Three-Dimensional Stress State Around Corrosive Cavities on Pressure Vessels

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Z. Abdulaliyev ◽  
S. Ataoglu ◽  
O. Bulut ◽  
E. S. Kayali
Keyword(s):  
Maximum Stress ◽  
High Stress ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Empirical Expression ◽  
Ellipsoidal Cavity ◽  
Industrial Sectors ◽  
Internal Surfaces ◽  
Different Types ◽  
Distribution Of Stress

Internal surfaces of pressure vessels used in many industrial sectors are subjected to corrosive effects leading to cavities. In this study, corrosive cavities on investigated pressure vessels are classified according to their shapes and dimensions. Distribution of stress was experimentally investigated around regions of different types of cavities using three-dimensional photoelastic models. An empirical expression is proposed to determine where maximum stress occurs in type of ellipsoidal cavity in the case of uniaxial loading. The obtained results show quite high stress levels around the cavity regions in pressure vessels, which increase the risk of crack formation.

scholarly journals Modular hemipelvic endoprosthesis with a sacral hook: a finite element study

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Bo Wang ◽  
Peidong Sun ◽  
Hao Yao ◽  
Jian Tu ◽  
Xianbiao Xie ◽  
...  
Keyword(s):  
Aseptic Loosening ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Biomechanical Properties ◽  
Stress Distributions ◽  
Three Dimensional Model ◽  
Connection Component ◽  
Static Conditions ◽  
Distribution Of Stress

Abstract Background A novel hemipelvic endoprosthesis with a sacral hook was introduced previously, and its clinical outcome with midterm follow-up showed decreased prosthesis-related complications, especially decreased rate of aseptic loosening. The aim of present study was to evaluate the role of a sacral hook in prosthesis stability and the biomechanical properties of this hemipelvic endoprosthesis. Methods A three-dimensional model of the postoperative pelvis was developed using computed tomography (CT) images. A force of 500 N was applied, and the distribution of stress and displacement was evaluated. Comparisons were performed to explore the role of the sacral hook in prosthesis stability. Prosthesis improvement was simulated to reduce unexpected breakage of the pubic connection plate. Results In the reconstructed hemipelvis, stress distributions were concentrated on the superior area of the acetabulum, sacral connection component, and sacral hook. A maximum stress of 250 MPa was observed at the root of the sacral connection component. The sacral hook reduced the maximum stress and displacement by 14.1% and 32.5%, respectively, when the prosthesis was well fixed and by 10.0% and 42.1%, respectively, when aseptic loosening occurred. Increasing the thickness of the pubic connection plate from 2 to 3.5 mm reduced the maximum stress by 32.0% and 15.8%, respectively. Conclusion A hemipelvic endoprosthesis with a sacral hook fulfills the biomechanical demands of the hemipelvis and is safe under static conditions. The sacral hook is important for prosthesis stability. Increasing the thickness of the pubic connection plate can reduce the maximum stress and risk of fatigue breakage.

Environmentally-Assisted Fatigue Analysis Using a Strain-Based Approach

2016 ◽  
Author(s):  
Timothy Gilman ◽  
Francis Ku
Keyword(s):  
High Stress ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Strain Range ◽  
Peak Stress ◽  
Uniaxial Stress ◽  
Pressure Vessels ◽  
Linear Superposition ◽  
Element Analysis ◽  
Plastic Analysis

