scholarly journals The Adaptive Power of Ammophila arenaria: Biomimetic Study, Systematic Observation, Parametric Design, and Experimental Tests with Bimetal

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2554
Author(s):  
Tarciana Araújo Brito de Andrade ◽  
José Nuno Dinis Cabral Beirão ◽  
Amilton José Vieira de Arruda ◽  
Cristina Cruz
Keyword(s):  
Parametric Design ◽  
Experimental Tests ◽  
Ammophila Arenaria ◽  
Systematic Observation ◽  
Natural Movement ◽  
Biomimetic Approach ◽  
Three Stages ◽  
Adaptive Power ◽  
Response To Temperature ◽  
Opening And Closing

The aim of our study was to apply a biomimetic approach, inspired by the Ammophila arenaria. This organism possesses a reversible leaf opening and closing mechanism that responds to water and salt stress (hydronastic movement). We adopted a problem-based biomimetic methodology in three stages: (i) two observation studies; (ii) how to abstract and develop a parametric model to simulate the leaf movement; and (iii) experiments with bimetal, a smart material that curls up when heated. We added creases to the bimetal active layer in analogy to the position of bulliform cells. These cells determine the leaf-closing pattern. The experiments demonstrated that creases influence and can change the direction of the bimetal natural movement. Thus, it is possible to replicate the Ammophila arenaria leaf-rolling mechanism in response to temperature variation and solar radiation in the bimetal. In future works, we will be able to propose responsive facade solutions based on these results.

A shape memory alloy–actuated soft crawling robot based on adaptive differential friction and enhanced antagonistic configuration

2020 ◽  
Vol 31 (16) ◽  
pp. 1920-1934 ◽  
Author(s):  
Chen Liang ◽  
Yongquan Wang ◽  
Tao Yao ◽  
Botao Zhu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Stride Length ◽  
Parametric Design ◽  
Thermoplastic Polyurethane ◽  
Interaction Mechanism ◽  
Experimental Tests ◽  
The Body ◽  
3D Printed ◽  
Miniature Robot

This article presents a soft crawling robot prototype with a simple architecture inspired by inchworms. The robot functionally integrates the torso (body) and feet in a monolithic curved structure that only needs a single shape memory alloy coil and differential friction to actuate it. A novel foot configuration is proposed, which makes the two feet, with an anti-symmetrical friction layout, can be alternately anchored, to match the contraction–recovery sequence of the body adaptively. Based on the antagonistic configuration between the shape memory alloy actuator and the elastic body, a vertically auxiliary spring was adopted to enhance the interaction mechanism. Force and kinematic analysis was undertaken, focusing on the parametric design of the special foot configuration. A miniature robot prototype was then 3D-printed (54 mm in length and 9.77 g in weight), using tailored thermoplastic polyurethane elastomer as the body material. A series of experimental tests and evaluations were carried out to assess its performance under different conditions. The results demonstrated that under appropriate actuation conditions, the compact robot prototype could accomplish a relative speed of 0.024 BL/s (with a stride length equivalent to 27% of its body length) and bear a load over five times to its own weight.

Recent Development of Self-Centering System for Seismic Design of Bridge Piers: Experimental and Theoretical Investigation

2013 ◽  
Vol 275-277 ◽  
pp. 1315-1320
Author(s):  
Hui Liu ◽  
Ming Hua He ◽  
Ke Gui Xin ◽  
Jia Guo ◽  
Wen Liu
Keyword(s):  
Seismic Design ◽  
Experimental Tests ◽  
Bridge Piers ◽  
Analytical Models ◽  
Structural Elements ◽  
Tsinghua University ◽  
Inelastic Demand ◽  
Opening And Closing ◽  
Original Concept ◽  
Structural Solution

