Some Recent Advances in Engineering Fracture Modeling for Turbomachinery

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
R. Craig McClung ◽  
Yi-Der Lee ◽  
James C. Sobotka ◽  
Jonathan P. Moody ◽  
Vikram Bhamidipati ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Fracture Analysis ◽  
Crack Size ◽  
Initial Crack ◽  
Displacement Control ◽  
3D Finite Element ◽  
Recent Advances ◽  
Fracture Modeling ◽  
Practical Engineering ◽  
Fracture Models

Recent advances in practical engineering methods for fracture analysis of turbomachinery components are described. A comprehensive set of weight function (WF) stress intensity factor (SIF) solutions for elliptical and straight cracks under univariant and bivariant stress gradients has been developed and verified. Specialized SIF solutions have been derived for curved through cracks, cracks at chamfered and angled corners, and cracks under displacement control. Automated fracture models are available to construct fatigue crack growth (FCG) life contours and critical initial crack size (CICS) contours for all nodal locations in two-dimensional or three-dimensional (2D or 3D) finite element (FE) models.

Some Recent Advances in Engineering Fracture Modeling for Turbomachinery

2018 ◽  
Author(s):  
R. Craig McClung ◽  
Yi-Der Lee ◽  
James C. Sobotka ◽  
Jonathan P. Moody ◽  
Vikram Bhamidipati ◽  
...  
Keyword(s):  
Fracture Analysis ◽  
Crack Size ◽  
Initial Crack ◽  
Finite Element Models ◽  
Displacement Control ◽  
Recent Advances ◽  
Fracture Modeling ◽  
Practical Engineering ◽  
Fracture Models ◽  
Fatigue Crack Growth Life

Recent advances in practical engineering methods for fracture analysis of turbomachinery components are described. A comprehensive set of weight function stress intensity factor (SIF) solutions for elliptical and straight cracks under univariant and bivariant stress gradients has been developed and verified. Specialized SIF solutions have been derived for curved through cracks, cracks at chamfered and angled corners, and cracks under displacement control. Automated fracture models are available to construct fatigue crack growth life contours and critical initial crack size contours for all nodal locations in 2D or 3D finite element models.

Analysis of Crack Growth in a 3D Voronoi Structure: A Model for Fatigue in Low Density Trabecular Bone

2002 ◽  
Vol 124 (5) ◽  
pp. 512-520 ◽  
Author(s):  
A. M. Makiyama ◽  
S. Vajjhala ◽  
L. J. Gibson
Keyword(s):  
Fatigue Life ◽  
Relative Density ◽  
Trabecular Bone ◽  
Crack Growth ◽  
Three Dimensional ◽  
Crack Size ◽  
Initial Crack ◽  
Low Density ◽  
Cycle Fatigue ◽  
Crack Growth Model

Both creep and crack growth contribute to the reduction in modulus associated with fatigue loading in bone. Here we simulate crack growth and subsequent strut failure in fatigue in an open-cell, three-dimensional Voronoi structure which is similar to that of low density, osteoporotic bone. The model indicates that sequential failure of struts leads to a precipitous drop in modulus: the failure of 1% of the struts leads to about a 10% decrease in modulus. A parametric study is performed to assess the influence of normalized stress range, relative density, initial crack size, crack shape and cell geometry on the fatigue life. The fatigue life is most sensitive to the relative density and the initial crack length. The results lead to a quantitative expression for the fatigue life associated with crack growth. Data for the fatigue life of trabecular bone are compared with the crack growth model described in this paper, as well as with a previous model for creep of a three-dimensional Voronoi structure. In our models, creep dominates the fatigue behavior in low cycle fatigue while crack growth dominates in high cycle fatigue, consistent with previous observations on cortical bone. The large scatter in the trabecular bone fatigue data make it impossible to identify a transition between creep dominated fatigue and crack growth dominated fatigue. The parametric study of the crack growth model indicates that variations in relative density among specimens, initial crack size within trabeculae and crack shape could easily produce such variability in the test results.

A Review of Hydraulic Fracture Modeling—II: 3D Modeling and Vertical Growth in Layered Rock

1984 ◽  
Vol 106 (4) ◽  
pp. 543-553 ◽  
Author(s):  
D. A. Mendelsohn
Keyword(s):  
Three Dimensional ◽  
Tectonic Stress ◽  
Future Research ◽  
Hydraulic Fractures ◽  
Vertical Growth ◽  
Linear Elastic ◽  
Rock Formations ◽  
Fracture Modeling ◽  
Fracture Models ◽  
Growth Problem

This is Part II of a two-part paper which reviews in depth the modeling of the propagation of large hydraulic fractures in underground rock formations. Based on experimental observations reviewed in Part I the need for models of the growth of general-shaped planar hydraulic fractures has been demonstrated. Part II contains reviews of both coupled fluid/solid three-dimensional fracture models and some more basic two and three-dimensional problems in linear elastic fracture mechanics applicable to the growth of fractures in the vicinity of in-situ discontinuities (interfaces) in rock-type and/or tectonic stress. The latter is referred to as the vertical growth problem since hydraulic fractures are quite often oriented vertically with respect to horizontal layering or stratification. The state of current research in both overall modeling and basic vertical growth studies is assessed and recommendations for future research are made.

