Characterization of Spatial Parasitic Motions of Compliant Mechanisms Induced by Manufacturing Errors

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Zhiwei Zhu ◽  
Suet To ◽  
Xiaoqin Zhou ◽  
Rongqi Wang ◽  
Xu Zhang
Keyword(s):  
Deformation Behavior ◽  
Laser Interferometer ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Wide Spectrum ◽  
Basic Element ◽  
Matrix Modeling ◽  
Manufacturing Errors

This paper proposes a theoretical model for characterizing manufacturing error induced spatial parasitic motions (MESPM) of compliant mechanisms (CM), and investigates the inherent statistic features of MESPM using Monte Carlo simulation. It also applies and extends a novel finite beam based matrix modeling (FBMM) method to theoretically derive the elastic deformation behavior of an imperfect flexural linkage (IFL), which is a basic element of a wide spectrum of compliant mechanisms. A case study of a well-known double parallelogram compliant mechanism (DPCM) is also conducted, and the practical parasitic motions of a prototype DPCM are characterized by laser interferometer based measurements.

Load-Transmitter Constraint Sets: Part I—An Effective Tool for Visualizing Load Flow in Compliant Mechanisms and Structures

2010 ◽  
Author(s):  
Girish Krishnan ◽  
Charles Kim ◽  
Sridhar Kota
Keyword(s):  
Building Block ◽  
Deformation Behavior ◽  
Design Methodology ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Load Flow ◽  
Mathematical Framework ◽  
Design Synthesis ◽  
Fundamental Building Block ◽  
Block Based

Visualizing load flow aids in conceptual design synthesis of machine components. In this paper, we present a mathematical framework to visualize load flow in compliant mechanisms and structures. This framework uses the concept of transferred forces to quantify load flow from input to the output of a compliant mechanism. The key contribution of this paper is the identification a fundamental building block known as the Load-Transmitter Constraint (LTC) set, which enables load flow in a particular direction. The transferred force in each LTC set is shown to be independent of successive LTC sets that are attached to it. This enables a continuous visualization of load flow from the input to the output. Furthermore, we mathematically relate the load flow with the deformation behavior of the mechanism. We can thus explain the deformation behavior of a number of compliant mechanisms from literature by identifying its LTC sets to visualize load flow. This method can also be used to visualize load flow in optimal stiff structure topologies. The insight obtained from this visualization tool facilitates a systematic building block based design methodology for compliant mechanisms and structural topologies.

Large Deformation Behavior of Compliant Mechanisms

2001 ◽  
Author(s):  
Jinyong Joo ◽  
Sridhar Kota ◽  
Noboru Kikuchi
Keyword(s):  
Shape Optimization ◽  
Large Deformation ◽  
Deformation Behavior ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Linear Formulation ◽  
Scaling Effect ◽  
Beam Elements ◽  
Linear And Nonlinear ◽  
Amplification Mechanism

Abstract This paper presents a non-linear formulation for size and shape optimization of compliant mechanisms using tapered beam elements. Designs based on linear and nonlinear formulations are compared using a stroke amplification mechanism example. Also, the scaling effect of the compliant mechanism is investigated.

Classification of Compliant Mechanisms and Determination of the Degrees of Freedom Using the Concepts of Compliance Number and Pseudo-Rigid-Body Model

2019 ◽  
Author(s):  
Pratheek Bagivalu Prasanna ◽  
Ashok Midha ◽  
Sushrut G. Bapat
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Body Model ◽  
Active Compliance ◽  
Kinematic Behavior ◽  
Rigid Body Model

Abstract Understanding the kinematic properties of a compliant mechanism has always proved to be a challenge. A concept of compliance number offered earlier emphasized the development of terminology that aided in its determination. A method to evaluate the elastic degrees of freedom associated with the flexible segments/links of a compliant mechanism using the pseudo-rigid-body model (PRBM) concept is provided. In this process, two distinct classes of compliant mechanisms are developed involving: (i) Active Compliance and (ii) Passive Compliance. Furthermore, these also aid in a better characterization of the kinematic behavior of a compliant mechanism. A more lucid interpretation of the significance of compliance number is provided. Applications of this method to both active and passive compliant mechanisms are exemplified. Finally, an experimental procedure that aids in visualizing the degrees of freedom as calculated is presented.

