts through the application to several case studies of underground cavities, considering both quarries collapsed in the past and quarries still stable. The stability graphs proposed by Perrotti et al. (2018) can be useful to evaluate, in a preliminary way, a safety margin for cavities that have not reached failure and to detect indications of predisposition to local or general instability phenomena. Alternatively, for sinkholes that already occurred, the graphs may be useful in identifying the conditions that led to the collapse, highlighting the importance of some structural elements (as pillars and internal walls) on the overall stability of the quarry system.

Thermomechanical Analysis of the Welding Process Using the Finite Element Method

1975 ◽  
Vol 97 (3) ◽  
pp. 206-213 ◽  
Author(s):  
E. Friedman
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Welding Process ◽  
Thermomechanical Analysis ◽  
Analytical Models ◽  
The Finite Element Method ◽  
Nonuniform Temperature ◽  
Butt Weld ◽  
Transverse Bending ◽  
Finite Element Formulations

Analytical models are developed for calculating temperatures, stresses and distortions resulting from the welding process. The models are implemented in finite element formulations and applied to a longitudinal butt weld. Nonuniform temperature transients are shown to result in the characteristic transverse bending distortions. Residual stresses are greatest in the weld metal and heat-affected zones, while the accumulated plastic strain is maximum at the interface of these two zones on the underside of the weldment.

Development of a Finite Element Model of the Inferior Glenohumeral Ligament of the Glenohumeral Joint

2003 ◽  
Author(s):  
William J. Newman ◽  
Richard E. Debski ◽  
Susan M. Moore ◽  
Jeffrey A. Weiss
Keyword(s):  
Finite Element ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Element Model ◽  
Fe Modeling ◽  
Glenohumeral Ligament ◽  
Subject Specific ◽  
Inferior Glenohumeral Ligament ◽  
Glenohumeral Capsule ◽  
Shoulder Stability

The shoulder is one of the most complex and often injured joints in the human body. The inferior glenohumeral ligament (IGHL), composed of the anterior band (AB), posterior band (PB) and the axillary pouch, has been shown to be an important contributor to anterior shoulder stability (Turkel, 1981). Injuries to the IGHL of the glenohumeral capsule are especially difficult to diagnose and treat effectively. The objective of this research was to develop a methodology for subject-specific finite element (FE) modeling of the ligamentous structures of the glenohumeral joint, specifically the IGHL, and to determine how changes in material properties affect predicted strains in the IGHL at 60° of external rotation. Using the techniques developed in this research, an improved understanding of the contribution of the IGHL to shoulder stability can be acquired.

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