Topology Optimization of Compliant Mechanisms Explicitly Considering Desired Kinematics and Stiffness Constraints

2016 ◽  
Author(s):  
Alexander Hasse
Keyword(s):  
Strain Energy ◽  
Compliant Mechanisms ◽  
Single Input Single Output ◽  
Output Displacement ◽  
Single Output ◽  
Input And Output ◽  
Optimization Formulation ◽  
Topology And Shape Optimization ◽  
Optimization Parameters ◽  
Single Input

A mechanism is designed to transform forces and/or displacements from an input to one or multiple outputs. This transformation is essentially ruled by the kinematics, i.e. the defined ratio between input and output displacements. Although the kinematics forms the basis for the design of conventional mechanisms, approaches for the topology and shape optimization of compliant mechanisms do not normally explicitly include the kinematics in their optimization formulation. The kinematics is more or less an outcome of the optimization process. A defined kinematics can only be realized by iteratively adjusting process-specific optimization parameters within the optimization formulation. Moreover, existing approaches normally minimize the strain energy that is stored in the compliant mechanisms according to a defined input and output displacement — although in some applications a certain amount of strain energy is required. This paper presents a new optimization formulation that solves the aforementioned problems. It is based on the principles of designing compliant mechanisms with selective compliance formerly presented by the author. The formulation is derived by means of an intensive workup of the design problem of compliant mechanisms. The method is validated for different design examples ranging from standard single-input/single-output mechanisms (force inverters) to multi-output mechanisms (shape-adaptive structures).

A Metric to Evaluate and Synthesize Distributed Compliant Mechanisms

2011 ◽  
Author(s):  
Girish Krishnan ◽  
Charles Kim ◽  
Sridhar Kota
Keyword(s):  
Range Of Motion ◽  
Cross Sections ◽  
Strain Energy ◽  
Compliant Mechanisms ◽  
Single Point ◽  
Single Input Single Output ◽  
Single Output ◽  
Physical Insight ◽  
Single Input ◽  
Flexural Hinges

It is widely accepted that compliant mechanisms with stresses distributed evenly throughout its geometry have better load bearing ability and larger range of motion than mechanisms with compliance and stresses lumped at flexural hinges. In this paper, we present a metric to quantify how uniformly stresses and thus strain energy is distributed throughout the mechanism topology. The resulting metric is used to optimize the cross-sections of conceptual compliant topologies leading to designs with maximal distribution of stresses. This optimization framework is demonstrated for both single point mechanisms and single-input single-output mechanisms. It is observed that the optimized designs have a larger range of motion and perform more output work or store more strain energy before failure than their non-optimized counterparts. Furthermore, the nondimensional nature of the metric coupled with the physical insight enables an objective comparison of various topologies and actuation schemes based on how evenly stresses are distributed in the constituent members.

A Metric to Evaluate and Synthesize Distributed Compliant Mechanisms

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Girish Krishnan ◽  
Charles Kim ◽  
Sridhar Kota
Keyword(s):  
Cross Sections ◽  
Strain Energy ◽  
Compliant Mechanisms ◽  
Single Port ◽  
Single Input Single Output ◽  
Optimization Framework ◽  
Single Output ◽  
Maximal Stress ◽  
Single Input ◽  
Flexural Hinges

Compliant mechanisms with evenly distributed stresses have better load-bearing ability and larger range of motion than mechanisms with compliance and stresses lumped at flexural hinges. In this paper, we present a metric to quantify how uniformly the strain energy of deformation and thus the stresses are distributed throughout the mechanism topology. The resulting metric is used to optimize cross-sections of conceptual compliant topologies leading to designs with maximal stress distribution. This optimization framework is demonstrated for both single-port mechanisms and single-input single-output mechanisms. It is observed that the optimized designs have lower stresses than their nonoptimized counterparts, which implies an ability for single-port mechanisms to store larger strain energy, and single-input single-output mechanisms to perform larger output work before failure.

Decomposition Strategies for the Synthesis of Single Input-Single Output and Dual Input-Single Output Compliant Mechanisms

2007 ◽  
Author(s):  
Charles Kim
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Single Point ◽  
Building Blocks ◽  
New Method ◽  
Single Input Single Output ◽  
Single Output ◽  
Alternative Method ◽  
Decomposition Strategies ◽  
Single Input

In this paper a new method for the synthesis of compliant mechanism topologies is presented which involves the decomposition of motion requirements into more easily solved sub-problems. The decomposition strategies are presented and demonstrated for both single input-single output (SISO) and dual input-single output (DISO) planar compliant mechanisms. The methodology makes use of the single point synthesis (SPS) which effectively generates topologies which satisfy motion requirements at one point by assembling compliant building blocks. The SPS utilizes compliance and stiffness ellipsoids to characterize building blocks and to combine them in an intelligent manner. Both the SISO and DISO problems are decomposed into sub-problems which may be addressed by the SPS. The decomposition strategies are demonstrated with illustrative example problems. This paper presents an alternative method for the synthesis of compliant mechanisms which augments designer insight.

