Design of Planar Multi-Degree-of-Freedom Morphing Mechanisms

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Lawrence W. Funke ◽  
James P. Schmiedeler ◽  
Kai Zhao
Keyword(s):  
Shape Matching ◽  
Design Space ◽  
Degree Of Freedom ◽  
Limiting Factor ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Extrusion Dies ◽  
Assur Group ◽  
Synthesis Procedure ◽  
Block Approach

This paper seeks to advance the design of planar multiloop shape-changing mechanisms used in a variety of applications, such as morphing extrusion dies and airfoils. The presence of defects is a limiting factor in finding suitable single-degree-of-freedom (DOF) morphing mechanisms, particularly when the number of shapes to achieve is large and/or the changes among those shapes are significant. This paper presents methods of designing multi-DOF mechanisms to expand the design space in which to find suitable defect-free solutions. The primary method uses a building block approach with Assur group of class II chains, similar to the current 1-DOF synthesis procedure. It is compared to both the 1-DOF procedure and an alternative multi-DOF procedure that generates mechanisms with single-DOF subchains. In all cases, a genetic algorithm is employed to search the design space. Two example problems involving four prescribed shapes demonstrate that mechanisms exhibiting superior shape matching are achieved with the primary multi-DOF procedure, as compared to the other two procedures.

Design of Planar Multi-Degree-of-Freedom Morphing Mechanisms

2014 ◽  
Author(s):  
Lawrence Funke ◽  
James P. Schmiedeler ◽  
Kai Zhao
Keyword(s):  
Shape Matching ◽  
Design Space ◽  
Degree Of Freedom ◽  
Limiting Factor ◽  
Primary Method ◽  
Single Degree Of Freedom ◽  
Extrusion Dies ◽  
Planar Shape ◽  
Synthesis Procedure ◽  
Block Approach

This paper seeks to advance the design of planar shape-changing mechanisms used in a variety of applications, such as morphing extrusion dies and airfoils. The presence of defects is a limiting factor in finding suitable single-degree-of-freedom (DOF) mechanisms, particularly when the number of shapes to achieve is large and/or the changes among those shapes are significant. This paper presents a new method of designing multi-DOF mechanisms to aid in avoiding these defects. The primary method uses a building-block approach similar to the current one-DOF synthesis procedure and is compared to alternative strategies that seek to leverage the use of multiple single-DOF subchains. While more complex in terms of determining the actuation pattern, the primary method offers a larger design space in which to find solutions. In all cases a genetic algorithm is employed to search the design space. Two example problems involving four prescribed shapes demonstrate the benefits of using multi-DOF mechanisms in terms of shape matching and mechanical advantage.

Single Degree-of-Freedom Morphing Wing (Design and Synthesis)

2004 ◽  
Author(s):  
Matthew D. Stubbs ◽  
William B. Whittier ◽  
Charles F. Reinholtz
Keyword(s):  
Shape Change ◽  
Degree Of Freedom ◽  
Morphing Wing ◽  
Single Degree Of Freedom ◽  
Aircraft Wings ◽  
Design And Synthesis ◽  
Single Degree ◽  
Synthesis Procedure ◽  
Langley Research Center ◽  
Novel Design

Recent research in morphing wing technology has focused on complex multiple-degree-of-freedom (MDOF) mechanisms and smart structures to provide a specified shape change; single degree-of-freedom actuation concepts have generally been ignored or overlooked. In this research, the authors propose a novel design for a single degree-of-freedom (SDOF) mechanism for mission morphing of aircraft wings. A general design methodology has been developed, and this has been applied to a Hyper-Elliptic Cambered Span (HECS) wing developed by engineers at NASA Langley Research Center. The design tools developed include a synthesis procedure for determining the dimensions of the single-degree-of-freedom morphing mechanism, and a sensitivity analysis to determine the effects of manufacturing errors.

Kinematic comparison of single degree-of-freedom robotic gait trainers

2021 ◽  
Vol 159 ◽  
pp. 104258
Author(s):  
Jeonghwan Lee ◽  
Lailu Li ◽  
Sung Yul Shin ◽  
Ashish D. Deshpande ◽  
James Sulzer
Keyword(s):  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Robotic Gait

Single-Degree-of-Freedom Based Pressure-Impulse Diagrams for Blast Damage Assessment

2014 ◽  
Vol 567 ◽  
pp. 499-504 ◽  
Author(s):  
Zubair Imam Syed ◽  
Mohd Shahir Liew ◽  
Muhammad Hasibul Hasan ◽  
Srikanth Venkatesan
Keyword(s):  
Damage Assessment ◽  
Structural Response ◽  
Blast Loading ◽  
Computational Effort ◽  
Degree Of Freedom ◽  
Negative Phase ◽  
Single Degree Of Freedom ◽  
Pressure Impulse ◽  
Single Degree ◽  
Structural Resistance

Pressure-impulse (P-I) diagrams, which relates damage with both impulse and pressure, are widely used in the design and damage assessment of structural elements under blast loading. Among many methods of deriving P-I diagrams, single degree of freedom (SDOF) models are widely used to develop P-I diagrams for damage assessment of structural members exposed to blast loading. The popularity of the SDOF method in structural response calculation in its simplicity and cost-effective approach that requires limited input data and less computational effort. The SDOF model gives reasonably good results if the response mode shape is representative of the real behaviour. Pressure-impulse diagrams based on SDOF models are derived based on idealised structural resistance functions and the effect of few of the parameters related to structural response and blast loading are ignored. Effects of idealisation of resistance function, inclusion of damping and load rise time on P-I diagrams constructed from SDOF models have been investigated in this study. In idealisation of load, the negative phase of the blast pressure pulse is ignored in SDOF analysis. The effect of this simplification has also been explored. Matrix Laboratory (MATLAB) codes were developed for response calculation of the SDOF system and for repeated analyses of the SDOF models to construct the P-I diagrams. Resistance functions were found to have significant effect on the P-I diagrams were observed. Inclusion of negative phase was found to have notable impact of the shape of P-I diagrams in the dynamic zone.

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