scholarly journals Mono–Material 4D Printing of Digital Shape–Memory Components

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3767
Author(s):  
Dalia Niazy ◽  
Ahmed Elsabbagh ◽  
Mostafa R. Ismail
Keyword(s):  
Energy Consumption ◽  
Built Environment ◽  
Shape Memory ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Interactive Systems ◽  
Scanning Calorimetry ◽  
Total Recovery ◽  
Temperature Range ◽  
Environment Temperature

Dynamic shading systems in buildings help reduce solar gain. Actuated systems, which depend on renewable energy with reduced mechanical parts, further reduce building energy consumption compared to traditional interactive systems. This paper investigates stimuli-responsive polymer application in architectural products for sustainable energy consumption, complying with sustainable development goals (SDGs). The proposed research method posits that, by varying the infill percentage in a pre-determined manner inside a 3D-printed mono-material component, directionally controlled shape change can be detected due to thermal stimuli application. Thus, motion behavior can be engineered into a material. In this study, PLA+, PETG, TPU and PA 6 printed components are investigated under a thermal cycle test to identify a thermally responsive shape-memory polymer candidate that actuates within the built environment temperature range. A differential scanning calorimetry (DSC) test is carried out on TPU 95A and PA 6 to interpret the material shape response in terms of transitional temperatures. All materials tested show an anisotropic shape-change reaction in a pre-programmed manner, complying with the behavior engineered into the matter. Four-dimensional (4D)-printed PA6 shows shape-shifting behavior and total recovery to initial position within the built environment temperature range.

Thermomechanical Characterization of a Series of Crosslinked Poly[ethylene-co-(vinyl acetate)] (PEVA) Copolymers

2015 ◽  
Vol 1718 ◽  
pp. 123-130 ◽  
Author(s):  
Matthias Heuchel ◽  
Laith Al-Qaisi ◽  
Karl Kratz ◽  
Ulrich Nöchel ◽  
Marc Behl ◽  
...  
Keyword(s):  
Shape Memory ◽  
Vinyl Acetate ◽  
Mechanical Stability ◽  
Shape Memory Polymer ◽  
Thermomechanical Properties ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Shape Memory Effects ◽  
Cross Links ◽  
Poly Ethylene

ABSTRACTCrosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) has been recently introduced as a polymer material, which can be functionalized with various shape-memory effects by solely altering the thermomechanical treatment called programming.In this study two series of cPEVAs with different vinyl acetate contents of 18 wt% (cPEVA18) and 28 wt% (cPEVA28) comprising different crosslink densities were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) in the temperature range of -130 °C to 120 °C. DMTA tests were performed in torsion mode, because such movements are highly relevant in the context of complex shape changes in shape-memory polymer based devices. Finally, the obtained DMTA results were compared with DMTA conducted in tension mode. Swelling experiments revealed a gel content in the range from 81% to 90% for cPEVA18 samples while for cPEVA28s a complete conversion was observed. The degree of swelling was found to decrease substantially with increasing crosslink density for both cPEVA series.The influence of VA content and extent of crosslinking on the appearance of the respective melting (Tm) and glass transition (Tg) as well as the thermomechanical properties of cPEVA systems could be demonstrated by discussing both DSC and DMTA results. The temperature range of mechanical stability correlates with the VA content and is determined by decreasing Tm values. The cross links do barely alter the stiffness of a PEVA up to the Tm rang, but lead to constant mechanical rigidity in the rubbery range above Tm.

scholarly journals Shape memory polymer network with thermally distinct elasticity and plasticity

2016 ◽  
Vol 2 (1) ◽  
pp. e1501297 ◽  
Author(s):  
Qian Zhao ◽  
Weike Zou ◽  
Yingwu Luo ◽  
Tao Xie
Keyword(s):  
Shape Memory ◽  
Molecular Design ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Polymer Network ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Device Applications ◽  
Temperature Ranges ◽  
Rational Molecular Design

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.

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

2018 ◽  
Vol 29 (18) ◽  
pp. 3667-3678 ◽  
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.

Active Rigidity Smart Joint for a Bat-Wing Micro Air Vehicle

2007 ◽  
Author(s):  
Justin E. Manzo ◽  
Ephrahim Garcia
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Aircraft Design ◽  
Passive State ◽  
External Loading ◽  
Arbitrary Length ◽  
Bat Wing ◽  
Biological Shape

