超高ひずみ速度下でのニッケル材の応力－ひずみ関係の同定とそのモデル化

抄録

Cold spraying is a surface coating technique in which a powder material is impacted on a base material at high speed without melting to form a dense coating layer. The advantage of cold spraying is that the base material is not exposed to high temperatures, which prevents oxidation and thermal alteration of the coating layer. However, the stress-strain relationship in an ultra-high strain rate range from 5000 to 100000 /s which is required for cold spraying, has not yet been fully determined, and the mechanisms of the formation of coating layers have not been elucidated. In this study, the stress-strain relationship at ultra-high strain rates from 5000 to 20000/s was experimentally identified for pure nickel as a powder material in order to clarify the coating layer formation process by numerical simulation. We also identified the stress-strain relationship in the range from quasi-static strain rate to medium strain rates of the 10²/s order, and developed a rate sensitive constitutive equation based on T-M2009 model covering a wide strain rate range from 10^-2/s to 10⁴/s.