Ordered Structure and the Coupling Degree of Planar Mechanism Based on Single-Open Chain and Its Application

2008 ◽  
Author(s):  
Ting-Li Yang ◽  
An-Xin Liu ◽  
Yu-Feng Luo ◽  
Xianwen Kong ◽  
Hui-Ping Shen ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Ordered Structure ◽  
Open Chain ◽  
Planar Mechanism ◽  
Structural Composition ◽  
Modular Method

A new viewpoint on structural composition of mechanism is proposed in this paper: any mechanism can be decomposed into a group of ordered single-open-chains (SOC). Based on the ordered SOC and its constraint property, the following concepts or principles are proposed or established: (1) the criteria for determination of basic kinematic chain (BKC). (2) the coupling degree of BKC, (3) the criteria for determination of types of degree-of-freedom, (4) the formula for calculation of number of mechanism configurations, and (5) a new unified modular method for structural, kinematic and dynamic analysis of mechanism.

scholarly journals An approach to quantify the influence of ground motion uncertainty on elastoplastic system acceleration in incremental dynamic analysis

2017 ◽  
Vol 20 (11) ◽  
pp. 1744-1756 ◽  
Author(s):  
Peng Deng ◽  
Shiling Pei ◽  
John W. van de Lindt ◽  
Hongyan Liu ◽  
Chao Zhang
Keyword(s):  
Dynamic Analysis ◽  
Ground Motion ◽  
Earthquake Engineering ◽  
Structural Response ◽  
Incremental Dynamic Analysis ◽  
Degree Of Freedom ◽  
Maximum Acceleration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Performance Based Earthquake Engineering

Inclusion of ground motion–induced uncertainty in structural response evaluation is an essential component for performance-based earthquake engineering. In current practice, ground motion uncertainty is often represented in performance-based earthquake engineering analysis empirically through the use of one or more ground motion suites. How to quantitatively characterize ground motion–induced structural response uncertainty propagation at different seismic hazard levels has not been thoroughly studied to date. In this study, a procedure to quantify the influence of ground motion uncertainty on elastoplastic single-degree-of-freedom acceleration responses in an incremental dynamic analysis is proposed. By modeling the shape of the incremental dynamic analysis curves, the formula to calculate uncertainty in maximum acceleration responses of linear systems and elastoplastic single-degree-of-freedom systems is constructed. This closed-form calculation provided a quantitative way to establish statistical equivalency for different ground motion suites with regard to acceleration response in these simple systems. This equivalence was validated through a numerical experiment, in which an equivalent ground motion suite for an existing ground motion suite was constructed and shown to yield statistically similar acceleration responses to that of the existing ground motion suite at all intensity levels.

Structure Based Grading of Kinematic Chains

2014 ◽  
Vol 575 ◽  
pp. 501-506 ◽  
Author(s):  
Shubhashis Sanyal ◽  
G.S. Bedi
Keyword(s):  
Structural Properties ◽  
Structural Property ◽  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Kinematic Chains ◽  
Structural Differences ◽  
The Individual ◽  
Independent Loops

Kinematic chains differ due to the structural differences between them. The location of links, joints and loops differ in each kinematic chain to make it unique. Two similar kinematic chains will produce similar motion properties and hence are avoided. The performance of these kinematic chains also depends on the individual topology, i.e. the placement of its entities. In the present work an attempt has been made to compare a family of kinematic chains based on its structural properties. The method is based on identifying the chains structural property by using its JOINT LOOP connectivity table. Nomenclature J - Number of joints, F - Degree of freedom of the chain, N - Number of links, L - Number of basic loops (independent loops plus one peripheral loop).

Accelerometer correction for the dynamic analysis of damped multi-degree of freedom systems

1969 ◽  
Vol 59 (4) ◽  
pp. 1591-1598
Author(s):  
G. A. McLennan
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Exact Method ◽  
Three Degrees Of Freedom

Abstract An exact method is developed to eliminate the accelerometer error in dynamic response calculations for damped multi-degree of freedom systems. It is shown that the exact responses of a system can be obtained from the approximate responses which are conventionally calculated from an accelerogram. Response calculations were performed for two typical systems with three degrees of freedom for an assumed pseudo-earthquake. The results showed that the approximate responses may contain large errors, and that the correction developed effectively eliminates these errors.

A Method for Detection of Distinct Mechanisms of a Planar Kinematic Chain

1988 ◽  
Vol 12 (1) ◽  
pp. 15-20 ◽  
Author(s):  
L.K. Patel ◽  
A.C. Rao
Keyword(s):  
Efficient Method ◽  
Numerical Scheme ◽  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
A Chain

This paper presents a computationally simple and efficient method for identification of distinct mechanisms of a planar kinematic chain having a single degree of freedom. It is proposed that velocity diagrams for all the inversions of a chain be drawn and the possible isomorphism among these velocity diagrams be detected. From the velocity diagram, a motion transfer point matrix can be prepared resulting in the development of a numerical scheme to be associated with a mechanism. Identical schemes lead to detection of isomorphism between mechanisms. The main advantage of this method is that, apart form detecteing isomorphism, it indicates which of the inversions is better kinematically e.g. higher the total number of vectors, better is the mechanism.

