Processing Methodology to Embedding NiTi Shape Memory Fibers into a Polymer-Based Composite Plate

2010 ◽  
Vol 643 ◽  
pp. 1-5
Author(s):  
Boniek Evangelista Leite ◽  
Rafael Feliciano De Macedo ◽  
Wanderley Ferreira Amorim Júnior ◽  
Carlos José de Araújo

The objective of this work was the development of a processing methodology for embedding NiTi fibers into a polymer-based composite plate. A carbon fiber reinforced polymer (CFRP) prepreg and NiTi thin wires were used. A uniaxial hot press was prepared to be used in the composite processing. Two prototypes were fabricated to provide fiber alignment and fixation fixture. A CFRP composite plate without fiber and another with NiTi fibers were processed. Micrometers and a universal materials testing machine were used to measure the plate thickness and Young's modulus. It was possible to develop a processing methodology for embedding NiTi fibers into a polymer-based composite plate. The CFRP plate without fiber presented almost no variation in plate thickness and Young's modulus measurement thus enabling the CFRP manufacture by the hot uniaxial press. The fiber fixation fixture developed was able to produce CFRP-NiTi fiber hybrid composites with different number of fibers embedded, the spacing distance between fibers was at least 1 mm and the fiber alignment was achieved.

2011 ◽  
Vol 689 ◽  
pp. 321-327 ◽  
Author(s):  
Qing Ping Shi ◽  
Dong Li Li ◽  
Wen Cai Xu

In this study, six kinds of different films from LDPE (Low-density polyethylene) modified by EVA (Ethylene - vinyl acetate copolymer) were made, and EVA / LDPE mass ratio was 0/50, 1/49, 1/ 19 4/21, and 1/3. Influence of EVA amount on the properties of LDPE film was investigated using the Instron universal testing machine, DSC, oxygen permeability tester and breathable apparatus. The mechanical properties of the blended films showed that when the EVA content was 5%, LDPE / EVA film transverse Young's modulus increased by about 50%, and the vertical Young's modulus increased by about 56%, which is good for improving the overprint accuracy of the LDPE / EVA film. DSC analysis showed that the melt blending has no effect on the thin-film processing temperature and thermal stability, but the result indicated that the crystallinity of the blended films was lowered with the increase of EVA amount. Barrier tests showed that with the increase of EVA content, the barrier of the modified films was decreased. The polarity of the film increased with more EVA component, which would augment the surface tension of LDPE and its ink adhesion.


Author(s):  
Lauren Patrin ◽  
Frank Chow ◽  
Gabriela Philippart ◽  
Feridun Delale ◽  
Benjamin Liaw ◽  
...  

Due to their high strength and stiffness carbon nanotubes (CNTs) have been considered as candidates for reinforcement of polymeric resins. It is also known that the addition of CNTs to polymeric matrix results in highly conductive nanocomposites, making the material multifunctional. Most of the CNT reinforced polymeric nanocomposite systems reported in the literature have been studied at room temperature. However, in many applications, materials may be subjected from low to elevated temperatures. Thus, the aim of this research is to study CNT reinforced polypropylene (PP) specimens at room, elevated and low temperatures. ASTM standard Type I specimens manufactured via injection molding and reinforced with 0.2%, 1%, 3%, and 6% CNTs were first subjected to tensile loads in a universal testing machine at room temperature. Neat PP resin specimens were also tested to provide baseline data. The tests were repeated at −54°C (−65°F), −20°C (−4°F), 49°C (120°F) and 71°C (160°F). The results were plotted as stress-strain curves and analyzed to delineate the effect of CNT reinforcement percentage and temperature on the mechanical properties. It was noted that as the percentage of CNT reinforcement increases, the resulting nanocomposite becomes stiffer (higher Young’s modulus), has higher strength and becomes more brittle. Temperature has a drastic effect on the behavior of the nanocomposite. As the temperature increases, at a given reinforcement percentage the material becomes more ductile with significantly lower Young’s modulus and strength compared to room temperature. At lower temperatures, the nanocomposite becomes more brittle with higher stiffness and strength, but significantly reduced failure strain. Also electrical measurements were conducted on the specimens to measure their resistance. For specimens reinforced with up to 3% of CNTs no electrical conductivity was detected. As expected at 6% CNT reinforcement (which is above the approximately 4% percolation limit reported in the literature), the specimens became electrically conductive. To predict the mechanical properties obtained experimentally, a micromechanics based model is presented and compared with the experimental results.


