A novel model for determining the strength and fracture parameters of Q235 steel using double symmetrical edges notched specimens

A fracture model has been established for simultaneously determining the strength and fracture parameters of materials without size effect using double symmetrical edges notched specimens of metal. The specific method is presented for determining yield strength and fracture toughness using experimental yield loads of the small specimens in laboratory. The formula of nominal stress of double symmetrical edges notched specimen under uniaxial tension considering plastic zone is derived. The influence of different plastic zones size on calculating the fracture and strength parameters has been analyzed. The complete fracture failure curves of the metal material are obtained. The theoretical minimum size of metal specimen satisfying the conditions of linear elastic fracture mechanics is given. The normal method is used to analyze the dispersion of small-size double symmetrical edges notched specimens of hot-rolled carbon steel to predict the fracture properties of large-size specimens. A novel approach has been provided for the rational determination of realistic material parameters and the prediction of load carrying capacity of large-size structures by experimental fracture tests for small-size specimens.