Ductile Failure Prediction of U-Notched Bainitic Functionally Graded Steel Specimens Using the Equivalent Material Concept Combined with the Averaged Strain Energy Density Criterion

H Salavati,H Mohammadi

doi:10.1134/s102995991903010x

Abstract

In this paper, the ductile fracture of bainitic functionally graded steel has been studied. Fracture tests was performed on U-notched specimens made of bainitic functionally graded steel under mode I. The averaged strain energy density criterion combined with equivalent material concept was employed to predict the ductile fracture of bainitic functionally graded steel. For this purpose, first, based on equivalent material concept, the mechanical properties of virtual brittle functionally graded steel were obtained. Then the averaged value of strain energy density over a well-defined control volume was calculated by finite element analysis for U-notched virtual brittle functionally graded steel. After that, the fracture loads was obtained based on the averaged strain energy density criterion. The agreement between experimental fracture loads and theoretical predictions was good.

Highlights

Prediction of fracture in presence of stress concentrator parts such as notch is a significant issue in the field of structural integrity
The tensile strength of the equivalent brittle material can be determined by assuming the same values of the tensile strain energy density required for both ductile and virtual brittle materials for crack initiation[22,23,24]
To predict the fracture of notched specimens made of FGMs by the averaged SED criterion, unlike homogeneous materials for which the outer boundary of the control volume is a circular arc, the strain energy density is averaged over a well-defined control volume which its outer boundary is an oval arc [27,28,29,30,31,32,33,34]

Summary

Introduction

Prediction of fracture in presence of stress concentrator parts such as notch is a significant issue in the field of structural integrity. By using the equivalent material concept [22], application of the averaged SED criterion has been extended for prediction of ductile fracture [23,24].

Results

Conclusion