Transient Thermal Analysis and Viscoplastic Damage Model for Life Prediction of Turbine Components

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
A. Staroselsky ◽  
T. J. Martin ◽  
B. Cassenti
Keyword(s):  
Finite Element ◽  
Life Prediction ◽  
Failure Modes ◽  
Damage Model ◽  
High Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Dissipated Energy ◽  
Transient Thermal ◽  
Turbine Airfoils

This paper reports the process and computer methodology for a physics-based prediction of overall deformation and local failure modes in cooled turbine airfoils, blade outer air seals, and other turbomachinery parts operating in severe high temperature and high stress environments. The computational analysis work incorporated time-accurate, coupled aerothermal computational fluid dynamics (CFD) with nonlinear deformation thermal-structural finite element model (FEM) with a slip-based constitutive model, evaluated at real engine characteristic mission times, and flight points for part life prediction. The methodology utilizes a fully coupled elastic-viscoplastic model that was based on crystal morphology, and a semi-empirical life prediction model introduced the use of dissipated energy to estimate the remaining part life in terms of cycles to failure. The method was effective for use with three-dimensional FEMs of realistic turbine airfoils using commercial finite element applications. The computationally predicted part life was calibrated and verified against test data for deformation and crack growth.

Transient Thermal Analysis and Visco-Plastic Damage Model for Life Prediction of Turbine Components

2014 ◽  
Author(s):  
A. Staroselsky ◽  
T. J. Martin ◽  
B. Cassenti
Keyword(s):  
Finite Element ◽  
Life Prediction ◽  
Failure Modes ◽  
Damage Model ◽  
High Stress ◽  
Three Dimensional ◽  
Dissipated Energy ◽  
Linear Deformation ◽  
Three Dimensional Finite Element ◽  
Turbine Airfoils

This paper reports the process and computer methodology for a physics-based prediction of overall deformation and local failure modes in cooled turbine airfoils, blade outer air seals, and other turbomachinery parts operating in severe high temperature and high stress environments. The computational analysis work incorporated time-accurate, coupled aerothermal CFD with non-linear deformation thermal-structural FEM with a slip-based constitutive model, evaluated at real engine characteristic mission times and flight points for part life prediction. The methodology utilizes a fully-coupled elastic-viscoplastic model that was based on crystal morphology, and a semi-empirical lifing model introduced the use of dissipated energy to estimate the remaining part life in terms of cycles to failure. The method was effective for use with three-dimensional finite element models of realistic turbine airfoils using commercial finite element applications. The computationally predicted part life was calibrated and verified against test data for deformation and crack growth.

scholarly journals Mechanical Response of Typical Cement Concrete Pavements under Impact Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Ding Fei ◽  
Yin Yan ◽  
Cai Liangcai ◽  
Tang Yaohong ◽  
Wang Xuancang
Keyword(s):  
Finite Element ◽  
Impact Loading ◽  
Mechanical Response ◽  
Impact Load ◽  
Damage Model ◽  
Three Dimensional ◽  
Element Model ◽  
Concrete Pavements ◽  
Cement Concrete ◽  
Concrete Damage

In order to study the mechanical response of cement concrete pavements under impact loading, four types of typical cement concrete pavement structures are investigated experimentally and numerically under an impact load. Full-scale three-dimensional pavement slots are tested under an impact load and are monitored for the mechanical characteristics including the deflection of the pavement surface layer, the strain distribution at the bottom of the slab, and the plastic damage and cracking under the dynamic impact load. Numerical analysis is performed by developing a three-dimensional finite element model and by utilizing a cement concrete damage model. The results show that the calculation results based on the cement concrete damage model are in reasonable agreement with the experimental results based on the three-dimensional test slot experiment. The peak values of stress and strain as monitored by the sensors are analyzed and compared with the numerical results, indicating that the errors of numerical results from the proposed model are mostly within 10%. The rationality of the finite element model is verified, and the model is expected to be a suitable reference for the analysis and design of cement concrete pavements.

