Design of Structures With Multiple Equilibrium Configurations

2018 ◽  
Author(s):  
Yang Li ◽  
Sergio Pellegrino
Keyword(s):  
Multiple Equilibrium ◽  
Design Parameters ◽  
Future Research ◽  
Equilibrium Constraints ◽  
Complex Problems ◽  
Equilibrium Configurations ◽  
Four Bar Linkage ◽  
Stable Structures

Being able to design structures with multiple equilibrium configurations is the basis for the design of multi-stable structures, which are of interest for future research on multi-configuration structures that require ‘simple’ actuation schemes. It is already known that adding elastic springs to a rigid mechanism can create structures with multiple equilibrium configurations. The spring properties, such as their rest positions, can be taken as design parameters that can be used to achieve specific equilibrium configurations of the structure. This paper provides a linearized formulation for the equilibrium constraints that can be solved for the rest positions of the springs. This method allows the design of specific equilibrium configurations. It can also handle more complex problems and is easier to solve in comparison to existent techniques. An example design of a four-bar linkage that has 5 equilibrium configurations is presented.

Synthesis of Compliant Mechanisms With Specified Equilibrium Positions

2005 ◽  
Author(s):  
Hai-Jun Su ◽  
J. Michael McCarthy
Keyword(s):  
Compliant Mechanisms ◽  
Equilibrium Constraints ◽  
Equilibrium Equations ◽  
Equilibrium Configurations ◽  
Form Design ◽  
Design Requirements ◽  
Synthesis Procedure ◽  
Position Synthesis ◽  
Four Bar Linkage ◽  
Sine And Cosine Functions

This paper presents a synthesis procedure for a compliant four-bar linkage with three specified equilibrium configurations. The finite position synthesis equations are combined with equilibrium constraints at the flexure pivots to form design equations. These equations are simplified by modeling the joint angle variables in the equilibrium equations using sine and cosine functions. Solutions to these design equations were computed using a polynomial homotopy solver. In order to provide a design specification, we first compute the six equilibrium configurations of a known compliant four-bar mechanism. We use these results as design requirements to synthesize a compliant four-bar. The solver obtained eight real solutions which we refined using a Newton-Raphson technique. A numerical example is provided to verify the design methodology.

Structures With Multiple Rigid Configurations Due to Prestress and Unilateral Contacts

2021 ◽  
Author(s):  
Charles Dorn ◽  
Yang Li ◽  
Sergio Pellegrino
Keyword(s):  
Degree Of Freedom ◽  
Multiple Equilibrium ◽  
Multiple Target ◽  
Unilateral Constraints ◽  
Equilibrium Configurations ◽  
Unilateral Contacts ◽  
Reaction Forces ◽  
Rf Antenna ◽  
Four Bar Linkage ◽  
Multiple Configurations

Abstract This paper presents structures with multiple equilibrium configurations arising from the combination of a state of prestress and unilateral contacts. A design problem is posed where preloaded elastic springs and unilateral constraints are embedded throughout a mechanism. The spring parameters are designed such that multiple target configurations are immobilized due to contact. In each of these configurations, the spring forces maintain compressive reaction forces, immobilizing the structure. Each immobilized configuration can rigidly resist perturbation forces up to some finite magnitude where contact is lost. Hence, this case of multiple configurations in equilibrium due to the combination of prestress and contact is referred to as multi-configuration rigidity. Two examples of structures exhibiting multi-configuration rigidity are presented. First, a four bar linkage with a single kinematic degree of freedom is used to introduce the concept. In the context of the linkage, multi-configuration rigidity is compared to multi-stability, exhibiting the key differences between the two concepts. Then, a 24-degree-of-freedom kirigami surface is presented that can morph between flat and spherical configurations, motivated by RF antenna applications. By embedding torsional springs and fold angle stops throughout the structure, flat and spherical configurations are made rigid. Actuation between the configurations can easily be achieved by snapping the structure between the rigid configurations.

