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Sridhar Kota - One of the best experts on this subject based on the ideXlab platform.

  • DETC2003/DAC-48775 PARAMETERIZATION STRATEGY FOR OPTIMIZATION OF SHAPE MORPHING Compliant Mechanisms USING LOAD PATH REPRESENTATION
    2020
    Co-Authors: Sridhar Kota
    Abstract:

    ABSTRACT The distributed compliance and smooth deformation field of Compliant Mechanisms provide a viable means to achieve shape morphing in many systems, such as flexible antenna reflectors and morphing aircraft wings. We previously developed a systematic synthesis approach to design shape morphing Compliant Mechanisms using Genetic Algorithm (GA). However, the design variable definition, in fact, allows the generation of invalid designs (disconnected structures) within the GA. In this research, we developed a load path representation to include the structure connectivity information into the design variables, thus improving the GA efficiency. The number of design variables is also independent of the number of elements in the finite element model that is used to solve for the structural deformation. The shape morphing synthesis approach, incorporating this path representation, is demonstrated through two examples, followed by discussions on further refinements

  • load transmitter constraint sets part ii a building block based methodology for the synthesis of Compliant Mechanisms
    ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference IDETC CIE2010, 2010
    Co-Authors: Girish Krishnan, Sridhar Kota
    Abstract:

    Designers have always conceptualized of load flow as a part of their initial design process for Mechanisms and structures. However, the lack of mathematical representation of load flow makes it inappropriate to be included in systematic design processes. Load Transmitter Constraint (LTC) sets provide a mathematical framework for visualizing load paths in Compliant Mechanisms. In this paper we propose a systematic design methodology for Compliant Mechanisms by systematic combination of LTC sets. This enables the designer to conceptualize load flow and choose relevant LTC sets to enforce it. Apart from being intuitive this process gives an understanding of the importance of each member in the mechanism. Furthermore this theory enables accurate and deterministic design for given motion specification without the aid of extensive computation. In this paper we propose guidelines for the design of Mechanisms with a single load flow path and multi load flow path, particularly relevant in shape morphing applications.Copyright © 2010 by ASME

  • design of Compliant Mechanisms for minimizing input power in dynamic applications
    Journal of Mechanical Design, 2007
    Co-Authors: Tanakorn Tantanawat, Sridhar Kota
    Abstract:

    In this paper, we investigate power flow in Compliant Mechanisms that are employed in dynamic applications. More specifically, we identify various elements of the energy storage and transfer between the input, external load, and strain energy stored within the Compliant transmission. The goal is to design Compliant Mechanisms for dynamic applications by exploiting the inherent energy storage capability of Compliant Mechanisms in the most effective manner. We present a detailed case study on a flapping mechanism, in which we compare the peak input power requirement in a rigid-body mechanism with attached springs versus a distributed Compliant mechanism. Through this case study, we present two approaches: (1) generative-load exploitation and (2) reactance cancellation, to describe the role of stored elastic energy in reducing the peak input power requirement. We propose a Compliant flapping mechanism and its evaluation using nonlinear transient analysis. The input power needed to drive the proposed Compliant flapping mechanism is found to be 50% less than a rigid-link four-bar flapping mechanism without a spring, and 15% less than the one with a spring. This reduction of peak input power is primarily due to the exploitation of elasticity in Compliant members. The results show that a Compliant mechanism can be a better alternative to a rigid-body mechanism with attached springs. DOI: 10.1115/1.2756086

  • topology and dimensional synthesis of Compliant Mechanisms using discrete optimization
    Journal of Mechanical Design, 2006
    Co-Authors: Kerr Jia Lu, Sridhar Kota
    Abstract:

    A unified approach to topology and dimensional synthesis of Compliant Mechanisms is presented in this paper as a discrete optimization problem employing both discrete (topology) and continuous (size) variables. The synthesis scheme features a design parameterization method that treats load paths as discrete design variables to represent various topologies, thereby ensuring structural connectivity among the input, output, and ground supports. The load path synthesis approach overcomes certain design issues, such as "gray areas" and disconnected structures, inherent in previous design schemes. Additionally, multiple gradations of structural resolution and a variety of configurations can be generated without increasing the number of design variables. By treating topology synthesis as a discrete optimization problem, the synthesis approach is incorporated in a genetic algorithm to search for feasible topologies for single-input single-output Compliant Mechanisms. Two design examples, commonly seen in the Compliant Mechanisms literature, are included to illustrate the synthesis procedure and to benchmark the performance. The results show that the load path synthesis approach can effectively generate well-connected Compliant mechanism designs that are free of gray areas.

