Towards a Constraint-Based Design of Soft Mechanisms

2016 ◽  
Author(s):  
Sreeshankar Satheeshbabu ◽  
Girish Krishnan
Keyword(s):  
Material Properties ◽  
Building Blocks ◽  
Analysis Framework ◽  
Mobility Analysis ◽  
Safe Operation ◽  
Global Geometry ◽  
In Series ◽  
Cbd Method ◽  
Synthesis Methodology ◽  
Systematic Synthesis

Soft compliant robots and mechanisms have generated great interest due to their adaptability, and inherently safe operation. However, a systematic synthesis methodology for these devices has always remained elusive owing to complexities in geometry, and nonlinearities in deformation and material properties. This paper builds the groundwork towards a constraint based design (CBD) method for a unique class of soft robotic building blocks known as fluid-filled fiber-reinforced elastomer enclosures (FREEs). First, the constraint behavior of FREEs with varying fiber angles is mapped using an automated mobility analysis framework that is based on matrix-based kinetostatic methods. Specifically, such an analysis seeks to establish the constraint behavior of FREEs as a function of not just the global geometry, but also its local anisotropic material constituents. Then, the paper demonstrates the principle of reconfigurable constraint by combining several FREEs in series in accordance to the rules of constraint-based design. Eventual extension to actuating FREEs will enable a comprehensive synthesis methodology for soft robots.

Safe Operation of DFIG based Wind Parks in Series Compensated Systems

2018 ◽  
Author(s):  
Ulas Karaagac ◽  
Jean Mahseredjian ◽  
Simon Jensen ◽  
Richard Gagnon ◽  
Martin Fecteau ◽  
...  
Keyword(s):  
Safe Operation ◽  
In Series

scholarly journals Optimization of Composite Fracture Properties: Method, Validation, and Applications

2016 ◽  
Vol 83 (7) ◽  
Author(s):  
Grace X. Gu ◽  
Leon Dimas ◽  
Zhao Qin ◽  
Markus J. Buehler
Keyword(s):  
Optimization Algorithm ◽  
Material Properties ◽  
Building Blocks ◽  
Test Case ◽  
Brute Force ◽  
Vast Number ◽  
Engineering Problems ◽  
Brute Force Method ◽  
Optimization Parameters ◽  
Underlying Mechanisms

A paradigm in nature is to architect composites with excellent material properties compared to its constituents, which themselves often have contrasting mechanical behavior. Most engineering materials sacrifice strength for toughness, whereas natural materials do not face this tradeoff. However, biology's designs, adapted for organism survival, may have features not needed for some engineering applications. Here, we postulate that mimicking nature's elegant use of multimaterial phases can lead to better optimization of engineered materials. We employ an optimization algorithm to explore and design composites using soft and stiff building blocks to study the underlying mechanisms of nature's tough materials. For different applications, optimization parameters may vary. Validation of the algorithm is carried out using a test suite of cases without cracks to optimize for stiffness and compliance individually. A test case with a crack is also performed to optimize for toughness. The validation shows excellent agreement between geometries obtained from the optimization algorithm and the brute force method. This study uses different objective functions to optimize toughness, stiffness and toughness, and compliance and toughness. The algorithm presented here can provide researchers a way to tune material properties for a vast number of engineering problems by adjusting the distribution of soft and stiff materials.

scholarly journals Polylactide (PLA) and Its Blends with Poly(butylene succinate) (PBS): A Brief Review

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1193 ◽  
Author(s):  
Shen Su ◽  
Rodion Kopitzky ◽  
Sengül Tolga ◽  
Stephan Kabasci
Keyword(s):  
Material Properties ◽  
Chemical Structure ◽  
Building Blocks ◽  
Processing Parameters ◽  
International Standards ◽  
Butylene Succinate ◽  
Reactive Compatibilization ◽  
Application Potential ◽  
Specific Material

