scholarly journals Prediction of Characteristic Length and Fracture Toughness in Ductile-Brittle Transition

2008 ◽  
Author(s):  
Z. X. Wang ◽  
H. M. Li ◽  
Y. J. Chao ◽  
P. S. Lam
Keyword(s):  
Finite Element Method ◽  
Fracture Toughness ◽  
Finite Element ◽  
Characteristic Length ◽  
Crack Tip ◽  
Critical Distance ◽  
Transition Regime ◽  
Temperature Dependent ◽  
Brittle Transition ◽  
Element Method

Finite element method was used to analyze the three-point bend experimental data of A533B-1 pressure vessel steel obtained by Sherry, Lidbury, and Beardsmore [1] from −160 to −45 °C within the ductile-brittle transition regime. As many researchers have shown, the failure stress (σf) of the material could be approximated as a constant. The characteristic length, or the critical distance (rc) from the crack tip, at which σf is reached, is shown to be temperature dependent based on the crack tip stress field calculated by the finite element method. With the J-A2 two-parameter constraint theory in fracture mechanics, the fracture toughness (JC or KJC) can be expressed as a function of the constraint level (A2) and the critical distance rc. This relationship is used to predict the fracture toughness of A533B-1 in the ductile-brittle transition regime with a constant σf and a set of temperature-dependent rc. It can be shown that the prediction agrees well with the test data for wide range of constraint levels from shallow cracks (a/W = 0.075) to deep cracks (a/W = 0.5), where a is the crack length and W is the specimen width.

scholarly journals The Numerical Simulation of the Crack Elastoplastic Extension Based on the Extended Finite Element Method

2013 ◽  
Vol 2013 ◽  
pp. 1-13
Author(s):  
Xia Xiaozhou ◽  
Zhang Qing ◽  
Wang Hong ◽  
Jiang Qun
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Basis Function ◽  
Extended Finite Element Method ◽  
Crack Tip ◽  
Function Form ◽  
Extended Finite Element ◽  
Polar Radius ◽  
Radius Function ◽  
Element Method

In the frame of the extended finite element method, the exponent disconnected function is introduced to reflect the discontinuous characteristic of crack and the crack tip enrichment function which is made of triangular basis function, and the linear polar radius function is adopted to describe the displacement field distribution of elastoplastic crack tip. Where, the linear polar radius function form is chosen to decrease the singularity characteristic induced by the plastic yield zone of crack tip, and the triangle basis function form is adopted to describe the displacement distribution character with the polar angle of crack tip. Based on the displacement model containing the above enrichment displacement function, the increment iterative form of elastoplastic extended finite element method is deduced by virtual work principle. For nonuniform hardening material such as concrete, in order to avoid the nonsymmetry characteristic of stiffness matrix induced by the non-associate flowing of plastic strain, the plastic flowing rule containing cross item based on the least energy dissipation principle is adopted. Finally, some numerical examples show that the elastoplastic X-FEM constructed in this paper is of validity.

Application of the Williams Expansion near a Bi-Material Interface

2017 ◽  
Vol 754 ◽  
pp. 206-209 ◽  
Author(s):  
Lucie Malíková ◽  
Stanislav Seitl
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Tip ◽  
Higher Order ◽  
Simplified Model ◽  
The Finite Element Method ◽  
Material Interface ◽  
Higher Order Terms ◽  
Element Method ◽  
Crack Tip Stress

A simplified model of a crack approaching a bi-material interface is modelled by means of the finite element method in order to investigate the significance of the higher-order terms of the Williams expansion for the proper approximation of the opening crack-tip stress near the bi-material interface. The discussion on results is presented and the importance of the higher-order terms proved.

scholarly journals ANALYSIS OF CRACKS AT THE TORSION VALLARS CAUSED WITHOUT LOADING

2021 ◽  
Vol 07 (03) ◽  
pp. 72-79
Author(s):  
Tehran Mammadli Tehran Mammadli
Keyword(s):  
Finite Element Method ◽  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Criterion ◽  
Fatigue Cracks ◽  
Tracked Vehicles ◽  
Element Method

Nowadays, the hull suspension systems that use torsion shafts as elastic suspension elements are fitted to the majority of modern tracked vehicles. The main type of failure in such systems is the fracture of the torsion shafts due to the formation of fatigue cracks, which leads to failure of the suspension assemblies. This work presents an analysis of fracture toughness of torsion shafts of a standard tracked chassis used to develop a family of multipurpose transport vehicles GT-TM, GT-TMS, etc. The analysis is carried out under an operating load level for a crack located on the cylindrical part of the torsion shaft, the plane of which is at an angle to the torsion shaft axis and coincides with the position of the main areas of the stress state. The calculation of fracture toughness is based on Irwin fracture criterion. The calculations of the maximum stress intensity factor along the crack front are performed using the finite element method in the ANSYS software package. The results of the analysis of fracture toughness are presented in the form of dependences of the critical depth of the crack on the ratio of the fracture half-length to its depth. The data obtained can be used to determine the residual life of torsion shafts of the tracked vehicles based on the chassis under consideration. Keywords: suspension system, fracture toughness of torsion shafts, edge crack, stress intensity factor, finite element method, Irwin fracture criterion.

Sign in / Sign up

Export Citation Format

Share Document