  • design of Compliant Mechanisms for minimizing input power in dynamic applications
    2006 ASME International Design Engineering Technical Conferences and Computers and Information In Engineering Conference DETC2006, 2006
    Co-Authors: Tanakorn Tantanawat, Sridhar Kota
    Abstract:

    In this paper, we investigate power flow in Compliant Mechanisms that are employed in dynamic applications. More specifically, we identify various elements of the energy storage and transfer between the input, external load, and the strain energy stored within the Compliant transmission. The goal is to design complaint Mechanisms for dynamic applications by exploiting the inherent energy storage capability of Compliant Mechanisms in the most effective manner. We present a detailed case study on a flapping mechanism in which we compare the peak input power requirement in a rigid-body mechanism with attached springs versus a distributed Compliant mechanism. Through this case study, we present two different approaches, (1) generative-load exploitation and (2) reactance cancellation, to describe the role of stored elastic energy in reducing the required input power. In contrast to a conventional mechanism with a spring, stress and strain in a Compliant mechanism are more uniformly distributed. The entire mechanism stores energy rather than just a spring, providing more energy storage per unit mass. We propose a Compliant flapping mechanism and its evaluation using nonlinear transient analysis. The input power requirement of the proposed Compliant flapping mechanism is found to be 48% and 10% less than those of the four-bar flapping mechanism without and with a spring, respectively. The results show that a Compliant mechanism can be a better alternative to a rigid-body mechanism with attached springs.Copyright © 2006 by ASME

Liyong Tong - One of the best experts on this subject based on the ideXlab platform.

  • A new multi-objective programming scheme for topology optimization of Compliant Mechanisms
    Structural and Multidisciplinary Optimization, 2009
    Co-Authors: Jiangzi Lin, Zhen Luo, Liyong Tong
    Abstract:

    This paper presents an alternative method in implementing multi-objective optimization of Compliant Mechanisms in the field of continuum-type topology optimization. The method is designated as “SIMP-PP” and it achieves multi-objective topology optimization by merging what is already a mature topology optimization method—solid isotropic material with penalization (SIMP) with a variation of the robust multi-objective optimization method—physical programming (PP). By taking advantages of both sides, the combination causes minimal variation in computation algorithm and numerical scheme, yet yields improvements in the multi-objective handling capability of topology optimization. The SIMP-PP multi-objective scheme is introduced into the systematic design of Compliant Mechanisms. The final optimization problem is formulated mathematically using the aggregate objective function which is derived from the original individual design objectives with PP, subjected to the specified constraints. A sequential convex programming method, the method of moving asymptotes (MMA) is then utilized to process the optimization evolvement based on the design sensitivity analysis. The main findings in this study include distinct advantages of the SIMP-PP method in various aspects such as computation efficiency, adaptability in convex and non-convex multi-criteria environment, and flexibility in problem formulation. Observations are made regarding its performance and the effect of multi-objective optimization on the final topologies. In general, the proposed SIMP-PP method is an appealing multi-objective topology optimization scheme suitable for “real world” problems, and it bridges the gap between standard topological design and multi-criteria optimization. The feasibility of the proposed topology optimization method is exhibited by benchmark examples.

  • a new level set method for systematic design of hinge free Compliant Mechanisms
    Computer Methods in Applied Mechanics and Engineering, 2008
    Co-Authors: Shikui Chen, Liyong Tong, Michael Yu Wang
    Abstract:

    Abstract This paper presents a new level set-based method to realize shape and topology optimization of hinge-free Compliant Mechanisms. A quadratic energy functional used in image processing applications is introduced in the level set method to control the geometric width of structural components in the created mechanism. A semi-implicit scheme with an additive operator splitting (AOS) algorithm is employed to solve the Hamilton–Jacobi partial differential equation (PDE) in the level set method. The design of Compliant Mechanisms is mathematically represented as a general non-linear programming with a new objective function augmented by the high-order energy term. The structural optimization is thus changed to a numerical process that describes the design as a sequence of motions by updating the implicit boundaries until the optimized structure is achieved under specified constraints. In doing so, it is expected that numerical difficulties such as the Courant–Friedrichs–Lewy (CFL) condition and periodically applied re-initialization procedures in most conventional level set methods can be eliminated. In addition, new holes can be created inside the design domain. The final mechanism configurations consist of strip-like members suitable for generating distributed compliance, and solving the de-facto hinge problem in the design of Compliant Mechanisms. Two widely studied numerical examples are studied to demonstrate the effectiveness of the proposed method in the context of designing distributed Compliant Mechanisms.