The original concept of self-centering system was first proposed under the PRESSS research project in 1991 in UC San Diego. The particularly promising and effective structural solution was initially defined as hybrid system in literature and then self-centering system recently. In the ductile connection of self-centering system, inelastic demand is accommodated through the opening and closing (control rocking) of a pre-existing gap at the critical interface, with no consequent damage such as the plastic hinges in traditional structural elements. This paper provides an overview of the recent advances of self-centering system, especially for bridge piers, to summarize several analytical models and experimental tests that were widely recognized. Besides, a brief introduction of the study conducted by Tsinghua University is presented, including a stiffness degrading analytical model and a series of experimental tests.

scholarly journals The interactive bending wrinkling behaviour of inflated beams

2016 ◽  
Vol 472 (2193) ◽  
pp. 20160504 ◽  
Author(s):  
Y. P. Liu ◽  
C. G. Wang ◽  
H. F. Tan ◽  
M. K. Wadee
Keyword(s):  
Fourier Series ◽  
Boundary Conditions ◽  
Experimental Tests ◽  
Equilibrium Path ◽  
Series Method ◽  
Simply Supported ◽  
Fourier Series Method ◽  
Three Stages ◽  
Interactive Buckling ◽  
Significant Support

A model is proposed based on a Fourier series method to analyse the interactive bending wrinkling behaviour of inflated beams. The whole wrinkling evolution is tracked and divided into three stages by identifying the bifurcations of the equilibrium path. The critical wrinkling and failure moments of the inflated beam can then be predicted. The global–local interactive buckling pattern is elucidated by the proposed theoretical model and also verified by non-contact experimental tests. The effects of geometric parameters, internal pressure and boundary conditions on the buckling of inflated beams are investigated finally. The results reveal that the interactive buckling characteristics of an inflated beam under bending are more sensitive to the dimensions of the structure and boundary conditions. We find that for beams which are simply supported at both ends or clamped and simply supported, boundary conditions may prevent the wrinkling formation. The results provide significant support for our understanding of the bending wrinkling behaviour of inflated beams.

scholarly journals Piecewise Model and Parameter Obtainment of Governor Actuator in Turbine

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Jie Zhao ◽  
Li Wang ◽  
Dichen Liu ◽  
Jun Wang
Keyword(s):  
Pid Controller ◽  
Particle Swarm Optimization Algorithm ◽  
Piecewise Linear ◽  
Heat Engine ◽  
Experimental Tests ◽  
Proportional Integral Derivative ◽  
Closing Time ◽  
Time Constants ◽  
Piecewise Model ◽  
Opening And Closing

The governor actuators in some heat-engine plants have nonlinear valves. This nonlinearity of valves may lead to the inaccuracy of the opening and closing time constants calculated based on the whole segment fully open and fully close experimental test curves of the valve. An improved mathematical model of the turbine governor actuator is proposed to reflect the nonlinearity of the valve, in which the main and auxiliary piecewise opening and closing time constants instead of the fixed oil motive opening and closing time constants are adopted to describe the characteristics of the actuator. The main opening and closing time constants are obtained from the linear segments of the whole fully open and close curves. The parameters of proportional integral derivative (PID) controller are identified based on the small disturbance experimental tests of the valve. Then the auxiliary opening and closing time constants and the piecewise opening and closing valve points are determined by the fully open/close experimental tests. Several testing functions are selected to compare genetic algorithm and particle swarm optimization algorithm (GA-PSO) with other basic intelligence algorithms. The effectiveness of the piecewise linear model and its parameters are validated by practical power plant case studies.

The Family Group in Golden Hamsters: Its Formation and Break-Up

Behaviour ◽  
1961 ◽  
Vol 17 (2-3) ◽  
pp. 81-94 ◽  
Author(s):  
T.E. Rowell
Keyword(s):  
Small Groups ◽  
Experimental Tests ◽  
Natural Conditions ◽  
Play Fighting ◽  
The Third ◽  
Contact Behaviour ◽  
The Family ◽  
Third Stage ◽  
Three Stages ◽  
Break Up