Synthesis of Bistable Compliant Four-Bar Mechanisms Using Polynomial Homotopy

2006 ◽  
Vol 129 (10) ◽  
pp. 1094-1098 ◽  
Author(s):  
Hai-Jun Su ◽  
J. Michael McCarthy
Keyword(s):  
Compliant Mechanisms ◽  
Homotopy Continuation ◽  
Equilibrium Constraints ◽  
Equilibrium Equations ◽  
Kinematic Synthesis ◽  
Equilibrium Configurations ◽  
Form Design ◽  
Four Bar Linkage ◽  
Sine And Cosine Functions ◽  
Cosine Functions

In this paper we formulate and solve the synthesis equations for a compliant four-bar linkage with three specified equilibrium configurations in the plane. The kinematic synthesis equations as for rigid-body mechanisms are combined with equilibrium constraints at the flexure pivots to form design equations. These equations are simplified by modeling the joint angle variables in the equilibrium equations using sine and cosine functions. Polynomial homotopy continuation is applied to compute all of the design candidates that satisfy these design equations, which are refined using a Newton-Raphson technique. A numerical example demonstrates design methodology in which the homotopy solver obtained eight real solutions. Two of them provide two stable and one unstable equilibrium, and hence, can be used as the prototype of bistable compliant mechanisms.

Quantum Computing and the Architectural, Engineering and Construction (AEC) Industry: Trends, Challenges, Near-Term Practical Opportunities and Future Outlook

2021 ◽  
Author(s):  
Oliver Barima ◽  
Keyword(s):  
Quantum Computing ◽  
Future Research ◽  
Communication Tools ◽  
Architectural Engineering ◽  
Complex Problems ◽  
Potential Impact ◽  
Near Term ◽  
Communication Methods ◽  
Industry Trends ◽  
Aec Industry

Digital computing and allied communication tools have been phenomenal, but they are fast reaching their technical limits and also their capacity to solve certain extant complex problems. Quantum computing has now emerged with a touted potential to deal with aspects of the latter complex problems and also significantly transform extant computing and communication methods. Yet, little studies exist in the Architectural, Engineering and Construction (AEC) industry related literature on quantum computing to boost awareness and also explore its prospective impact on the AEC industry. This study discusses the underpinning basic concepts, technologies and trends in the quantum computing domain to build awareness to boost Architecture, Engineering and Construction (AEC) industry capacity on the topic. The research dissects the challenges in this novel area. And also examines the near-term practical opportunities and potential impact of quantum computing on the AEC industry. The study concludes with suggestions for practice and future research.

scholarly journals Effect of a dual tire pressure on the design parameters of thick asphalt pavements using finite element freeware

DYNA ◽  
2016 ◽  
Vol 83 (196) ◽  
pp. 194-203
Author(s):  
Myriam Rocío Pallares Muñoz ◽  
Julián Andrés Pulecio-Díaz
Keyword(s):  
Finite Element ◽  
Analytical Methods ◽  
Asphalt Pavement ◽  
Field Tests ◽  
Asphalt Pavements ◽  
Design Parameters ◽  
Future Research ◽  
Tire Pressure ◽  
The Cost ◽  
Cost Of Construction

<p>The effect of a dual tire pressure on the design parameters of thick asphalt pavements using finite element freeware EverStressFE©1.0 is evaluated. This is trying to represent more adjusted the footprint shape and intensity of stress generated by the tires of vehicles. To validate the elastic multilayer EverStress©5.0 software was used. The results of the deformations can be concluded that the asphalt pavement designs made with analytical methods may be slightly oversized and consequently increase the cost of construction of pavements. This study marks a route to analyze the sensitivity of various factors that may affect the design of asphalt pavements. Future research is expected to integrate dynamic conditions by introducing results of field tests to full scale.</p>

Coordinate Analysis of the Characteristics of the New Servo Valve and its Work Condition

2012 ◽  
Vol 619 ◽  
pp. 419-424
Author(s):  
Ting Ting Liu ◽  
Hui Wang ◽  
Geng Wang
Keyword(s):  
Comparative Analysis ◽  
Visual Design ◽  
Design Parameters ◽  
Control Parameters ◽  
Work Condition ◽  
Servo Valve ◽  
Complex Problems ◽  
Hydraulic Servo

The paper gives an introduction of the structure and working principles of the new gap-type electro-hydraulic servo valve and advances the performance law of throttle by a comparative analysis of the performance of gap-type electro-hydraulic servo valve and the traditional rectangular orifice. In the meanwhile, combined with the introduction of the coordinate of working state, this paper aims to solve such complex problems as the design parameters of hydraulic components and provide a basis for the visual design of the performance of hydraulic components and cavity control parameters of servo valve and the main valve.