Polylactide (PLA), poly(butylene succinate) (PBS) and blends thereof have been researched in the last two decades due to their commercial availability and the upcoming requirements for using bio-based chemical building blocks. Blends consisting of PLA and PBS offer specific material properties. However, their thermodynamically favored biphasic composition often restricts their applications. Many approaches have been taken to achieve better compatibility for tailored and improved material properties. This review focuses on the modification of PLA/PBS blends in the timeframe from 2007 to early 2019. Firstly, neat polymers of PLA and PBS are introduced in respect of their origin, their chemical structure, thermal and mechanical properties. Secondly, recent studies for improving blend properties are reviewed mainly under the focus of the toughness modification using methods including simple blending, plasticization, reactive compatibilization, and copolymerization. Thirdly, we follow up by reviewing the effect of PBS addition, stereocomplexation, nucleation, and processing parameters on the crystallization of PLA. Next, the biodegradation and disintegration of PLA/PBS blends are summarized regarding the European and International Standards, influencing factors, and degradation mechanisms. Furthermore, the recycling and application potential of the blends are outlined.

Safe Operation of DFIG-Based Wind Parks in Series-Compensated Systems

2018 ◽  
Vol 33 (2) ◽  
pp. 709-718 ◽  
Author(s):  
Ulas Karaagac ◽  
Jean Mahseredjian ◽  
Simon Jensen ◽  
Richard Gagnon ◽  
Martin Fecteau ◽  
...  
Keyword(s):  
Safe Operation ◽  
In Series

Metal-Free Halogenation of N-Substituted Enaminoesters and Enaminones: A Facile Access to Functionalized α,α-Dihaloimines

Synthesis ◽  
2020 ◽  
Vol 52 (08) ◽  
pp. 1301-1314 ◽  
Author(s):  
Changfu Qiu ◽  
Heshui Yu ◽  
Chuanjiang Qiu ◽  
Fangyi Li ◽  
Tongchuan Suo ◽  
...  
Keyword(s):  
Transition Metals ◽  
Building Blocks ◽  
Synthetic Method ◽  
Safe Operation ◽  
Reaction Conditions ◽  
Metal Free ◽  
Synthetic Utility ◽  
General Method

An efficient and general method for the synthesis of functionalized α,α-dihaloimines via halogenation of N-substituted enaminoesters and enaminones is described. This reaction, in which both α,α-dihaloimines and mixed α,α-dihaloimines could be achieved in good to excellent yields, is believed to proceed via an α-monohalogenated enamine intermediate. This synthetic method features no use of transition metals, readily accessible substrates, mild reaction conditions, simple and safe operation, and gram scale synthesis. Furthermore, the synthetic utility of the products was demonstrated by their efficient transformations to further useful nitrogen-containing heterocycles and building blocks.

Design of Miura-Ori Patterns With Acoustic Bandgaps

2017 ◽  
Author(s):  
Phanisri P. Pratapa ◽  
Phanish Suryanarayana ◽  
Glaucio H. Paulino
Keyword(s):  
Wave Propagation ◽  
Material Properties ◽  
Bloch Wave ◽  
Acoustic Metamaterials ◽  
Analysis Framework ◽  
Wave Analysis ◽  
Material Inhomogeneity ◽  
Propagation Behavior ◽  
Unit Cells ◽  
Bloch Wave Analysis

We study the wave propagation behavior in Miura-ori patterns by using the Bloch-wave analysis framework. Our investigation focuses on acoustic bandgaps that act as stopping bands for wave propagation at certain frequencies in periodic solids or structures. We show that bandgaps can be created in two-dimensional periodic Miura-ori patterns by introducing material inhomogeneity. First, we perform Bloch-wave analysis of homogeneous Miura-ori patterns with finite panel rigidity and find that no bandgaps are present. We then introduce bandgaps by making the pattern non-uniform — by changing the mass and axial rigidity of origami panels of alternating unit cells. We discuss the dependence of the magnitude of the bandgap on the contrast between material properties. We find that higher magnitudes of bandgaps are possible by using higher contrast ratios (mass and stiffness). These observations indicate the potential of origami-based patterns to be useful as acoustic metamaterials for vibration control.