AbstractI. Behaviour of the golden hamster during normal parturition is described. 2. This is compared with behaviour of mothers who did not rear their litters because of faulty response to suckling attempts by the pups. Absence of milk at the nipples is suggested as a cause for this unwillingness to nurse. 3. Pups which are not born in the nest are often abandoned. 4. Pups born dead are often treated as food, but live pups are not eaten until after parturition is over. 5. Litters do not form into the characteristic compact unit until they have fed and been brooded. 6. Three stages in family break-up are recognised: (i) At about twentyfive days the mother begins to wean her litter, stops rebuilding the old nest, and may build a smaller one elsewhere. It is possible she would normally leave her litter at this point. (ii) During their fifth week the pups stop trying to suckle and showing contact behaviour ; they begin to sleep in small groups, and seem to try to escape from the mother's cage. At this time the mother attacks them occasionally. (iii) With sexual maturity of the females (six weeks) play-fighting stops, and marking was not seen. If a female becomes pregnant she becomes dominant in a few days, but does not dare fight the mother. 7. It is likely that the third stage is an artefact of captivity and that the litter would be left by the mother in stage (i) and would largely disperse during stage (ii) in natural conditions. 8. The interpretations of observations described are necessarily tentative, and need experimental tests before they can be accepted.

scholarly journals Design, Analysis, and Experimental Evaluation of a Double Coil Magnetorheological Fluid Damper

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Guoliang Hu ◽  
Fengshuo Liu ◽  
Zheng Xie ◽  
Ming Xu
Keyword(s):  
Dynamic Range ◽  
Parametric Design ◽  
Mr Damper ◽  
Optimization Procedure ◽  
Experimental Tests ◽  
Element Model ◽  
Reverse Direction ◽  
Semiactive Control ◽  
Damping Force ◽  
Mr Dampers

A magnetorheological (MR) damper is one of the most advanced devices used in a semiactive control system to mitigate unwanted vibration because the damping force can be controlled by changing the viscosity of the internal magnetorheological (MR) fluids. This study proposes a typical double coil MR damper where the damping force and dynamic range were derived from a quasistatic model based on the Bingham model of MR fluid. A finite element model was built to study the performance of this double coil MR damper by investigating seven different piston configurations, including the numbers and shapes of their chamfered ends. The objective function of an optimization problem was proposed and then an optimization procedure was constructed using the ANSYS parametric design language (APDL) to obtain the optimal damping performance of a double coil MR damper. Furthermore, experimental tests were also carried out, and the effects of the same direction and reverse direction of the currents on the damping forces were also analyzed. The relevant results of this analysis can easily be extended to the design of other types of MR dampers.

Optimization design, manufacturing and mechanical performance of box girder made by carbon fiber-reinforced epoxy composites

2018 ◽  
Vol 25 (2) ◽  
pp. 297-307 ◽  
Author(s):  
Bin Yang ◽  
Lili Tong ◽  
Cheav Por Chea
Keyword(s):  
Composite Structures ◽  
Optimization Design ◽  
High Efficiency ◽  
Mechanical Performance ◽  
Parametric Design ◽  
Design Procedure ◽  
Optimization Procedure ◽  
Experimental Tests ◽  
Bending Test ◽  
Box Girder

AbstractOptimization design and manufacturing play an important role in obtaining successful composite structures with high efficiency and safe use of materials. In this paper, we first present the optimization design procedure for a composite box girder by ANSYS parametric design language (APDL) in the ANSYS software. The input parameters used in the simulation work were determined via fundamental experimental tests of composite specimens. Then we manufactured the designed composite box girder by mold-pressing prepreg technology according to the optimization results. The finial composite girder structure composed of arch top, web and bottom composite plate was obtained. The optimization procedure indicated that the use of stiffening plates in a girder could decrease the weight and increase the failure load. The location and ply mode of the stiffening plates in girder were suggested. The three-point-bending test was performed on the girder, and the test indicated that load-carrying capacity in unit mass of the optimized girder was as high as 107.8 N/g. Simulation and experimental results match well, and the maximum and minimum stresses in each layer were within the strength limitation of carbon material after optimized in the procedure.