Traditional design fatigue analyses of pressure vessels and piping equipment have typically used linear-elastic stress analyses, where the stresses caused by various loads, such as thermal, pressure, bending moments, etc. are combined using the principle of linear superposition. Based on high stress locations, geometric and material discontinuities, and other engineering judgements, stress classification lines (SCLs) were defined for where fatigue usage factors would be calculated. It was then necessary to apply simplified elastic-plastic penalty factors, based on the through-wall linearized stresses, to the peak stress amplitudes, in order to account for the nonlinear behavior of materials. Nonlinear finite element analysis that directly calculates strains were not typically used, because of computing and material modeling limitations. However, such analyses, even for complex three-dimensional structures, have become much more practical today with advancements in computing speed and storage capacity. ASME Section III Subarticle NB-3200 includes a provision for performing nonlinear (or “plastic”) analysis (NB-3228.4(c)), but little to no guidance is provided for how to perform the analysis itself. In addition, the procedure for computing the strain range, as currently written in the Code, has been identified as being limited to a uniaxial stress condition and is fundamentally inconsistent with the traditional elastic methodology. This paper provides a proposal for an improved approach for computing fatigue usage and strain rates using nonlinear plastic analysis. Additional guidance for performing these analyses is provided, as they are expected to be used more frequently into the future.

Synthesis of Flexure Based Translational Springs

2019 ◽  
Author(s):  
Abhijit Ashish Chattopadhyay ◽  
Hong Zhou
Keyword(s):  
Maximum Stress ◽  
High Stress ◽  
Three Dimensional ◽  
One Dimensional ◽  
Spring Strip ◽  
Coiled Spring ◽  
Translational Spring ◽  
The One ◽  
Monolithic Structures ◽  
Force Displacement

Abstract Translational springs are employed to generate desired force-displacement relationships. Conventional translational springs utilize elastic deformations of coiled spring strips to fulfill their functions. The one-dimensional motion of a conventional translational spring is produced by the three-dimensional deformation of its coiled spring strip, which is bending plus twisting of the coiled spring strip. Different from conventional translational springs, flexure based translational springs usually have simple planar monolithic structures, and are convenient to manufacture and maintain. The translation of a flexure based translational spring is from the two-dimensional elastic or recoverable deformations of its planar flexible members. The flexure based translational springs synthesized in this research are required to endure large input translations. Because of large deformation and geometric nonlinearity, flexure based translational springs face difficulties that include parasitic drift, spring stiffness deviation, and high stress in the deformed springs. The research of this paper is motivated by surmounting these difficulties. Flexure based translational springs with different arrangements are synthesized to eliminate parasitic drifts and have desired spring rates and reasonable maximum stress.

The Effect of Pedicle Screw Thread Shape on the Stress Concentration Under Lateral Bending

2019 ◽  
Author(s):  
Yucheng Yang ◽  
Qin Ma
Keyword(s):  
Stress Concentration ◽  
Maximum Stress ◽  
High Stress ◽  
Three Dimensional ◽  
Spinal Column ◽  
Pedicle Screws ◽  
Screw Thread ◽  
Lateral Bending ◽  
High Stress Concentration ◽  
Stress Patterns

Abstract Pedicle screws (PS) are frequently used in medical spinal column fixation. Despite 7 out of 100 pedicle screws fracture inside of the patients’ body and under the claim that lateral bending is the main failure mode, little research has addressed the stress characteristics and the fracture location of the PS under lateral bending. This study focuses on the effect of thread design on the magnitude and location of maximum stress concentration. Four types of thread shapes are considered including V-shape, square-shape, buttress, and reverse buttress. Three-dimensional (3D) finite element (FE) methods are used in this investigation. A load of 150 Newton is applied at the screw head to simulate lateral bending. The models are created in SolidWorks. The 3D FE analysis is performed using the standard coding of ANSYS Workbench 19.1. Based on this study, it is found that the high stress concentration is located at the cortical bone region rather than at the cancellous bone region. Although the general stress patterns are similar, the PS thread shape design and the thread fillet radius may significantly affect on the magnitude and location of maximum stress concentration.

