A Study of Conditions That Affect the Distribution of Compliance in Compliant Mechanisms

2008 ◽  
Author(s):  
Stephen L. Canfield ◽  
Daniel L. Chlarson ◽  
Alexander Shibakov ◽  
Joseph D. Richardson ◽  
Anupam Saxena
Keyword(s):  
Strain Energy ◽  
Compliant Mechanisms ◽  
Optimization Process ◽  
Objective Functions ◽  
Compatibility Analysis ◽  
Pareto Sets ◽  
Show Evidence ◽  
Final Design ◽  
Additional Constraints ◽  
Insight Into

Researchers in the field of optimal synthesis of compliant mechanisms have been working to develop design tools that yield distributed compliant devices from a continuum design domain. However, it has been demonstrated in the literature that much of this work has resulted in mechanisms that localize compliance rather than distribute it as desired. Inaccurate representation of the stiffness or strain energy due to the existence of point flexures in the mechanism was identified as the cause of this behavior by early researchers. To eliminate this cause, several approaches have been tried to improve the design of distributed mechanisms, for example additional constraints on the optimization process, alternate parameterization techniques that avoid point flexures and additional objective functions evaluated as Pareto sets. In this paper, the authors further investigate the fundamental reasons for the prevalence of lumped designs. Representative simple compliant mechanisms are investigated analytically and numerically and the influence of various additional objectives on the final design is evaluated. To extrapolate these results to more complex mechanisms, examples are constructed that show evidence that a preference remains for lumped compliance, despite the countermeasures that have been applied. Pareto compatibility analysis developed by the authors is used to analyze the influence of various objectives on the distributive nature of the final design. These conditions that influence the distribution of compliance fall into two basic categories: those specific to the numerical methods applied and those of purely mechanical (i.e. fundamental) nature. This work will examine conditions of the latter type and will demonstrate that such a preference for lumped compliance exists. This preference is shown to be contained in the classic objectives; flexibility and stiffness. Based on these results, greater insight into the optimization process is gained and applied to improve the search for distributed compliant mechanisms.

Effective Generation of Pareto Sets Using Genetic Programming

2001 ◽  
Author(s):  
John Eddy ◽  
Kemper Lewis
Keyword(s):  
Genetic Programming ◽  
Optimization Problem ◽  
Complete Solution ◽  
Pareto Frontier ◽  
Multi Objective ◽  
Pareto Sets ◽  
Effective Generation ◽  
Final Design ◽  
The Individual ◽  
Measure Of Performance

Abstract Many designers concede that there is typically more than one measure of performance for an artifact. Often, a large system is decomposed into smaller subsystems each having its own set of objectives, constraints, and parameters. The performance of the final design is a function of the performances of the individual subsystems. It then becomes necessary to consider the tradeoffs that occur in a multi-objective design problem. The complete solution to a multi-objective optimization problem is the entire set of non-dominated configurations commonly referred to as the Pareto set. Common methods of generating points along a Pareto frontier involve repeated conversion of multi-objective problems into single objective problems using weights. These methods have been shown to perform poorly when attempting to populate a Pareto frontier. This work presents an efficient means of generating a thorough spread of points along a Pareto frontier using genetic programming.

Towards Uniformly Distributed Compliance in Compliant Mechanisms: A Multi-Objective Approach

2006 ◽  
Author(s):  
Stephen L. Canfield ◽  
Daniel L. Chlarson ◽  
Alexander Shibakov ◽  
Patrick V. Hull
Keyword(s):  
Finite Element ◽  
Objective Function ◽  
Compliant Mechanisms ◽  
Optimality Criteria ◽  
Optimal Designs ◽  
Limiting Factors ◽  
Objective Functions ◽  
Multi Objective ◽  
Simple Addition ◽  
Current Formulation

Researchers in the field of optimal synthesis of compliant mechanisms have been working to develop tools that yield distributed compliant devices to perform specific tasks. However, it has been demonstrated in the literature that much of this work has resulted in mechanisms that localize compliance rather than distribute it as desired. In fact, Yin and Ananthasuresh (2003) [1] demonstrate that based on the current formulation of optimality criteria and analysis via the finite element (FE) technique, a lumped compliant device will always exist as the minimizing solution to the objective function. The addition of constraints on allowable strain simply moves the solution back from this objective. Therefore, modification to the standard optimality criteria needs to take place. Yin and Ananthasuresh [1] proposed and compared several approaches that include distributivity-based measures within the optimality criteria, and demonstrated the effectiveness of this approach. In this paper, the authors propose to build on this problem. In a similar manner, a general approach to the topology synthesis problem will be suggested to yield mechanisms in which the compliance is distributed throughout the device. This work will be based on the idea of including compliance distribution directly within the objective functions, while addressing some of the potential limiting factors in past approaches. The technique will be generalized to allow simple addition of criteria in the future, and to deliver optimal designs through to manufacture. This work will first revisit and propose several quantitative definitions for distributed compliant devices. Then, a multi-objective formulation based on a non-dominating sort and Pareto set method will be incorporated that will provide information on the nature of the problem and compatibility of employed objective functions.

