Bai Yilong, male, Han nationality, is a native of Xiangyun, Yunnan Province. His ancestral home is in Tianjin. He was born in 1940, graduated from the Chinese University of Science and Technology in 1963. He is a specialist in mechanics.
Instead of usually presuming that the material becomes unstable at a stress maximum, Bai Yilong derived the model equations governing the thermo-plastic shear deformation. Then he obtained the criterion to the shear instability, the evolving law of localization and some new features of the late-stage shear band, which were referred to as the 'Bai Model' and 'Bai Criterion' in some references. According to the analysis on the localization, he applied the concept of instability and shear band to ductile limit and failure, and explained some previously unexplainable observations. By creating the technique of sub-microsecond stress pulse, he founded the experimental and non-equilibrium statistical basis of numerous micro damages occurring in materials subjected to impact loading.