Fracture Analysis of Piezoceramic CT-Specimen for Different Types of Crack Face Boundary Conditions

2015 ◽  
Vol 725-726 ◽  
pp. 949-954
Author(s):  
Ilia V. Ivashov ◽  
Artem S. Semenov

At the moment a problem of fracture and lifetime estimation for piezoelectric materials is not completely solved. The paper considers fundamentals of linear fracture electromechanics, fracture parameters and fracture criteria. The main difference from linear mechanics is crack face boundary conditions taking into account relative permeability of media inside the crack gap and coulomb traction. Different types of crack face boundary conditions and their numerical implementation are described. The paper presents results of finite element modeling of fracture toughness experiments on the compact tension specimens under combined electromechanical loading. Different types of crack face boundary conditions were tested and comparison of fracture parameters and fracture criteria was carried out.

2016 ◽  
Vol 8 (4) ◽  
pp. 573-587 ◽  
Author(s):  
R. R. Bhargava ◽  
Pooja Raj Verma

AbstractA problem of two equal, semi-permeable, collinear cracks, situated normal to the edges of an infinitely long piezoelectric strip is considered. Piezoelectric strip being prescribed out-of-plane shear stress and in-plane electric-displacement. The Fourier series and integral equation methods are adopted to obtain analytical solution of the problem. Closed-form analytic expressions are derived for various fracture parameters viz. crack-sliding displacement, crack opening potential drop, field intensity factors and energy release rate. An numerical case study is considered for poled PZT–5H, BaTiO3 and PZT–6B piezoelectric ceramics to study the effect of applied electro-mechanical loadings, crack-face boundary conditions as well as inter-crack distance on fracture parameters. The obtained results are presented graphically, discussed and concluded.


2021 ◽  
Vol 53 (1) ◽  
pp. 251-278
Author(s):  
Adrián González Casanova ◽  
Juan Carlos Pardo ◽  
José Luis Pérez

AbstractIn this paper, we introduce a family of processes with values on the nonnegative integers that describes the dynamics of populations where individuals are allowed to have different types of interactions. The types of interactions that we consider include pairwise interactions, such as competition, annihilation, and cooperation; and interactions among several individuals that can be viewed as catastrophes. We call such families of processes branching processes with interactions. Our aim is to study their long-term behaviour under a specific regime of the pairwise interaction parameters that we introduce as the subcritical cooperative regime. Under such a regime, we prove that a process in this class comes down from infinity and has a moment dual which turns out to be a jump-diffusion that can be thought as the evolution of the frequency of a trait or phenotype, and whose parameters have a classical interpretation in terms of population genetics. The moment dual is an important tool for characterizing the stationary distribution of branching processes with interactions whenever such a distribution exists; it is also an interesting object in its own right.


2022 ◽  
Vol 14 (1) ◽  
pp. 30
Author(s):  
Hazrat Ali ◽  
Md. Kamrujjaman ◽  
Md. Shafiqul Islam

This study proposed a scheme originated from the Galerkin finite element method (GFEM) for solving nonlinear parabolic partial differential equations (PDEs) numerically with initial and different types of boundary conditions. The scheme is applied generally handling the nonlinear terms in a simple way and throwing over restrictive assumptions. The convergence and stability analysis of the method are derived. The error of the method is estimated. In the series, eminent problems are solved, such as  Fisher's equation, Newell-Whitehead-Segel equation, Burger's equation, and  Burgers-Huxley equation to demonstrate the validity, efficiency, accuracy, simplicity and applicability of this scheme. In each example, the comparison results are presented both numerically and graphically


Author(s):  
Angga Rahagiyanto

Indonesian: Indonesian SIBI has been widely reviewed by researchers using different types of cameras and sensors. The ultimate goal is to produce a strong, fast and accurate movement recognition process. One that supports talk of movement using sensors on the MYO Armband tool. This paper explains how to use raw data generated from the MYO Armband sensor and extract integration so that it can be used to facilitate complete hand, arm and combination movements in the SIBI sign language dictionary. MYO armband uses five sensors: accelerometer, gyroscope, orientation, euler-orientation and EMG. Each sensor produces data that is different in scale and size. This requires a process to make the data uniform. This study uses the min-max method to normalize any data on the MYO Armband sensor and the Moment Invariant method to extract the vector features of hand movements. Testing is done using sign language Movement statistics both dynamic signals. Testing is done using cross validation.