Design of Compliant Structural Mechanisms Using B-Spline Elements

2011 ◽  
Author(s):  
Ashok V. Kumar ◽  
Anand Parthasarathy
Keyword(s):  
Inverse Problem ◽  
Topology Optimization ◽  
Compliant Mechanisms ◽  
Spline Approximation ◽  
Structural Response ◽  
Field Application ◽  
Optimization Approach ◽  
Objective Functions ◽  
B Spline ◽  
Spline Basis

Structural design is an inverse problem where the geometry that fits a specific design objective is found iteratively through repeated analysis or forward problem solving. In the case of compliant structures, the goal is to design the structure for a particular desired structural response that mimics traditional mechanisms and linkages. It is possible to state the inverse problem in many different ways depending on the choice of objective functions used and the method used to represent the shape. In this paper, some of the objective functions that have been used in the past, for the topology optimization approach to designing compliant mechanisms are compared and discussed. Topology optimization using traditional finite elements often do not yield well-defined smooth boundaries. The computed optimal material distributions have shape irregularities unless special techniques are used to suppress them. In this paper, shape is represented as the contours or level sets of a characteristic function that is defined using B-spline approximation to ensure that the contours, which represent the boundaries, are smooth. The analysis is also performed using B-spline elements which use B-spline basis functions to represent the displacement field. Application of this approach to design a few simple mechanisms is presented.

Multistable Behavior of Compliant Kaleidocycles

2015 ◽  
Author(s):  
Thomas A. Evans ◽  
Brett G. Rowberry ◽  
Spencer P. Magleby ◽  
Larry L. Howell
Keyword(s):  
Strain Energy ◽  
Stable Equilibrium ◽  
Compliant Mechanisms ◽  
Neutral Stability ◽  
Energy Characteristics ◽  
Continuous Rotation

We present an analysis of the compliant kaleidocycle, a mechanism which, unlike other compliant mechanisms, may undergo continuous rotation. We analyze the strain energy characteristics of this mechanism during its motion and show that by varying the stiffness and orientation of the flexures, kaleidocycles may be designed to achieve customizable multistable behavior. These devices may be designed to include up to four distinct stable equilibrium positions and may also include regions of neutral stability.

Mathematical Modeling of the Unit Load Formation

2013 ◽  
Vol 309 ◽  
pp. 358-365 ◽  
Author(s):  
Béla Illés ◽  
Gabriella Bognár
Keyword(s):  
Mathematical Modeling ◽  
Supply Chain ◽  
Significant Role ◽  
Mathematical Description ◽  
Raw Materials ◽  
Transport Processes ◽  
Optimization Process ◽  
Objective Functions ◽  
Unit Load ◽  
Major Factors

A fast and efficient way of handling and storing components, raw materials, semi-finished and finished products play a significant role in the development of transport, storage and distribution design within the supply chain. One of the most important issues in storage and transport processes is the formation of unit loads. Our main goal is to give a mathematical description of a model involving the major factors of the unit load formation. The optimization process is exhibited applying the determined objective functions and constraints related to the basic tasks.

On the Multi-Level Unit Load Formation Model

2013 ◽  
Vol 581 ◽  
pp. 519-526 ◽  
Author(s):  
Béla Illés ◽  
Gabriella Bognár
Keyword(s):  
Transport Processes ◽  
Optimization Process ◽  
Objective Functions ◽  
Formation Model ◽  
Unit Load ◽  
Multi Level ◽  
Major Factors

One of the most important issues in storage and transport processes is the formation of unit loads. Our main goal is to investigate the homogeneous and multi-level unit load formation cases. We give a model involving the major factors and parameters of the unit load formations. The optimization process is introduced using the formulated objective functions and constraints related to the basic tasks. The aim of the optimization process is to maximize the volume of goods that can fit into the unit load formation equipment.

