A new algorithm of dangerous points accurately identification on mechanical structure under dynamic loads

Abstract

Identification of dangerous moment of mechanical structure is a key process for dynamic response optimization. The dangerous moment of identification method for solution space of dynamic response based spectral element was proposed according to the insufficient of traditional method, which was difficult to accurately determine structure dangerous moment. The solution space of structure dynamic response was obtained by using the modal superposition method. The matrices of time points and their corresponding solution space values of dynamic stress were constructed. The Lagrange interpolation method was applied in the solution space domain to getting dynamic response function of high precision. Finally, the most dangerous moment of structure under dynamic loads was found by executing the global optimizer, though constructing a mathematical model to identify dangerous moment. The theoretical research results were applied to engine piston with dynamic loads to verify, and results showed that dynamic stress and dynamic displacement was not simultaneously reach extreme moment of the dynamic load, due to the nonlinear relationship between stress-strain and strain-displacement of structural. The existence of a time gap between them leads to dynamic optimization design is inaccurate. Dynamic optimization design should also consider two dangerous moments in order to avoid structure inaccurate design. This paper is the foundation of dynamic response optimization of piston.