  • shape and topology optimization of Compliant Mechanisms using a parameterization level set method
    Journal of Computational Physics, 2007
    Co-Authors: Liyong Tong, Michael Yu Wang, Shengyin Wang
    Abstract:

    In this paper, a parameterization level set method is presented to simultaneously perform shape and topology optimization of Compliant Mechanisms. The structural shape boundary is implicitly embedded into a higher-dimensional scalar function as its zero level set, resultantly, establishing the level set model. By applying the compactly supported radial basis function with favorable smoothness and accuracy to interpolate the level set function, the temporal and spatial Hamilton-Jacobi equation from the conventional level set method is then discretized into a series of algebraic equations. Accordingly, the original shape and topology optimization is now fully transformed into a parameterization problem, namely, size optimization with the expansion coefficients of interpolants as a limited number of design variables. Design of Compliant Mechanisms is mathematically formulated as a general optimization problem with a nonconvex objective function and two additionally specified constraints. The structural shape boundary is then advanced as a process of renewing the level set function by iteratively finding the expansion coefficients of the size optimization with a sequential convex programming method. It is highlighted that the present method can not only inherit the merits of the implicit boundary representation, but also avoid some unfavorable features of the conventional discrete level set method, such as the CFL condition restriction, the re-initialization procedure and the velocity extension algorithm. Finally, an extensively investigated example is presented to demonstrate the benefits and advantages of the present method, especially, its capability of creating new holes inside the design domain.

Michael Yu Wang - One of the best experts on this subject based on the ideXlab platform.

  • a new level set method for systematic design of hinge free Compliant Mechanisms
    Computer Methods in Applied Mechanics and Engineering, 2008
    Co-Authors: Shikui Chen, Liyong Tong, Michael Yu Wang
    Abstract:

    Abstract This paper presents a new level set-based method to realize shape and topology optimization of hinge-free Compliant Mechanisms. A quadratic energy functional used in image processing applications is introduced in the level set method to control the geometric width of structural components in the created mechanism. A semi-implicit scheme with an additive operator splitting (AOS) algorithm is employed to solve the Hamilton–Jacobi partial differential equation (PDE) in the level set method. The design of Compliant Mechanisms is mathematically represented as a general non-linear programming with a new objective function augmented by the high-order energy term. The structural optimization is thus changed to a numerical process that describes the design as a sequence of motions by updating the implicit boundaries until the optimized structure is achieved under specified constraints. In doing so, it is expected that numerical difficulties such as the Courant–Friedrichs–Lewy (CFL) condition and periodically applied re-initialization procedures in most conventional level set methods can be eliminated. In addition, new holes can be created inside the design domain. The final mechanism configurations consist of strip-like members suitable for generating distributed compliance, and solving the de-facto hinge problem in the design of Compliant Mechanisms. Two widely studied numerical examples are studied to demonstrate the effectiveness of the proposed method in the context of designing distributed Compliant Mechanisms.

  • shape and topology optimization of Compliant Mechanisms using a parameterization level set method
    Journal of Computational Physics, 2007
    Co-Authors: Liyong Tong, Michael Yu Wang, Shengyin Wang
    Abstract:

    In this paper, a parameterization level set method is presented to simultaneously perform shape and topology optimization of Compliant Mechanisms. The structural shape boundary is implicitly embedded into a higher-dimensional scalar function as its zero level set, resultantly, establishing the level set model. By applying the compactly supported radial basis function with favorable smoothness and accuracy to interpolate the level set function, the temporal and spatial Hamilton-Jacobi equation from the conventional level set method is then discretized into a series of algebraic equations. Accordingly, the original shape and topology optimization is now fully transformed into a parameterization problem, namely, size optimization with the expansion coefficients of interpolants as a limited number of design variables. Design of Compliant Mechanisms is mathematically formulated as a general optimization problem with a nonconvex objective function and two additionally specified constraints. The structural shape boundary is then advanced as a process of renewing the level set function by iteratively finding the expansion coefficients of the size optimization with a sequential convex programming method. It is highlighted that the present method can not only inherit the merits of the implicit boundary representation, but also avoid some unfavorable features of the conventional discrete level set method, such as the CFL condition restriction, the re-initialization procedure and the velocity extension algorithm. Finally, an extensively investigated example is presented to demonstrate the benefits and advantages of the present method, especially, its capability of creating new holes inside the design domain.