Full Three-Dimensional Optimization Platform of Turbine Blades Considering the Film Cooling

2013 ◽  
Author(s):  
Shaopeng Lu ◽  
Zhongran Chi ◽  
Songtao Wang ◽  
Fengbo Wen ◽  
Guotai Feng
Keyword(s):  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Optimization Process ◽  
Pareto Optimal ◽  
Cooling Efficiency ◽  
Objective Functions ◽  
Nsga Ii ◽  
Aerodynamic Efficiency ◽  
Film Cooling Efficiency

In this paper, an optimization platform was established with Isight, cfx and the self-programming program which is used to generate the mesh. Film cooling effect can be taken into account. 15 parameters are selected as optimization variables. During the optimization process, the baseline blade and cooling holes are given by parameterized method. There are two objective functions during the optimization process. The first one is aerodynamic efficiency and the second one is film cooling efficiency. As there are two objective functions, NSGA-II is chosen as the multi-objective optimization algorithm. Then the Pareto-optimal front can be got. The results show that aerodynamic efficiency and film cooling efficiency restrict each other. It’s impossible to get the best solutions in one example, so the Pareto optimal set can provide a lot of choices. Different shapes make different effects on the aerodynamic efficiency and film cooling efficiency. From the above, it can be seen that the platform is helpful especially in the case that aerodynamic efficiency and film cooling efficiency restrict each other. This paper also discusses the prospects for platform applications.

A Framework for Energy-Based Kinetostatic Modeling of Compliant Mechanisms

2017 ◽  
Author(s):  
Guimin Chen ◽  
Fulei Ma ◽  
Ruiyu Bai ◽  
Spencer P. Magleby ◽  
Larry L. Howell
Keyword(s):  
Strain Energy ◽  
Compliant Mechanisms ◽  
Modeling Framework ◽  
Geometric Nonlinearities ◽  
Complementary Strain ◽  
Minimum Strain Energy ◽  
Constraint Model ◽  
Future Work

Although energy-based methods have advantages over the Newtonian methods for kinetostatic modeling, the geometric nonlinearities inherent in deflections of compliant mechanisms preclude most of the energy-based theorems. Castigliano’s first theorem and the Crotti-Engesser theorem, which don’t require the problem being solved to be linear, are selected to construct the energy-based kinetostatic modeling framework for compliant mechanisms in this work. Utilization of these two theorems requires explicitly formulating the strain energy in terms of deflections and the complementary strain energy in terms of loads, which are derived based on the beam constraint model. The kinetostatic modeling of two compliant mechanisms are provided to demonstrate the effectiveness of using Castigliano’s first theorem and the Crotti-Engesser theorem with the explicit formulations in this framework. Future work will be focused on incorporating use of the principle of minimum strain energy and the principle of minimum complementary strain energy.

scholarly journals An Energy-Based Framework for Nonlinear Kinetostatic Modeling of Compliant Mechanisms Utilizing Beam Flexures

2021 ◽  
pp. 1-18
Author(s):  
Guimin Chen ◽  
Fulei Ma ◽  
Ruiyu Bai ◽  
Weidong Zhu ◽  
Spencer P Magleby ◽  
...  
Keyword(s):  
Strain Energy ◽  
Compliant Mechanisms ◽  
Modeling Framework ◽  
Geometric Nonlinearities ◽  
Complementary Strain ◽  
Constraint Model

Abstract Although energy-based methods have advantages over the Newtonian methods for kinetostatic modeling, the geometric nonlinearities inherent in deflections of compliant mechanisms preclude most of the energy-based theorems. Castigliano's first theorem and the Crotti-Engesser theorem, which don't require the problem being solved to be linear, are selected to construct the energy-based kinetostatic modeling framework for compliant mechanisms in this work. Utilization of these two theorems requires explicitly formulating the strain energy in terms of deflections and the complementary strain energy in terms of loads, which are derived based on the beam constraint model. The kinetostatic modeling of two compliant mechanisms are provided to demonstrate the effectiveness of the explicit formulations in this framework derived from Castigliano's first theorem and the Crotti-Engesser theorem.

scholarly journals Award winning first Hungarian active house refurbishment

2020 ◽  
Vol 15 (2) ◽  
pp. 233-244
Author(s):  
Kristóf Roland Horváth ◽  
István Kistelegdi
Keyword(s):  
Energy Performance ◽  
Building Envelope ◽  
Interior Space ◽  
Building Shape ◽  
Award Winning ◽  
Space Organization ◽  
Final Design ◽  
Calculation Results ◽  
Thermal Simulations ◽  
Insight Into

Abstract:First Hungarian Active House refurbishment won the Active House Award and the Energy Globe Hungary prize in 2017. This paper provides insight into the renewal design process of the typical home from the 70’s under disadvantageous site conditions. Dynamic thermal simulations helped to gain insight into space organization and building envelope concepts and their effects on comfort and energy performance. The Active House Standard was applied to evaluate the calculation results. The most advantageous concept was selected for final design elaboration and construction. The implemented building proved that in the refurbishment process it is possible to achieve highest level of efficiency in operation energy consumption with positive yearly balance by simultaneously being able to rearrange the complete interior space and as a consequence the building shape and envelope into a competitive design at international level.

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