Collisions and Damage of Offshore Structures: A State-of-the-Art

1985 ◽  
Vol 107 (3) ◽  
pp. 297-314 ◽  
Author(s):  
C. P. Ellinas ◽  
S. Valsgard
Keyword(s):  
State Of The Art ◽  
Offshore Structures ◽  
The State ◽  
Design Parameters ◽  
Future Research ◽  
Research Activity ◽  
Comprehensive Information ◽  
Major Interest ◽  
Offshore Industry ◽  
Available Information

Over the recent years, following the very rapid increase in the construction and installation of offshore structures, there has been a considerable growth of interest in the assessment of the probabilities and consequences of collision and damage of such structures. This is reflected by the very large number of papers published over the last 15 yr and the multitude of conferences and meetings held on the subject. Many research programs have been completed or are in progress at many centers and institutions over the world. Accidental loading and damage are now accepted design parameters recommended for consideration in a number of Codes for the design in offshore structures. This paper reviews the state-of-the-art with respect to the probabilities and consequences of collisions and accidental loading in general, and methods for the assessment of the design of steel offshore structures against damage. Most of the available information in the field of offshore collisions and accidental loading emanates from research and experience related to ship safety. However, in this paper emphasis is placed on research activity and available information concerned with offshore structures, such as platforms, semisubmersibles, etc. There is a considerable amount of information available on methods for evaluating the extent and effects on damage of these structures and in estimating their residual strength in the damaged condition. As this is an area currently of major interest in the offshore industry, the paper presents comprehensive information and some new results relating to all major structural components. The state-of-the-art with regards to methods and principles for design against damage is also reviewed and commented upon. The paper concludes with general recommendations and indications of areas where future research could be most usefully directed.

scholarly journals Numerical Analysis of Design Parameters With Strong Influence on the Aerodynamic Efficiency of a Small-Scale Self-Pitch VAWT

2015 ◽  
Author(s):  
Carlos Xisto ◽  
José Páscoa ◽  
Michele Trancossi
Keyword(s):  
Wind Turbine ◽  
Strong Influence ◽  
Vertical Axis ◽  
Periodic Variation ◽  
Numerical Approach ◽  
Design Parameters ◽  
Speed Ratio ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Four Bar Linkage

In the paper, four key design parameters with a strong influence on the performance of a small-scale high solidity variable pitch VAWT (Vertical Axis Wind Turbine), operating at low tip-speed-ratio (TSR) are addressed. To this aim a numerical approach, based on a finite-volume discretization of two-dimensional Unsteady RANS equations on a multiple sliding mesh, is proposed and validated against experimental data. The self-pitch VAWT design is based on a straight blade Darrieus wind turbine with blades that are allowed to pitch around a feathering axis, which is also parallel to the axis of rotation. The pitch angle amplitude and periodic variation are dynamically controlled by a four-bar-linkage system. We only consider the efficiency at low and intermediate TSR, therefore the pitch amplitude is chosen to be a sinusoidal function with a considerable amplitude. The results of this parametric analysis will contribute to define the guidelines for building a full size prototype of a small scale turbine of increased efficiency.

Considerations for Finding the Optimal Design Parameters for a Novel Pole Climbing Robot

2008 ◽  
Author(s):  
Gabriel Goldman ◽  
Dennis Hong
Keyword(s):  
Optimal Design ◽  
Central Body ◽  
Design Parameters ◽  
Future Research ◽  
Climbing Robot ◽  
Serial Chain ◽  
Allowable Range ◽  
The Given ◽  
Selection Of ◽  
Do So

HyDRAS (Hyper-redundant Discrete Robotic Articulated Serpentine) is a novel serpentine robot comprising a serial chain of actuated universal joints for climbing structures such as poles or scaffoldings. To do so, it wraps its body around the structure in a helical shape, and rotates its body along its own central body axis to roll up the structure. This paper presents a method and considerations for selecting the optimal design parameters for the development of HyDRAS. The geometry equations derived in this paper will allow for a parametric approach that will aid in the selection of the appropriate design parameters such as module length, module diameter, helical pitch, and allowable range of motion for the given task of climbing pole like structures. Several examples are used to illustrate the method. The results obtained will be used in the analysis of the mechanical advantage of the mechanism and future research on the motion planning of HyDRAS.

Multiply Separated Position Design of the Geared Five-Bar Function Generator

1971 ◽  
Vol 93 (1) ◽  
pp. 74-84 ◽  
Author(s):  
S. A. Oleksa ◽  
D. Tesar
Keyword(s):  
Design Parameters ◽  
Function Generator ◽  
Function Generation ◽  
Four Bar Linkage ◽  
Generation Problem ◽  
Made In

The geared five-bar linkage is the foundation for a function generation problem meeting specifications for 5 multiply separated positions and containing 4 free design parameters. The four-bar linkage is shown to be a member of this class of mechanisms. Design examples of rarely treated functions are given with the quality of the generated approximation. Suggestions are made in terms of the 4 design parameters to assist the designer in obtaining good results.

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