Viscoelastic behavior of epoxy resin reinforced with shape-memory-alloy wires

2020 ◽  
pp. 1045389X2097549
Author(s):  
Niloufar Bagheri ◽  
Mahmood M Shokrieh ◽  
Ali Saeedi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Epoxy Resin ◽  
Volume Fraction ◽  
Niti Alloy ◽  
Micromechanical Model ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Reinforced Polymer ◽  
Small Volume Fraction

The effect of NiTi alloy long wires on the viscoelastic behavior of epoxy resin was investigated by utilizing the dynamic mechanical analysis (DMA) and a novel micromechanical model. The present model is capable of predicting the viscoelastic properties of the shape-memory-alloy (SMA) reinforced polymer as a function of the SMA volume fraction, initial martensite volume fraction, pre-strain level in wires, and the temperature variations. The model was verified by conducting experiments. Good agreement between the theoretical and experimental results was achieved. A parametric study was also performed to investigate the effect of SMA parameters. According to the results, by the addition of a small volume fraction of SMA, the storage modulus of the composite increases significantly, especially at higher temperatures. Moreover, applying a 4% pre-strain caused a 10% increase in the maximum value of the loss factor of the SMA reinforced epoxy in comparison with the 0% pre-strained SMA reinforced epoxy.

Analysis of the Linearly Viscoelastic Behavior of Nanotube-Reinforced Polymer Composites

2004 ◽  
Author(s):  
K. Li ◽  
X.-L. Gao ◽  
A. K. Roy
Keyword(s):  
Polymer Composites ◽  
Small Volume ◽  
Physical Aging ◽  
Volume Fraction ◽  
Viscoelastic Behavior ◽  
Analytical Models ◽  
Limited Attention ◽  
Creep Stress ◽  
Reinforced Polymer ◽  
Small Volume Fraction

In the last few years a lot of efforts have been made to demonstrate that the addition of carbon nanotubes, even with a small volume fraction, can substantially enhance the stiffness and strength of polymers [1]. Nevertheless, very limited attention has been paid to the viscoelastic responses of nanotube-reinforced polymer composites. Several groups have investigated the changes in glass transition temperatures of polymers induced by adding nanotubes to polymers [2–4]. Fisher [4] also studied the frequency response and the physical aging of polymers with or without nanotubes. However, the creep/stress relaxation behavior of nanotube-reinforced polymer composites is still not well understood. Experimental characterization tends to be configuration specific and expensive. Therefore, there is a need to develop analytical models that can predict the said behavior. The objective of this communication is to present a study on the creep behavior of carbon nanotube-reinforced polymer composites using a continuum-based micromechanics model.

A Measurement of Volume Resistivity in Fe-Based Shape Memory Alloy under Tensile Deformation and its Evaluation of Strain Rate Sensitivity

2016 ◽  
Vol 725 ◽  
pp. 72-76 ◽  
Author(s):  
Bo Cao ◽  
Yutaro Moriyama ◽  
Kazuki Fujita ◽  
Takeshi Iwamoto
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Speed ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Niti Alloy ◽  
Rate Sensitivity ◽  
Volume Resistivity ◽  
Strain Rates ◽  
Vibration Absorbers

Fe-based shape memory alloy (Fe-SMA) shows the smaller shape memory effect (SME) compared with the widely-used NiTi alloy. However, because its production cost is much lower than the NiTi alloy, Fe-SMA is challenged to be applied in civil engineering fields such as vibration absorbers and joints. A key of the SME is stress-induced martensitic transformation. Thus, it is important to evaluate an amount of martensite, which can control such excellent performance of Fe-SMA, for increasing a reliability of the Fe-SMA. However, until now, it is quite hard to find studies to evaluate the amount of martensite in Fe-SMA experimentally during deformation at various strain rates, especially during high speed deformation. Instead of the evaluation, it is convenient to capture change in volume resistivity, which has a correlation with the amount of martensite, at various strain rates. In the past, the volume fraction of α’ martensite is evaluated by using a resistance measurement based on the four point-probes method. The advantages of the method are quite simple and relatively high precision, however, its disadvantages are a requirement of strictly-precise reference resistor and power supply, and it is easily affected from noise. In this study, at first, a circuit of Kelvin double bridge with a higher precision is assembled. Then, the rate sensitivity of volume resistivity in Fe-28Mn-6Si-5Cr alloy, which is a kind of Fe-SMA, is experimentally estimated by using the assembled circuit of Kelvin double bridge during tensile testing at various strain rates.