Efficient Fracture Design for Complex Turbine Engine Components

2004 ◽  
Author(s):  
R. Craig McClung ◽  
Michael P. Enright ◽  
Yi-Der Lee ◽  
Luc J. Huyse ◽  
Simeon H. K. Fitch
Keyword(s):  
Three Dimensional ◽  
Fracture Analysis ◽  
High Energy ◽  
Computational Approach ◽  
Stress Fields ◽  
Fracture Plane ◽  
Turbine Engine ◽  
Fracture Models ◽  
Engine Components ◽  
3D Graphical User Interface

Many high-energy turbine engine components are fracture critical. However, the complex three-dimensional (3d) geometries and stress fields associated with these components can make accurate fracture analysis impractical. This paper describes a new computational approach to efficient fracture design for complex turbine engine components. The approach employs a powerful 3D graphical user interface (GUI) for manipulation of geometry models and calculated component stresses to formulate simpler 2D fracture models. New weight function stress intensity factor solutions are derived to address stress gradients that vary in all directions on the fracture plane.

Pavement Damage Due to Conventional and New Generation of Wide-Base Super Single Tires

2005 ◽  
Vol 33 (4) ◽  
pp. 210-226 ◽  
Author(s):  
I. L. Al-Qadi ◽  
M. A. Elseifi ◽  
P. J. Yoo ◽  
I. Janajreh
Keyword(s):  
Carrying Capacity ◽  
Material Properties ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Load Carrying Capacity ◽  
Inflation Pressure ◽  
3D Finite Element ◽  
Load Carrying ◽  
Pavement Damage ◽  
New Generation

Abstract The objective of this study was to quantify pavement damage due to a conventional (385/65R22.5) and a new generation of wide-base (445/50R22.5) tires using three-dimensional (3D) finite element (FE) analysis. The investigated new generation of wide-base tires has wider treads and greater load-carrying capacity than the conventional wide-base tire. In addition, the contact patch is less sensitive to loading and is especially designed to operate at 690kPa inflation pressure at 121km/hr speed for full load of 151kN tandem axle. The developed FE models simulated the tread sizes and applicable contact pressure for each tread and utilized laboratory-measured pavement material properties. In addition, the models were calibrated and properly validated using field-measured stresses and strains. Comparison was established between the two wide-base tire types and the dual-tire assembly. Results indicated that the 445/50R22.5 wide-base tire would cause more fatigue damage, approximately the same rutting damage and less surface-initiated top-down cracking than the conventional dual-tire assembly. On the other hand, the conventional 385/65R22.5 wide-base tire, which was introduced more than two decades ago, caused the most damage.

Disorganization of a hole tone feedback loop by an axisymmetric obstacle on a downstream end plate

2014 ◽  
Vol 757 ◽  
pp. 908-942 ◽  
Author(s):  
K. Matsuura ◽  
M. Nakano
Keyword(s):  
Nozzle Exit ◽  
Passive Control ◽  
Control Method ◽  
Three Dimensional ◽  
Acoustic Power ◽  
Shear Layers ◽  
Mean Velocity ◽  
End Plate ◽  
Air Jet ◽  
Practical Engineering

AbstractThis study investigates the suppression of the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. The mean velocity of the air jet $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}u_0$ was $6\text {--}12\ \mathrm{m}\ {\mathrm{s}}^{-1}$. The nozzle and the end plate hole both had a diameter of 51 mm, and the impingement length $L_{im}$ between the nozzle and the end plate was 50–90 mm. We propose a novel passive control method of suppressing the tone with an axisymmetric obstacle on the end plate. We find that the effect of the obstacle is well described by the combination ($W/L_{im}$, $h$) where $W$ is the distance from the edge of the end plate hole to the inner wall of the obstacle, and $h$ is the obstacle height. The tone is suppressed when backflows from the obstacle affect the jet shear layers near the nozzle exit. We do a direct sound computation for a typical case where the tone is successfully suppressed. Axisymmetric uniformity observed in the uncontrolled case is broken almost completely in the controlled case. The destruction is maintained by the process in which three-dimensional vortices in the jet shear layers convect downstream, interact with the obstacle and recursively disturb the jet flow from the nozzle exit. While regions near the edge of the end plate hole are responsible for producing the sound in the controlled case as well as in the uncontrolled case, acoustic power in the controlled case is much lower than in the uncontrolled case because of the disorganized state.

scholarly journals Recent advances in metalloporphyrin-based catalyst design towards carbon dioxide reduction: from bio-inspired second coordination sphere modifications to hierarchical architectures

2020 ◽  
Vol 49 (8) ◽  
pp. 2381-2396 ◽  
Author(s):  
Philipp Gotico ◽  
Zakaria Halime ◽  
Ally Aukauloo
Keyword(s):  
Carbon Dioxide ◽  
Coordination Sphere ◽  
Three Dimensional ◽  
Carbon Dioxide Reduction ◽  
Catalyst Design ◽  
Recent Advances ◽  
Hierarchical Architectures ◽  
Second Coordination Sphere

The progress in CO2 reduction catalyst design was examined starting from simple metalloporphyrin structures and progressing to three-dimensional active architectures.

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