scholarly journals Optimisation of stress distribution in a highly loaded radial-axial gas microturbine using FEM

2020 ◽  
Vol 10 (1) ◽  
pp. 318-335 ◽  
Author(s):  
Paweł Zych ◽  
Grzegorz Żywica
Keyword(s):  
Stress Reduction ◽  
High Speed ◽  
Three Dimensional ◽  
Design Stage ◽  
Industrial Sectors ◽  
Reduction Methods ◽  
Scientists And Engineers ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Highly Loaded

AbstractThe article discusses the stress optimisation process of the highly loaded disc of a high-speed radial-axial microturbine. At the design stage, the strength optimisation is vitally important for these types of devices because they must withstand very high temperatures (600∘C in this case) and be capable of operating at high rotational speeds (96,000 rpm in this case). Calculations were made using a three dimensional FE numerical model. The optimisation process is strictly connected with the choice of materials — which in this case are Inconel 738 (nickel-cobalt super alloy) and silicon nitride. Several stress reduction methods were developed, which took into account the mass of the disc, the rotational speed of the rotor and the complex shape of the rear part of the disc. Numerical computations helped to choose the best optimisation method, which decreased maximum reduced von Mises stresses by about 45% (from 1,288 MPa to 705 MPa). The methods proposed in this article are universal and can be implemented in the design process of various high-speed radial-axial microturbines. This article could be of interest to scientists and engineers who deal with highly loaded microturbines, which are increasingly used in many industrial sectors.

Mechanics of Composite Layered Rough Medium in Contact

2013 ◽  
Vol 703 ◽  
pp. 200-203
Author(s):  
Shao Biao Cai ◽  
Yong Li Zhao
Keyword(s):  
Material Properties ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Normal Loading ◽  
Layered Coatings ◽  
Pressure Profiles ◽  
Tangential Traction ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Tangential Friction

This study presents a first attempt to develop a numerical three-dimensional multilayered (more than 2 composite layered coatings) elasticperfectly plastic rough solids model to investigate the contact behavior under combined normal loading and tangential traction. Contact analyses are performed to study the effects composite thin film layers. Local contact pressure profiles, von Mises stresses, and shear stresses as a function of material properties and applied normal and tangential friction loads are calculated.

scholarly journals Effect of Augmentation Material Stiffness on Adjacent Vertebrae after Osteoporotic Vertebroplasty Using Finite Element Analysis with Different Loading Methods

2015 ◽  
Vol 6;18 (6;11) ◽  
pp. E1101-E1110
Author(s):  
Ah-Reum Cho
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bone Cement ◽  
Vertebral Fractures ◽  
Three Dimensional ◽  
Element Model ◽  
Element Analysis ◽  
Adjacent Vertebral Body ◽  
Von Mises ◽  
Von Mises Stresses

Background: Vertebroplasty is an effective treatment for osteoporotic vertebral fractures, which are one of the most common fractures associated with osteoporosis. However, clinical observation has shown that the risk of adjacent vertebral body fractures may increase after vertebroplasty. The mechanism underlying adjacent vertebral body fracture after vertebroplasty is not clear; excessive stiffness resulting from polymethyl methacrylate has been suspected as an important mechanism. Objectives: The aim of our study was to compare the effects of bone cement stiffness on adjacent vertebrae after osteoporotic vertebroplasty under load-controlled versus displacementcontrolled conditions. Study Design: An experimental computer study using a finite element analysis. Setting: Medical research institute, university hospital, Korea. Methods: A three-dimensional digital anatomic model of L1/2 bone structure was reconstructed from human computed tomographic images. The reconstructed three-dimensional geometry was processed for finite element analysis such as meshing elements and applying material properties. Two boundary conditions, load-controlled and displacement-controlled methods, were applied to each of 5 deformation modes: compression, flexion, extension, lateral bending, and torsion. Results: The adjacent L1 vertebra, irrespective of augmentation, revealed nearly similar maximum von Mises stresses under the load-controlled condition. However, for the displacementcontrolled condition, the maximum von Mises stresses in the cortical bone and inferior endplate of the adjacent L1 vertebra increased significantly after cement augmentation. This increase was more significant than that with stiffer bone cement under all modes, except the torsion mode. Limitations: The finite element model was simplified, excluding muscular forces and incorporating a large volume of bone cement, to more clearly demonstrate effects of bone cement stiffness on adjacent vertebrae after vertebroplasty. Conclusion: Excessive stiffness of augmented bone cement increases the risk of adjacent vertebral fractures after vertebroplasty in an osteoporotic finite element model. This result was most prominently observed using the displacement-controlled method. Key words: Bone cements, displacement-controlled method, finite element analysis, loadcontrolled method, osteoporosis, osteoporotic fracture, polymethyl methacrylate, vertebroplasty

