scholarly journals Design and control of a prototype structure that adapts to loading through large shape changes

2020 ◽  
Vol 53 (2) ◽  
pp. 8377-8382
Author(s):  
Arka P. Reksowardojo ◽  
Gennaro Senatore ◽  
Apoorv Srivastava ◽  
Ian F.C. Smith ◽  
Henry Unterreiner ◽  
...  
Keyword(s):  
Prototype Structure ◽  
And Control ◽  
Shape Changes ◽  
Large Shape

scholarly journals Design of Structures That Adapt to Loads through Large Shape Changes

2020 ◽  
Vol 146 (5) ◽  
pp. 04020068 ◽  
Author(s):  
Arka P. Reksowardojo ◽  
Gennaro Senatore ◽  
Ian F. C. Smith
Keyword(s):  
Shape Changes ◽  
Large Shape

Shape Memory Alloy Morphing Airfoil Sections

2016 ◽  
Vol 101 ◽  
pp. 112-120
Author(s):  
Dimitris Saravanos ◽  
Theodoros Machairas ◽  
Alex Solomou ◽  
Anargyros Karakalas
Keyword(s):  
Shape Memory ◽  
Geometrical Nonlinearity ◽  
Turbine Blades ◽  
Aerodynamic Load ◽  
Weight Restrictions ◽  
Wind Turbine Blades ◽  
Structural Shape ◽  
Single Target ◽  
Shape Changes ◽  
Large Shape

Shape memory alloys (SMA) provide common solid state actuators with reliable and unique characteristics. Their special behavior is based on a reversible phase transformation and can provide high power density, induced strain and block force which render them indispensable for use in morphing structures that require large shape changes while space and weight restrictions are imposed. Yet, their implementation into morphing structures faces challenges related to their complex multi-disciplinary behavior, their interaction with the passive structural components, geometrical nonlinearity due to large shape changes, the lack of experimental data, and above all, the lack of modelling tools which can robustly simulate the complex thermomechanical behavior and make feasible their design. We briefly review the material characterization process, the developed modelling tools which can simulate the complex thermomechanical response of morphing structures with SMA actuators which can undergo large shape changes under severe geometric nonlinearity, and the testing of prototype morphing components. The design and validation of two morphing structural concepts for curvature control are presented. A morphing strip capable to deform towards a single target shape is initially presented. Subsequently, a morphing airfoil concept implementing an articulated mechanism capable to achieve multiple target shapes for aerodynamic load control is presented. The challenging task to continuously adapt the structural shape to time varying demands, dictates the use of antagonistic actuator configurations to maximize and control the range of morphing. The previously mentioned morphing airfoil configuration is used to alleviate the aerodynamic fatigue loads in wind turbine blades and aircraft wings.

scholarly journals Swim-like motion of bodies immersed in an ideal fluid

2019 ◽  
Vol 25 ◽  
pp. 16 ◽  
Author(s):  
Marta Zoppello ◽  
Franco Cardin
Keyword(s):  
Recent Literature ◽  
The Body ◽  
Riemann Mapping Theorem ◽  
First Order ◽  
Order Expansion ◽  
And Control ◽  
Small Deformations ◽  
Initial Impulse ◽  
Shape Changes ◽  
Planar Body

The connection between swimming and control theory is attracting increasing attention in the recent literature. Starting from an idea of Alberto Bressan [A. Bressan, Discrete Contin. Dyn. Syst. 20 (2008) 1–35]. we study the system of a planar body whose position and shape are described by a finite number of parameters, and is immersed in a 2-dimensional ideal and incompressible fluid in terms of gauge field on the space of shapes. We focus on a class of deformations measure preserving which are diffeomeorphisms whose existence is ensured by the Riemann Mapping Theorem. After making the first order expansion for small deformations, we face a crucial problem: the presence of possible non vanishing initial impulse. If the body starts with zero initial impulse we recover the results present in literature (Marsden, Munnier and oths). If instead the body starts with an initial impulse different from zero, the swimmer can self-propel in almost any direction if it can undergo shape changes without any bound on their velocity. This interesting observation, together with the analysis of the controllability of this system, seems innovative.

scholarly journals Investigating Human Torso Asymmetries: An Observational Longitudinal Study of Fluctuating and Directional Asymmetry in the Scoliotic Torso

