Preliminary Study On System Analogy Between Catastrophic Phenominon Of Molecular Ring Turnover And Snap-through Of Macroscopic Model

The snap-through of molecular ring turnover is an universal progress in chemical reaction mechanism, therefore, how to deeply understand the mechanical essence of snap-through, and communicate with molecular of microscopic attribution of quantum chemistry and molecular mechanics, is an important and problem. There is not a right way to reflect this change in reaction mechanism yet.According to the catastrophic phenomenon of molecular ring turn- over in elementary reaction from 2-methylpyridine to intermediate of nitrogen heterocyclic norbornane diene in pyrolysis mechanism of 2- methylpyridine, we analyzed the change of atoms displacements pre and post molecular ring turnover. It can be considered that z coordinate direction was the main direction of the atoms displacements, which was the direction of snap-through. Therefore, the change of atoms displacements is in accordance with general conditions for snap-through of macroscopic model.In this work, the snap-through occurred in model of structure composed of circular plate, conical shallow shell and annular plate was studied under uniform load by ANSYS10.0/LS-DYNA. The influence of various parameters on snap-through of the structure was analyzed, and the system analogy between snap-through of model of composite structure and displacement change of the atoms in molecular ring was studied. A single degree of freedom of shanley model under impulsed loading was studied by ANSYS10.0/LS-DYNA. The results of the dynamic counterintuitive response was studied and analyzed, the system analogy between dynamic counterintuitive response of shanley model and displacement change of the atoms in molecular ring was studied, so that the reasonable explanation of catastrophic phenomenon in turnover of microscopic molecular ring can be obtained. It is concluded that the size effect of model had an important influence on snap-through of molecular ring, theθ=∠C6-C1-C4 representing the special molecular geometry is the decisive factor to turnover of molecular ring.