  • shape and topology optimization for Compliant Mechanisms using level set based parameterization method
    2007
    Co-Authors: Michael Yu Wang
    Abstract:

    A new parameterization approach 1 for optimal synthesis of Compliant Mechanisms using level set-based shape and topology optimization approach is presented in this work. The structural free design boundary is implicitly represented by embedding into a higher-dimensional scalar function as its zero level set. The compactly supported radial basis function with a favourable smoothness is introduced to construct the trial func- tion. Structural optimization is advanced by iteratively evaluat- ing the optimization problem using a sequential convex pro- gramming scheme. The coefficients together with the collection matrix of the radial basis functions are then utilized to renew the level set function by performing the size optimization. Therefore, the presented method is capable of addressing shape fidelity and topology changes simultaneously, especially with the capability of keeping design boundary smooth during the optimization process. Optimal synthesis of Compliant Mechanisms is applied to demonstrate the potentials, in which the mechanical efficiency is treated as the objective function, while the limitation of the maximal input displacement and the prescribed material usage are treated as two global constraints to further narrow the de- sign domain. A benchmark example is applied to demonstrate the benefits and the advantages of the proposed method.

Xianmin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Design of Compliant Mechanisms using continuum topology optimization: A review
    Mechanism and Machine Theory, 2020
    Co-Authors: Benliang Zhu, Xianmin Zhang, Hongchuan Zhang, Junwen Liang, Haoyan Zang, Rixin Wang
    Abstract:

    Abstract Compliant Mechanisms have become an important branch of modern Mechanisms. Unlike conventional rigid body Mechanisms, Compliant Mechanisms transform the displacement and force at least partly through the deformation of their structural components, which can offer a great reduction in friction, lubrication and assemblage. Therefore, Compliant Mechanisms are particularly suitable for applications in microscale/nanoscale manipulation systems. The significant demand of practical applications has also promoted the development of systematic design methods for Compliant Mechanisms. Several methods have been developed to design Compliant Mechanisms. In this paper, we focus on the continuum topology optimization methods and present a survey of the state-of-the-art design advances in this research area over the past 20 years. The presented overview can be helpful to those engaged in the topology optimization of Compliant Mechanisms who desire to be apprised of the field’s recent state and research tendency.

  • topological synthesis of Compliant Mechanisms using a level set based robust formulation
    International Conference on Intelligent Robotics and Applications, 2019
    Co-Authors: Benliang Zhu, Xianmin Zhang, Mohui Jin, Hongchuan Zhang
    Abstract:

    Topology optimized Compliant Mechanisms have been widely utilized as the microdevices in microelectromechanical system. In applying topology optimization to design Compliant Mechanisms, one of the longstanding problems is that the obtained Mechanisms often have highly localized compliance regions which make them very difficult to fabricate. In order to obtain manufacturable topology optimized Compliant Mechanisms, this paper presents a robust formulation based on the level set method. In the formulation, the goal is to maximize the objective for the worst case of three different structural configurations which are represented by three different level set functions. Not only the formulation can eliminate the highly localized compliance regions, it also can precisely control the minimum length scale in the obtained Mechanisms. The validity and different aspects of the proposed formulation are demonstrated on several benchmark problems.

  • design and analysis of a multi notched flexure hinge for Compliant Mechanisms
    Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2017
    Co-Authors: Min Liu, Xianmin Zhang, Sergej Fatikow
    Abstract:

    Abstract This article presents a new multi-notched flexure hinge, which consists of two right circular and two parabolic notches, for positioning stages based on Compliant Mechanisms. First, the configuration of the presented multi-notched hinge is obtained using topology optimization, and the final shape is proposed based on post-processing. Second, the dimensionless empirical equations for the stiffness, rotational precision and stress levels of the flexure hinges are developed using finite element analysis (FEA). Third, based on the established equations, the influences of the geometric parameters on the performance of the flexure hinge are investigated. Finally, to further understand the characteristics of this type of flexure hinge, comparisons with flexure hinges of various shapes are performed in terms of stiffness, rotational precision and stress levels.

  • A numerical method for static analysis of pseudo-rigid-body model of Compliant Mechanisms
    Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2014
    Co-Authors: Mohui Jin, Xianmin Zhang, Benliang Zhu
    Abstract:

    This paper presents a numerical method for analyzing the pseudo-rigid-body model of Compliant Mechanisms based on finite elements and the principle of minimum potential energy. The proposed method ...

