Thermoviscoplastic behaviors of anisotropic shape memory elastomeric composites for cold programmed non-affine shape change

Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices.

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Blocking force measurement of shape memory polymer composite hinges for space deployable structures

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x18798950 ◽

2018 ◽

Vol 29 (18) ◽

pp. 3667-3678 ◽

Cited By ~ 2

Author(s):

Thanh Duc Dao ◽

Nam Seo Goo ◽

Woong Ryeol Yu

Keyword(s):

Shape Memory ◽

Polymer Composite ◽

Mechanical Performance ◽

Force Measurement ◽

Shape Change ◽

Shape Memory Polymer ◽

Mass System ◽

Manufacturing Method ◽

Moment Arms ◽

Repeated Test

This study introduces a method for measuring the blocking force of a shape memory polymer composite hinge to quantify the performance of a shape memory polymer composite hinge for space deployable structure applications. A detailed design of how to select heating elements for a self-deployable configuration is also suggested. The shape memory polymer composite hinge consists of two reverse carpenter shape memory polymer composite tapes that were made from carbon-epoxy fabric, shape memory polymer resin, and two heating elements. The heating elements were attached to the shape memory polymer composite tape using the composite manufacturing method, and they were used as the heating source in the deployment test. The blocking force and moment of the hinge were measured using a pulley–mass system setup to examine the mechanical performance of the hinge. During the test, the shape change was recorded with a camera to calculate the moment arms. While the blocking force was 7.21 N in the initial test, it decreased slightly with the working cycle and was 6.27 N in the repeated test. The maximum hinge moment was 0.47 N m in the repeated test. In addition, the results revealed that a pop-up phenomenon occurred at the middle period of deployment. These results confirm that the shape memory polymer composite hinge works well with heating elements and provide a guideline for performance evaluation of the shape memory polymer composite hinge.

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Shape-Memory Polymers for Biomedical Applications

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.54.96 ◽

2008 ◽

Vol 54 ◽

pp. 96-102 ◽

Cited By ~ 33

Author(s):

Andreas Lendlein ◽

Marc Behl

Keyword(s):

Shape Memory ◽

Material Properties ◽

Biomedical Applications ◽

Traditional Approach ◽

Shape Change ◽

Shape Memory Polymers ◽

Thermally Induced ◽

Wide Range ◽

Multifunctional Polymers ◽

Suitable Process

Most polymers used in clinical applications today are materials that have been developed originally for application areas other than biomedicine. On the other side, different biomedical applications are demanding different combinations of material properties and functionalities. Compared to the intrinsic material properties, a functionality is not given by nature but result from the combination of the polymer architecture and a suitable process. Examples for functionalities that play a prominent role in the development of multifunctional polymers for medical applications are biofunctionality (e.g. cell or tissue specificity), degradability, or shape-memory functionality. In this sense, an important aim for developing multifunctional polymers is tailoring of biomaterials for specific biomedical applications. Here the traditional approach, which is designing a single new homo- or copolymer, reaches its limits. The strategy, that is applied here, is the development of polymer systems whose macroscopic properties can be tailored over a wide range by variation of molecular parameters. The Shape-memory capability of a material is its ability to trigger a predefined shape change by exposure to an external stimulus. A change in shape initiated by heat is called thermally-induced shape-memory effect. Thermally, light-, and magnetically induced shape-memory polymers will be presented, that were developed especially for minimally invasive surgery and other biomedical applications. Furthermore triple-shape polymers will be introduced, that have the capability to perform two subsequent shape changes. Thus enabling more complex movements of a polymeric material.

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Shape Memory Alloys: A Summary of Recent Achievements

Materials Science Forum ◽

10.4028/www.scientific.net/msf.583.21 ◽

2008 ◽

Vol 583 ◽

pp. 21-41 ◽

Cited By ~ 49

Author(s):

Peter Entel ◽

Vasiliy D. Buchelnikov ◽

Markus E. Gruner ◽

Alfred Hucht ◽

Vladimir V. Khovailo ◽

...

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Shape Memory ◽

Shape Change ◽

Heusler Alloys ◽

Systematic Change ◽

Magnetic Shape Memory ◽

Electronic Density ◽

Modulated Phases ◽

Modulated Structures

The Ni-Mn-Ga shape memory alloy displays the largest shape change of all known magnetic Heusler alloys with a strain of the order of 10% in an external magnetic field of less than one Tesla. In addition, the alloys exhibit a sequence of intermediate martensites with the modulated structures usually appearing at c/a < 1 while the low-temperature non- modulated tetragonal structures have c/a > 1. Typically, in the Ni-based alloys, the martensitic transformation is accompanied by a systematic change of the electronic structure in the vicinity of the Fermi energy, where a peak in the electronic density of states from the non-bonding Ni states is shifted from the occupied region to the unoccupied energy range, which is associated with a reconstruction of the Fermi surface, and, in most cases, by pronounced phonon anomalies. The latter appear in high-temperature cubic austenite, premartensite but also in the modulated phases. In addition, the modulated phases have highly mobile twin boundaries which can be rearranged by an external magnetic field due to the high magnetic anisotropy, which builds up in the martensitic phases and which is the origin of the magnetic shape memory effect. This overall scenario is confirmed by first-principles calculations.