Runner Optimization for In-Mold Assembly of Multi-Material Compliant Mechanisms

2011 ◽  
Author(s):  
Wojciech Bejgerowski ◽  
Satyandra K. Gupta
Keyword(s):  
Optimization Problem ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Polymer Melt ◽  
Injection Molding Process ◽  
Optimization Approach ◽  
Assembly Process ◽  
Molding Process ◽  
Design Variables

The runner system in injection molding process is used to supply the polymer melt from injection nozzle to the gates of final part cavities. Realizing complex multi-material mechanisms by in-mold assembly process requires special runner layout design considerations due to the existence of the first stage components. This paper presents the development of an optimization approach for runner systems in the in-mold assembly of multi-material compliant mechanisms. First, the issues specific to the in-mold assembly process are identified and analyzed. Second, the general optimization problem is formulated by identification of all parameters, design variables, objective functions and constraints. Third, the implementation of the optimization problem in Matlab® environment is described based on a case study of a runner system for an in-mold assembly of a MAV drive mechanism. This multi-material compliant mechanism consists of seven rigid links interconnected by six compliant hinges. Finally, several optimization approaches are analyzed to study their performance in solving the formulated problem. The most appropriate optimization approach is selected. The case study showed the applicability of the developed optimization approach to runner systems for complex in-mold assembled multi-material mechanism designs.

Functional Characterization of Compliant Building Blocks Utilizing Eigentwists and Eigenwrenches

2008 ◽  
Author(s):  
Charles J. Kim
Keyword(s):  
Building Block ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Deformable Body ◽  
Functional Characterization ◽  
Building Blocks ◽  
Future Research ◽  
Special Cases ◽  
Block Approach

Compliant mechanisms are devices which utilize the flexibility of their constituent members to transmit motion and forces. Unlike their rigid body counterparts, compliant mechanisms typically contain no traditional joints. The focus of this research is the development of a building block approach for the synthesis of compliant mechanisms. Building block methods better facilitate the augmentation of designer intuition while offering a systematic approach to open-ended problems. In this paper, we investigate the use of the eigentwists and eigenwrenches of a deformable body to characterize basic kinematic function. The eigentwists and eigenwrenches are shown to demonstrate parametric behavior when applied to the compliant dyad building block, and in special cases may be compared to compliance ellipsoids. The paper concludes by articulating future research in a building block approach to compliant mechanism synthesis.

scholarly journals Endoscopic spectrum and practical classification of small bowel gastrointestinal stromal tumors (GISTs) detected during double-balloon enteroscopy

2021 ◽  
Vol 09 (04) ◽  
pp. E507-E512
Author(s):  
Alvaro Martinez-Alcalá ◽  
Lucía C. Fry ◽  
Thomas Kröner ◽  
Shajan Peter ◽  
Carlo Contreras ◽  
...  
Keyword(s):  
Small Bowel ◽  
Wide Spectrum ◽  
Case Series ◽  
Normal Mucosa ◽  
Tumor Characteristics ◽  
Double Balloon Enteroscopy ◽  
Endoscopic Characteristics