2021 ◽  
Vol 11 (1) ◽  
pp. 55-64
Author(s):  
Pardis Ghahramani ◽  
Kamran Behdinan ◽  
Rasool Moradi-Dastjerdi ◽  
Hani E. Naguib

Abstract In this article, Young’s modulus of a flexible piezoresistive nanocomposite made of a certain amount of multiwalled carbon nanotube (MWCNT) contents dispersed in polydimethylsiloxane (PDMS) has been investigated using theoretical and experimental approaches. The PDMS/MWCNT nanocomposites with the governing factor of MWCNT weight fraction (e.g., 0.1, 0.25, and 0.5 wt%) were synthesized by the solution casting fabrication method. The nanocomposite samples were subjected to a standard compression test to measure their elastic modulus using Instron Universal testing machine under force control displacement mode. Due to the costs and limitations of experimental tests, theoretical predictions on the elasticity modulus of such flexible nanocomposites have also been performed using Eshelby–Mori–Tanaka (EMT) and Halpin–Tsai (HT) approaches. The theoretical results showed that HT’s approach at lower MWCNT contents and EMT’s approach at higher MWCNT contents have a better agreement to experimental results in predicting the elastic modulus of PDMS/MWCNT nanocomposites. The experimental results indicated that the inclusion of MWCNT in the PDMS matrix resulted in a noticeable improvement in Young’s modulus of PDMS/MWCNT nanocomposite at small values of MWCNT contents (up to w f = 0.25%); however, exceeding this nanofiller content did not elevate Young’s modulus due to the emergence of MWCNT agglomerations in the nanocomposite structure.


Author(s):  
Vladislav Sevostianov

The paper focuses on the effect of decalcification on microstructure and the mechanical and electrical properties of cortical bone. Decalcification is produced by placing the specimens into 5% vinegar acid for 72 hours. This acid treatment leads to a decrease in mass of the specimens 7.78 % (averaged over ten acid treated specimens). Microstructure of natural bone and acid treated bone is then compared using confocal microscopy. To estimate effect of acid treatment on electrical resistivity of bone, the specimens are rinsed and saturated with 0.9% NaCl solution for ten minutes. Then electrical resistance is measured by the four-point method and electrical resistivity is calculated. Averaging over ten acid treated specimens and ten control specimens show that decalcification lead to increase of electrical resistivity 5.85 times. Comparison of mechanical properties of natural and acid treated bones is done by three point bending using Instron 5882 testing machine. It is observed that 7.78 % mass loss in cortical bone yields reduction of the Young’s modulus about 2.7 times and bending strength of the specimens by 35%. A positive correlation between change in strength and Young’s modulus and electrical resistivity of the individual specimens is observed. The obtained results allows one to estimate changes in mechanical and electrical properties of bone from known losses in bone mass and, thus, non-destructively evaluate the decrease in bone strength through changes in electrical resistivity.


2016 ◽  
Vol 718 ◽  
pp. 62-66 ◽  
Author(s):  
Pongsatorn Taweetanawanit ◽  
Thana Radpukdee ◽  
Nguyen Thanh Giao ◽  
Sumana Siripattanakul-Ratpukdi

There has been increasing interest of alginate gel utilization for environmental application. This study was aimed to investigate influence of sodium alginate and barium chloride concentrations on mechanical and chemical stabilities of the barium alginate gel. The barium alginate beads were mechanically tested using universal testing machine while the beads were soaked in the solutions with pHs of 5 to 9 or salts (sodium chloride, potassium chloride, and sodium hydrogen carbonate) for chemical stability test. The result showed that concentrations of barium chloride and sodium alginate obviously affected mechanical and chemical stabilities. Higher barium chloride concentrations decreased stress and Young’s modulus of beads whereas higher alginate concentrations resulted to higher gel strength and flexibility. The stress and Young’s modulus of 0.57 and 37.71 MPa were found in the best preparation condition (barium chloride of 1% and sodium alginate of 5%). For the chemical tests, the gel beads mostly tolerated in the solutions with different pHs and salt solutions excluding NaHCO3. The gel beads prepared in this work sound potential for practice.