scholarly journals Análise numérica de ligação parafusada semirrígida em perfis formados a frio

ForScience ◽  
2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Emerson Cardoso de Castro ◽  
Flávio Teixeira de Souza ◽  
Arlene Maria Cunha Sarmanho
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Finite Elements ◽  
Three Dimensional ◽  
Structural Performance ◽  
Similar Tendency ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Bolt Connection ◽  
Force Displacement

O presente trabalho constitui-se de uma análise numérica, por meio de elementos finitos, objetivando a reprodução via software de um ensaio experimental de ligação parafusada semirrígida em perfis formados a frio, dada no âmbito tridimensional. A análise consistiu-se a partir da reprodução da geometria do protótipo, das condições de contorno e aplicação de carregamento. Para melhor previsão do comportamento da ligação, foram inseridas ao modelo a não linearidade física e geométrica. Foram obtidas as curvas força-deslocamento e a evolução das tensões de Von Mises para os diferentes componentes do protótipo. Os resultados indicaram que o modelo numérico é cerca de duas vezes mais rígido que o experimental. Todavia, foi possível observar que o comportamento do modelo numérico possui tendência similar ao do modelo experimental e também foi possível avaliar a contribuição dos elementos da ligação para o desempenho da mesma.Palavras-chave: Análise numérica. Ligação parafusada semirrígida. Perfis formados a frio. Desempenho estrutural.Numerical analysis of semi-rigid bolt connection in cold formed profilesAbstractThe current paper is based on a numerical analysis by means of finite elements aiming at the software reproduction of an experimental test of semi-rigid bolt connection in cold formed profiles occurred in the three-dimensional scope. The analysis consisted of the reproduction of the prototype geometry, the boundary conditions, and the loading application. For a better forecast of the connection behavior, physical and geometric non-linearity were inserted to the model. The force-displacement curves and the evolution of the Von Mises stresses for the different prototype components were obtained. The results indicated that the numerical model is about twice as rigid as the experimental one. However, it was possible to observe that the behavior of the numerical model has a similar tendency  if compared to  the experimental model and it was still possible to evaluate the contribution of the connection elements to its performance.Keywords: Numerical analysis. Semi-rigid bolt connection. Cold-formed profiles. Structural performance.

scholarly journals DESCRIBING STRESS CONCENTRATION FACTORS OF AN INTERNALLY PRESSURIZED CYLINDER WITH AN IMBEDDED HOLE BY NEW FORMULATION

2020 ◽  
Author(s):  
javad jafari fesharaki
Keyword(s):  
Stress Concentration ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Internal Diameter ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
New Formulation ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Pressurized Cylinder

The purpose of this paper is to investigate the stress concentration factor(SCF) for an internallypressurized cylinder with hole and based on detailed three-dimensional elastic FE analysis, a newcomprehensive set of formulas for SCFs are proposed. These stress concentration factors are presentedand discussed as a function of the ratio of cylinder diameter to the thickness of cylinder and hole diameter.The first ratio “D/100t” is equal to 1, 1.25, 1.5, 1.75, 2, 2.5, 2.75, 3, 3.25 and 3.5 and the second ratio“D/10d”, cylinder internal diameter to the hole diameter, varies from 0.6, 0.9, 1.2, 1.5, 1.8, 2, 2.3, 2.7,3.1and 3.5. Results are also presented for SCF of longitudinal, circumferential and Von Mises stresses.

scholarly journals Stress distribution in a mandibular premolar after separated nickel-titanium instrument removal and root canal preparation: a three-dimensional finite element analysis

