scholarly journals Fracture Mechanisms of S355 Steel—Experimental Research, FEM Simulation and SEM Observation

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3959 ◽  
Author(s):  
Ihor Dzioba ◽  
Sebastian Lipiec
Keyword(s):  
Experimental Research ◽  
Ferritic Steel ◽  
Fem Simulation ◽  
Local Area ◽  
True Stress ◽  
Fracture Mechanisms ◽  
The Finite Element Method ◽  
Characteristic Values ◽  
Cracking Process ◽  
Made In

In this study, the fracture mechanisms of S355 ferritic steel were analyzed. In order to obtain different mechanisms of fracture (completely brittle, mixed brittle and ductile or completely ductile), tests were carried out over a temperature range of −120 to +20 °C. Our experimental research was supplemented with scanning electron microscopy (SEM) observations of the specimens’ fracture surfaces. Modeling and load simulations of specimens were performed using the finite element method (FEM) in the ABAQUS program, and accurate calibration of the true stress–strain material dependence was made. In addition, the development of mechanical fields before the crack tip of the cracking process in the steel was analyzed. The distributions of stresses and strains in the local area before the crack front were determined for specimens fractured according to different mechanisms. Finally, the conditions and characteristic values of stresses and strains which caused different mechanisms of fracture—fully brittle, mixed brittle and ductile or fully ductile—were determined.

scholarly journals Underwater Spiral Wave Sound Source Based on Phased Array with Three Transducers

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3192
Author(s):  
Lu ◽  
Guo ◽  
Lan ◽  
Sun ◽  
Li ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Sound Source ◽  
Piezoelectric Ceramic ◽  
Phased Array ◽  
Fem Simulation ◽  
Spiral Wave ◽  
Sound Field ◽  
The Finite Element Method ◽  
The Relationship ◽  
Made In

This paper realizes an underwater spiral wave sound source by using three omni-directional spherical transducers with three different phases. The pressure distribution of the sound field for a phased array is derived using the superposition theory of sound field. The generation of spiral wave field is presented, the relationship between the performance of phased array sound field and the array parameters is analyzed, and also verified by the finite element method (FEM). A spiral wave sound source with three spherical piezoelectric ceramic transducers is then designed and fabricated based on FEM simulation, and the performance of the sound source is analyzed. Measurements are made in a reverberation pool, and the result shows that the fabricated spiral wave sound source is capable of producing a spiral sound wave. Under a frequency of 3.5 kHz, the phase directivity has a fluctuation of ±21°, and the amplitude directivity range is 4.3 dB, which verifies the realization of the spiral wave sound source.

Microanalysis of precipitates in a ferritic steel

1978 ◽  
Vol 36 (1) ◽  
pp. 618-619
Author(s):  
J.M. Titchmarsh
Keyword(s):  
Ferritic Steel ◽  
Particle Identification ◽  
Energy Dispersive ◽  
Objective Lens ◽  
Ferritic Steels ◽  
Replica Technique ◽  
X Ray ◽  
Large Numbers ◽  
Scanning Transmission ◽  
Made In

The advances in recent years in the microanalytical capabilities of conventional TEM's fitted with probe forming lenses allow much more detailed investigations to be made of the microstructures of complex alloys, such as ferritic steels, than have been possible previously. In particular, the identification of individual precipitate particles with dimensions of a few tens of nanometers in alloys containing high densities of several chemically and crystallographically different precipitate types is feasible. The aim of the investigation described in this paper was to establish a method which allowed individual particle identification to be made in a few seconds so that large numbers of particles could be examined in a few hours.A Philips EM400 microscope, fitted with the scanning transmission (STEM) objective lens pole-pieces and an EDAX energy dispersive X-ray analyser, was used at 120 kV with a thermal W hairpin filament. The precipitates examined were extracted using a standard C replica technique from specimens of a 2¼Cr-lMo ferritic steel in a quenched and tempered condition.

