A Study on the Design of Large Displacement Compliant Mechanisms with a Strength Criteria Using Topology Optimization

Leon, Daniel M. De; Gonçalves, Juliano F.; Souza, Carlos E. de

doi:10.1007/978-3-319-67988-4_72

Cited by 3 publications

(5 citation statements)

References 25 publications

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“…De Leon et al [28] as well as Conlan-Smith [29] implemented stress constraints in the synthesis of compliant mechanisms with topology optimization, albeit only for linear finite-element analysis. This was then expanded in the work by De Leon et al [30] for nonlinear finite-element analysis and was applied to the maximum displacement objective. A further problem is that stress is a field variable varying for each element and hence necessitating for a large number of constraints.…”

Section: Problem Type IImentioning

confidence: 99%

“…Several approaches to resolve this issue are reported in literature. Bruns and Tortorelli [42] and De Leon et al [30] suggested to use hyperelastic material laws with increased stiffness at high deformations instead of the Saint Venant-Kirchhoff law. Pedersen et al [14] reported, that the approach of Bruns and Tortorelli was unsuccessful resolving the issues for their numerical examples.…”

Section: Design Variables and Their Stabilizationmentioning

confidence: 99%

“…The sensitivity functions of the stress constraint Equation ( 27) are changed if multiresolution topology optimization is used. Due to the use of the stress values σ C,i,j at each integration point (or subelement) j, the p-norm function changes to Equation (30). This affects the partial derivative of the normalized p-norm which for the MTOP approach is written as…”

Section: Sensitivity Analysis For Multiresolution Topology Optimizationmentioning

confidence: 99%

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Multiresolution Topology Optimization of Large-Deformation Path-Generation Compliant Mechanisms with Stress Constraints

2021

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Topology optimization is a powerful numerical tool in the synthesis of lightweight structures and compliant mechanisms. Compliant mechanisms present challenges for topology optimization, as they typically exhibit large displacements and rotations. Path-generation mechanisms are a class of mechanisms that are designed to follow an exact path. The characteristics of compliant mechanisms therefore exclude the validity of linear finite-element analysis to ensure the proper modeling of deformation and stresses. As stresses can exceed the limit when neglected, stress constraints are needed in the synthesis of compliant mechanisms. Both nonlinear finite-element analysis as well as the consideration of stress constraints significantly increase computational cost of topology optimization. Multiresolution topology optimization, which employs different levels of discretization for the finite-element analysis and the representation of the material distribution, allows an important reduction of computational effort. A multiresolution topology optimization methodology is proposed integrating stress constraints based on nonlinear finite-element analysis for path-generation mechanisms. Two objective formulations are used to motivate and validate this methodology: maximum-displacement mechanisms and path-generation mechanisms. The formulation of the stress constraints and their sensitivities within nonlinear finite-element analysis and multiresolution topology optimization are explained. We introduce two academic benchmark examples to demonstrate the results for each of the objective formulations. To show the practical, large-scale application of this method, results for the compliant mechanism structure of a droop-nose morphing wing concept are shown.

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Section: Problem Type IImentioning

confidence: 99%

Section: Design Variables and Their Stabilizationmentioning

confidence: 99%

Section: Sensitivity Analysis For Multiresolution Topology Optimizationmentioning

confidence: 99%

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Multiresolution Topology Optimization of Large-Deformation Path-Generation Compliant Mechanisms with Stress Constraints

2021

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“…Many stress constraint schemes 46,47,[65][66][67][68][69][70][71][72] also were adopted to prevent the formulation of hinges. A global stress constraint was used in de Leon et al 67 in order to alleviate one-node hinges, resulting in very thin compliant regions replacing the hinges.…”

Section: Introductionmentioning

confidence: 99%

“…A disadvantage of the stress constraint schemes is that the maximum von-Mises stress and structural volume largely change at some iterations during an early optimization process. 71,72 Sigmund 73 and Lazarov et al 44,74 proposed the use of both erode and dilate operators to simulate the uncertainties associated to the fabrication of compliant mechanisms, as a worst case design problem, and the results obtained have no hinges and no gray regions. Lin et al 75 and Lee et al, 76 respectively, proposed a strain energy based topology optimization method, reducing localized high strain in compliant joints, thus hindering the appearance of hinges.…”

Section: Introductionmentioning

confidence: 99%

A new method for optimizing the topology of hinge‐free and fully decoupled compliant mechanisms with multiple inputs and multiple outputs

Rong

Luo

et al. 2021

Numerical Meth Engineering

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Compliant mechanisms with multiple inputs and multiple outputs have a wide range of applications in precision mechanics, for example, cell manipulations, electronic microscopes, and so on. The movement uncoupling and maximum desired output displacements among these devices all become critical because many inputs and outputs are involved. The topology optimization design of compliant mechanisms, which can solve output coupling and input coupling problems, hinge and gray region problems, and the multiple-objective optimal problem, is an important topic of researches for achieving fully decoupled motion. It is also a challenge area of research due to serious conflicts of between the four of output and input uncoupling constraints, volume constraint, the hinge-free requirement, and the good black/white solution requirement. In order to comprehensively solve these problems, a simple optimization model overcoming these serious conflicts is posed, which includes small change rate constraints of structural compliances corresponding to the driving input loads and output point virtual loads. Then, the multiple output displacement functions of the model are equivalently converted into non-negative functions. The multiple-objective model is converted into a single-objective optimization model by using a bound variable. The method of moving asymptotes (MMA) algorithm is adopted to solve it. Several examples are presented to demonstrate the validity of the proposed method.

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Never better than 5/6: The fundamental limit of energy absorption efficiency for negative-stiffness curved-beam honeycombs

Liu,

Mehreganian,

Sareh

2024

Materials & Design

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A Study on the Design of Large Displacement Compliant Mechanisms with a Strength Criteria Using Topology Optimization

Cited by 3 publications

References 25 publications

Multiresolution Topology Optimization of Large-Deformation Path-Generation Compliant Mechanisms with Stress Constraints

Multiresolution Topology Optimization of Large-Deformation Path-Generation Compliant Mechanisms with Stress Constraints

A new method for optimizing the topology of hinge‐free and fully decoupled compliant mechanisms with multiple inputs and multiple outputs

Never better than 5/6: The fundamental limit of energy absorption efficiency for negative-stiffness curved-beam honeycombs

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