scholarly journals Actuator Behaviour of Tailored Poly(thiourethane) Shape Memory Thermosets

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1571
Author(s):  
Francesco Gamardella ◽  
Angels Serra ◽  
Xavier Ramis ◽  
Silvia De la Flor
Keyword(s):  
Shape Memory ◽  
Beam Theory ◽  
Recovery Process ◽  
Hexamethylene Diisocyanate ◽  
Isophorone Diisocyanate ◽  
New Family ◽  
Bending Mode ◽  
Cantilever Bending ◽  
Constrained Conditions ◽  
Real Complex

In this work, a new family of poly(thiourethane) shape memory thermosetting actuators was developed and characterized. These materials can be easily prepared from mixtures of two different aliphatic diisocyanates and a trithiol in the presence of a latent catalyst, allowing an easy manipulation of the formulation. Rheological studies of the curing process confirm the latent character of the formulations. The glass transition temperatures and the mechanical properties can be modified by varying the proportion of diisocyanates (hexamethylene diisocyanate, HDI, and isophorone diisocyanate, IPDI) with stoichiometric amounts of trimethylolpropane tris(3-mercaptopropionate). The shape-memory behavior was deeply investigated under three different conditions: unconstrained, partially constrained, and fully constrained. Tests were performed in single cantilever bending mode to simulate conditions closer to real complex mechanics of thermomechanical actuators under flexural performances. The complex recovery process in single cantilever bending mode was compared with that obtained using tensile mode. The results evidenced that the amount of recovery force in fully constrained conditions, or energy released during the recovery process in partially constrained, can be modulated by simply changing the proportion of both diisocyanates. A simple model based on Timoshenko beam theory was used for the prediction of the amount of work performed. The reported results are an important guideline to design shape-memory materials based on poly(thiourethane) networks, establishing criteria for the choice of the material depending on the expected application.

Investigate of Electrical Conductivity of Shape-Memory Polymer Filled with Carbon Black

2008 ◽  
Vol 47-50 ◽  
pp. 714-717 ◽  
Author(s):  
Xin Lan ◽  
Jin Song Leng ◽  
Yan Ju Liu ◽  
Shan Yi Du
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Shape Memory ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Recovery Process ◽  
Thermomechanical Properties ◽  
Electrically Conductive ◽  
New System

A new system of thermoset styrene-based shape-memory polymer (SMP) filled with carbon black (CB) is investigated. To realize the electroactive stimuli of SMP, the electrical conductivity of SMP filled with various amounts of CB is characterized. The percolation threshold of electrically conductive SMP filled with CB is about 3% (volume fraction of CB), which is much lower than many other electrically conductive polymers. When applying a voltage of 30V, the shape recovery process of SMP/CB(10 vol%) can be realized in about 100s. In addition, the thermomechanical properties are also characterized by differential scanning calorimetery (DSC).

scholarly journals Isocyanate Modified GO Shape-Memory Polyurethane Composite

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 118 ◽  
Author(s):  
Yuanchi Zhang ◽  
Jinlian Hu
Keyword(s):  
Graphene Oxide ◽  
Minimally Invasive ◽  
Shape Memory ◽  
Bone Repair ◽  
Recovery Process ◽  
Invasive Treatment ◽  
Element Analysis ◽  
Polyurethane Composite ◽  
Shape Memory Effects ◽  
Shape Memory Polyurethane

Shape-memory composites have benefits for minimally invasive surgery, but their wider applications for bone repair are hindered by conflicts between the mechanical and memory performances, especially at load-bearing locations. In this study, we fabricated a graphene oxide shape-memory polyurethane composite through the chemical combination of graphene oxide and isocyanate, in order to realize satisfactory mechanical and shape-memory effects. As desired, a modulus of ~339 MPa and a shape recovery ratio of 98% were achieved, respectively, in the composite. In addition, finite element analysis demonstrated that, after being implanted in a defective bone through a minimally invasive treatment, where the highest stress was distributed at the implant–bone interface, this composite could offer a generated force during the recovery process. Furthermore, we also discuss the origins of the improved mechanical and memory properties of the composites, which arise from increased net-points and the stable molecular structure inside. Therefore, with its superior structure and properties, we envision that this shape-memory composite can provide new insights toward the practical application of shape-memory polymers and composites in the field of bone repair.

