Probabilistic Surface Damage Tolerance Assessment of Aircraft Turbine Rotors

2003 ◽  
Author(s):  
Michael P. Enright ◽  
Yi-Der Lee ◽  
R. Craig McClung ◽  
Luc Huyse ◽  
Gerald R. Leverant ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Graphical User Interface ◽  
Damage Tolerance ◽  
Surface Damage ◽  
Jet Engine ◽  
Risk Of Fracture ◽  
Crack Location ◽  
Software Code ◽  
Initial Framework

This paper describes some of the new surface damage capabilities in DARWIN™, a probabilistic fracture mechanics software code developed to evaluate the risk of fracture associated with aircraft jet engine titanium rotors/disks. An initial framework is presented in which a graphical user interface (GUI) is used to explicitly define the stresses and temperatures at the crack location for several crack geometries. A summary of the approach used to develop new stress intensity factor solutions for these geometries is also presented, including selected validation results.

Evaluation of Constraint Effect due to Crack Location and Bottom Head Shape

2016 ◽  
Author(s):  
Shin-Beom Choi ◽  
Han-Bum Surh ◽  
Jong-Wook Kim
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Head Shape ◽  
Constraint Effect ◽  
Crack Location ◽  
Spherical Bottom ◽  
Axial Crack ◽  
Elliptical Bottom ◽  
The Difference

The aim of this paper is to evaluate the constraint effect due to the crack location and bottom head shape. To do so, two types of bottom head shape such as a semi-spherical bottom head and semi-elliptical bottom head were considered. In addition, five types of axial crack and two types of circumferential crack, classified by location, were adopted to conduct FE analyses. As a result, the bottom head shape does not affect the stress intensity factor of the circumferential flaw. Moreover, the crack location is not a sensitive parameter of the stress intensity factor for an axial crack located at the semi-spherical bottom head. In contrast, the crack location should be considered when the stress intensity factor of an axial crack located at the semi-elliptical bottom head is calculated. In addition, a heatup curve and cooldown curve were derived from the FE analysis results. As a result, the constraint effect owing to a crack location, except for the transition area, is not shown in the case of a semi-spherical bottom head. In the case of a semi-elliptical bottom head, the difference between each crack location is shown. These results will be helpful to enhance the understanding of the constraint effect and P-T limit curve.

Study on the Stress Intensity Factor of Double Cracks Parallel to and Lying on the Interface in the Cladding Material Structure

2011 ◽  
Vol 308-310 ◽  
pp. 224-227
Author(s):  
Jun Ru Yang ◽  
Gong Ling Chen ◽  
Li Li Zhang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Thickness Ratio ◽  
Material Structure ◽  
Crack Location ◽  
Finite Element Software ◽  
Cladding Material ◽  
Crack Space

Taking the cladding material structure with double interface cracks parallel to and lying on the interface as the study object, based on the theoretical study on the crack tip stress intensity factor(SIF), using the finite element software ANSYS, the SIFs are researched by changing the crack space, crack length, thickness ratio, load and crack location. The results show that, the crack SIFs increase firstly and then decrease with the crack space increase, increase with the increases of the crack length and the load, decrease a little with the thickness ratio increase, decrease firstly and then increase with the increase of distance between the crack and the boundary.

A New Tool for Design and Certification of Aircraft Turbine Rotors

2002 ◽  
Author(s):  
Gerald R. Leverant ◽  
R. Craig McClung ◽  
Harry R. Millwater ◽  
Michael P. Enright
Keyword(s):  
Damage Tolerance ◽  
Fatigue Tests ◽  
Test Results ◽  
Time Efficiency ◽  
Jet Engine ◽  
Software Code ◽  
Turbine Rotors

This paper summarizes recent enhancements to a probabilistic damage tolerance software code, DARWIN™, that can be used for design certification of aircraft jet engine titanium disks/rotors that may contain melt-related anomalies. Evaluations of DARWIN™ by engine manufacturers are also discussed, including comparisons with existing codes for accuracy and time efficiency. In addition, relevant test results, including various fatigue tests on material containing melt-related anomalies, are summarized.

scholarly journals An Analysis Of Stress Intensity Factor Due To Normal Stress For A Cracked Plate Reinforced With A Sheet By Seam Welding

2015 ◽  
Vol 60 (2) ◽  
pp. 1441-1444 ◽  
Author(s):  
O-H. Kim ◽  
Y.C. Kim
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Damage Tolerance ◽  
Tolerance Design ◽  
Stiffness Ratio ◽  
Reinforcement Effect ◽  
Seam Welding ◽  
Cracked Plate ◽  
Welding Line

Abstract It is essential in damage tolerance design to determine the stress intensity factor theoretically. The stress intensity factor for a cracked plate that is reinforced with a sheet by seam welding is determined theoretically and plotted as function of the seam welding location and stiffness ratio. The singular integral equation is derived based on the compatibility condition between the cracked plate and the reinforcement plate, and it is solved by means of Erdogan and Gupta‘s method. The theory is verified by comparing the results of the present analysis with those of a numerical analysis. The results from the present analysis show that the reinforcement effect improves as the welding line is situated closer to the crack and as the stiffness ratio of the cracked plate and the reinforcement plate increases.