Innovative Design and Static Analysis of Magnesium Alloy Automobile Wheel

2011 ◽  
Vol 120 ◽  
pp. 85-88 ◽  
Author(s):  
Shan Ling Han ◽  
Lei Yang ◽  
Gui Shen Wang ◽  
Qing Liang Zeng
Keyword(s):  
Magnesium Alloy ◽  
Maximum Stress ◽  
High Stress ◽  
Three Dimensional ◽  
Transitional Region ◽  
Cad Model ◽  
Innovative Design ◽  
Alloy Wheel ◽  
Bolt Holes ◽  
Automobile Wheel

The utilization of magnesium alloy wheels is useful for automobile lightweight. A kind of magnesium alloy wheel was designed by using TRIZ theory, and then the three-dimensional CAD model was created using UG NX 7.0. According to these, the static structural analysis of the magnesium alloy wheel had been simulated with finite-element method. It can be shown that the high stress distributes mainly in the region of bolt holes and the transitional region between the rim and spokes of the wheel. The maximum stress is less than the yield stress of magnesium alloy. Some valuable references are provided for the design and development of magnesium alloy wheel.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

A Study on Utilization of Three-Dimensional Sensor Lip Image for Developing a Pronunciation Recognition System

2019 ◽  
Vol 63 (5) ◽  
pp. 50402-1-50402-9 ◽  
Author(s):  
Ing-Jr Ding ◽  
Chong-Min Ruan
Keyword(s):  
Principal Component Analysis ◽  
Automatic Speech Recognition ◽  
Feature Fusion ◽  
Three Dimensional ◽  
Principal Component ◽  
Recognition System ◽  
Geometrical Characteristics ◽  
3D Geometry ◽  
Different Types ◽  
The Disabled

Abstract The acoustic-based automatic speech recognition (ASR) technique has been a matured technique and widely seen to be used in numerous applications. However, acoustic-based ASR will not maintain a standard performance for the disabled group with an abnormal face, that is atypical eye or mouth geometrical characteristics. For governing this problem, this article develops a three-dimensional (3D) sensor lip image based pronunciation recognition system where the 3D sensor is efficiently used to acquire the action variations of the lip shapes of the pronunciation action from a speaker. In this work, two different types of 3D lip features for pronunciation recognition are presented, 3D-(x, y, z) coordinate lip feature and 3D geometry lip feature parameters. For the 3D-(x, y, z) coordinate lip feature design, 18 location points, each of which has 3D-sized coordinates, around the outer and inner lips are properly defined. In the design of 3D geometry lip features, eight types of features considering the geometrical space characteristics of the inner lip are developed. In addition, feature fusion to combine both 3D-(x, y, z) coordinate and 3D geometry lip features is further considered. The presented 3D sensor lip image based feature evaluated the performance and effectiveness using the principal component analysis based classification calculation approach. Experimental results on pronunciation recognition of two different datasets, Mandarin syllables and Mandarin phrases, demonstrate the competitive performance of the presented 3D sensor lip image based pronunciation recognition system.

Simulating Self-Regeneration and Self-Replication Processes Using Movable Cellular Automata with a Mutual Equilibrium Neighborhood

2020 ◽  
Vol 29 (4) ◽  
pp. 741-757
Author(s):  
Kateryna Hazdiuk ◽  
◽  
Volodymyr Zhikharevich ◽  
Serhiy Ostapov ◽  
◽  
...  
Keyword(s):  
Cellular Automata ◽  
Cellular Automaton ◽  
Three Dimensional ◽  
Computer Models ◽  
The Self ◽  
Model Construction ◽  
Natural Phenomena ◽  
Different Types ◽  
Movable Cellular Automata ◽  
Self Replication

This paper deals with the issue of model construction of the self-regeneration and self-replication processes using movable cellular automata (MCAs). The rules of cellular automaton (CA) interactions are found according to the concept of equilibrium neighborhood. The method is implemented by establishing these rules between different types of cellular automata (CAs). Several models for two- and three-dimensional cases are described, which depict both stable and unstable structures. As a result, computer models imitating such natural phenomena as self-replication and self-regeneration are obtained and graphically presented.

