scholarly journals Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

2000 ◽  
Vol 124 (1) ◽  
pp. 161-176 ◽  
Author(s):  
N. K. Arakere ◽  
G. Swanson
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Single Crystal ◽  
Fatigue Failure ◽  
Failure Criterion ◽  
Crystal Orientation ◽  
Rocket Engine ◽  
Turbine Blades ◽  
Element Model

High cycle fatigue (HCF) induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Single crystal nickel turbine blades are being utilized in rocket engine turbopumps and jet engines throughout industry because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493, PWA 1484, RENE’ N-5 and CMSX-4. These alloys play an important role in commercial, military and space propulsion systems. Single crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. The failure modes of single crystal turbine blades are complicated to predict due to the material orthotropy and variations in crystal orientations. Fatigue life estimation of single crystal turbine blades represents an important aspect of durability assessment. It is therefore of practical interest to develop effective fatigue failure criteria for single crystal nickel alloys and to investigate the effects of variation of primary and secondary crystal orientation on fatigue life. A fatigue failure criterion based on the maximum shear stress amplitude [Δτmax] on the 24 octahedral and 6 cube slip systems, is presented for single crystal nickel superalloys (FCC crystal). This criterion reduces the scatter in uniaxial LCF test data considerably for PWA 1493 at 1200°F in air. Additionally, single crystal turbine blades used in the alternate advanced high-pressure fuel turbopump (AHPFTP/AT) are modeled using a large-scale three-dimensional finite element model. This finite element model is capable of accounting for material orthotrophy and variation in primary and secondary crystal orientation. Effects of variation in crystal orientation on blade stress response are studied based on 297 finite element model runs. Fatigue lives at critical points in the blade are computed using finite element stress results and the failure criterion developed. Stress analysis results in the blade attachment region are also presented. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to significantly increase a component’s resistance to fatigue crack growth without adding additional weight or cost.

scholarly journals Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

2000 ◽  
Author(s):  
Nagaraj K. Arakere ◽  
Gregory Swanson
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Turbine Blade ◽  
Fatigue Failure ◽  
Failure Criterion ◽  
Crystal Orientation ◽  
Rocket Engine ◽  
Maximum Shear Stress ◽  
Turbine Blades ◽  
Fe Model

High Cycle Fatigue (HCF) induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Single crystal nickel turbine blades are being utilized in rocket engine turbopumps and jet engines throughout industry because of their superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over polycrystalline alloys. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493, PWA 1484, RENE’ N-5 and CMSX-4. These alloys play an important role in commercial, military and space propulsion systems. Single crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. The failure modes of single crystal turbine blades are complicated to predict due to the material orthotropy and variations in crystal orientations. Fatigue life estimation of single crystal turbine blades represents an important aspect of durability assessment. It is therefore of practical interest to develop effective fatigue failure criteria for single crystal nickel alloys and to investigate the effects of variation of primary and secondary crystal orientation on fatigue life. A fatigue failure criterion based on the maximum shear stress amplitude [Δτmax] on the 24 octahedral and 6 cube slip systems, is presented for single crystal nickel superalloys (FCC crystal). This criterion reduces the scatter in uniaxial LCF test data considerably for PWA 1493 at 1200F in air. Additionally, single crystal turbine blades used in the alternate advanced high-pressure fuel turbopump (AHPFTP/AT) are modeled using a large-scale 3D finite element (FE) model. This FE model is capable of accounting for material orthotrophy and variation in primary and secondary crystal orientation. Effects of variation in crystal orientation on blade stress response are studied based on 297 FE model runs. Fatigue lives at critical points in the blade are computed using FE stress results and the failure criterion developed. Stress analysis results in the blade attachment region are also presented. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to significantly increase a component’s resistance to fatigue crack growth without adding additional weight or cost.

Multi-Fidelity Surrogate Model-Assisted Fatigue Analysis of Welded Joints

2020 ◽  
Author(s):  
Lili Zhang ◽  
Tingli Xie ◽  
Jiexiang Hu ◽  
Ping Jiang ◽  
Jasuk Koo ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Surrogate Model ◽  
Element Model ◽  
Leg Length ◽  
Verification Method ◽  
Leave One Out ◽  
The Finite Element Model

Abstract In this study, an additive scaling function based multi-fidelity (ASF-MF) surrogate model is constructed to fast predict fatigue life as well as the stress distribution for the welded single lap joint. The influence of leg length, leg height, the width of the specimen and load in the fatigue test are taken into consideration. In the construction of the MF surrogate model, the finite element model that is calibrated with the experiment is chosen as the high-fidelity (HF) model. While the finite element model that is not calibrated with the experiment is considered as the low-fidelity (LF) model, aiming to capture the trend of the HF model. The Leave-one-out (LOO) verification method is utilized to compare the prediction performance of the ASF-MF surrogate model with that of the single-fidelity Kriging surrogate model. Results show that the ASF-MF surrogate model can better predict the fatigue life as well as the stress distribution.