2019 ◽  
Vol 47 (4) ◽  
pp. 1555-1564 ◽  
Author(s):  
Na Ni ◽  
Jing Ye ◽  
Liyuan Wang ◽  
Simin Shen ◽  
Lei Han ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Cervical Region ◽  
Element Analysis ◽  
Straight Line ◽  
Mandibular First Premolar ◽  
Von Mises ◽  
Von Mises Stresses

Objective This study used finite element analysis (FEA) to assess the von Mises stresses of a mandibular first premolar after removing a separated instrument with an ultrasonic technique. Methods FEA models of the original and treated mandibular first premolar were reconstructed, and three models (the original canal, size 30/taper 0.04 canal, and separated instrument removal canal) were created. Two-direction (vertical and lateral) loading patterns were simulated with a 175-N force. The maximum von Mises stresses of the models within the roots from the apex to the cervical region were collected and summarized. Results Under vertical and lateral loads, all maximal values in the three models were localized in the straight-line access region. Compared with the original model (model 1), the treated models (models 2 and 3) had greater maximum stress values from the apex to the cervical region. Greater differences in the maximum von Mises stresses between models 2 and 3 were present in the straight-line access region. Conclusions Separated instrument removal caused changes in stress distribution and increases in stress concentration in the straight-line access region of roots.

Deformations and Stresses in Soft Body Tissues of a Sitting Person

1978 ◽  
Vol 100 (2) ◽  
pp. 79-87 ◽  
Author(s):  
W. W. Chow ◽  
E. I. Odell
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Surface Friction ◽  
Element Model ◽  
The Finite Element Method ◽  
Decubitus Ulcers ◽  
Surface Pressure Distribution ◽  
Body Tissues ◽  
Von Mises ◽  
Von Mises Stresses

This paper investigates the deformations and stresses in the buttocks of a person when he sits on a cushion. The study is motivated by the need for a better understanding of the design of wheelchair cushions and the prevention of decubitus ulcers. The finite element method is used on an axisymmetric model. Surface pressure distribution, surface friction, hydrostatic pressures and von Mises stresses are obtained. The finite element model reveals the three-dimensional state of stress at all internal locations for a typical human body. Thus the study complements the experimental measurements performed by many physicians and bioengineers.

scholarly journals Evaluation of Micromovements and Stresses around Single Wide-Diameter and Double Implants for Replacing Mandibular Molar: A Three-Dimensional FEA

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Shrikar R. Desai ◽  
I. Karthikeyan ◽  
Rika Singh
Keyword(s):  
Stress Reduction ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Implant Design ◽  
Immediate Loading ◽  
3D Fem ◽  
Wide Diameter ◽  
Force Magnitude ◽  
Mandibular Molar ◽  
Von Mises

Purpose. The purpose of this finite element study was to compare stresses, strains, and displacements of double versus single implant, in immediate loading for replacing mandibular molar. Materials and Methods. Two 3D FEM models were made to simulate implant designs. The first model used 6 mm wide-diameter implant to support a single molar crown. The second model used 3.75-3.75 double implant design. Each model was analyzed with a single force magnitude of 70 N in oblique axis in three locations. Results. This FEM study suggested that micromotion can be well controlled by both double implants and 6 mm single wide-diameter implant. The Von Mises stress for double implant had 31%–43% stress reduction compared to the 6 mm implant. Conclusion. Within the limitations of the paper, when the mesiodistal space for artificial tooth is more than 12.5 mm, under immediate loading, the double implant support should be considered.

scholarly journals Finite Element Analysis Comparison of Plate Designs in Managing Fractures Involving the Mental Foramen

2013 ◽  
Vol 6 (2) ◽  
pp. 93-97 ◽  
Author(s):  
Neralla Mahathi ◽  
Emmanuel Azariah ◽  
C. Ravindran
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Mental Foramen ◽  
Stress Generation ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Plate Design ◽  
Von Mises ◽  
Von Mises Stresses