scholarly journals Key Properties of a Bioactive Ag-SiO2/TiO2 Coating on NiTi Shape Memory Alloy as Necessary at the Development of a New Class of Biomedical Materials

2021 ◽  
Vol 22 (2) ◽  
pp. 507
Author(s):  
Mateusz Dulski ◽  
Robert Gawecki ◽  
Sławomir Sułowicz ◽  
Michal Cichomski ◽  
Alicja Kazek-Kęsik ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Dermal Fibroblast ◽  
Niti Alloy ◽  
Bacterial Biofilm ◽  
Niti Shape Memory Alloy ◽  
Normal Human Dermal Fibroblast ◽  
Water Contact ◽  
Nano Coating

Recent years have seen the dynamic development of methods for functionalizing the surface of implants using biomaterials that can mimic the physical and mechanical nature of native tissue, prevent the formation of bacterial biofilm, promote osteoconduction, and have the ability to sustain cell proliferation. One of the concepts for achieving this goal, which is presented in this work, is to functionalize the surface of NiTi shape memory alloy by an atypical glass-like nanocomposite that consists of SiO2-TiO2 with silver nanoparticles. However, determining the potential medical uses of bio(nano)coating prepared in this way requires an analysis of its surface roughness, tribology, or wettability, especially in the context of the commonly used reference coat-forming hydroxyapatite (HAp). According to our results, the surface roughness ranged between (112 ± 3) nm (Ag-SiO2)—(141 ± 5) nm (HAp), the water contact angle was in the range (74.8 ± 1.6)° (Ag-SiO2)—(70.6 ± 1.2)° (HAp), while the surface free energy was in the range of 45.4 mJ/m2 (Ag-SiO2)—46.8 mJ/m2 (HAp). The adhesive force and friction coefficient were determined to be 1.04 (Ag-SiO2)—1.14 (HAp) and 0.247 ± 0.012 (Ag-SiO2) and 0.397 ± 0.034 (HAp), respectively. The chemical data showed that the release of the metal, mainly Ni from the covered NiTi substrate or Ag from Ag-SiO2 coating had a negligible effect. It was revealed that the NiTi alloy that was coated with Ag-SiO2 did not favor the formation of E. coli or S. aureus biofilm compared to the HAp-coated alloy. Moreover, both approaches to surface functionalization indicated good viability of the normal human dermal fibroblast and osteoblast cells and confirmed the high osteoconductive features of the biomaterial. The similarities of both types of coat-forming materials indicate an excellent potential of the silver-silica composite as a new material for the functionalization of the surface of a biomaterial and the development of a new type of functionalized implants.

EFFECTS OF PARTICLE SIZE AND SINTERING TEMPERATURE ON SUPERELASTICITY BEHAVIOR OF NiTi SHAPE MEMORY ALLOY USING NANOINDENTATION

2021 ◽  
pp. 2150024
Author(s):  
C. VELMURUGAN ◽  
V. SENTHILKUMAR
Keyword(s):  
Particle Size ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Sintering Temperature ◽  
Niti Alloy ◽  
Indentation Load ◽  
Niti Shape Memory Alloy ◽  
Recovery Ratio ◽  
Work Recovery ◽  
Niti Sma

The present study investigates the superelasticity properties of spark plasma sintered (SPS) nickel titanium shape memory alloy (NiTi SMA) with the influence of sintering temperature and particle size. The nanoindentation is conducted on the surface of the NiTi SMA at various loads such as 100, 300 and 500[Formula: see text]mN. The nanoindentation technique determines the quantitative results of elasto-plastic properties such as depth recovery in the form of superelasticity, stiffness, hardness and work recovery ratio from load–depth ([Formula: see text]–[Formula: see text]) data during loading and unloading of the indenter. Experimental findings show that the depth and work recovery ratio increases with the decrease of indentation load and particle size. In contrast, increasing the sintering temperature exhibited a better depth and work recovery due to the removal of pores which could enhance the reverse transformation. The contact stiffness is influenced by [Formula: see text] which leads to attain a maximum stiffness at the highest load (500[Formula: see text]mN) and particle size (45[Formula: see text][Formula: see text]m) along with the lowest sintering temperature (700∘C). NiTi alloy exhibited a maximum hardness of 9.46[Formula: see text]GPa when subjected to indent at the lowest load and particle size sintered at 800∘C. The present study reveals a better superelastic behavior in NiTi SMA by reducing the particle size and indentation load associated with the enhancement of sintering temperature.