Detailed Finite Element Modeling of a High Capacity Mooring Steel Wire Rope: Calculation of the Stress Concentration Near the Connection

2020 ◽  
Author(s):  
Michaël Martinez ◽  
Sébastien Montalvo
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Finite Element Model ◽  
Steel Wire ◽  
High Capacity ◽  
Element Model ◽  
Wire Rope ◽  
Contact Forces ◽  
Life Assessment

Abstract The mooring of floating platforms is an important challenge for the offshore industry. It is an important part of the design engineering and, often, a critical point for the fatigue life assessment. A solution that could improve the fatigue life is to directly connect the mooring rope to the platform, without an intermediate chain. However this solution is not widespread and the behavior of a rope near such a connection is little known. The present paper proposes to better understand this behavior, thanks to a detailed finite element model of the rope. The study case is a steel wire rope directly connected to a floating wind turbine. A local finite element model of the rope has been built, where the wires are individually modeled with beam elements. One end of the rope is clamped, simulating the connection, while tension and cyclic bending oscillations are applied to the other end. A localized bending takes place near the connection, leading to stress concentration in the wires. The stress concentration and the local contact forces are calculated for each wire. These data are important entry parameters for a local failure or fatigue analysis. This latter is however not presented here. Despite IFPEN experience in the development of local finite element models of steel wire ropes, it is the first time that such a high capacity rope (MBL = 12 500 kN) is modeled. This is challenging because of the large diameter of the rope and the large number of wires. However this modeling approach is very valuable for such ropes, because the experimental tests are rare and very expensive.

Fundamental Frequencies of Turbine Blades With Geometry Mismatch in Fir-Tree Attachments

2006 ◽  
Vol 128 (3) ◽  
pp. 512-516 ◽  
Author(s):  
Fei Qin ◽  
Liming Chen ◽  
Ying Li ◽  
Xiaofeng Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Significant Influence ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Element Model ◽  
Gap Size ◽  
Fundamental Frequencies ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Geometry mismatch in a turbine blade root, which arose in manufacturing process or caused by wearing out during service, leads to contact conditions changed in fir-tree attachments. As a result, shifting of the fundamental frequencies and redistribution of stress in the blade base possibly cause failure of the blade. A three-dimensional finite element model of a blade and its fir-tree attachments have been constructed and analyzed by taking into account contact nonlinearity in the attachments and large deformation effect of the blade. The geometry mismatch was introduced into the finite element model by defining gaps between two contact surfaces in the attachments. The influence of gap configuration and gap size on contact and fundamental frequencies was investigated. Results showed that gap configuration has significant influence on fundamental frequencies of the blade, especially on its bending modes. Gap size has little influence on the frequencies but significant influence on the contact status and thus changes stress distribution in the attachments. The results also suggest that modeling contact behavior in fir-tree attachments is necessary to obtain more accurate fundamental frequencies.

Towards Truly Multiscale Simulation of Fatigue Processes in Metallic Structures

2009 ◽  
Author(s):  
John M. Emery ◽  
Jeffrey E. Bozek ◽  
Anthony R. Ingraffea
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Life Prediction ◽  
Element Model ◽  
Multiscale Simulation ◽  
Fatigue Life Prediction ◽  
Length Scale ◽  
Metallic Structures

The fatigue resistance of metallic structures is inherently random due to environmental and boundary conditions, and microstructural geometry, including discontinuities, and material properties. A new methodology for fatigue life prediction is under development to account for these sources of randomness. One essential aspect of the methodology is the ability to perform truly multiscale simulations: simulations that directly link the boundary conditions on the structural length scale to the damage mechanisms of the microstructural length scale. This presentation compares and contrasts two multiscale methods suitable for fatigue life prediction. The first is a brute force method employing the widely-used multipoint constraint technique which couples a finite element model of the microstructure within the finite element model of the structural component. The second is a more subtle, modified multi-grid method which alternates analyses between the two finite element models while representing the evolving microstructural damage. Examples and comparisons are made for several geometries and preliminary validation is achieved with comparison to experimental tests conducted by the Northrop Grumman Corporation on a wing-panel structural geometry.

