scholarly journals Experimental and theoretical analysis of heat flux at fatigue crack tip under mixed mode loading

2019 ◽  
Vol 18 ◽  
pp. 608-615
Author(s):  
A. Vshivkov ◽  
A. Iziumova ◽  
R. Yarullin ◽  
V. Shlyannikov ◽  
O. Plekhov
Keyword(s):  
Heat Flux ◽  
Fatigue Crack ◽  
Theoretical Analysis ◽  
Mixed Mode ◽  
Crack Tip ◽  
Mixed Mode Loading

Cyclic Plasticity of a Cracked Structure Subjected to Mixed Mode Loading

2007 ◽  
Vol 348-349 ◽  
pp. 105-108 ◽  
Author(s):  
Sylvie Pommier
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Mixed Mode ◽  
Crack Tip ◽  
Cyclic Plasticity ◽  
Loading Conditions ◽  
Mixed Mode Loading ◽  
Crack Tip Plasticity

Cyclic plasticity in the crack tip region is at the origin of various history effects in fatigue. For instance, fatigue crack growth in mode I is delayed after the application of an overload because of the existence of compressive residual stresses in the overload’s plastic zone. Moreover, if the overload’s ratio is large enough, the crack may grow under mixed mode condition until it has gone round the overload’s plastic zone. Thus, crack tip plasticity modifies both the kinetics and the crack’s plane. Therefore modeling the growth of a fatigue crack under complex loading conditions requires considering the effects of crack tip plasticity. Finite element analyses are useful for analyzing crack tip plasticity under various loading conditions. However, the simulation of mixed mode fatigue crack growth by elastic-plastic finite element computations leads to huge computation costs, in particular if the crack doesn’t remain planer. Therefore, in this paper, the finite element method is employed only to build a global constitutive model for crack tip plasticity under mixed mode loading conditions. Then this model can be employed, independently of any FE computation, in a mixed mode fatigue crack growth criterion including memory effects inherited from crack tip plasticity. This model is developed within the framework of the thermodynamics of dissipative processes and includes internal variables that allow modeling the effect of internal stresses and to account for memory effects. The model was developed initially for pure mode I conditions. It was identified and validated for a 0.48%C carbon steel. It was shown that the model allows modeling fatigue crack growth under various variable amplitude loading conditions [1]. The present paper aims at showing that a similar approach can be applied for mixed mode loading conditions so as to model, finally, mixed mode fatigue crack growth.

Detailed Crack-Tip Stress Field Description in a Specimen Subjected to Mixed-Mode Loading

2013 ◽  
Vol 577-578 ◽  
pp. 317-320 ◽  
Author(s):  
Lucie Šestáková
Keyword(s):  
Stress Distribution ◽  
Mixed Mode ◽  
Crack Tip ◽  
Analytical Description ◽  
Initial Crack ◽  
Propagation Direction ◽  
Mixed Mode Loading ◽  
Crack Propagation Direction ◽  
Higher Order Terms ◽  
Accurate Stress

A mixed-mode cracked configuration is investigated using the multi-parameter fracture mechanics concept based on the analytical description of the stress/displacement field near a crack tip by means of the Williams series expansion. It is shown that using only one (singular) parameter as it is usual for brittle materials is not sufficient if the accurate stress distribution also further from the crack tip shall be known. Tangential stress distribution in various distances from the crack tip is presented and importance of the higher-order terms of the Williams expansion emphasized. Moreover, initial crack propagation direction is investigated by means of the MTS criterion and utilization of its generalized form is discussed.

Numerical Simulation of Fatigue Crack Growth for Curved Cracks Emanating from Fastener Holes in Sheets by the MVCCI Method

2006 ◽  
Vol 324-325 ◽  
pp. 863-866
Author(s):  
Holger Theilig ◽  
M. Goth ◽  
Michael Wünsche
Keyword(s):  
Numerical Simulation ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Plane Stress ◽  
Mixed Mode ◽  
Mixed Mode Loading ◽  
Multiple Crack ◽  
2D Structure ◽  
Predictor Corrector

The paper presents the results of a continued study of curved fatigue crack growth in a multiple arbitrarily pre-cracked isotropic sheet under plane stress loading. The predictor-corrector method (PCM) was extended in order to analyse the growth of multiple crack systems in a finite 2D structure. Together with the recently proposed improved modified virtual crack closure integral (MVCCI) method we can obtain accurate SIF values also for interacting cracks, and furthermore we can simulate fatigue crack growth of multiple crack systems in plane sheets under proportional mixed mode loading conditions. As a result, the program PCCS-2D is written to run within ANSYS to simulate interacting curved cracks. In order to check the accuracy and efficiency of the proposed method several example problems are solved. Especially curved cracks emanating from loaded fastener holes in sheets are analysed.

Mixed Mode Loading of an Interface Crack Subjected to Creep Conditions

2003 ◽  
Author(s):  
Ali P. Gordon ◽  
David L. McDowell
Keyword(s):  
Transition Layer ◽  
Mixed Mode ◽  
Elevated Temperatures ◽  
Numerical Solutions ◽  
Crack Tip ◽  
Functionally Graded ◽  
Pure Mode ◽  
Mixed Mode Loading ◽  
Creep Ductility ◽  
Interface Cracks

Interface cracks are seldom subjected to pure Mode I or pure Mode II conditions. Stationary interface cracks between two distinct, bonded elastic-creep materials subjected to remotely applied mixed mode loading are simulated. The finite element method (FEM) is used to examine crack tip fields and candidate driving force parameters for crack growth. Plane strain conditions are assumed. In most cases a functionally graded transition layer is included between the two materials. Examples of such systems include weld metal (WM) and base metal (BM) interfaces in welded or repaired boiler components subjected to elevated temperatures. Numerical solutions based on the asymptotic fields of the homogeneous and heterogeneous Arcan-type specimens are presented. Creep ductility-based damage models are used to predict the initial crack propagation trajectory. The incorporation of functionally graded transition layer regions affects the evolution of time-dependent stress components in the vicinity of the crack tip. The magnitude and direction of crack tip propagation can then be optimized with respect to interface properties.

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