Influence of Materials on the Performance Limits of Microactuators

2007 ◽  
Vol 1052 ◽  
Author(s):  
Prasanna Srinivasan ◽  
S. Mark Spearing
Keyword(s):  
Thin Films ◽  
Shape Memory ◽  
High Performance ◽  
Low Frequency ◽  
Beam Theory ◽  
Performance Limits ◽  
Low Frequencies ◽  
Thermal Actuators ◽  
Work Volume ◽  
Selection Of

AbstractThe selection of actuators at the micro-scale requires an understanding of the performance limits of different actuation mechanisms governed by the optimal selection of materials. This paper presents the results of analyses for elastic bi-material actuators based on simple beam theory and lumped parameter thermal models. Comparisons are made among commonly employed actuation schemes (electro-thermal, piezoelectric and shape memory) at micro scales and promising candidate materials are identified. Polymeric films on Si subjected to electro-thermal heating are optimal candidates for high displacement, low frequency devices while ferroelectric thin films of Pb-based ceramics on Si/ DLC are optimal for high force, high frequency devices. The ability to achieve ∼10 kHz at scales < 100μm make electro-thermal actuators competitive with piezoelectric actuators considering the low work/volume obtained in piezoelectric actuation (∼ 10−8J.m−3.mV−2). Although shape memory alloy (SMA) actuators such as Ni-Ti on Si deliver larger work (∼ 1 J.m−3K−2) than electro-thermal actuators at relatively low frequencies (∼ 1 kHz), the critical scale associated with the cessation of the shape memory effect forms the bounding limit for the actuator design. The built-in compressive stress levels (∼ 1GPa) in thin films of Si and DLC could be exploited for realizing a high performance actuator by electro-thermal buckling.

Dynamic analysis of a shape memory alloy beam with pseudoelastic behavior

2018 ◽  
Vol 29 (9) ◽  
pp. 1835-1849 ◽  
Author(s):  
Reza Razavilar ◽  
Alireza Fathi ◽  
Morteza Dardel ◽  
Jamal Arghavani Hadi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Frequency Response ◽  
Kinetic Equations ◽  
Elastic Beam ◽  
Beam Theory ◽  
Response Analysis ◽  
Interesting Phenomenon ◽  
Time Saving ◽  
Solution Approach

This article aims at developing a semi-analytic approach for studying the free and forced vibrations of a pseudoelastically behaving shape memory alloy beam. Based on the Euler–Bernoulli beam theory, equations of motion were derived through Hamilton principle, and the obtained partial differential equations were decomposed by applying the Galerkin approach and were solved using Newmark integration method. A three-dimensional phenomenological model of shape memory alloy, which is capable of identifying the main properties of the shape memory alloy, was employed to model the behavior of the shape memory alloy beam. A closed-form numerical algorithm was introduced to simulate the governing kinetic equations of the shape memory alloy beam coupled with transformation strain. The presented novel solution approach is simple, flexible, and time-saving. Stability analysis was performed using phase state trajectories to show dynamic characteristics of the shape memory alloy beam. Due to hysteric behavior of the shape memory alloy, energy dissipation was clearly observed in early stages of the free vibration and within the transient regions of the forced vibration. The numerical results showed that, due to the hysteric induced damping effect, the vibration amplitude is smaller in comparison to an equivalent elastic beam, and consequently, the shape memory alloy beam exhibits more stable behavior at the resonant frequencies. This property can potentially find applications in energy damping applications and vibration control. Moreover, an interesting phenomenon called jumping was observed in the results of frequency response analysis. At jumping frequency, the amplitude of the frequency response has two distinct levels. This jumping frequency is as a result of the hysteresis behavior of the shape memory alloy, and it is a function of the exciting amplitude.

Developing a beam formulation for semi-crystalline two-way shape memory polymers

2020 ◽  
Vol 31 (12) ◽  
pp. 1465-1476
Author(s):  
Mohammad-Ali Maleki-Bigdeli ◽  
Majid Baniassadi ◽  
Kui Wang ◽  
Mostafa Baghani
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Beam Theory ◽  
Shape Memory Polymers ◽  
Bernoulli Beam ◽  
Von Karman ◽  
Von Kármán ◽  
Euler Bernoulli Beam ◽  
Beam Theories

In this research, the bending of a two-way shape memory polymer beam is examined implementing a one-dimensional phenomenological macroscopic constitutive model into Euler–Bernoulli and von-Karman beam theories. Since bending loading is a fundamental problem in engineering applications, a combination of bending problem and two-way shape memory effect capable of switching between two temporary shapes can be used in different applications, for example, thermally activated sensors and actuators. Shape memory polymers as a branch of soft materials can undergo large deformation. Hence, Euler–Bernoulli beam theory does not apply to the bending of a shape memory polymer beam where moderate rotations may occur. To overcome this limitation, von-Karman beam theory accounting for the mid-plane stretching as well as moderate rotations can be employed. To investigate the difference between the two beam theories, the deflection and rotating angles of a shape memory polymer cantilever beam are analyzed under small and moderate deflections and rotations. A semi-analytical approach is used to inspect Euler–Bernoulli beam theory, while finite-element method is employed to study von-Karman beam theory. In the following, a smart structure is analyzed using a prepared user-defined subroutine, VUMAT, in finite-element package, ABAQUS/EXPLICIT. Utilizing generated user-defined subroutine, smart structures composed of shape memory polymer material can be analyzed under complex loading circumstances through the two-way shape memory effect.