  • topology optimization of hinge free Compliant Mechanisms with multiple outputs using level set method
    Structural and Multidisciplinary Optimization, 2013
    Co-Authors: Benliang Zhu, Xianmin Zhang, Nianfeng Wang
    Abstract:

    A method for topology optimization of hinge-free Compliant Mechanisms with multiple outputs using level set method is presented in this paper. The focus of this paper is on how to prevent generating the flexible hinges during the process of topology optimization of Compliant Mechanisms. In the proposed method, two types of mean compliances are introduced and built in the proposed multi-objective function for topology optimization of hinge-free Compliant Mechanisms with multiple outputs, therefore, the spring model widely used for topology optimization of Compliant Mechanisms is no longer needed. Some numerical examples are presented to illustrate the validity of the proposed method.

Benliang Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Design of Compliant Mechanisms using continuum topology optimization: A review
    Mechanism and Machine Theory, 2020
    Co-Authors: Benliang Zhu, Xianmin Zhang, Hongchuan Zhang, Junwen Liang, Haoyan Zang, Rixin Wang
    Abstract:

    Abstract Compliant Mechanisms have become an important branch of modern Mechanisms. Unlike conventional rigid body Mechanisms, Compliant Mechanisms transform the displacement and force at least partly through the deformation of their structural components, which can offer a great reduction in friction, lubrication and assemblage. Therefore, Compliant Mechanisms are particularly suitable for applications in microscale/nanoscale manipulation systems. The significant demand of practical applications has also promoted the development of systematic design methods for Compliant Mechanisms. Several methods have been developed to design Compliant Mechanisms. In this paper, we focus on the continuum topology optimization methods and present a survey of the state-of-the-art design advances in this research area over the past 20 years. The presented overview can be helpful to those engaged in the topology optimization of Compliant Mechanisms who desire to be apprised of the field’s recent state and research tendency.

  • topological synthesis of Compliant Mechanisms using a level set based robust formulation
    International Conference on Intelligent Robotics and Applications, 2019
    Co-Authors: Benliang Zhu, Xianmin Zhang, Mohui Jin, Hongchuan Zhang
    Abstract:

    Topology optimized Compliant Mechanisms have been widely utilized as the microdevices in microelectromechanical system. In applying topology optimization to design Compliant Mechanisms, one of the longstanding problems is that the obtained Mechanisms often have highly localized compliance regions which make them very difficult to fabricate. In order to obtain manufacturable topology optimized Compliant Mechanisms, this paper presents a robust formulation based on the level set method. In the formulation, the goal is to maximize the objective for the worst case of three different structural configurations which are represented by three different level set functions. Not only the formulation can eliminate the highly localized compliance regions, it also can precisely control the minimum length scale in the obtained Mechanisms. The validity and different aspects of the proposed formulation are demonstrated on several benchmark problems.

  • A numerical method for static analysis of pseudo-rigid-body model of Compliant Mechanisms
    Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2014
    Co-Authors: Mohui Jin, Xianmin Zhang, Benliang Zhu
    Abstract:

    This paper presents a numerical method for analyzing the pseudo-rigid-body model of Compliant Mechanisms based on finite elements and the principle of minimum potential energy. The proposed method ...

  • topology optimization of hinge free Compliant Mechanisms with multiple outputs using level set method
    Structural and Multidisciplinary Optimization, 2013
    Co-Authors: Benliang Zhu, Xianmin Zhang, Nianfeng Wang
    Abstract:

    A method for topology optimization of hinge-free Compliant Mechanisms with multiple outputs using level set method is presented in this paper. The focus of this paper is on how to prevent generating the flexible hinges during the process of topology optimization of Compliant Mechanisms. In the proposed method, two types of mean compliances are introduced and built in the proposed multi-objective function for topology optimization of hinge-free Compliant Mechanisms with multiple outputs, therefore, the spring model widely used for topology optimization of Compliant Mechanisms is no longer needed. Some numerical examples are presented to illustrate the validity of the proposed method.

  • a new level set method for topology optimization of distributed Compliant Mechanisms
    International Journal for Numerical Methods in Engineering, 2012
    Co-Authors: Benliang Zhu, Xianmin Zhang
    Abstract:

    SUMMARY A new level set method for topology optimization of distributed Compliant mechanism is presented in this study. By taking two types of mean compliance into consideration, several new objective functions are developed and built in the conventional level set method to avoid generating the de facto hinges in the created Mechanisms. Aimed at eliminating the costly reinitialization procedure during the evolution of the level set function, an accelerated level set evolution algorithm is developed by adding an extra energy function, which can force the level set function to close to a signed distance function during the evolution. Two widely studied numerical examples in topology optimization of Compliant Mechanisms are studied to demonstrate the effectiveness of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.