Geological Field Sketches and Illustrations

2019 ◽  
Author(s):  
Matthew J. Genge
Keyword(s):  
Cross Sections ◽  
Earth Science ◽  
Three Dimensional ◽  
Worked Examples ◽  
Scientific Publications ◽  
Thin Sections ◽  
Geological Features ◽  
Different Types ◽  
The Subject

Drawings, illustrations, and field sketches play an important role in Earth Science since they are used to record field observations, develop interpretations, and communicate results in reports and scientific publications. Drawing geology in the field furthermore facilitates observation and maximizes the value of fieldwork. Every geologist, whether a student, academic, professional, or amateur enthusiast, will benefit from the ability to draw geological features accurately. This book describes how and what to draw in geology. Essential drawing techniques, together with practical advice in creating high quality diagrams, are described the opening chapters. How to draw different types of geology, including faults, folds, metamorphic rocks, sedimentary rocks, igneous rocks, and fossils, are the subjects of separate chapters, and include descriptions of what are the important features to draw and describe. Different types of sketch, such as drawings of three-dimensional outcrops, landscapes, thin-sections, and hand-specimens of rocks, crystals, and minerals, are discussed. The methods used to create technical diagrams such as geological maps and cross-sections are also covered. Finally, modern techniques in the acquisition and recording of field data, including photogrammetry and aerial surveys, and digital methods of illustration, are the subject of the final chapter of the book. Throughout, worked examples of field sketches and illustrations are provided as well as descriptions of the common mistakes to be avoided.

Effect of Carbide Content on Temper Embrittlement of 2.25Cr1Mo Steel

2016 ◽  
Author(s):  
Yian Wang ◽  
Guoshan Xie ◽  
Zheng Zhang ◽  
Xiaolong Qian ◽  
Yufeng Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Vessel ◽  
High Stress ◽  
Temper Embrittlement ◽  
Damage Mechanism ◽  
Pressure Vessels ◽  
Nondestructive Method ◽  
Operating Conditions ◽  
Low Alloy Steels ◽  
Carbide Content

Temper embrittlement is a common damage mechanism of pressure vessels in the chemical and petrochemical industry serviced in high temperature, which results in the reduction of roughness due to metallurgical change in some low alloy steels. Pressure vessels that are temper embrittled may be susceptible to brittle fracture under certain operating conditions which cause high stress by thermal gradients, e.g., during start-up and shutdown. 2.25Cr1-Mo steel is widely used to make hydrogenation reactor due to its superior combination of high mechanical strength, good weldability, excellent high temperature hydrogen attack (HTHA) and oxidation-resistance. However, 2.25Cr-1Mo steel is particularly susceptible to temper embrittlement. In this paper, the effect of carbide on temper embrittlement of 2.25Cr-1Mo steel was investigated. Mechanical properties and the ductile-brittle transition temperature (DBTT) of 2.25Cr-1Mo steel were measured by tensile test and impact test. The tests were performed at two positions (base metal and weld metal) and three states (original, step cooling treated and in-service for a hundred thousand hours). The content and distribution of carbides were analyzed by scanning electron microscope (SEM). The content of Cr and Mo elements in carbide was measured by energy dispersive X-ray analysis (EDS). The results showed that the embrittlement could increase the strength and reduce the plasticity. Higher carbide contents appear to be responsible for the higher DBTT. The in-service 2.25Cr-1Mo steel showed the highest DBTT and carbide content, followed by step cooling treated 2.25Cr-1Mo steel, while the as-received 2.25Cr-1Mo steel has the minimum DBTT and carbide content. At the same time, the Cr and Mo contents in carbide increased with the increasing of DBTT. It is well known that the specimen analyzed by SEM is very small in size, sampling SEM specimen is convenient and nondestructive to pressure vessel. Therefore, the relationship between DBTT and the content of carbide offers a feasible nondestructive method for quantitative measuring the temper embrittlement of 2.25Cr-1Mo steel pressure vessel.

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