مدلسازي خواص مكانيكي با كي پيپر نانو كامپوزيت به روش ديناميك مولكولي قابل اجرا بر روي واحد پردازش گرافيكي

چكيده انگليسي :

Mechanical Properties Evaluation of Buckypaper Composite Using Molecular Dynamic Method Executable on Graphical Processing Units Nima Nouri n nouri@me iut ac ir 25th October 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranLanguage Farsi Degree M ScProf Saeed Ziaei Rad szrad@cc iut ac irAbstractIn this thesis the mechanical properties of buckypaper composites are evaluated by the molecular dynamics method In order to obtain precise behavior of the material under different mechanical and thermal loadings a large numberof atoms should be used in the simulation as well as enough time for the system to equilibrate The fact that thesimulations will take a long time about 100 days with 50000 atoms on a single processor makes it impossible touse today s commercial molecular dynamic programs which are executed on the central processing units CPUs For acquiring the results in a logical period and with a large number of atoms a molecular dynamic package withClass II force fields GPIUTMD is developed on the Graphical Processing Units GPUs GPUs have densecomputational and parallel architecture which makes them capable to simulate the system several hundred times faster than the existing programs on the CPUs Buckypaper is made of carbon nanotube sheets By adding the resin and the hardner to the buckypaper and thencuring it in a specific temperature and pressure the buckypaper composite will be produced For simulating thedetailed and exact behavior of the system and to be sure of the computational accuracy of the package severalbenchmarks are considered from the literautre In the first and second benchmark one nanotube reaction and a resinmolecule and a nanotube reaction and a hardner molecule is considered The total energy change of the system ismonitored and compared with those reported in the references qualitatively The third model consists of the hardnerand the resin molecules In this benchmark the temperature of the system is decreased under constant atmosphericpressure and the density and the volume of the system is monitored From this simulation the Young s modulus andthe phase transition temperature with longitude expansion coefficient in both phases are acquired The benchmarkresults are compared to the available data reported in the literature After regulating the solution parameters the lastmodel which was the buckypaper composite is modeled The results have shown good agreement with the existing experimental tests as well as the available data The results of the simulation of the short fiber buckypaper composite showed that this material has a Young smodulus about 35 GPa in the fiber direction however with the infinite fiber buckypaper composite models theYoung s modulus reached up to 180 GPa in the fiber direction Nevertheless this material is week in the normaldirection of the nanotube sheets and has a Young s modulus about 10 GPa which is near to the matrix modulus It isnoticeable that the resulting elastic modulus of the composite is bigger than the both resin matrix and also thebuckypaper which is due to a better force transfer between the nanotubes and the resin Also this material showedauxetic behavior in some directions and with the structure presented in the thesis it has a poisson s ratio about 0 02 to 0 2 which is a good verification for the use of this material in artificial muscles Key wordsBuckypaper Molecular Dynamics Composite GPU computing Elastic Modulus

نوري، نيما

مدلسازي خواص مكانيكي با كي پيپر نانو كامپوزيت به روش ديناميك مولكولي قابل اجرا بر روي واحد پردازش گرافيكي

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