Kinematic and Workspace Modelling of a 6-PUS Parallel Mechanism

2018 ◽  
Author(s):  
Jérôme Landuré ◽  
Clément Gosselin
Keyword(s):  
Kinematic Analysis ◽  
Parallel Mechanism ◽  
Inverse Kinematic ◽  
Degree Of Freedom ◽  
Accurate Description ◽  
Transmission Ratio ◽  
Inverse Kinematic Problem ◽  
Jacobian Matrices ◽  
Six Degree Of Freedom

This article presents the kinematic analysis of a six-degree-of-freedom six-legged parallel mechanism of the 6-PUS architecture. The inverse kinematic problem is recalled and the Jacobian matrices are derived. Then, an algorithm for the geometric determination of the workspace is presented, which yields a very fast and accurate description of the workspace of the mechanism. Singular boundaries and a transmission ratio index are then introduced and studied for a set of architectural parameters. The proposed analysis yields conceptual architectures whose properties can be adjusted to fit given applications.

A Novel Method for Constructing Multi-Mode Deployable Polyhedron Mechanisms Using Symmetric Spatial RRR Compositional Units

2018 ◽  
Author(s):  
Jieyu Wang ◽  
Xianwen Kong
Keyword(s):  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Single Loop ◽  
Kinematic Chains ◽  
The Third ◽  
Motion Modes ◽  
3D Printed ◽  
Novel Method ◽  
Multi Mode ◽  
Motion Mode

A novel construction method is proposed to construct multimode deployable polyhedron mechanisms (DPMs) using symmetric spatial RRR compositional units, a serial kinematic chain in which the axes of the first and the third revolute (R) joints are perpendicular to the axis of the second R joint. Single-loop deployable linkages are first constructed using RRR units and are further assembled into polyhedron mechanisms by connecting single-loop kinematic chains using RRR units. The proposed mechanisms are over-constrained and can be deployed through two approaches. The prism mechanism constructed using two Bricard linkages and six RRR limbs has one degree-of-freedom (DOF). When removing three of the RRR limbs, the mechanism obtains one additional 1-DOF motion mode. The DPMs based on 8R and 10R linkages also have multiple modes, and several mechanisms are variable-DOF mechanisms. The DPMs can switch among different motion modes through transition positions. Prototypes are 3D-printed to verify the feasibility of the mechanisms.

scholarly journals Investigation of Complex Structural Designing of Mobile Facilities for Shipbuilding in Lithuanian Sea Region

Mechanika ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 237-243
Author(s):  
Tadas ASTRAUSKAS ◽  
Michail SAMOFALOV
Keyword(s):  
Dynamic Analysis ◽  
Longitudinal Direction ◽  
Cross Sectional ◽  
Climatological Data ◽  
Second Stage ◽  
Third Stage ◽  
Calculation Results ◽  
Complex Structural ◽  
Mobile Facilities

In the paper, it is proposed to cover by a mobile moving facility the shipyard open site, in Klaipeda, Lithuania (the EU). The facility of 40 m span consists of transversal frames, which are arranged by the step of 6.0 m, and a system of braces. Two types of steel frames have been considered: trussed and continuous. The actions are specified according to the design codes (Eurocode 3) and climatological data. In dynamic analysis, the longitudinal direction is defined for an inertia action, simulating braking. For calculating, a special algorithm of three stages has been prepared. At the first stage, three calculation schemes of one transversal frame were created. For the proposed schemes of the mobile moving facility, the calculation of only a transversal frame is effective in the preliminary determination of the cross-sectional areas and of the total structural weight. At the second stage, the frames were joined by braces. A preliminary comparison of the calculation results of the models was carried out after the first and second stages of the analysis. At the third stage, the dynamic analysis was performed and the influence of the dynamic impact was estimated. Finally, we compared the calculation results of three different FEM models and chose the most appropriate one. To sum up the investigations, conclusions and recommendations are presented.

scholarly journals Numbering method for the kinematic chain isomorphism recognition of a planar mechanism

2021 ◽  
Vol 1983 (1) ◽  
pp. 012028
Author(s):  
Qing Tian ◽  
Xiaohui Wei ◽  
Cai Li ◽  
Ge Liu ◽  
Yumei Deng
Keyword(s):  
Kinematic Chain ◽  
Planar Mechanism

scholarly journals Determination of Neuromuscular Control of the Upper Limbs in Children - Case Study

2020 ◽  
Vol 11 (4Sup1) ◽  
pp. 46-61
Author(s):  
Carmen-Magdalena Camenidis ◽  
◽  
Irina Băițel ◽  
Amalia Oatu ◽  
Octavian Amzulescu ◽  
...  
Keyword(s):  
Kinematic Chain ◽  
Neuromuscular Control ◽  
Female Gender ◽  
Upper Limbs ◽  
Motor Action ◽  
Muscle Groups ◽  
The Moment ◽  
The Right

The objective of this case study is to observe the existence of an anticipation mechanism at the muscle groups level of the upper limbs. We tried to highlighted this anticipation process by measuring the potential of surface electric for some muscle groups representing the kinematic chain on the right side, involved in the motor action of catching a basketball and a 3kg medicine ball with two hands to the chest. We conducted a case study of a 13-year-old child, female gender. As a measurement method, we used surface electromyography signals of the EMG Trigno Delsys wireless system with 16 electrodes. We determined the moment when the muscles come into action by increasing the potential of surface electric and the moment when the action of catching the ball takes place, using the information provided by the accelerometers incorporated in the sensors of the Delsys equipment used. Therefore, we obtained information about how different muscle groups come into action which helped us to get an idea of how the child's movement is structured. Based on results of accelerations and EMG signals acquired we have formulated conclusions regarding the neuromuscular control of the tested subject. We also planned for the future to test a larger group of participants in the study research of anticipation mechanism in children who do not practice any performance sports.

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