Abstract Background and study aims Information about the endoscopic characterization of small bowel gastrointestinal tumors (GISTs) is limited. The aim of this case study was to describe the endoscopic spectrum of small bowel GISTs and to present a practical classification. Patients and methods Observational, retrospective, consecutive case series of patients with small bowel GIST. Results A total of 10 small bowel GISTs were found in patients (6 male, 4 female, mean age 52 years, range 28 to 68).). All patients presented with obscure gastrointestinal bleeding (overt, n = 8, occult, n = 2). Most GISTs were present in the proximal or middle small bowel (n = 7). The endoscopic tumor characteristics could be categorized as follows: submucosal round (n = 4), submucosal sessile (n = 2), and invasive/penetrating) (n = 4). The mucosa overlying the tumor was normal (n = 4), grooved (n = 3) or frankly ulcerated (n = 3). Tumor size ranged from 8 mm to 50 mm. Biopsy was negative in all patients with normal mucosa but showed tumor in all patients with ulcerations. Regardless of biopsy results, all patients were sent for surgery. Nine resections were carried out. One patient refused surgery. There were no complications of endoscopy in this cohort. Conclusion Our series shows that GISTs have a wider spectrum of endoscopic characteristics than previously described. The round type with normal overlying mucosa was equally prevalent as the grooved or ulcerated variant. Endoscopists should be aware of this wide spectrum of presentation of small bowel GIST.

Design of Compliant Mechanisms for Minimizing Input Power in Dynamic Applications

2006 ◽  
Vol 129 (10) ◽  
pp. 1064-1075 ◽  
Author(s):  
Tanakorn Tantanawat ◽  
Sridhar Kota
Keyword(s):  
Energy Storage ◽  
Rigid Body ◽  
Power Flow ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Input Power ◽  
Power Requirement ◽  
Effective Manner ◽  
Flapping Mechanism

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.

scholarly journals Compliant Mechanism Road Bicycle Brake: A Rigid-Body Replacement Case Study

2011 ◽  
Author(s):  
Brian M. Olsen ◽  
Larry L. Howell ◽  
Spencer P. Magleby
Keyword(s):  
Rigid Body ◽  
High Performance ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Element Analysis ◽  
Low Weight ◽  
Rigid Body Model ◽  
Compliant Mechanism Design

This paper demonstrates rigid-body replacement synthesis in the design a mechanism with known design objectives. The design of high-performance bicycle brakes is complicated by a variety of competing design objectives, including increased performance and low weight. But this challenge also provides a good case study to demonstrate the design of compliant mechanisms to replace traditional rigid-link mechanisms. This paper briefly reviews current road brake designs, demonstrates the use of rigid-body replacement synthesis to design a compliant mechanism, and illustrates the combination of compliant mechanism design tools. The resulting concept was generated from the modified dual-pivot brake design and is a partially compliant mechanism where one pin has the dual role of a joint and a mounting pin. The pseudo-rigid-body model, finite element analysis, and optimization algorithms are used to generate design dimensions, and designs are considered for both titanium and E-glass flexures. The resulting design has the potential of reducing the part count and overall weight while maintaining a performance similar to the benchmark.

A Kinetostatic Formulation for Load-Flow Visualization in Compliant Mechanisms

2013 ◽  
Vol 5 (2) ◽  
Author(s):  
Girish Krishnan ◽  
Charles Kim ◽  
Sridhar Kota
Keyword(s):  
Flow Visualization ◽  
Deformation Behavior ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Flow Behavior ◽  
Building Blocks ◽  
Load Flow ◽  
Assembly Design ◽  
Fundamental Building Block ◽  
Machine Assembly

Load flow visualization, which is an important step in structural and machine assembly design may aid in the analysis and eventual synthesis of compliant mechanisms. In this paper, we present a kineto-static formulation to visualize load flow in compliant mechanisms. This formulation uses the concept of transferred forces to quantify load flow from input to the output of a compliant mechanism. The magnitude and direction of load flow in the constituent members enables functional decomposition of the compliant mechanism into (i) Constraints (C): members that are constrained to deform in a particular direction and (ii) Transmitters (T): members that transmit load to the output. Furthermore, it is shown that a constraint member and an adjacent transmitter member can be grouped together to constitute a fundamental building block known as an CT set whose load flow behavior is maximally decoupled from the rest of the mechanism. We can thereby explain the deformation behavior of a number of compliant mechanisms from literature by visualizing load flow, and identifying building blocks.

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