15541

1569 دكتري

دكتري

تكنولوژي

اصفهان : دانشگاه صنعتي اصفهان

1398

150

عبدالكريم حسيني راوندي

سعيد ضيائي راد، روح الله باقرزاده، حسين فشندي

1399/02/22

كتابنامه

نساجي

مهندسي نساجي

1399/02/22

2606673

132AbstractBy developments in the nanoscience and the creation of nanobeams nanoplates application ofthese components has grown widespread in micro and nano structures such as micro electro mechanics and nano electronics due to their mechanical chemical and electronic properties andthese components have attracted the attention of many researchers as energy harvester Therefore today the study of the mechanical properties of nanostructures due to their increasing use hasbecome specifically important On the other hand due to the small dimensions of nanostructuresand some of the fractures there are differences between the modeling of these structures and themacro structures To study the nanostructures the use of atomic testing or modeling likemolecular dynamics is appropriate However since testing and controlling it in nanoscaledimensions is very costly and methods such as molecular dynamics are costly researchers arenow seeking to model nanostructures with theories of mechanics of non classic continuum model For this reason as the mechanics of classic continuum model makes error in predicting thebehavior of these structures due to the lack size effect the use of higher order theories such ascouple stress theory been expanded as they can take into account the effect size in the calculations The results showed that comprehensive and complete modeling of porous viscoelastic and orthotropic piezoelectric sizedependent plate structures at the nanoscale has not beenperformed so far Therefore in this study the main purpose of the model is to model theenergy harvesting plate structure produced by polyvinylidine fluoride nanofibers withpiezoelectric viscoelastic properties Obviously the results of this study will be able toprovide a good understanding of the prediction behavior of energy harvesting structureswith these properties To achieve this two dimensional viscoelastic and piezoelectric thinplate models were used with von Karman displacement field In the experimental section to evaluate the proposed model an attempt was made toproduce a piezoelectrically nanofibers sample by polyvinylidene fluoride polymer Initially the experimental design was performed using response surface methodology andthe most important parameters affecting the electrospinning process were extracted fromfour independent parameters of concentration voltage feed rate and roller speed Theresults of the experimental design showed the effect of the roller speed parameter on theintensity of the piezoelectric property Different morphological and microstructuralcharacterizations were performed to better understand and understand the behavior ofnanofluid structures produced at different rolling speeds The results of small angle X raydiffraction showed good beta phase formation for all samples and Fourier spectroscopywas used to investigate the crystal structure of the samples Scanning electron microscopyalso determined the fiber arrangement and diameter Investigation of fiber structureshowed a decrease in diameter and improved uniformity of fibers with increasingrotational speed of harvesting roller and the piezoelectric output response increased withincreasing fiber fineness with increasing arrangement The output voltage response atconstant force and frequency was recorded for all samples by a piezoelectric propertyanalyzer The maximum fiber arangement percentage was 87 at 2000 rpm and the porousnano web with 57 porosity had the highest output voltage response of 14 mV N Thetheoretical model output voltage response intensity for the selected sample was 12 mV N The results show that there is good agreement between experimental data and modeling Keywords Nano fiber web Piezoelectric nano plates Couple stress theory polyvinylidene fluoride PVDF

عبدالكريم حسيني راوندي

سعيد ضيائي راد، روح الله باقرزاده، حسين فشندي