An analytical model of an I-cored coil located above a conductive material with a hole

2018 ◽  
Vol 82 (2) ◽  
pp. 21001
Author(s):  
Grzegorz Tytko ◽  
Leszek Dziczkowski
Keyword(s):  
Test Object ◽  
Middle Layer ◽  
Axially Symmetric ◽  
The Finite Element Method ◽  
Cylindrical Coordinate ◽  
Air Space ◽  
Through Hole ◽  
Tree Method ◽  
Good Agreement ◽  
Made In

The paper examines the problem of an axially symmetric I-cored coil located above a three-layered plate with a hole in the middle layer. A cylindrical coordinate system was applied, wherein the solution domain was truncated in the radial direction. The employment of the truncated region eigenfunction expansion (TREE) method resulted in deriving the final formulas for the change of the coil impedance with regard to the air space, and also pertaining to the test object without a flaw. Formulas for various configurations of the test object, among others for a surface hole, a subsurface hole and a through hole, have been presented. For the purpose of defectoscopy, the influence of the hole in the plate on the impedance components was investigated. The calculations were made in Matlab for frequencies from 100 Hz to 50 kHz. The obtained results were verified using the finite element method (FEM) in Comsol Multiphysics package. A very good agreement was observed in the case of both the resistance and reactance.

scholarly journals In-Depth Verification of a Numerical Model for an Axisymmetric RC Dome

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2152
Author(s):  
Przemysław Czumaj ◽  
Sławomir Dudziak ◽  
Zbigniew Kacprzyk
Keyword(s):  
Three Dimensional ◽  
Spatial Models ◽  
Detailed Comparison ◽  
The Finite Element Method ◽  
Robot System ◽  
Engineering Structures ◽  
Computational Analyses ◽  
Computational Systems ◽  
Good Agreement ◽  
Made In

The designers of civil engineering structures often have to face the problem of the reliability of complex computational analyses performed most often with the Finite Element Method (FEM). Any assessment of reliability of such analyses is difficult and can only be approximate. The present paper puts forward a new method of verification and validation of the structural analyses upon an illustrative example of a dome strengthened by circumferential ribs along the upper and lower edges. Four computational systems were used, namely Abaqus, Autodesk Robot, Dlubal RFEM, and FEAS. Different models were also analyzed—two-dimensional (2D) and three-dimensional (3D) ones using continuum, bar, and shell finite elements. The results of the static (with two kinds of load—self-weight and load distributed along the upper ring) and modal analyses are presented. A detailed comparison between the systems’ and models’ predictions was made. In general, the spatial models predicted a less stiff behavior of the analyzed dome than the planar models. The good agreement between different models and systems was obtained for the first natural frequency with axisymmetric eigenmodes (except from the Autodesk Robot system). The presented approach to the verification of complex shell–bar models can be effectively applied by structural designers.

scholarly journals Aspects regarding FEM simulation of stress in hammer mill working tool

2019 ◽  
Vol 112 ◽  
pp. 03018 ◽  
Author(s):  
Georgiana Moiceanu ◽  
Gigel Paraschiv ◽  
Edmond Maican ◽  
Mirela Dincă ◽  
Iulia Găgeanu ◽  
...  
Keyword(s):  
Experimental Research ◽  
Geometric Model ◽  
Fem Simulation ◽  
Hammer Mill ◽  
Processing Equipment ◽  
Simulation And Modelling ◽  
Biomass Processing ◽  
Maximum Reaction

Considering the need for development and improvement of biomass processing equipment, researchers bring contribution by making suggestions to design also through simulation and modelling of different stresses that occur on equipment’s working tools. In this paper the stress in hammer mill working tools was analysed using FEM simulation with the help of SolidWorks 2016 Premium, projecting the geometric model and FEM simulation for a MC 22 hammer mill. The hammer mill has a four bolts rotor on which are the hammer disposed. The hammer mills rotor frequency is about 2940 rot/min. An important result in FEM simulation was the fact that the maximum reaction in the hammer joint was 11635 N. After FEM simulation experimental research were done using shredded miscanthus and energetic willow, the mill being equipped alternately with 4 types of hammers, with corners processed differently.