Finite element analyses on punch shear behaviors of three-dimensional braided composites at microstructure level

2016 ◽  
Vol 26 (7) ◽  
pp. 968-988 ◽  
Author(s):  
Yuanyuan Li ◽  
Wei Zhang ◽  
Rotich K Gideon ◽  
Bohong Gu ◽  
Baozhong Sun
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
High Strain ◽  
Three Dimensional ◽  
Rate Sensitivity ◽  
Element Model ◽  
Shear Loading ◽  
Composite Panel ◽  
Braided Composites ◽  
Braided Composite

The punch shear properties of three-dimensional carbon/epoxy braided composites were studied at quasi-static and high strain rates with finite element method at microstructure level. A microstructure model was developed to analyze the stress distribution and progressive damage of the braided composite panel with different thickness. The braiding yarns were considered as an elastic and transversely isotropic material. Ductile and shear criterion were used in finite element model to obtain the damage evolution. It was found that the braided composite exhibited high strain rate sensitivity under punch shear loading. The thickness influences the punch shear strength significantly. The braiding yarns at surface and corner parts have tensile and pullout failure modes, while at inner part have shear damage mode.

Behaviour of concrete block masonry prisms under axial compression

1995 ◽  
Vol 22 (5) ◽  
pp. 898-915 ◽  
Author(s):  
E. H. Fahmy ◽  
T. G. M. Ghoneim
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Modulus Of Elasticity ◽  
Failure Modes ◽  
Three Dimensional ◽  
Concrete Block ◽  
Element Model ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A nonlinear three-dimensional finite element model was developed to study the complex behavior of ungrouted and grouted concrete block masonry prisms under axial compression. The model detects crack initiation and traces crack propagation in the masonry assemblage. Variable strengths for blocks, mortar, and grout were used to study the effect of the mechanical properties of prism constituents, and their combinations, on the prism strength and modulus of elasticity. The effect of the number of courses was also investigated. The results of the finite element analysis were used to develop simplified relationships to predict prism strength and modulus of elasticity. Good agreement was observed between the available experimental data and the predicted prism strengths. Key words: compressive strength, concrete blocks, failure modes, finite element, masonry, modulus of elasticity, prisms.

Mechanical and failure behavior of three-dimensional six-directional braided composites bolted joint

2017 ◽  
Vol 36 (10) ◽  
pp. 739-753 ◽  
Author(s):  
Yuling Tang ◽  
Zhengong Zhou ◽  
Shidong Pan ◽  
Zhiyong Tan ◽  
Hongwei Wu
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Characteristic Curve ◽  
Damage Model ◽  
Three Dimensional ◽  
Reference Value ◽  
Failure Criteria ◽  
Failure Behavior ◽  
Bolted Joint ◽  
Braided Composites

Experiments and finite element simulation were used to investigate the influence of geometric parameters on failure response of a single-lap bolted joint. Single- and double-bolt joints in three-dimensional six-directional braided composites were tested. The failure modes and mechanisms of the joints were evaluated. To accurately predict bearing strength, a three-dimensional composite damage model was used, which included the Yamada–Sun failure criteria based on the characteristic curve method. The finite element method (FEM) was validated by experimental results. The geometric reference value and failure envelope for the single-lap bolted joint were obtained. The results showed that the carrying capacity of the single-lap bolted joint decreased and the failure mode also changed owing to the secondary bending. It can also be obtained that increased the number of bolt rows can effectively reduce the secondary bending of the plates and thus generated less severe net tensile stresses.

Finite Element Analysis of a Flexible Pipe Interlocked Carcass Under Tension Loads

2021 ◽  
Author(s):  
Fernando Geremias Toni ◽  
Rodrigo Provasi ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Three Dimensional ◽  
Element Model ◽  
Cylindrical Layer ◽  
Stress Concentrations ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Realistic Representation ◽  
Three Dimensional Finite Element

Abstract To correctly model the structural behavior of a flexible pipe, the contribution of all the layers must be completely understood, among them the interlocked carcass. That carcass is a metallic layer designed to provide radial stiffness to a flexible pipe, mainly supporting pressure differentials and thus preventing failure modes such as collapse and crushing, but its behavior under other loads is worth of investigation. This paper contributes to understanding the carcass behavior under tension. Given its complex helical and interlocked geometry, modelling the carcass through the Finite Element Method is a challenging task, not only due to the large size of the models, but also due to the nonlinearities and convergence difficulties that arise from the self-contacts at the interlocking. For these reasons, most works developed over the past decades have adopted an equivalent layer approach, in which the carcass is replaced by an orthotropic cylindrical layer with equivalent mechanical properties. Although practical, this approach disregards the effects from the interlocking, such as stiffness variations and stress concentrations. Therefore, aiming a more realistic representation and a better understanding of the mechanical behavior of the interlocked carcass, this work presents four different carcass finite element models to analyze this layer under tension loads. The first one is a complete three-dimensional finite element model of an interlocked carcass discretized with second order isoparametric solid elements and surface-to-surface contact elements. The second model consists of a version of the first one with the addition of an inner polymeric sheath. As for the third and fourth models, it was adopted the simplifying ring hypothesis, that is, a carcass with 90 degree lay angle, thus allowing the axisymmetric modelling of the two previous configurations, representing a substantial computational gain by using two-dimensional meshes. The results of those models are then presented and compared, and the validity of the adopted simplifying hypothesis is verified.