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1821
Author(s):  
José María González-Ruiz ◽  
María Isabel Pérez-Núñez ◽  
María Dolores García-Alfaro ◽  
Markus Bastir
Keyword(s):  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Fluctuating Asymmetry ◽  
Directional Asymmetry ◽  
Control Group ◽  
Control Groups ◽  
3D Shape ◽  
And Control ◽  
The Impact ◽  
Shape Changes

The presence of directional and fluctuating asymmetry in adolescent idiopathic scoliosis has not been deeply studied. We aimed to test the presence of both in a scoliosis group and a control group. 24 patients with adolescent idiopathic scoliosis and 24 control subjects were subjected to geometric morphometrics analyses to address our main hypotheses and to make qualitative visualizations of the 3D shape changes in patients with scoliosis. Our results support the hypothesis that both asymmetric traits are present in the scoliosis and control groups, but to a greater degree in patients. A qualitative visualization tool that allows us to measure the impact that directional and fluctuating asymmetry have on the 3D shape of our patients has been developed. Adolescent idiopathic scoliosis is the result of developmental instabilities during growth and the visualization of the 3D shape changes in response to both asymmetric variables has shown different morphological behaviors. Measuring these variables is important, as they can prevent the localization and deformation that is expected to occur during the course of scoliosis in every individual patient and therefore acts as a key clinical finding that may be used in the prognosis of the condition.

scholarly journals Analysis of cardiomyocyte nuclei in human cardiomyopathy reveals orientation dependent defects in shape

2020 ◽  
Author(s):  
Daniel Brayson ◽  
Elisabeth Ehler ◽  
Cristobal G dos Remedios ◽  
Catherine M Shanahan
Keyword(s):  
General Feature ◽  
Important Determinant ◽  
Diagnostic Value ◽  
Transverse Plane ◽  
Nucleus Shape ◽  
Genes Encoding ◽  
And Control ◽  
Shape Changes ◽  
Control Samples

Cardiomyopathies are progressive diseases of heart muscle often caused by mutations in genes encoding sarcomeric, cytoskeletal and nucleoskeletal proteins though in many cases the cause of disease is not identified. Whilst nucleus hypertrophy has been described, it is not known whether nucleus shape changes are a general feature of cardiomyopathy. Due to the rod-shaped nature of cardiomyocytes and their elliptical nuclei we hypothesised that orientation of analysis would be an important determinant of any changes observed between patients exhibiting primarily unexplained cardiomyopathy and control samples from non-failing donors. To investigate this we performed image analysis of cardiomyocyte nuclei in myocardial cryosections from a cohort of cardiomyopathy patients. We discovered that circularity, solidity and aspect ratio were sensitive to orientation of the myocardium and that in the transverse plane only circularity was reduced in cardiomyocyte nuclei of cardiomyopathy patients. These findings show that orientation dependent changes in nucleus shape may be a property of cardiomyopathy and with appropriate follow up studies, may prove to have mechanistic and diagnostic value.

Design and Control Concept for Reconfigurable Architecture

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Eftychios G. Christoforou ◽  
Andreas Müller ◽  
Marios C. Phocas ◽  
Maria Matheou ◽  
Socrates Arnos
Keyword(s):  
Shape Control ◽  
Degrees Of Freedom ◽  
Energy Performance ◽  
Building Envelope ◽  
Intermediate Step ◽  
Planar Mechanisms ◽  
Control Concept ◽  
The Individual ◽  
And Control ◽  
Shape Changes

Shape-control in an architectural context is expected to provide unique opportunities for buildings with enhanced functionality, flexibility, energy performance, and occupants comfort. An architectural concept is proposed which consists of a parallel arrangement of planar n-bar mechanisms formulating its skeleton structure and a membrane material stretched over it to define the building envelope. Overall shape changes involve coordinated motion of the individual planar mechanisms. Each linkage is equipped with one motion actuator as well as brakes installed on every joint. Reconfigurations of the building are based on the “effective 4-bar (E4B)” concept allowing stepwise adjustments. Each intermediate step involves the selective locking of (n − 4) joints on each closed-loop linkage effectively reducing it to a single degrees-of-freedom (DOF) 4-bar mechanism, the configuration of which can be adjusted using the available motion actuator. A reconfiguration of the mechanism can be realized through alternative control sequences and an optimal one can be selected based on specific criteria. The paper reports the fundamental design and control concepts. A simulation and an experimental study are presented to demonstrate the implementation of the general reconfiguration approach and examine relevant issues.

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