In order to maximize lift for use in turning and landing maneuvers, bats make use of continuous camber change along their fifth metacarpal more effectively than all modern-day aircraft flaps. This biological shape change produces lower drag than modern aircraft, allowing for greater flight efficiency and lower noise signatures. A mechanism to replicate this demands a seamless actuator to avoid gaps and discontinuities, and requires the use of morphing structures. However, a recurring problem in morphing aircraft design is inefficiency of both space and power consumption. Problems often stem from the replacement of rigid structural elements with actuator elements that must be powered in order to carry static loads. To resolve this issue, a ‘smart joint’ concept is proposed which allows rigidity in its passive state, and becomes compliant while serving as an actuator by way of a composite of smart materials. Using a network of shape memory alloy and shape memory polymer, the joint is capable of rotations on the order of 5 percent camber over an arbitrary length when placed along a skeletal element of a bat-like wing structure. An analytical model is used to predict the behavior of the joint as a function of resistive heating and external loading, and is used to examine the layer thicknesses and locations (i.e. bimorph vs. unimorph) and placement of rigid elastic members in order to maximize deflection under a given load. Validation of the joint using is conducted via finite element modeling, and expected airfoil data for a generic shape maneuver to be accomplished by this joint is shown.

scholarly journals Two-Way Shape Memory Effect Induced by Tensile Deformation in Columnar-Grained Cu71.7Al18.1Mn10.2 Alloy

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2109 ◽  
Author(s):  
Pei-Sheng Yao ◽  
Hai-You Huang ◽  
Yan-Jing Su ◽  
Jian-Xin Xie
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Tensile Deformation ◽  
Shape Change ◽  
Uniaxial Tensile ◽  
Scanning Calorimetry ◽  
Transformation Temperatures ◽  
Deformation Strain ◽  
The Relationship

Columnar-grained Cu71.7Al18.1Mn10.2 shape memory alloy (SMA) was prepared by a directional solidification method and exhibited a high superelasticity of 8.18% and excellent ductility at room temperature, which provided the possibility of obtaining high shape memory. However, proper pre-deformation is an essential part of repeatedly obtaining large and stable shape change. In this paper, one-time uniaxial tensile pre-deformation was carried out at the temperature range −70–−80 °C. Then, the two-way shape memory effect (TWSME) of the alloy was evaluated by the martensitic transformation strain (εM) which was measured by a thermal expansion test to investigate the relationship between the pre-deformation strain (εT) and the TWSME. The results showed that εM of the columnar-grained Cu71.7Al18.1Mn10.2 alloy increased at first and then decreased with the increase of εT. The maximum value 2.91% of the εM could be reached when εT was 6%. The effects of the εT on transformation temperatures were also measured by differential scanning calorimetry. Based on the variations of transformation temperatures, the relationship between the internal stress induced by the pre-deformation process and the εM, and the influence mechanism of the pre-deformation strain on the TWSME in columnar-grained Cu71.7Al18.1Mn10.2 alloy, were discussed. The results obtained from this work may provide reference for potential applications of Cu-based SMAs, such as self-control components, fasteners, etc.

Shape-Memory Actuation of Individual Micro-/Nanofibers

MRS Advances ◽  
2020 ◽  
Vol 5 (46-47) ◽  
pp. 2391-2399
Author(s):  
Yue Liu ◽  
Oliver E. C. Gould ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Fiber Contact ◽  
Physical Functions ◽  
Robotic Devices ◽  
The Stability ◽  
Soft Actuators ◽  
Working Distance

AbstractAdvances in the fabrication and characterization of polymeric nanomaterials has greatly advanced the miniaturization of soft actuators, creating materials capable of replicating the functional physical behavior previously limited to the macroscale. Here, we demonstrate how a reversible shape-memory polymer actuation can be generated in a single micro/nano object, where the shape change during actuation of an individual fiber can be dictated by programming using an AFM-based method. Electrospinning was used to prepare poly(ε-caprolactone) micro-/nanofibers, which were fixed and crosslinked on a structured silicon wafer. The programming as well as the observation of recovery and reversible displacement of the fiber were performed by vertical three point bending, using an AFM testing platform introduced here. A plateau tip was utilized to improve the stability of the fiber contact and working distance, enabling larger deformations and greater rbSMPA performance. Values for the reversible elongation of εrev = 3.4 ± 0.1% and 10.5 ± 0.1% were obtained for a single micro (d = 1.0 ± 0.2 μm) and nanofiber (d = 300 ± 100 nm) in cyclic testing between the temperatures 10 and 60 °C. The reversible actuation of the nanofiber was successfully characterized for 10 cycles. The demonstration and characterization of individual shape-memory nano and microfiber actuators represents an important step in the creation of miniaturized robotic devices capable of performing complex physical functions at the length scale of cells and structural component of the extracellular matrix.

Synthesis and Characterization of IPDI Based Shape Memory Polyurethane

2020 ◽  
Vol 1010 ◽  
pp. 142-147
Author(s):  
Nur Athirah Rasli @ Rosli ◽  
Syazana Ahmad Zubir
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Soft Segment ◽  
Shape Memory Polymer ◽  
Palm Kernel ◽  
Hexamethylene Diisocyanate ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Chain Flexibility

Various polyurethane-based shape memory polymer was synthesized using polycaprolactone (PCL) as soft segment and, hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) as the hard segments. Palm kernel oil-based polyol was used to replace part of the petroleum-based polyol due to the increasing demand on renewable resources as a result of environmental awareness. The synthesis has been carried out using two step polymerization method. The effects of varying the molar ratio of IPDI/HMDI on material properties such as crystallinity, transition temperature, morphology, shape memory effect and tensile strength were investigated by using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), shape memory test and tensile test. A high IPDI content in SMPU results in better shape memory effect, whereas increasing HMDI content leads to a better chain flexibility. In this work, the incorporation of IPDI contributes to the formation of phase separation which enhance the formation of crystalline soft segment structure while the incorporation of HMDI as isocyanate tend to promote phase mixing which enhance the chain flexibility of the SMPU backbone.

