Elevation of mechanically robust and reprocessable thermoset polyurea composites towards permanent shape reconfiguration controlled by heat and electricity

2021 ◽  
pp. 128354
Author(s):  
Liang Jiang ◽  
Yuan Lei ◽  
Yao Xiao ◽  
Hualiang Xu ◽  
Anqian Yuan ◽  
...  
Keyword(s):  
Permanent Shape

Facile water-assisted permanent shape reconfiguration of zwitterionic polyurethanes

Polymer ◽  
2018 ◽  
Vol 158 ◽  
pp. 25-31 ◽  
Author(s):  
Haitao Zhuo ◽  
Hao Wen ◽  
Guanlun Liu ◽  
Heng Chen ◽  
Shaojun Chen
Keyword(s):  
Permanent Shape

Stability of periodic waves in shallow water

1974 ◽  
Vol 66 (1) ◽  
pp. 81-96 ◽  
Author(s):  
P. J. Bryant
Keyword(s):  
Shallow Water ◽  
Wave Train ◽  
Periodic Wave ◽  
Fundamental Wave ◽  
Cnoidal Waves ◽  
Margin Of Stability ◽  
Fundamental Wavelength ◽  
Stokes Waves ◽  
Wave Trains ◽  
Permanent Shape

Waves of small but finite amplitude in shallow water can occur as periodic wave trains of permanent shape in two known forms, either as Stokes waves for the shorter wavelengths or as cnoidal waves for the longer wavelengths. Calculations are made here of the periodic wave trains of permanent shape which span uniformly the range of increasing wavelength from Stokes waves to cnoidal waves and beyond. The present investigation is concerned with the stability of such permanent waves to periodic disturbances of greater or equal wavelength travelling in the same direction. The waves are found to be stable to infinitesimal and to small but finite disturbances of wavelength greater than the fundamental, the margin of stability decreasing either as the fundamental wave becomes more nonlinear (i.e. contains more harmonics), or as the wavelength of the periodic disturbance becomes large compared with the fundamental wavelength. The decreasing margin of stability is associated with an increasing loss of spatial periodicity of the wave train, to the extent that small but finite disturbances can cause a form of interaction between consecutive crests of the disturbed wave train. In such a case, a small but finite disturbance of wavelength n times the fundamental wavelength converts the wave train into n interacting wave trains. The amplitude of the disturbance subharmonic is then nearly periodic, the time scale being the time taken for repetitions of the pattern of interactions. When the disturbance is of the same wavelength as the permanent wave, the wave is found to be neutrally stable both to infinitesimal and to small but finite disturbances.

scholarly journals Creep and Material Design

2012 ◽  
Vol 9 (1) ◽  
pp. 169-171
Author(s):  
Ram Oruganti
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Room Temperature ◽  
Shape Change ◽  
Creep Damage ◽  
Material Design ◽  
The Other ◽  
Permanent Shape ◽  
Total Life

When a material is subjected to temperature and stress, it deforms slowly resulting in permanent shape change. If the same amount of stress were applied at room temperature, the material would not budge. This deformation at high temperature under low stresses is called creep. This phenomenon is important for OEM’S like GE etc. since turbine components are exposed to low stress and high temperature and the resulting shape change is not a desirable consequence. Apart from the change in shape, the components can eventually rupture leading to catastrophic consequences. So it is imperative that the nature of this phenomenon is understood well. Some of the questions to be answered are 1) What makes one material more resistant to creep that the other 2) How can a material’s creep resistance be improved 3) How can the current creep damage in a component be measured 4) Is it possible to say what fraction of the total life of a component has been consumed by creep.

scholarly journals Water Triggered Shape Memory Materials

2013 ◽  
Vol 3 (1) ◽  
pp. 49-50 ◽  
Author(s):  
Guoguang Niu
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Electrical Current ◽  
Light Illumination ◽  
Poly Ethylene Glycol ◽  
Thermally Induced ◽  
Permanent Shape ◽  
Poly Ethylene ◽  
Novel Strategy

The term "shape memory effect" refers to the ability of a material to be deformed and fixed into a temporary shape, and to recover its original, permanent shape upon an external stimulus (1). Shape memory polymers have attracted much interest because of their unique properties, and applied tremendously in medical area, such as biodegradable sutures, actuators, catheters and smart stents (2, 3). Shape memory usually is a thermally induced process, although it can be activated by light illumination, electrical current, magnetic, or electromagnetic field (4-6). During the process, the materials are heated directly or indirectly above their glass transition temperature (Tg) or the melting temperature (Tm) in order to recover the original shape. Non-thermally induced shape memory polymers eliminate the temperature constrains and enable the manipulation of the shape recovered under ambient temperature (7, 8). Herein, we report a novel strategy of water induced shape memory, in which the formation and dissolution of poly(ethylene glycol) (PEG) crystal is utilized for the fixation and recovery of temporary deformation of hydrophilic polymer. This water-induced shape recovery is less sensitive to temperature, of which 95% deformation is fixed in circumstance and over 75% recovery is reached even at 0 oC.