Assessing of Mechanical Properties of Natural Fiber Reinforced Polymer Matrix Hybrid Composites

2015 ◽  
Vol 766-767 ◽  
pp. 199-204 ◽  
Author(s):  
Kumar Jayachandran Nirmal ◽  
D. Premkumar
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Hybrid Composites ◽  
Natural Fibres ◽  
Fiber Reinforced Polymer ◽  
Resin Matrix ◽  
Reinforced Polymer ◽  
Individual Type

An experimental analysis has been carried out to investigate the mechanical properties of composites reinforced by sisal, coir, and banana fibres into epoxy resin matrix. The natural fibres were extracted by retting and manual processes. The composites fabricated by epoxy resin and reinforcement in the hybrid combination of Sisal-Banana and Sisal-Coir with the volume fraction of fibres varying from 5% to 30%. It has been identified that the mechanical properties increase with the increase of volume fraction of fibres to a certain extent and then decreases. The hybridization of the reinforcement in the composite shows greater mechanical properties when compared to individual type of natural fibres reinforced. For all the composites tested, the tensile strength of the composite increased up to 25% of volume fraction of the fibres and further for the increase in the volume fraction of fibre the mechanical properties were decreased. As same as tensile properties, the flexural and impact strength also increased linearly up to 25% of volume fraction of fibres and further for the increase in the volume fraction of fibre the mechanical properties were slightly decreased. Key Words: Sisal, Banana, Coir, Epoxy, Hybrid composite.

Viscoelastic behavior of an epoxy resin during cure below the glass transition temperature: Characterization and modeling

2018 ◽  
Vol 53 (2) ◽  
pp. 155-171 ◽  
Author(s):  
Alice Courtois ◽  
Martin Hirsekorn ◽  
Maria Benavente ◽  
Agathe Jaillon ◽  
Lionel Marcin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Strain History ◽  
Model Parameters ◽  
Degree Of Cure ◽  
Model Predictions

This paper presents a viscoelastic temperature- and degree-of-cure-dependent constitutive model for an epoxy resin. Multi-temperature relaxation tests on fully and partially cured rectangular epoxy specimens were conducted in a dynamic mechanical analysis apparatus with a three-point bending clamp. Master curves were constructed from the relaxation test results based on the time–temperature superposition hypothesis. The influence of the degree of cure was included through the cure-dependent glass transition temperature which was used as reference temperature for the shift factors. The model parameters were optimized by minimization of the differences between the model predictions and the experimental data. The model predictions were successfully validated against an independent creep-like strain history over which the temperature varied.

Interphase influences on the mechanical behavior of carbon nanotube–shape memory polymer nanocomposites: A micromechanical approach

2018 ◽  
Vol 30 (3) ◽  
pp. 463-478 ◽  
Author(s):  
MK Hassanzadeh-Aghdam ◽  
MJ Mahmoodi ◽  
R Ansari ◽  
A Darvizeh
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Shape Memory ◽  
Polymer Nanocomposites ◽  
Elastic Moduli ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Micromechanical Model ◽  
Elastic Behavior ◽  
Interphase Region

The effects of interphase characteristics on the elastic behavior of randomly dispersed carbon nanotube–reinforced shape memory polymer nanocomposites are investigated using a three-dimensional unit cell–based micromechanical method. The interphase region is formed due to non-bonded van der Waals interaction between a carbon nanotube and a shape memory polymer. The influences of temperature, diameter, volume fraction, and arrangement type of carbon nanotubes within the matrix as well as two interphase factors, including adhesion exponent and thickness on the carbon nanotube/shape memory polymer nanocomposite’s longitudinal and transverse elastic moduli, are explored extensively. Moreover, the results are presented for the shape memory polymer nanocomposites containing randomly oriented carbon nanotubes. The obtained results clearly demonstrate that the interphase region plays a crucial role in the modeling of the carbon nanotube/shape memory polymer nanocomposite’s elastic moduli. It is observed that the nanocomposite’s elastic moduli remarkably increase with increasing interphase thickness or decreasing adhesion exponent. It is found that when the interphase is considered in the micromechanical simulation, the shape memory polymer nanocomposite’s elastic moduli non-linearly increase as the carbon nanotube diameter decreases. The predictions of the present micromechanical model are compared with those of other analytical methods and available experiments.

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