Electro-thermo-mechanical behavior of carbon nanopaper shape memory polymer composites

2021 ◽  
pp. 1045389X2110188
Author(s):  
Veli Bugra Ozdemir ◽  
Kawai Kwok
Keyword(s):  
Mechanical Behavior ◽  
Shape Memory ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Axial Loading ◽  
Element Model ◽  
Close Correlation ◽  
Stimuli Responsive ◽  
Shape Memory Composites ◽  
Shape Programming

An electro-active composite based on carbon nanopaper (CNP) shape memory polymer (SMP) composite is proposed for actuating deployment of composite deployable structures. Carbon nanopaper shape memory composites are stimuli-responsive materials that can change between programmed shapes and the original shape by a voltage input. The proposed composite is a sandwich structure where the CNP layer acts as a flexible electrical heater when a voltage difference is applied. The shape change behavior of CNP-SMP composite presents a coupled electrical-thermal-structural problem. This paper presents a combined experimental, numerical, and analytical study of the time-dependent shape programming, stowage, and actuation of the CNP-SMP composite. The governing equations for the multiphysics behavior are derived. Characterization of the electrical and mechanical properties of the materials are carried out and employed in a nonlinear, fully coupled electrical-thermal-structural finite element model. Shape programming, stowage and actuation characteristics of the composite are investigated experimentally under axial loading. An analytical model is derived for the thermo-mechanical behavior of the composite which directly expresses the recovery over time through the creep compliance function. Close correlation is obtained between experimental measurements and numerical simulations. The proposed model can accurately predict the load and shape characteristics throughout programming, stowage, and actuation.

Magnetic Shape Memory - Polymer Hybrids

2016 ◽  
Vol 879 ◽  
pp. 133-138 ◽  
Author(s):  
Ilkka Aaltio ◽  
Frans Nilsén ◽  
Joonas Lehtonen ◽  
Yan Ling Ge ◽  
Steven Spoljaric ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shape Memory ◽  
Single Crystals ◽  
Magnetic Particles ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Raw Material ◽  
Magnetic Shape Memory ◽  
Polymer Hybrids ◽  
The Magnetic Field

Martensitic Ni-Mn-Ga based alloys are known for the Magnetic Shape Memory (MSM) effect, which upon application of an external magnetic field can generate a strain up to 12 % depending on the microstructure of the martensite. The MSM effect occurs by rearrangement of the martensite variants, which is most advantageous in single crystals. Single crystals are, however, rather tedious to produce and there has been attempts to achieve MSM effect in polycrystals. However, in polycrystals the magnetic field induced shape change remains low as compared to single crystals. As an alternative to the former, hybrid MSM materials offer several advantages. When compared to single crystals, hybrids have extended freedom of shaping, lower raw material price, relatively large MSM strain and easier manufacturability. Embedding MSM particles into a suitable polymer matrix results in actuation function or good vibration damping performance. In the present study we report on the mechanical, structural and magnetic properties of MSM polymer hybrids, which are prepared by mixing gas-atomized Ni-Mn-Ga MSM powder into epoxy matrix and aligning the magnetic particles in a magnetic field.

Toward Material Parameters for Modeling Devices Made From an Epoxy-Based Shape Memory Polymer

2015 ◽  
Author(s):  
Veysel Erel ◽  
Jessica L. Berry ◽  
Arun Srinivasa ◽  
Terry S. Creasy
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Scanning Calorimetry ◽  
Element Analysis ◽  
Simple Tension ◽  
Nonlinear Elastic ◽  
Tension Experiments

Designing devices made from epoxy-based shape memory polymers is difficult because few material behavior parameters are available for these materials in the rubbery/shape changing region. This work examines the rubbery state, greater than 20° C above the glass transition temperature (Tg), as an elastomeric regime suited to characterization with simple tension and planar tension experiments. Differential scanning calorimetry (DSC) results show a 70° C Tg, which agrees with prior research. Simple tension experiments at 100° C exhibited nonlinear elastic behavior, and finite element analysis (FEA) agreed with the constitutive behavior exhibited in the experiments. Planar tension experiments exhibited novel results. The stress/strain response was sigmoidal with a significant plateau in stress followed by rising stress to failure. The typical 10:1 gage width/gage length ratio seemed to over constrain the material. The strain to failure is small, and suggests the material behavior is a hybrid of elastic and hyperelastic behavior.

Sign in / Sign up

Export Citation Format

Share Document