scholarly journals Light-Stimulated Permanent Shape Reconfiguration in Cross-Linked Polymer Microparticles

2017 ◽  
Vol 9 (16) ◽  
pp. 14422-14428 ◽  
Author(s):  
Lewis Michael Cox ◽  
Xiaohao Sun ◽  
Chen Wang ◽  
Nancy Sowan ◽  
Jason P. Killgore ◽  
...  
Keyword(s):  
Permanent Shape ◽  
Polymer Microparticles

scholarly journals Bioinspired fiber-regulated composite with tunable permanent shape and shape memory properties via 3d magnetic printing

2019 ◽  
Vol 164 ◽  
pp. 458-466 ◽  
Author(s):  
Luquan Ren ◽  
Bingqian Li ◽  
Zhengyi Song ◽  
Qingping Liu ◽  
Lei Ren ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Properties ◽  
Permanent Shape

scholarly journals Albanien als Krisen- und Kriegsgebiet 1908–1921

2014 ◽  
Vol 73 (1) ◽  
pp. 23-50 ◽  
Author(s):  
Björn Opfer-Klinger
Keyword(s):  
World War I ◽  
Great Powers ◽  
Self Concept ◽  
The Political ◽  
Eastern European ◽  
International Conflicts ◽  
World War ◽  
Postwar Europe ◽  
Foreign Intervention ◽  
Permanent Shape

Abstract The Albanian national movement was still quite young and heterogeneous when international conflicts lead to the foundation of the Albanian state in 1912/13. Located by the strategically important Strait of Otranto, it came into existence as a compromise and under the protection of the Great Powers in a time when the Osman Empire was collapsing and the South-eastern European States were practising an aggressive policy of expansion. Only a few months later World War I broke out and affected the region severely. Consequently, it took another ten years for the Albanian state to take permanent shape within the changed order of postwar Europe. At this point, however, the political self-concept of Albania had altered pertinently due to constant foreign intervention and occupation by opposing war parties. Some of these influences continue to affect Albania to the present day.

Nonlinear waves in compacting media

1986 ◽  
Vol 164 ◽  
pp. 429-448 ◽  
Author(s):  
Victor Barcilon ◽  
Frank M. Richter
Keyword(s):  
Mathematical Model ◽  
Solitary Waves ◽  
Nonlinear Waves ◽  
Nonlinear Interaction ◽  
Phase Speed ◽  
Governing Equations ◽  
One Dimensional ◽  
The Earth ◽  
Permanent Shape ◽  
The Mathematical Model

An investigation of the mathematical model of a compacting medium proposed by McKenzie (1984) for the purpose of understanding the migration and segregation of melts in the Earth is presented. The numerical observation that the governing equations admit solutions in the form of nonlinear one-dimensional waves of permanent shape is confirmed analytically. The properties of these solitary waves are presented, namely phase speed as a function of melt content, nonlinear interaction and conservation quantities. The information at hand suggests that these waves are not solitons.

scholarly journals Photothermally and magnetically controlled reconfiguration of polymer composites for soft robotics

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw2897 ◽  
Author(s):  
Jessica A.-C. Liu ◽  
Jonathan H. Gillen ◽  
Sumeet R. Mishra ◽  
Benjamin A. Evans ◽  
Joseph B. Tracy
Keyword(s):  
Magnetic Field ◽  
Shape Memory Polymer ◽  
Composite Films ◽  
Soft Robotics ◽  
Magnetic Actuation ◽  
New Materials ◽  
Photothermal Heating ◽  
Multiple Cycles ◽  
Permanent Shape ◽  
The Magnetic Field

New materials are advancing the field of soft robotics. Composite films of magnetic iron microparticles dispersed in a shape memory polymer matrix are demonstrated for reconfigurable, remotely actuated soft robots. The composite films simultaneously respond to magnetic fields and light. Temporary shapes obtained through combined magnetic actuation and photothermal heating can be locked by switching off the light and magnetic field. Subsequent illumination in the absence of the magnetic field drives recovery of the permanent shape. In cantilevers and flowers, multiple cycles of locking and unlocking are demonstrated. Scrolls show that the permanent shape of the film can be programmed, and they can be frozen in intermediate configurations. Bistable snappers can be magnetically and optically actuated, as well as biased, by controlling the permanent shape. Grabbers can pick up and release objects repeatedly. Simulations of combined photothermal heating and magnetic actuation are useful for guiding the design of new devices.

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