Glass Based Inductors, Capacitors and System-In-Package for RF Applications

2016 ◽  
Vol 2016 (1) ◽  
pp. 000299-000304
Author(s):  
Jeb H Flemming ◽  
Roger Cook ◽  
Kyle McWethy
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Building Blocks ◽  
Packaging Materials ◽  
Current Crowding ◽  
High Q ◽  
Passive Devices ◽  
Glassy Materials ◽  
Rf Applications ◽  
Power Inductors

Abstract Glassy materials offer a number of advantages over traditional packaging materials, such as laminates and ceramics including: (1) Better material properties, (2) decreased surface roughness to mitigate current crowding, (3) the ability to create small precise features with greater densities, and (4) the opportunity to integrate passive devices such as power inductors and High-Q inductors into an interposer substrate along with other active and passive devices. This paper will cover an overview of our efforts to create APEX® Glass based devices that form the building blocks for a variety of RF applications including power inductors, High-Q inductors, capacitors, filters and interposers. We also demonstrate the power of integrating these individual building blocks into more complex devices that offer compelling solutions for the increasingly complex RF market. Performance data is presented for power inductors and the in-glass inductors.

Risk-Based Considerations in Developing Strategies to Ensure Pipeline Integrity—Part II: Applications

1994 ◽  
Vol 116 (3) ◽  
pp. 284-289
Author(s):  
S. Rahman ◽  
B. N. Leis
Keyword(s):  
Probabilistic Models ◽  
Pipe Steel ◽  
Risk Assessments ◽  
Probabilistic Framework ◽  
Safe Operation ◽  
Line Pipe ◽  
Numerical Predictions ◽  
In Series ◽  
Line Pipe Steel ◽  
Developing Strategies

This is the second in series of two papers generated from a recent study on risk-based analysis for developing strategies to ensure pipeline integrity. This paper (Part II—Applications) focuses on the applications of the proposed deterministic and probabilistic models presented in the first paper (Part I—Theory) (Leis and Rahman, 1994) for stochastic pipe fracture evaluations. Using these models, numerical predictions are made for line-pipe steel typically used in gas transmission pipelines and are compared with the available test data. Thereafter, the paper explores the significance of the random variables related to serviceability in pipelines subjected to flaw growth in service. The results are discussed in the light of a hydrotest-based approach to ensure pipeline integrity. It is concluded that analysis of hydrotest strategies to optimize safety for such populations (e.g., Leis and Brust, 1992) should be based on a probabilistic analysis that permits risk assessments associated with pipeline operating decisions and the type and frequency of hydrotests done to ensure continued safe operation of the line. This same probabilistic framework could be used to assess the operating and safety implications for flaw populations characterized by in-line inspection.

A Metameric Crawling Robot Enabled by Origami and Smart Materials

2017 ◽  
Author(s):  
Oyuna Angatkina ◽  
Brian Chien ◽  
Alexander Pagano ◽  
Tongxi Yan ◽  
Andrew Alleyne ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Smart Materials ◽  
Power Efficiency ◽  
Control Algorithm ◽  
Building Blocks ◽  
Robot Design ◽  
Forward Motion ◽  
Muscle Tissues ◽  
In Series ◽  
Future Work

Metamerism, in biology, occurs when a creature has multiple segments, which are similar in structure and configured in series. True metamerism means that these connected segments include a repetition of all organs and muscle tissues. Earthworms are examples of true metameric creatures. Animals use metameric structures to increase maneuverability and enable multiple modes (gaits) of locomotion along with other functions. This work presents the design of a crawling robot that is inspired by the crawling gait and true metamerism of earthworms. The building block of each segment is a bistable origami structure that extends and contracts its length. The robot moves forward by using directional friction on its feet to enable forward motion and turning. [1]. Using a series of connected origami building blocks provides the robot with a modular metameric structure. This paper presents a true metameric robot design where different segments can be detached and reattached to one another but remain fully functional in each state. The docking system uses shape memory alloy (SMA) wire coils as actuators for a clutching mechanism to disengage the different segments. A directional magnetic arrangement is used to reattach the segments. The actuation architecture exploits the bistability of the origami building blocks to improve the power efficiency of the robot. Future work includes implementing a control algorithm to plan the paths of the different segments and allow for autonomous segmentation and docking in various operational environments.

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