Closed-Form Stress Intensity Factor Solutions for Circumferential Through-Wall Cracks in Cylinder

2014 ◽  
Author(s):  
Do-Jun Shim ◽  
Steven Xu ◽  
Darrell Lee
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Practical Applications ◽  
Axial Tension ◽  
Bending Loads ◽  
Crack Stability ◽  
Software Code

The stress intensity factor (SIF) solutions for circumferential through-wall cracks (TWCs) in cylinders are used for various fracture mechanics analyses. For example, it can be used to calculate the crack growth rate for stress corrosion cracking and to calculate the elastic J value which is needed to obtain the total J value for crack stability calculations. Thus, numerous SIF solutions have been published for circumferential TWCs in cylinders under axial tension and global bending. However, recently, it has been indicated that there is a need (e.g., for xLPR software code and ASME BPV Code Case N-513) to expand the solutions to wider ranges of crack lengths and cylinder geometries. In this paper, solutions from Lacire et al., API 579-1/ASME FFS-1 and Zang (SINTAP) were compared against results from independent finite element (FE) analyses performed by the authors. From these comparisons, it was demonstrated that the Zang (SINTAP) solution provided the most accurate results. Hence, additional FE calculations were performed to expand the Zang (SINTAP) solution to cover Ri/t between 2 and 100 and crack length between 1% and 85% of the cylinder circumference. Furthermore, for practical applications, closed-formed solutions were developed for both axial tension and global bending loads. These new solutions were planned for use in the xLPR software code and ASME BPV Code.

A New Tool for Design and Certification of Aircraft Turbine Rotors

2004 ◽  
Vol 126 (1) ◽  
pp. 155-159 ◽  
Author(s):  
G. R. Leverant ◽  
H. R. Millwater ◽  
R. C. McClung ◽  
M. P. Enright
Keyword(s):  
Damage Tolerance ◽  
Fatigue Tests ◽  
Test Results ◽  
Time Efficiency ◽  
Jet Engine ◽  
Software Code ◽  
Turbine Rotors

This paper summarizes recent enhancements to a probabilistic damage tolerance software code, DARWINTM, that can be used for design certification of aircraft jet engine titanium disks/rotors that may contain melt-related anomalies. Evaluations of DARWINTM by engine manufacturers are also discussed, including comparisons with existing codes for accuracy and time efficiency. In addition, relevant test results, including various fatigue tests on material containing melt-related anomalies, are summarized.

scholarly journals Fatigue life prediction under mixed-mode loading using equivalent stress intensity factor models

2018 ◽  
Vol 172 ◽  
pp. 03005 ◽  
Author(s):  
S. Sajith ◽  
K.S.R. K. Murthy ◽  
P.S. Robi
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Mixed Mode ◽  
Life Prediction ◽  
Damage Tolerance ◽  
Equivalent Stress ◽  
Fatigue Life Prediction

Damage tolerance principles are widely used to assess the structural integrity and failure of engineering components. The advances in numerical simulation techniques facilitate the prediction of fatigue life of engineering component, which is essential in damage tolerance design. For the components under mixed mode (I/II) loading, the fatigue crack growth and life is predicted by using a modified form of Paris' law along with the equivalent stress intensity factor (ΔKeq). Numerous ΔKeq models are available for correlating the equivalent stress intensity factor range and the fatigue crack growth rate. The knowledge of proper ΔKeq model is essential for the accurate fatigue life estimation. In this work, the authors numerically assess the performance of ΔKeq models in mixed mode fatigue life prediction with the help of published experimental mixed mode data.

scholarly journals Analysis of Damage Tolerance of the Stiffened Structure Based on XFEM

2021 ◽  
Vol 2101 (1) ◽  
pp. 012027
Author(s):  
Juan Zhang ◽  
Wenming She ◽  
Wei Zhou ◽  
Wenya Yang ◽  
Jicheng Wei ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Growth ◽  
Calculation Method ◽  
Damage Tolerance ◽  
Improvement Effect ◽  
Calculation Results ◽  
Crack Propagation Process ◽  
Expansion Model

Abstract A calculation method of damage tolerance of stiffened structure based on extended finite element method (XFEM) is proposed.The crack propagation process is divided into small intervals to calculate the amplitude of stress intensity factor of the structure under different crack lengths. Each small interval is integrated to calculate the crack growth life. The accuracy of the method is verified by calculating the stress intensity factor, the load at both ends and crack growth life. The flat slab structure model with different numbers of stiffeners is established. The above calculation method shows that the stiffeners can share the load for the structure, reduce the amplitude of stress intensity factor, increase the fatigue life.The more the number of stiffeners, the more obvious the improvement effect. The equivalent treatment of the stiffened structure was conducted, and the equal area widening model, unfolding model and thickening model were established. The calculation results show that the calculation results of expansion model is very close to the stiffened structure. It shows that the stiffeners share the load for the structure by increasing the local thickness of the area, reduce the amplitude of stress intensity factor and improve the fatigue intensity.

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