Free-Form Design of Electrical Machine Rotor Cores for Production Using Additive Manufacturing

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Michele Garibaldi ◽  
Christopher Gerada ◽  
Ian Ashcroft ◽  
Richard Hague
Keyword(s):  
Structural Integrity ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Free Form ◽  
Electrical Machine ◽  
Element Analysis ◽  
Torque Density ◽  
Magnetostatic Problem ◽  
Form Design ◽  
3D Printed

This work presents a finite element analysis-based, topology optimization (TO) methodology for the combined magnetostatic and structural design of electrical machine cores. Our methodology uses the Bi-directional Evolutionary Structural Optimization (BESO) heuristics to remove inefficient elements from a meshed model based on elemental energies. The algorithm improves the average torque density while maintaining structural integrity. To the best of our knowledge, this work represents the first effort to address the structural-magnetostatic problem of electrical machine design using a free-form approach. Using a surface-mounted permanent magnet motor (PMM) as a case study, the methodology is first tested on linear and nonlinear two-dimensional problems whereby it is shown that the rapid convergence achieved makes the algorithm suitable for real-world applications. The proposed optimization scheme can be easily extended to three dimensions, and we propose that the resulting designs are suitable for manufacturing using selective laser melting, a 3D printing technology capable of producing fully dense high-silicon steel components with good soft magnetic properties. Three-dimensional TO results show that the weight of a PMM rotor can be slashed by 50% without affecting its rated torque profile when the actual magnetic permeability of the 3D-printed material is considered.

Oyster Creek Nuclear Generating Station Containment Drywell Buckling Analysis

2010 ◽  
Author(s):  
Soo Bee Kok ◽  
Shu S. Tang ◽  
Francis H. Ku ◽  
Marcos L. Herrera ◽  
John F. O’Rourke ◽  
...  
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Buckling Analysis ◽  
Eigenvalues And Eigenvectors ◽  
Analysis Software ◽  
Element Analysis ◽  
3D Finite Element ◽  
Buckling Stability ◽  
Stability Limits

This article presents the overall methodology and the results of the three-dimensional (3D) finite element buckling analysis of the primary containment drywell shell at the Oyster Creek Nuclear Generating Station (Oyster Creek). The buckling stresses, eigenvalues, and eigenvectors are computed using ANSYS finite element analysis software [1], and the structural integrity of the drywell in terms of the buckling (stability) limits are based on the ASME B&PV Code Case N-284-1 [2].

Improving Cutting Path on Custom 3D-Printed Surgical Guides for Bone-Tumor Resection

2019 ◽  
Author(s):  
Carlos G. Helguero ◽  
Juan Castro ◽  
César Ochoa ◽  
Fausto Maldonado ◽  
Emilio A. Ramírez ◽  
...  
Keyword(s):  
Bone Tumor ◽  
Tumor Resection ◽  
Three Dimensional ◽  
Element Analysis ◽  
Surgical Guides ◽  
Orthopedic Oncology ◽  
3D Printed ◽  
Bone Tumor Resection ◽  
High Level ◽  
Cutting Path

Abstract Custom three-dimensional (3D) printed guides are being used in the operative room as an aid to surgeons for increasing the accuracy of their cutting and resection techniques. In terms of bone-tumor resection, the cutting path printed in the custom jig is significantly important for two main purposes: first, the required fit for the implant that will replace the resected bone section and, second, the interaction between the remaining, healthy bone and the new implant in terms of forces, stresses and deformation. Bone tumor resection has posed a challenge in orthopedic oncology, specifically due to a high level of difficulty in performing a limb-sparing surgery with negative margins on the remaining bone. A straight cutting path is usually used in clinical procedures due to the type of tooling available inside the operative room. 3D printed cutting path guides offer the possibility to evolve from a straight to a different path, e.g. a tapered path, and overcome fitting problems during surgery. This work investigates the current straight cutting path used for typical bone tumor resection and compares it to a proposed tapered cutting path in terms of both implant fitting and stress analysis. Finite element analysis software is used to simulate a compression force exerted over the femur bone. Different taper cut angles are studied and results are reported to obtain an ideal angle for resection. Results are presented to evidence the need to evolve from the current resection technique in order to minimize the number of revision surgeries and for a better quality of life of patients under this type of surgical procedure.

