scholarly journals Numerical modeling of crack initiation and propagation processes in various specimen’s types using the GTN material damage model

2021 ◽  
Vol 5 (1) ◽  
pp. 49-56
Author(s):  
Andrew Kravchuk ◽  
Eugene Kondriakov ◽  
Valery Kharchenko
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Crack Initiation ◽  
Damage Model ◽  
Material Damage ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation

Problematic. A combination of experimental and computational methods for studying the processes of crack initiation and propagation in various specimen’s types is used to determine the mechanical properties of materials, as well as to improve the accuracy of assessing the strength and durability of structural elements. Research objective. Determination of the parameters of the Gurson-Tvergaard-Needleman (GTN) material damage model based on the numerical modeling results of various specimen’s types under various types of loading for steel 22K using the finite element method. Realization technique. Using the finite element method, numerical modeling of the processes of cracks nucleation and propagation in cylindrical specimens under uniaxial tension, in Charpy specimens under dynamic loading, and also in CT specimens under quasi-static loading was carried out for steel 22K using the GTN material damage model. The results of research. By comparing the experimental and numerical results, the full set of GTN material model parameters for steel 22K was determined. The stress state in the crack tip area and the kinetics of its propagation in the material of various specimen’s types under static and dynamic loading were estimated. Conclusions. The GTN material damage model with the parameter values determined from experiments, can be used for numerical simulation of the processes of crack initiation and propagation both in specimens of various types under various loading types, and in structural elements.

scholarly journals Numerical modelling strategies using implicit and explicit methods to simulate quasi-static and dynamic three-points bend fracture tests of a ductile steel

2021 ◽  
Vol 250 ◽  
pp. 02033
Author(s):  
Frédéric Nozères ◽  
Hervé Couque ◽  
Rémi Boulanger ◽  
Yann Quirion ◽  
Patrice Bailly ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Initiation ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Fracture Tests ◽  
Point Bend ◽  
Dynamic Loading Conditions ◽  
Implicit And Explicit ◽  
Static And Dynamic Loading

Three-point bend fracture tests have been conducted at different loading rates with a quadratic martensitic steel. The failure energy has been found to increase with loading rate. To get insights in this increase a numerical investigation has been undertaken with different strategies using ABAQUS and IMPETUS softwares in order to address quasi-static and dynamic loading conditions. Simulations were conducted with the ABAQUS software in order to carry out a comparative analysis of both implicit and explicit approaches. In addition to standard Finite Element Method (FEM) applied to quasi-static and dynamic conditions, the eXtended-Finite Element Method (X-FEM) was applied to quasistatic conditions. In both approaches, implicit and explicit, crack initiation and propagation were governed by a critical plastic strain threshold combined with a displacement-based damage evolution criterion. Simulations conducted with the IMPETUS software use an explicit approach and second order elements for both quasi-static and dynamic loading conditions. A node-splitting method using an energy-based damage criterion was employed to simulate the crack initiation and propagation. Experimental data and numerical results have been compared, allowing to determine the ability of these two softwares to simulate accurately three-point bend fracture tests.

Study of Crack Initiation and Propagation in TBCs by Experiments and Extended Finite Element Method

2013 ◽  
Vol 331 ◽  
pp. 129-132 ◽  
Author(s):  
Jing Xin Su ◽  
Zhao Hui Ji ◽  
Zhi Yong Han ◽  
Hua Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Initiation ◽  
Thermal Cycling ◽  
Extended Finite Element Method ◽  
Interface Roughness ◽  
Crack Initiation And Propagation ◽  
Extended Finite Element ◽  
Initiation And Propagation ◽  
Element Method

CoNiCrAlY bond coat (BC) and top ceramic coating (TCC) was fabricated on the GH99 super alloy by high velocity oxyfuel spray (HVOF) and air plasma spray (APS), respectively. Thermal cycling treatment was applied to the thermal barrier coatings (TBCs). The cross-sectional images of crack initiation and propagation of TBCs after treatment were investigated by scanning electron micrograph (SEM), meanwhile crack initiation and propagation in TBCs were analyzed based upon ABAQUS software using extended finite element method (XFEM). The results show that, crack initiation and propagation can be easily traced via microscopy at the interface areas in TBCs; after thermal cycling treatments, the crack associated with the TCC/TGO interface morphology initiates at interface peak area and propagates along TCC/TGO interface with thermal cycles; the interface roughness affects the crack magnitude in length and width obviously, the rougher the morphology, the bigger the crack is; the XFEM is a novel and effective method to well predict the crack initiation and calculate the crack propagation, and simulation and experimental results fit well.