Design and Fatigue Life Analysis of a Motorcycle Frame

2014 ◽  
Author(s):  
Massimiliano Gobbi ◽  
Giorgio Previati ◽  
Giampiero Mastinu
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Experimental Tests ◽  
Element Model ◽  
Fe Model ◽  
Static Test ◽  
Weld Toe ◽  
Fatigue Life Analysis ◽  
Motorcycle Frame

An off-road motorcycle frame has been analyzed and modified to optimize its fatigue life. The fatigue life of the frame is very important to define the service life of the motorcycle. The strain levels on key parts of the frame were collected during experimental tests. It has been possible to locate the areas where the maximum stress level is reached. A finite element (FE) model of the frame has been developed and used for estimating its fatigue life. Static test bench results have been used to validate the FE model. The accuracy of the finite element model is good, the errors are always below 5% with respect to measured data. The mission profile of the motorcycle is dominated by off-road use, with stress levels close to yield point, so a strain-life approach has been applied for estimating the fatigue life of the frame. Particular attention has been paid to the analysis of the welded connections. A shell and a 3D FE model have been combined to simulate the stress histories at the welds. Two reference maneuvers have been considered as loading conditions. The computed stresses have been used to assess the life of the frame according to the notch stress approach (Radaj & Seeger). The method correlates the stress range in a idealized notch, characterized by a fictitious radius in the weld toe or root, to the fatigue life by using a single S-N curve. New technical frame layouts have been proposed and verified by means of the developed finite element model. The considered approach allows to speed up the design process and to reduce the testing phase.

Design Optimization of Compound Cylinders Subjected to Autofrettage and Shrink-Fitting Processes

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Ossama R. Abdelsalam ◽  
Ramin Sedaghati
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Design Optimization ◽  
Element Model ◽  
Pressure Vessels ◽  
Stress Profile ◽  
Shrink Fitting ◽  
Shrink Fit ◽  
Optimal Configurations

The autofrettage and shrink-fit processes are used to increase the load bearing capacity and fatigue life of the pressure vessels under thermomechanical loads. In this paper, a design optimization methodology has been proposed to identify optimal configurations of a two-layer cylinder subjected to different combinations of shrink-fit and autofrettage processes. The objective is to find the optimal thickness of each layer, autofrettage pressure and radial interference for each shrink-fit, and autofrettage combination in order to increase the fatigue life of the compound cylinder by maximizing the beneficial and minimizing the detrimental residual stresses induced by these processes. A finite element model has been developed in ansys environment to accurately evaluate the tangential stress profile through the thickness of the cylinder. The finite element model is then utilized in combination with design of experiment (DOE) and the response surface method (RSM) to develop a smooth response function which can be effectively used in the design optimization formulation. Finally, genetic algorithm (GA) combined with sequential quadratic programming (SQP) has been used to find global optimum configuration for each combination of autofrettage and shrink-fit processes. The residual stress distributions and the mechanical fatigue life based on the ASME code for high pressure vessels have been calculated for the optimal configurations and then compared. It is found that the combination of shrink-fitting of two base layers then performing double autofrettage (exterior autofrettage prior to interior autofrettage) on the whole assembly can provide higher fatigue life time for both inner and outer layers of the cylinder.

Instantaneous Dynamic Analysis of the New Stirring Kneader Shaft

2011 ◽  
Vol 221 ◽  
pp. 472-477
Author(s):  
Zhi Min Fan ◽  
Guang Ting Zhou ◽  
Jian Ping Liu
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Dynamic Response ◽  
Finite Element Model ◽  
Dynamic Analysis ◽  
Structural Parameters ◽  
Element Model ◽  
Fatigue Analysis ◽  
Exciting Force ◽  
The Finite Element Model

The finite element model of the stirring kneader shaft was built by PRO/E software, which was inserted into ANSYS. Next, the instantaneous dynamic analysis of the new stirring kneader shaft was carried out. The instantaneous dynamic response of stirring shaft about the exciting force of fluid was obtained, which was to optimize the structural parameters of the stirring shaft. The foundation for the next fatigue analysis was laid based on the instantaneous dynamic response; the fatigue life of stirring kneader shaft can be predicted.

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