Quantifying the Constraint of Three-Dimensional Biaxially Loaded Specimens Containing Semi-Elliptical Cracks Using the J-A2 Method

2012 ◽  
Author(s):  
L. W. Sharpe ◽  
Y. J. Chao
Keyword(s):  
Fracture Toughness ◽  
Structural Integrity ◽  
Biaxial Loading ◽  
Three Dimensional ◽  
Flat Plates ◽  
Constraint Effect ◽  
Element Analysis ◽  
Applied Loading ◽  
Analysis Models ◽  
Elliptical Cracks

Fracture toughness is an important material property used to assess the structural integrity of mechanical components containing cracks. Often, the fracture toughness depends upon the geometry of the component as well as the applied loading. This dependence is referred to as the constraint effect in fracture. The two parameter J-A2 method can be used to quantify the constraint effect. The J-A2 method is a more accurate representation of the stress fields near the crack compared to the classical HRR solution, as additional terms from the series solution are used. The subject of the current study is to apply the J-A2 method to published fracture toughness data of three-dimensional, flat plates containing semi-elliptical cracks and subjected to both uniaxial and biaxial loading to determine the constraint effect and also to determine if the method can be used to predict fracture. The J-A2 results of the flat plates are compared to those of 3PB specimens to determine if loss of constraint exists. Finite element analysis models were developed for each specimen to determine the constraint parameter A2 for each applied loading. The results of the current study reveal that both the uniaxial and biaxial loaded plates exhibit loss of constraint relative to the 3PB specimen and biaxial load increases the constraint of the uniaxially loaded specimen. Further, the J-A2 method shows potential as a tool to predict failure with different constraint level.

Living the heart in three dimensions: applications of 3D printing in CHD

2019 ◽  
Vol 29 (06) ◽  
pp. 733-743 ◽  
Author(s):  
Mari Nieves Velasco Forte ◽  
Tarique Hussain ◽  
Arno Roest ◽  
Gorka Gomez ◽  
Monique Jongbloed ◽  
...  
Keyword(s):  
3D Printing ◽  
Heart Surgery ◽  
Wide Spectrum ◽  
Three Dimensional ◽  
Structural Heart Disease ◽  
Medical Personnel ◽  
Three Dimensions ◽  
Patient Specific ◽  
3D Printed

AbstractAdvances in biomedical engineering have led to three-dimensional (3D)-printed models being used for a broad range of different applications. Teaching medical personnel, communicating with patients and relatives, planning complex heart surgery, or designing new techniques for repair of CHD via cardiac catheterisation are now options available using patient-specific 3D-printed models. The management of CHD can be challenging owing to the wide spectrum of morphological conditions and the differences between patients. Direct visualisation and manipulation of the patients’ individual anatomy has opened new horizons in personalised treatment, providing the possibility of performing the whole procedure in vitro beforehand, thus anticipating complications and possible outcomes. In this review, we discuss the workflow to implement 3D printing in clinical practice, the imaging modalities used for anatomical segmentation, the applications of this emerging technique in patients with structural heart disease, and its limitations and future directions.

Improving Turbine Component Efficiency

1979 ◽  
Author(s):  
K. D. Mach
Keyword(s):  
Structural Integrity ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Computation Method ◽  
Test Procedures ◽  
Aerodynamic Efficiency ◽  
Turbine Engine ◽  
Careful Control ◽  
Component Efficiency

The thermal efficiency of a gas turbine engine depends on the cycle pressure and temperature ratio and on the aerodynamic efficiencies of the gas path components. Maintaining and/or improving structural integrity and aerodynamic efficiency in this high pressure, high temperature environment is the preeminent problem of the turbine designer. High gas temperatures require at least some of the metal structures to be cooled, yet cooling air is a loss to the cycle and its consumption must be kept to a minimum. Research into cooling techniques and boundary layer behavior on airfoils and endwalls and into test procedures for obtaining heat transfer data are providing some of the answers the designer needs. Increased operating pressures generate increased mechanical stresses. Finite element analyses and automated design procedures are proving to be powerful aids to the designer. Improving aerodynamic efficiency requires careful control of the flow in three dimensions, particularly in low aspect ratio machines. The first practical computation method for three-dimensional, viscous, transonic flows became available in late 1977 and has made this one of the most exciting areas of turbine technology. Additional gains in aerodynamic efficiency can be realized by controlling leakages, especially those over the rotor tip, by accounting for the transient interactions between rotor and stator and by careful control of discharged coolant flow. This paper briefly describes the turbine cooling research conducted by the Air Force Aero Propulsion Laboratory and describes mor extensively the AFAPL programs in turbine aerodynamics, including applications of three-dimensional flow analysis.