2018 ◽  
Vol 929 ◽  
pp. 186-190 ◽  
Author(s):  
M.N. Chai ◽  
M.M. Chai ◽  
M.I.N. Isa

In this paper, the mechanical properties of carboxymethyl cellulose-oleic acid (CMC-OA) solid bio-polymer electrolyte (SBE) were examined. The host, CMC was doped with different weight percentage (wt. %) of OA in the CMC-OA solution. The SBEs were tested by using the Universal Material Testing Machine where the readings of tensile strength and Young’s modulus can be obtained from the stress-strain curve produced by the software during the tension test. The sample of CMC doped with 20% wt. of OA was found to obtain the highest value of tensile strength and Young’s modulus which is 0.2069 MPa and 4.615 MPa respectively.


2013 ◽  
Vol 290 ◽  
pp. 15-20
Author(s):  
Dong Mei Luo ◽  
Hong Yang ◽  
Qiu Yan Chen ◽  
Ying Long Zhou

In this paper, two kinds of micro-mechanical models are utilized to predict the effective Young's modulus for hybrid composites including fiber-like, spherical and needle inclusions in an isotropic matrix. The two models of Multi-Phase Mori-Tanaka Model (MP model) and Multi-Step Mori-Tanaka Model (MS model) are proposed by the authors in a series of interrelated research. The results show that the shape and the Young’s modulus of inclusion, aspect ratio of fiber-like inclusion are the controlling factors to influence the Young's modulus, and MP model is more rational to predict the effective Young’s modulus of hybrid composites reinforced with multi-shape inclusions.


2004 ◽  
Vol 449-452 ◽  
pp. 673-676
Author(s):  
Chang Seog Kang ◽  
Sung Kil Hong

An attempt has been made to measure the temperature dependence of dynamic Young's modulus together with the related variation of internal friction in polycrystalline copper. A mechanical spectroscopy study was used a standard servo hydraulic fatigue testing machine equipped with a scanning laser extensometer. Dynamic Young’s modulus and internal friction are measured over a temperature range of 298 to 873K at very low frequencies of 0.1, 0.05 and 0.01Hz. One internal friction peak was observed over the ranges 450K to 700K, together with marked decreases in the dynamic Young.s modulus in the same temperature ranges. From a quantitative analysis of the experimental data with the relaxation strength, relaxation time and activation energy, it is concluded that the peak phenomenon is due to grain-boundary sliding relaxation.


Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1976
Author(s):  
Robert Adamski ◽  
Dorota Siuta

The aim of this work was to fabricate novel bioactive composites based on chitosan and non-organic silica, reinforced with calcium β-glycerophosphate (Ca-GP), sodium β-glycerophosphate pentahydrate (Na-GP), and hydroxyapatite powder (HAp) in a range of concentrations using the sol–gel method. The effect of HAp, Na-GP, and Ca-GP contents on the mechanical properties, i.e., Young’s modulus, compressive strength, and yield strain, of hybrid composites was analyzed. The microstructure of the materials obtained was visualized by SEM. Moreover, the molecular interactions according to FTIR analysis and biocompatibility of composites obtained were examined. The CS/Si/HAp/Ca-GP developed from all composites analyzed was characterized by the well-developed surface of pores of two sizes: large ones of 100 μm and many smaller pores below 10 µm, the behavior of which positively influenced cell proliferation and growth, as well as compressive strength in a range of 0.3 to 10 MPa, Young’s modulus from 5.2 to 100 MPa, and volumetric shrinkage below 60%. This proved to be a promising composite for applications in tissue engineering, e.g., filling small bone defects.


2019 ◽  
Vol 106 ◽  
pp. 4-8
Author(s):  
CEZARY GOZDECKI

Application of the modified hybrid rule of mixture (ROHM) and Halpin–Tsai equation for predicting mechanical properties of wood/hemp/polymer composites. An object of investigations was hybrid wood-polymer composite containing HDPE, hemp fibers and wood particles. The degree of addition of hemp and wood particles ranged from 0 to 60% of filler. The usefulness of the mathematical models ROHM and Halpin-Tsai to predict the Young's modulus of composites was tested. Additionally, experimental research was carried out. It was found that the hemp content in the wood-polymer composite significantly influences the growth of the composite module. The usefulness of mathematical models for predicting the Young's modulus of hybrid composites was also confirmed.


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