Space Environment Damage Behavior Research Of PVDF/POSS Nano Composite Materials

With the development of aerospace technology, PVDF material has been widely used in the aerospace industry. In order to improve the performance of PVDF material to resist oxidation in space, PVDF material mixed with POSS material makes good oxidation resistance, so this thesis studies the damage behavior of the PVDF/POSS material in the space environment. The damage behavior under tension and bending conditions and oxygen radiation has been simulated by using ABAQUS software and LAMMPS software, respectively. And the influence of the POSS material to the damage behavior of the PVDF material has been discussed. Simultaneously, the influence of the amount of POSS material to the damage behavior under tension and bending conditions has also been discussed.In this thesis, damage behavior of the PVDF/POSS material under tension and bending conditions was analyzed by cohesive element in ABAQUS software. The established cohesive element was inserted into the entity unit by MATLAB software, each unit parameter was determined by combination of theory and experiment. To determine the mechanical properties of the particles, the homogenization method of mesomechanics was used. The material parameter of the particle and matrix cohesive elements was determined by the relation of fracture toughness and mechanical properties. The comparison result of simulation and experiment verified the correctness of the cohesive element parameters. Three methods including the area of damage model, the initial injury time and damage and failure rate of material were used to analyze the simulation results. The results show that the mix of POSS material has a certain inhibition for damage behavior of PVDF material. With the addition of POSS(POSS mass fraction is considered within5%), the inhibition for damage behavior is enhanced. But when the mass fraction of POSS is greater than5%(considering the mass fraction is less than8%), the inhibition for damage behavior of the PVDF material diminishes.The damage behavior of PVDF/POSS material under oxygen radiation was also analyzed in LAMMPS software. Molecular Cellular was established and optimized in MATERIAL STUDIO software. Choosing periodic boundary conditions and combining with ReaxFF Molecular stance, equilibrium model under the NpT Ensemble was solved. At last, the oxygen radiation combining with NVE Ensemble was simulated too. In allusion to the simulation results, the effect of oxygen radiation was studied from three aspects:energetic atomic oxygen rises the temperature of PVDF/POSS material, energetic particles erosions loses the quality of PVDF/POSS material and volatile products of the chemical reaction between strong oxidizing atomic oxygen and the material loses the quality of PVDF/POSS material. In conclusion, the POSS material can prevent the reaction between the oxygen atoms and PVDF material effectively and make its reflection, so as to protect the matrix material from oxidation and erosion of the high-speed atomic oxygen.