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Crystallographic Characteristics of Shape Memory Alloys

MRS Proceedings ◽

10.1557/opl.2011.359 ◽

2011 ◽

Vol 1295 ◽

Cited By ~ 2

Author(s):

Madangopal Krishnan

Keyword(s):

Shape Memory Alloys ◽

Shape Memory ◽

Shape Change ◽

Parent Phase ◽

The Self ◽

Intermetallic Alloys ◽

Martensitic Microstructure ◽

Crystallographic Characteristics ◽

Macroscopic Shape ◽

Microstructural Examination

ABSTRACTThe martensitic microstructure of shape memory alloys is an aggregate of self accommodating plate groups. The principal character of this aggregate is its demonstration of pseudoplasticity, wherein a macroscopic shape change is brought about by extensive rearrangement and reorientation of the self accommodating martensite variants, and that of microstructural reversibility, wherein the polyvariant microstructure transforms back to the original grain of the parent phase after pseudoplastic deformation. These aspects of the shape memory intermetallic alloys are intriguing and, to a great extent, unsolved. The aim of this paper is to show that the underlying crystallographic interrelationships of the self accommodating microstructure of intermetallic alloys are responsible for the observed effect. The paper will discuss the relation between autocatalytic nucleation and self accommodation, the relation between microstructural reversibility and intervariant interfaces of the martensitic microstructure and the manifestations of microstructural irreversibility using results from the microstructural examination of the self accommodating microstructures.

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Thermoelastic Martensitic Transformations and the Nature of the Shape Memory Effect

MRS Proceedings ◽

10.1557/proc-21-657 ◽

1983 ◽

Vol 21 ◽

Cited By ~ 6

Author(s):

C. M. Wayman

Keyword(s):

Single Crystal ◽

Shape Memory ◽

Crystal Structures ◽

Shape Memory Effect ◽

Memory Effect ◽

Shape Change ◽

Parent Phase ◽

Shape Deformation ◽

Initial Shape ◽

Plate Group

ABSTRACTInvestigations of the shape memory effect in alloys forming thermoelastic martensites with various crystal structures (2H, 3R, 9R and 18R) reveal that universal behavior exists. A unified explanation of the martensite deformation processes and subsequent shape recovery is now in hand, even though the various martensites are both internally twinned and internally faulted and, in addition, have different crystal structures. In cases studied to date, an initial parent phase single crystal transforms into self-accommodating arrangements of martensite variants (plates) which are characterized by “plate groups.” Each group consists of four variants. The average shape deformation in a plate group is essentially zero.Upon stressing below the Mf temperature the martensite undergoes deformation by detwinning (2H and 3R only), variant-variant coalescence and twinning processes, and further group-to-group coalescence. The deformed specimen eventually becomes a single crystal of martensite consisting of that particular habit plane variant whose shape deformation permits maximum extension in the direction of the applied stress. The deformed martensite persists after unloading has occurred; reverse rearrangements of twins and variants do not occur. Specimens deformed below Mf regain their initial shape characteristic of the initial parent phase upon heating from As to Af, during which the single crystal of martensite obtained by stressing the 24-variant configuration transforms back to the original parent phase single crystal in a unique manner, which is basically a simple “unshearing” process. The unshearing is the essence of the memory.The two-way shape memory effect results after the initial martensitic transformation upon cooling is preprogrammed by the introduction of stresses which preferentially bias the transformation so that only a single variant of martensite forms upon cooling. The shape change of this single variant causes the characteristic spontaneous “bending” upon cooling. The characteristic “unbending upon heating is as with the conventional “one-way” shape memory effect.

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Shape memory materials with reversible shape change and self-healing abilities: A review

Materials Today Proceedings ◽

10.1016/j.matpr.2020.10.820 ◽

2020 ◽

Author(s):

Brijesh Mishra ◽

Sumit Sharma

Keyword(s):

Shape Memory ◽

Shape Change ◽

Self Healing ◽

Shape Memory Materials

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Macroscopic shape change of Cu13Zn15Al shape memory alloy on successive heating

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2006.11.026 ◽

2008 ◽

Vol 452 (2) ◽

pp. 307-311 ◽

Cited By ~ 17

Author(s):

Z. Li ◽

S. Gong ◽

M.P. Wang

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Shape Change ◽

Macroscopic Shape ◽

Successive Heating

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4D Printing of Complex Ceramic Structures via Controlling Zirconia Contents and Patterns

Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation ◽

10.1115/msec2021-63642 ◽

2021 ◽

Author(s):

Zhicheng Rong ◽

Chang Liu ◽

Yingbin Hu

Keyword(s):

3D Printing ◽

Shape Memory ◽

Shape Change ◽

Three Dimensional ◽

Ceramic Materials ◽

Full Potential ◽

Sintering Process ◽

4D Printing ◽

3D Printed ◽

Dynamic Components

Abstract In recent years, more and more attentions have been attracted on integrating three-dimensional (3D) printing with fields (such as magnetic field) or innovating new methods to reap the full potential of 3D printing in manufacturing high-quality parts and processing nano-scaled composites. Among all of newly innovated methods, four-dimensional (4D) printing has been proved to be an effective way of creating dynamic components from simple structures. Common feeding materials in 4D printing include shape memory hydrogels, shape memory polymers, and shape memory alloys. However, few attempts have been made on 4D printing of ceramic materials to shape ceramics into intricate structures, owing to ceramics’ inherent brittleness nature. Facing this problem, this investigation aims at filling the gap between 4D printing and fabrication of complex ceramic structures. Inspired by swelling-and-shrinking-induced self-folding, a 4D printing method is innovated to add an additional shape change of ceramic structures by controlling ZrO2 contents and patterns. Experimental results evidenced that by deliberately controlling ZrO2 contents and patterns, 3D-printed ceramic parts would undergo bending and twisting during the sintering process. To demonstrate the capabilities of this method, more complex structures (such as a flower-like structure) were fabricated. In addition, functional parts with magnetic behaviors were 4D-printed by incorporating iron into the PDMS-ZrO2 ink.

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