A novel direct resolution method for coupled systems in finite element analysis

2020 ◽  
Vol 39 (5) ◽  
pp. 1271-1280
Author(s):  
Youcef Boutora ◽  
Noureddine Takorabet
Keyword(s):  
Finite Elements ◽  
Linear Systems ◽  
Symmetric Matrix ◽  
Direct Method ◽  
Three Dimensional ◽  
Coupled Systems ◽  
Resolution Method ◽  
Element Analysis ◽  
Content Type ◽  
Magnetostatic Problem

Purpose This paper aims to propose a novel direct method for indefinite algebraic linear systems. It is well adapted for sparse linear systems, such as those of two-dimensional (2-D) finite elements problems, especially for coupled systems. Design/methodology/approach The proposed method is developed on an example of an indefinite symmetric matrix. The algorithm of the method is given next, and a comparison between the numbers of operations required by the method and the Cholesky method is also given. Finally, an application on a magnetostatic problem for classical methods (Gauss and Cholesky) shows the relative efficiency of the proposed method. Findings The proposed method can be used advantageously for 2-D finite elements in stepping methods without using a block decomposition of matrices. Research limitations/implications This method is advantageous for direct linear solving for 2-D problems, but it is not recommended at this time for three-dimensional problems. Originality/value The proposed method is the first direct solver for algebraic linear systems proposed since more than a half century. It is not limited for symmetric positive systems such as many of direct and iterative methods.

A Three-Dimensional Finite Element Analysis of Restored Deciduous Canine

2015 ◽  
Vol 638 ◽  
pp. 123-129 ◽  
Author(s):  
Florin Baciu ◽  
Claudia Bratosin ◽  
Aurelia Rusu-Casandra
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Bone Structure ◽  
Three Dimensional ◽  
Medical Problem ◽  
Ct Scanner ◽  
Chronic Infections ◽  
Element Analysis ◽  
Tooth Structure ◽  
Three Dimensional Finite Element

The literature reports that dental cavities are an international public health challenge and treatment of decays especially for young children is a medical problem of great importance. Early childhood caries progress rapidly and can cause functional, physical and dentofacial aesthetic impairment. Recent studies show that caries lesions can compromise children’s quality of life due to the pain and discomfort which could lead to disfigurement, acute and chronic infections and to alteration of meals and sleeping habits. Tooth decay occurs when acids in the mouth dissolve the outer layers of the tooth, stripping the tooth of important minerals. Because dental decay often goes untreated, the cavity grows and more tooth structure is lost. Restorative dentistry has the main purpose of rehabilitating the function and aesthetic of tooth. The structural integrity of the restored teeth depends on the state of stress in their different regions due to occlusal loads. The aim of this study performed with the finite element method is to evaluate the stress and strain distributions in bone structure-primary canine-restorative material assembly when a load of 120N is applied all over the upper surface of the model. Particular attention was given to an accurate computer reconstruction of the canine. Therefore with the aid of a CT scanner the tomography images obtained were processed with a special software (Mimics). Two dental restorative materials, commonly used in practice were chosen for the analysis and the results acquired are compared. Also the contact pressure at the interface bone-deciduous canine and deciduous canine-dental material is evaluated in both cases.

Structural Integrity Assessment Criteria and Service Life Prediction of Cold Wrinklebends

2012 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Finite Element ◽  
Service Life ◽  
Structural Integrity ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Computation Time ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Fea Model ◽  
Hardening Models

Three-dimensional elastic-plastic finite element analysis (FEA) is performed in this paper to simulate the complicated stresses and deformation of wrinklebends in a pipeline from its bending formation to operation under cyclic loading. Three plastic hardening models (isotropic, kinematic and combined isotropic/kinematic) are discussed and used in FEA of wrinklebend response that considers strain hardening and Bauschinger effects. The FEA simulation is carried out first for an elbow held at constant pressure while subject to cyclic bending, which serves as a benchmark case. The results show that the three hardening models lead to very different outcomes. Comparable FEA simulations are then developed for wrinklebends under cyclic pressure. Detailed parametric analysis is considered, including finite-element type, element sensitivity, computation time, and material input data. Based on those results viable nonlinear FEA model is developed as the basis to quantify wrinklebend response under service-like conditions. Based on the FEA results, fatigue damage is quantified using the Smith, Watson and Topper (SWT) parameter, and thereafter a damage criterion is proposed to predict the fatigue life of a wrinklebend under the pressure cycles of 72%–10% of SMYS for typical X42 pipeline steel. The results show that the wrinkle aspect ratio H/L is a key parameter to control the service life of a wrinklebend.

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