scholarly journals Development of an optimal relief method for the palatal plate by stress analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tomoko Mukai ◽  
Yuji Sato ◽  
Osamu Shimodaira ◽  
Junichi Furuya ◽  
Akio Isobe ◽  
...  
Keyword(s):  
Finite Element ◽  
High Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Distribution Volume ◽  
The Other ◽  
Palatal Plate ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Palatal Mucosa

Abstract Background Plate dentures cannot be easily modified after fabrication; therefore, the sites and magnitude of relief must be effectively assessed at the time of fabrication. However, a considerable variation exists in the magnitude of optimal relief and relief range, and there are no guidelines that present these clearly, leading the dentists to decide subjectively. Thus, this study aims to develop an optimal relief method to improve the stress bearing capacity of the palatal mucosa. Methods The objective of this study, namely, the borderline, was set in steps. A three-dimensional finite element model for the pseudopalatal plate was created and used to evaluate the changes in stress distribution in the palatal mucosa due to the selective relief of stresses above the borderline. The resulting data were used to develop the optimal relief method. Results In the relief model with a borderline of 0.04 MPa or higher, the distribution volume at which a high stress of 0.20 MPa or higher is generated was approximately 800% of that with the no-relief model, and in the relief model with a borderline of 0.06 MPa or higher, the respective ratio was approximately 280%. On the other hand, the relief models with a borderline of 0.14 MPa or higher were approximately 60%. In the mid-palatal relief model, the distribution volume at which a stress of 0.20 MPa or higher was generated was 180% of that in the relief model. Conclusions The supportive strength of plates can be increased by selectively applying optimal relief rather than standard relief, allowing for easier and more effective plate-denture treatment.

Simplified Finite Element Models to Study the Dry Collapse of Straight and Curved Flexible Pipes

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clóvis de Arruda Martins ◽  
Eduardo Ribeiro Malta ◽  
Rafael Loureiro Tanaka ◽  
Carlos Alberto Ferreira Godinho
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Computational Cost ◽  
Three Dimensional ◽  
Element Model ◽  
External Pressure ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Simplified Modeling ◽  
Good Agreement

Dry collapse is one of the possible failure modes of flexible pipes. It refers to the situation in which no damage occurs in the flexible pipe external sheath. In this scenario, all layers of the pipe withstand the external pressure loading in a deep-water application. Such a situation is addressed in this work, which proposes some simplified modeling techniques to represent straight and curved flexible pipes subjected to external pressure, undergoing dry collapse during simulation procedure. The results of the proposed models are compared to other reference results, from a fully three-dimensional (3D) finite element model. Good agreement has been got, even with the proposed simplifications with a large reduction in computational cost when compared to full 3D model.

Torsional Analysis of a Steel Cord-Rubber Tire Belt Structure

1996 ◽  
Vol 24 (4) ◽  
pp. 339-348 ◽  
Author(s):  
R. M. V. Pidaparti
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structures ◽  
Three Dimensional ◽  
Element Model ◽  
Torsional Stiffness ◽  
Element Analysis ◽  
Rubber Belt ◽  
Steel Cord ◽  
Torsional Analysis

Abstract A three-dimensional (3D) beam finite element model was developed to investigate the torsional stiffness of a twisted steel-reinforced cord-rubber belt structure. The present 3D beam element takes into account the coupled extension, bending, and twisting deformations characteristic of the complex behavior of cord-rubber composite structures. The extension-twisting coupling due to the twisted nature of the cords was also considered in the finite element model. The results of torsional stiffness obtained from the finite element analysis for twisted cords and the two-ply steel cord-rubber belt structure are compared to the experimental data and other alternate solutions available in the literature. The effects of cord orientation, anisotropy, and rubber core surrounding the twisted cords on the torsional stiffness properties are presented and discussed.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

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