Design of Single-Input-Single-Output Compliant Mechanisms for Practical Applications Using Selection Maps

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Sudarshan Hegde ◽  
G. K. Ananthasuresh
Keyword(s):  
Compliant Mechanisms ◽  
Material Selection ◽  
Design Procedure ◽  
Single Input Single Output ◽  
Practical Applications ◽  
Beam Elements ◽  
Single Output ◽  
Out Of Plane ◽  
Single Input ◽  
Interactive Map

We present an interactive map-based technique for designing single-input-single-output compliant mechanisms that meet the requirements of practical applications. Our map juxtaposes user-specifications with the attributes of real compliant mechanisms stored in a database so that not only the practical feasibility of the specifications can be discerned quickly but also modifications can be done interactively to the existing compliant mechanisms. The practical utility of the method presented here exceeds that of shape and size optimizations because it accounts for manufacturing considerations, stress limits, and material selection. The premise for the method is the spring-leverage (SL) model, which characterizes the kinematic and elastostatic behavior of compliant mechanisms with only three SL constants. The user-specifications are met interactively using the beam-based 2D models of compliant mechanisms by changing their attributes such as: (i) overall size in two planar orthogonal directions, separately and together, (ii) uniform resizing of the in-plane widths of all the beam elements, (iii) uniform resizing of the out-of-plane thicknesses of the beam elements, and (iv) the material. We present a design software program with a graphical user interface for interactive design. A case-study that describes the design procedure in detail is also presented while additional case-studies are posted on a website.

Conceptual Insightful Synthesis of Spatial Compliant Mechanisms Using the Load Flow Formulation

2019 ◽  
Vol 142 (5) ◽  
Author(s):  
Girish Krishnan ◽  
Sree Kalyan Patiballa
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Building Blocks ◽  
Load Flow ◽  
Load Path ◽  
Single Input Single Output ◽  
Single Output ◽  
Load Paths ◽  
Single Input ◽  
Computationally Intensive

Abstract Conceptual design of spatial compliant mechanisms with distinct input and output ports may be hard because of its complex interconnected topology and is currently accomplished by computationally intensive automated techniques. This paper proposes a user insightful method for generating conceptual compliant topology solutions. The method builds on recent advances where the compliant mechanism deformation is represented as load flow in its constituent members. The nature of load flow enables functional decomposition of compliant mechanisms into maximally decoupled building blocks, namely, a transmitter member and a constraint member. The proposed design methodology seeks to synthesize spatial compliant designs by systematically combining transmitter-constraint members first, identifying kinematically feasible transmitter load paths between input(s) and output(s), and then selecting appropriate constraints that enforce the load path. The paper proposes four design steps to generate feasible solutions and four additional guidelines to optimize load paths and constraint orientations. The method is applied with equal ease to three spatial complaint mechanism examples that belong to single-input single-output, multiple-input single output, and single-input multiple-output mechanisms.

Comparative analysis of SISO and wavelength diversity-based FSO systems at different transmitter power levels

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Varun Srivastava ◽  
Abhilash Mandloi ◽  
Dhiraj Kumar Patel
Keyword(s):  
Optical Signal ◽  
Free Space Optical ◽  
Optical Source ◽  
Transmit Power ◽  
Single Input Single Output ◽  
Transmitter Power ◽  
Single Output ◽  
Communication Links ◽  
Single Input ◽  
Matching Performance

AbstractFree space optical (FSO) communication refers to a line of sight technology, which comprises optical source and detector to create a link without the use of physical connections. Similar to other wireless communication links, these are severely affected by losses that emerged due to atmospheric turbulence and lead to deteriorated intensity of the optical signal at the receiver. This impairment can be compensated easily by enhancing the transmitter power. However, increasing the transmitter power has some limitations as per radiation regulations. The requirement of high transmit power can be reduced by employing diversity methods. This paper presents, a wavelength-based diversity method with equal gain combining receiver, an effective technique to provide matching performance to single input single output at a comparatively low transmit power.

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