Introduction The aim of the study was to propose an ideal plating design for fractures running through the mental foramen. Methods The study compared three plating designs—two four-hole miniplates, 2 × 2-hole three-dimensional (3D) plate, and modified 2 × 2-hole 3D plate (posterior strut removed)—using finite element analysis. Von Mises stresses generated around the plates and bone were measured, as well as the mobility that is generated between the fracture fragments by applying muscle forces to generate bite force in one test and applying a force of 500 N over the premolars and first molar region in the second test. Results Von Mises stress in bone with miniplates measured 9.24 MPa in test 1 and 131.99 MPa in test 2. The stress with unmodified 3D plates measured 34.9 MPa in test 1 and150.03 MPa in test 2. The stress with modified 3D plates measured 24.98 MPa in test 1 and 150.59 MPa in test 2. Von Mises stress on the plates and screws measured 28.23 MPa, 95.97 MPa, 72.93 MPa in test 1 and 458.63 MPa, 779.01 MPa, 742.39 MPa in test 2 on miniplates, unmodified 3D plates, and modified 3D plates, respectively. The fracture mobility generated in the model with miniplates measured 0.001 mm in test 1 and 0.01 mm in test 2 and 0.007 mm and 0.02 mm in the model with unmodified 3D plates in test 1 and in test 2, respectively. In the model with modified 3D plates, the value was 0.001 mm and 0.01 mm in tests 1 and 2, respectively. Conclusion The ideal plate design is the two-plate technique with minimal stress generation on the bone and the hardware. The modified 3D plate has adequate strength to be used in the region but needs to be studied in detail.

Influence of Implant Inclination and Prosthetic Abutment Type on the Biomechanics of Implant-Supported Fixed Partial Dentures

2019 ◽  
Vol 45 (5) ◽  
pp. 343-350 ◽  
Author(s):  
Victório Poletto-Neto ◽  
Pedro Henrique Wentz Tretto ◽  
Bruno Massucato Zen ◽  
Ataís Bacchi ◽  
Mateus Bertolini Fernandes dos Santos
Keyword(s):  
Stress Reduction ◽  
Finite Element Models ◽  
Analysis Software ◽  
3 Dimensional ◽  
Implant Placement ◽  
Specific Analysis ◽  
Dimensional Finite Element ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Do So

Obtaining parallelism during implant placement is often difficult, leading to inclination of implants. The present study evaluated the stress distribution in 3-unit fixed partial dentures supported by 2 implants with different inclinations and prosthetic abutments. Universal castable long abutments (UCLAs) or tapered abutments were used considering 17° of implant angulation in different directions (mesial, distal, buccal, or lingual). To do so, 3-dimensional finite element models were built and exported to specific analysis software. Forces were applied to the functional cusps. Data were obtained with regard to the maximum principal and von Mises stresses (in MPa). No relevant differences were observed in the stress values in the cortical and cancellous bone nor in the prosthesis with UCLA or tapered abutments. However, a relevant stress reduction in the prosthetic screws of the tilted implant was observed when using UCLA abutments. According to the obtained results, it is possible to suggest that both UCLA or tapered abutments can be used for 3-unit fixed partial dentures when 1 of the implants is tilted. UCLA abutment might lead to less biomechanical problems related to screw loosening or fracture.

Optimal Design of a Composite Scarf Repair Patch Under Tensile Loading

2009 ◽  
Author(s):  
T. D. Breitzman ◽  
E. V. Iarve ◽  
E. R. Ripberger
Keyword(s):  
Optimal Design ◽  
Three Dimensional ◽  
Tensile Loading ◽  
Composite Repair ◽  
Repair Patch ◽  
Design Variables ◽  
Open Hole ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Multidimensional Optimization

Mechanics of the composite scarf repair under tensile loading with and without overlay plies was examined for nontraditional patch ply orientations. Three-dimensional nonlinear analysis was performed for repair failure prediction and good baseline comparison for open-hole scarfed panels and panels repaired by using standard ply-by-ply replacement patch composition was achieved. Multidimensional optimization was performed to calculate the repair patch ply orientations which minimize the von Mises stresses in the adhesive. These optimal stacking sequences achieved significant reduction of the stress levels and resulted in predicted up to 75% and 85% strength restoration for flush and single ply thickness over-ply repair. These results are intended to illustrate additional design variables available for efficient composite repair design, namely the composition of the repair patch.

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