scholarly journals Special Issue “Applications of Finite Element Modeling for Mechanical and Mechatronic Systems”

2021 ◽  
Vol 11 (11) ◽  
pp. 5170
Author(s):  
Marek Krawczuk ◽  
Magdalena Palacz
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Engineering Practice ◽  
The Finite Element Method ◽  
Special Issue ◽  
Mechatronic Systems ◽  
Modeling And Analysis ◽  
Modern Engineering ◽  
Concise Description

Modern engineering practice requires advanced numerical modeling because, among other things, it reduces the costs associated with prototyping or predicting the occurrence of potentially dangerous situations during operation in certain defined conditions. Different methods have so far been used to implement the real structure into the numerical version. The most popular have been variations of the finite element method (FEM). The aim of this Special Issue has been to familiarize the reader with the latest applications of the FEM for the modeling and analysis of diverse mechanical problems. Authors are encouraged to provide a concise description of the specific application or a potential application of the Special Issue.

DESIGN FEATURES OF CARBIDE ASSEMBLY WORKING ELEMENTS OF DEFORMING BROACHES

2021 ◽  
pp. 134-142
Author(s):  
Я.Б. Немировский ◽  
И.В. Шепеленко ◽  
С.Е. Шейкин ◽  
Ю.А. Цеханов ◽  
Ф.Й. Златопольский ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Hard Alloy ◽  
Contact Surface ◽  
Design Parameters ◽  
The Finite Element Method ◽  
Design Features ◽  
Working Element ◽  
External Loads

Разработан алгоритм и проведена оценка прочности сборных твердосплавных элементов со сплошной и дискретной рабочими поверхностями. Получены зависимости, позволяющие установить связь между конструктивными параметрами сборных деформирующих инструментов и их прочностью. Выполнены прочностные расчеты деформирующего инструмента для обработки отверстий значительного диаметра со сплошной и дискретной рабочими поверхностями. Численным моделированием, методом конечных элементов получены распределения эквивалентных напряжений в элементах инструмента и контактных напряжений по поверхности контакта твердосплавная вставка-корпус, что позволило проанализировать прочность инструмента под нагрузкой. Определены конструктивные параметры инструмента и приведены алгоритмы последовательности расчета сборных деформирующих элементов (ДЭ). Разработан алгоритм последовательности расчета сборного ДЭ для дискретного протягивания. Предложенная конструкция сборного рабочего элемента позволяет не только улучшить обрабатываемость изделия резания, но и уменьшить расход остродефицитного твердого сплава по сравнению с твердосплавным ДЭ аналогичных размеров на 6 кг. Полученные результаты можно использовать в инженерных расчетах при проектировании сборного инструмента для дискретного деформирования, а также для оценки прочности сборных инструментов, например, фрез, зенкеров, разверток при уточнении внешних нагрузок We developed an algorithm and assessed the strength of prefabricated carbide elements with solid and discrete working surfaces. We obtained dependencies that make it possible to establish a relationship between the design parameters of prefabricated deforming tools and their strength. We performed strength calculations of the deforming tool for machining holes of significant diameter with solid and discrete working surfaces. We obtained the distributions of equivalent stresses in the elements of the tool and contact stresses over the contact surface of the hard-alloy insert - body by numerical modeling, by the finite element method, which made it possible to analyze the strength of the tool under load. We determined the design parameters of the tool and here we give algorithms for the sequence of calculation of prefabricated deforming elements (DE). We developed an algorithm for the sequence of calculating the prefabricated DE for discrete broaching. The proposed design of the prefabricated working element allows not only to improve the machinability of the cutting product but also to reduce the consumption of an acutely deficient hard alloy in comparison with a hard alloy DE of similar dimensions by 6 kg. The results obtained can be used in engineering calculations when designing a prefabricated tool for discrete deformation, as well as for assessing the strength of prefabricated tools, for example, cutters, countersinks, reamers when specifying external loads

Numerical modeling of structural capacity of corroded bolted assembly

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rachid Radouani ◽  
Mohamed Essahli ◽  
Younes Ech-Charqy
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Stress Corrosion Cracking ◽  
Design Methodology ◽  
Bolted Joint ◽  
The Finite Element Method ◽  
Content Type ◽  
Structural Capacity ◽  
Resistant Moment

PurposeValidate the resistance of bolted connections in terms of stresses, resistant moment and contact pressure.Design/methodology/approachFinite element modeling of corroded bolted joint.FindingsThe three types of corroded assemblies are resistant to the applied loads.Originality/valueThe research is original, it studies the stress corrosion cracking of a bolted assembly's end plate by the finite element method.

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