Author(s):  
Rabi Pathak

The Formula Student competitions are held everyyear. This paper is the result of the analysis done on the sample car design that can be presented in the Formula Student competition. The purpose of the paper is to provide a final summary on chassis analysis and structural performance. It also talks about all the important analysis that is to be done on a Formula Student car to make it safe and perform well on the track. The design has been made such that it focusses on maximum adjustability, reliability, performance, safety, weight reduction and ease of manufacturing. The analysis was done to make sure the objectives of design are fulfilled. After going through many papers, documents, blogs and videos we found that many people get confused about the loading conditions and boundary conditions for different types of tests so this paper prioritizes to make people understand about those conditions as well as about the major tests required to perform complete analysis of Formula Student cars. The weight of the chassis was calculated as 36 kg approximately according to the data obtained from design modeler of Ansys workbench as well as Solidworks. The design sustained all the loading conditions and passed all the tests. Thus, one of the objective of this paper is to help other universities and passionate students to successfully design and analyze their cars that can pass all necessary tests included in the paper. KEYWORDS—Formula Student; FEA; Boundary Conditions; Loading Conditions; Ansys; Solidworks


Author(s):  
Наталья Алексеевна Макарова

Статья посвящена рассмотрению особенностей и формулированию практических рекомендаций по разрешению иерархических юридических коллизий в российском праве. Автор статьи предлагает трактовать иерархическую (субординационную) юридическую коллизию расширительно: не только как противоречие между двумя или более нормативно-правовыми актами, но и как возможное противоречие между правовыми актами разных типов, включая правоприменительные (индивидуальные) и интерпретационные акты. Подчеркивается, что базовым правилом разрешения любой иерархической юридической коллизии должно быть правило юридической силы. В то же время в настоящий момент в российском праве нормы, определяющие данное понятие, а равно устанавливающие четкие механизмы преодоления юридических коллизий, включая иерархические, отсутствуют. Под юридической силой предлагается понимать особое свойство правовых актов, благодаря наличию которого данные акты формируют иерархию, и нижестоящие акты вышестоящим противоречить не могут. Выдвигается тезис о том, что не типичные иерархические коллизии в праве (коллизии между нормативно-правовым актом, с одной стороны, и правоприменительным или интерпретационным актом, с другой, а равно несколькими правоприменительными и (или) интерпретационными актами между собой) как разновидность иерархической юридической коллизии должны разрешаться с обязательным использованием правила юридической силы. То есть акты нормативного толкования и правоприменения должны быть приравнены по юридической силе к интерпретируемым и применяемым актам. Именно такой путь позволит избежать остановок в работе механизма реализации права, которых, как известно, современное правовое государство позволить себе не может. The article is devoted to the consideration of the features and the development of practical recommendations for resolving hierarchical legal collisions in Russian law. The author of the article proposes to interpret the hierarchical legal collision broadly, not only as a contradiction between regulatory legal acts, but also as a possible contradiction between legal acts of different types. It is emphasized that the basic rule for resolving any hierarchical legal collision should be the rule of legal force. However, at the moment in Russian law there are no norms defining this concept, as well as establishing clear mechanisms for overcoming legal conflicts, including hierarchical ones. It is proposed to understand legal force as a special property of legal acts, due to the presence of which these acts form a hierarchy, and lower-level acts cannot contradict higher-level ones. The thesis is put forward that non-typical hierarchical collisions in law should also be resolved with the obligatory use of the rule of legal force. This means that the acts of normative interpretation and law enforcement should be equated in legal force with the interpreted and applied acts. This is the way to avoid stoppages in the work of the mechanism for the implementation of the law, which, as you know, the modern constitutional state cannot afford.


2019 ◽  
Vol 97 ◽  
pp. 03003
Author(s):  
Anna Avershyeva ◽  
Sergey Kuznetsov

A mathematical model for analyzing Lamb waves propagating in stratified media with arbitrary elastic anisotropy is worked out. The model incorporates a combined Fundamental Matrix (FM) and Modified Transfer Matrix (MTM) methods. Multilayered unbounded plates with different types of boundary conditions imposed on the outer surfaces are considered. Closed form fundamental matrices and secular equations for dispersion relations are derived.


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