On Functional Behavior of Strain-Aged Ti-Ni Alloy

2008 ◽  
Vol 59 ◽  
pp. 162-167 ◽  
Author(s):  
Elena P. Ryklina ◽  
Sergey Prokoshkin ◽  
A.A. Chernavina ◽  
Natasha N. Perevoshchikova
Keyword(s):  
Shape Memory ◽  
Thermomechanical Treatment ◽  
Functional Properties ◽  
Shape Recovery ◽  
Critical Temperatures ◽  
Functional Behavior ◽  
Bending Mode ◽  
Ni Alloy ◽  
External Training ◽  
Loading Modes

The functional properties of the Shape Memory Alloys (SMA): critical temperatures, recovery strain, shape recovery rate, two-way shape memory effect (TWSME) value, residual strain etc are determined by an alloy structure which is effectively regulated by thermomechanical treatment. External training parameters strongly affect the final properties as well. The main of them are as follows: strain and loading modes, loading temperature regime (phase state under deformation), load value, loading time, number of training cycles. Actual technical and medical SME articles are functioning on bending mode in most cases. Nevertheless, the influence of external training parameters under bending on properties was not systematically studied. The present work relates to study the combined influence of structure realized under various Low- Temperature Thermomechanical Treatment (LTMT) regimes, including isothermal annealing (strain aging), and external training parameters under bending on functional properties of Ti- 50.7at.%Ni alloy. Variation of training parameters enables additional regulation of final functional properties. The obtained results can be used for development elements functioning in conditions of TWSME realization.

Perfluoropolyether Modified Waterborne Shape Memory Polyurethaneurea Ionomers for Potential Medical Implant Application

2012 ◽  
Vol 499 ◽  
pp. 53-57
Author(s):  
Qun Xia Li ◽  
Zhong Yu Hou
Keyword(s):  
Molecular Structure ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Shape Memory ◽  
Soft Segment ◽  
Cross Linking ◽  
Isophorone Diisocyanate ◽  
Scanning Calorimetry ◽  
Weight Percentage ◽  
Ft Ir

A series of cross-linked fluorinated waterborne shape memory polyurethaneurea (PUU) ionomers were synthesized from polycaprolactone diol, perfluoropolyether diol (PFPE), dimethylolproionic acid, isophorone diisocyanate, ethylenediamine (EDA) and diethylenetriamine (DETA). The effect of PFPE content in the soft segment and the degree of cross-linking on the molecular structure and the properties of for these PUU films was examined and studied. Differential scanning calorimetry showed that the transition temperature for these Tm type shape memory PUU could be facially tuned by PFPE weight percentage and EDA/DETA ratio in the range between 30°C to 50°C, in the vicinity of body temperature. The dependence of their properties on hydrogen-bonds evaluated by FT-IR was also discussed.

scholarly journals Nonlinear Free and Forced Vibration Behavior of Shear-Deformable Composite Beams with Shape Memory Alloy Fibers

2016 ◽  
Vol 2016 ◽  
pp. 1-16
Author(s):  
Ren Yongsheng ◽  
Du Chenggang ◽  
Shi Yuyan
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shear Deformation ◽  
Forced Vibration ◽  
Volume Fraction ◽  
Equations Of Motion ◽  
Beam Theory ◽  
Composite Beams ◽  
Vibration Behavior ◽  
Shear Deformable

The nonlinear free and forced vibration of the composite beams embedded with shape memory alloy (SMA) fibers are investigated based on first-order shear deformation beam theory and the von Kármán type nonlinear strain-displacement equation. A thermomechanical constitutive equation of SMA proposed by Brinson is used to calculate the recovery stress of the constrained SMA fibers. The equations of motion are derived by using Hamilton’s principle. The approximate solution is obtained for vibration analysis of the composite beams based on the Galerkin approach. The parametric study is carried out to display the effect of the actuation temperature, the volume fraction, the initial strain of SMA fibers, and the length-to-thickness ratio. The shear deformation is shown to have a significant contribution to nonlinear vibration behavior of the composite beams with SMA fibers.

scholarly journals Temperature-Induced Shape Memory Characteristics of Epoxy Resin-Based Fabric-Reinforced Composites

2013 ◽  
Vol 747 ◽  
pp. 785-787
Author(s):  
József Karger-Kocsis
Keyword(s):  
Carbon Fiber ◽  
Shape Memory ◽  
Epoxy Resin ◽  
Reinforced Composites ◽  
Recovery Stress ◽  
Dynamic Mechanical Analyzer ◽  
Carbon Fiber Fabric ◽  
Bending Mode ◽  
Fiber Fabric ◽  
Memory Characteristics

Shape memory characteristics of woven glass and carbon fiber fabric reinforced epoxy resin-based composites were assessed in bending mode using a dynamic mechanical analyzer. The reinforcement strongly improved the recovery stress but impaired the bending deformability. Composites with asymmetric fabric lay-up showed better performance when the reinforced section experienced local tension than compression during flexural loading.

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