Stiffness Analysis and Experimental Validation for the 6-Dof Jaw Opening-Closing Training Parallel Robot WY-5 (Waseda Yamanashi 5)

2004 ◽  
Vol 16 (6) ◽  
pp. 570-578
Author(s):  
Giuseppe Carbone ◽  
◽  
Hideaki Takanobu ◽  
Marco Ceccarelli ◽  
Atsuo Takanishi ◽  
...  
Keyword(s):  
Stiffness Matrix ◽  
Experimental Validation ◽  
Mouth Opening ◽  
Experimental Tests ◽  
Parallel Robot ◽  
Stiffness Analysis ◽  
Jaw Opening ◽  
Proposed Model ◽  
Stiffness Characteristics ◽  
Opening And Closing

In this paper a mouth opening and closing training robot named as WY-5 (Waseda Yamanashi version 5) is analyzed in terms of stiffness characteristics. Basic models and a formulation are proposed in order to deduce the stiffness matrix as a function of the most important stiffness parameters of the WY-5 architecture. A numerical simulation is carried out as based on the proposed formulation. Experimental tests are carried out in order to validate the proposed model that can be used for design/control purposes in order to improve the performance of WY-5.

Research of Static and Dynamic Characteristic Simulation and Experiment for the Sliding Valve

2013 ◽  
Vol 756-759 ◽  
pp. 4357-4362
Author(s):  
Rong Wu ◽  
Zheng Fei Yu ◽  
Ren Yang ◽  
Yan Jun Chen
Keyword(s):  
Structural Parameters ◽  
Experimental Tests ◽  
Static And Dynamic Characteristics ◽  
Control Signals ◽  
Simulation And Experiment ◽  
Dynamic Quality ◽  
Spool Valves ◽  
Opening And Closing ◽  
Spool Valve ◽  
Practical Implications

in the hydraulic and pneumatic system, spool valve is the spool component which is widely used in various types of control valves. Generally, valve spool, use fluid pressures as control signals, regulates the opening and closing of the pipeline, the pressure and flow of the system automatically. The spool valves static and dynamic quality impacts the system performance greatly. Researching its characteristic has practical implications to improve the performance of related products and optimize the system design. This article aims at researching the influences, on the static and dynamic characteristics of the sliding spool valve, caused by different structural parameters, through mathematical modeling, computer simulation and experimental tests.

The tolerance of wheat to high temperatures during reproductive growth. I. Survey procedures and general response patterns

1989 ◽  
Vol 40 (1) ◽  
pp. 1 ◽  
Author(s):  
IF Wardlaw ◽  
IA Dawson ◽  
P Munibi ◽  
R Fewster
Keyword(s):  
High Temperature ◽  
North Africa ◽  
Temperature Response ◽  
Response Patterns ◽  
Enhanced Sensitivity ◽  
Stage Of Development ◽  
Three Stages ◽  
General Response ◽  
Response To Temperature ◽  
Pollination And Fertilization

Selected cultivars of wheat from both a wide geographic and genetic background were examined under controlled conditions in the Canberra phytotron, for their response to high temperature at three stages of development: booting (late ear development), anthesis (pollination and fertilization) and grain growth (from 6 days after anthesis to maturity).The overall response to temperature, based on 28 cultivars from Afghanistan, Australia, Europe, India, Mexico, the Middle East and north Africa, demonstrated the sensitivity ofgrain number to high temperature during booting and the sensitivity of weight per grain to high temperature after anthesis. The data indicate a general reduction in yield per ear of 3-4% for each 1�C rise in temperature above a mean of 15�C. The response to temperature varied with the stage of development, and some cultivars sensitive to high temperature at booting were amongst the least sensitive during grain development. Also, the temperature response was found to be dependent on light, with an enhanced sensitivity to high temperature at low irradiance (<10 MJ m-2 day-1). The data did not reveal any clear relationship between the response to temperature, and weight per grain, the number of grains in a head or grains per spikelet of control (18/13�C) plants.

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