A Discussion on natural strain and geological structure - The finite element method and the solution of some geophysical problems

1976 ◽  
Vol 283 (1312) ◽  
pp. 139-151 ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Geological Structure ◽  
The Finite Element Method ◽  
Recent Developments ◽  
Limited Application ◽  
Discrete Problems ◽  
The Finite Difference Method ◽  
Made In ◽  
Element Method

The finite element method has become established as a powerful tool for the solution of many problems of continuum mechanics where its physical interpretation, by analogy with discrete problems of structural analysis permits the user to exercise a considerable degree of insight and judgement in its use. Further it is now a recognized mathematical procedure of approximation which embraces many older methodologies (such as the finite difference method) as a subclass. In the field of geological studies its impact is fairly recent and only a limited application has been made to date. The techniques used here have been limited to those established over a decade ago in the parallel fields and recent developments and possibilities barely touched upon. In this paper the author therefore attempts to ( a ) outline some of the general mathematical and practical aspects of the method with illustrations from various fields which are relevant to geological problems, ( b ) survey accomplishments already made in geology and geotechnical fields, and ( c ) suggest some possible new extensions of application.

scholarly journals Bilingualism, cognition, and aging

2014 ◽  
Vol 18 (1) ◽  
pp. 1-2 ◽  
Author(s):  
JUBIN ABUTALEBI ◽  
HARALD CLAHSEN
Keyword(s):  
Foreign Language ◽  
Old Age ◽  
Experimental Research ◽  
State Of The Art ◽  
The Public ◽  
Potential Benefits ◽  
Cognition And Aging ◽  
The Guardian ◽  
Made In

Topics in psycholinguistics and the neurocognition of language rarely attract the attention of journalists or the general public. One topic that has done so, however, is the potential benefits of bilingualism for general cognitive functioning and development, and as a precaution against cognitive decline in old age. Sensational claims have been made in the public domain, mostly by journalists and politicians. Recently (September 4, 2014) The Guardian reported that “learning a foreign language can increase the size of your brain”, and Michael Gove, the UK's previous Education Secretary, noted in an interview with The Guardian (September 30, 2011) that “learning languages makes you smarter”. The present issue of BLC addresses these topics by providing a state-of-the-art overview of theoretical and experimental research on the role of bilingualism for cognition in children and adults.

FEM Simulation of PD Acoustic Signal Propagation in Transformers

2013 ◽  
Vol 448-453 ◽  
pp. 2278-2285
Author(s):  
Yue Dong ◽  
Yong Qian ◽  
Hai Feng Ye ◽  
Xiu Chen Jiang
Keyword(s):  
Power Transformer ◽  
Ultrasonic Method ◽  
Partial Discharge ◽  
Fem Simulation ◽  
Signal Amplitude ◽  
Signal Propagation ◽  
Ultrasonic Waves ◽  
Diagnostic Methods ◽  
Power Transformers ◽  
The Finite Element Method

In order to study propagation process of partial discharge ultrasonic signal in power transformer, the finite element method is used for simulation modeling and calculation. Ultrasonic waves can be activated by partial discharges (PD) in power transformers. The ultrasonic method is used for evaluating the insulation condition of power transformers by analyzing the partial discharge signals information which is detected by AE sensors. Compared with other diagnostic methods the AE method causes relatively low disturbance, and measuring apparatus is simple and easy to use. This technique is noninvasive and immune to electromagnetic noise. Simulate partial discharge sources of different positions respectively. Achieved results indicate that the space and time distributions of the acoustic pressure depend on the induction position. Furthermore, a greater pressure gradient is observed in domains with higher speed of sound while the signal amplitude decays when it moves away from the PD source.

PLATINUM-BASED CONE MICROELECTRODES FOR IMPLANTABLE NEURAL RECORDING APPLICATIONS

2010 ◽  
Vol 22 (03) ◽  
pp. 249-254
Author(s):  
Mohammad Hossein Zarifi ◽  
Javad Frounchi ◽  
Mohammad Ali Tinati ◽  
Jack W. Judy
Keyword(s):  
Fem Simulation ◽  
Microelectrode Arrays ◽  
Neural Recording ◽  
Field Extension ◽  
Chemical Environment ◽  
Simulation Environment ◽  
The Finite Element Method ◽  
Electrical Field ◽  
Neural Signal ◽  
Front End

There have been significant advances in fabrication of high-density microelectrode arrays using silicon micromachining technology in neural signal recording systems. The interface between microelectrodes and chemical environment is of great interest to researchers, working on extracellular stimulation. This interface is quite complex and must be modeled carefully to match experimental results. Computer simulation is a method to increase the knowledge about these arrays and to this end the finite element method (FEM) provides a strong environment for investigation of relative changes of the electrical field extension surrounding an electrode positioned in chemical environment. In this paper FEM simulation environment is used for modeling the metal–chemical interface, which provides helpful information about noise, impedance, and bandwidth for circuit designers to design the front-end electronics of these systems, more efficiently and reliable.

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