Fracture Behavior of Ceramics Used in Multilayer Capacitors

1986 ◽  
Vol 72 ◽  
Author(s):  
Theresa L. Baker ◽  
Stephen W. Freiman
Keyword(s):  
Crack Growth ◽  
Fracture Behavior ◽  
Ceramic Materials ◽  
Fatigue Tests ◽  
Internal Stresses ◽  
Crack Growth Behavior ◽  
Multilayer Capacitors ◽  
Materials Used ◽  
Aging Phenomena

AbstractThis study involved the determination of the effects of composition and microstructure on the fracture toughness and susceptibility to environmentally enhanced crack growth of several ceramic materials used in multilayer capacitors. Indentation-fracture procedures were used to measure KIC as well as to assess the possible effects of internal stresses on the fracture behavior of these materials and to correlate dielectric aging phenomena with strength. The environmentally enhanced crack growth behavior of these materials was determined by conducting dynamic fatigue tests in water.

Fatigue Crack Growth Experiments of Resonating Micro-Samples

2007 ◽  
Vol 345-346 ◽  
pp. 817-820
Author(s):  
Andrea Cambruzzi ◽  
Jürg Dual
Keyword(s):  
Crack Growth ◽  
Fatigue Behaviour ◽  
Phase Lock Loop ◽  
Fatigue Tests ◽  
Crack Growth Behavior ◽  
Micro Electro Mechanical Systems ◽  
Micro Scale ◽  
Growth Experiments

The reliability and optimal design of Micro Electro Mechanical Systems (MEMS) can be achieved only with the determination of material properties at the micro-scale. The major challenges in performing fatigue tests at the micro-scale are related to the accurate measurement of tiny deformations, to the control of very low forces and to the preparation, handling and positioning of μm-sized samples. In order to investigate the fatigue behaviour of MEMS components a new experimental setup based on the Phase Lock Loop (PLL) technique and a continuum mechanical model were developed for the characterization of micro-sized test samples. The main advantage of PLL is the achievable resolution in the crack length measurement, which increases with the decreasing of specimen size. Therefore, micro-beams with notches and without notches were prepared by electroplating Nickel in a SU8 photoresist mold (UV-LIGA). Investigations on the initiation and near-threshold crack growth behavior were performed to improve the understanding of the micro-mechanisms involved in fatigue phenomena.

Effect of KIII on Fatigue Crack Growth Behavior

2010 ◽  
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Chikako Ohdama
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Tests ◽  
Crack Growth Behavior ◽  
Crack Growth Simulation ◽  
Slant Surface ◽  
Cracked Specimens

Mixed mode fatigue tests are conducted using surface cracked specimen. Slant surface cracked specimens are made where crack angle is 15°, 30°, 45° and 60°. It is shown that factory roof is made at deepest point of surface crack due to ΔKIII, and crack growth rate decreases by the factory roof. Fatigue crack growth is simulated using S-version FEM (Finite Element Method) using crack growth criteria. It is shown that conventional crack growth criteria are not available to predict fatigue crack growth with factory roof. In this study, modified criterion for the prediction of crack growth rate is proposed. By using this criterion, fatigue crack growth simulation is conducted, and results are compared with those of experiments and discussed.

scholarly journals Determination of minor and trace elements in geological materials used as raw ceramic materials

2016 ◽  
Vol 55 (5) ◽  
pp. 185-196 ◽  
Author(s):  
María Fernanda Gazulla Barreda ◽  
Marta Rodrigo Edo ◽  
Mónica Orduña Cordero ◽  
María Jesús Ventura Vaquer
Keyword(s):  
Trace Elements ◽  
Ceramic Materials ◽  
Minor And Trace Elements ◽  
Geological Materials ◽  
Materials Used

scholarly journals IMPROVEMENT OF FATIGUE LIFE OF A HOLED SPECIMEN OF ALUMINUM-ALLOY 2024-T3 BY INDENTATION AND HOLE EXPANSION

2012 ◽  
Vol 06 ◽  
pp. 336-342 ◽  
Author(s):  
MD. SHAFIUL FERDOUS ◽  
CHOBIN MAKABE ◽  
TATSUJIRO MIYAZAKI ◽  
NOBUSUKE HATTORI
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Crack Growth ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Local Plastic ◽  
Aluminum Alloy 2024 ◽  
Pull Tests

A method of improving the fatigue life and crack growth behavior of a center holed specimen was investigated. Local plastic deformation was applied around the hole by indentation to achieve the purpose. A series of fatigue tests was conducted on aluminum-alloy 2024-T3. Push-pull tests were performed under a stress ratio of R= -1 and a frequency of 10Hz. The observations of the crack initiation and growth were performed with a microscope, and hardness around the hole was measured by Vickers hardness testing machine. In the present study, the longest fatigue life was observed in the case of an indentation specimen with the highest load. The indentation was performed on both sides of the hole edges. The crack growth rate was decreased by indentation or expansion of the material around the hole. From the experimental results, it is found that the fatigue life and crack growth behavior of a holed or notched specimen can be improved by a simple technical method that is related to the local plastic working.

Existence and Convergence Questions in Computational Modelling of Crack Growth in Brittle and Quasi-Brittle Materials

2016 ◽  
Vol 258 ◽  
pp. 157-160 ◽  
Author(s):  
Jiří Vala
Keyword(s):  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Computational Modelling ◽  
Brittle Materials ◽  
Zone Model ◽  
Static Tests ◽  
Materials Used ◽  
Proper Analysis

Computational modelling of the crack growth in brittle and quasi-brittle materials used in mechanical, civil, etc. engineering applies the cohesive zone model with various traction separation laws; determination of micro-mechanical parameters comes then from static tests, microscopic observation and numerical calibration. Although most authors refer to ill-possedness and need of artificial regularization in inverse problems (identification of material parameters), some difficulties originate even in nonlinear formulations of direct and sensitivity problems. This paper demonstrates the possibility of proper analysis of the existence of a weak solution and of the convergence of a corresponding numerical algorithm for such model problem, avoiding non-physical assumptions.

Stress Corrosion Cracking Analysis under Thermal Residual Stress Field Using S-FEM

2011 ◽  
Vol 462-463 ◽  
pp. 431-436 ◽  
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Yuto Shimizu ◽  
Yu Long Li
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Crack Growth ◽  
Fracture Behavior ◽  
Three Dimensional ◽  
Stress Fields ◽  
Crack Growth Behavior ◽  
Residual Stress Field ◽  
Energy Agency ◽  
Thermal Stress Field

Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. In order to confirm the validity of this analysis, numerical results are compared with previously-reported analytical and experimental results. Then, crack growth analysis in piping structure with welding joint was conducted. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. Using S-FEM, two- and three-dimensional analyses are conducted, and crack growth behavior under thermal stress field is studied and discussed.

Numerical Simulation of Stress Corrosion Cracking in a Pipe Using S-Version FEM

2010 ◽  
Vol 452-453 ◽  
pp. 577-580
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Yuto Shimizu ◽  
Yu Long Li
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Crack Growth ◽  
Fracture Behavior ◽  
Three Dimensional ◽  
Stress Fields ◽  
Crack Growth Behavior ◽  
Stress Distributions ◽  
Residual Stress Field ◽  
Energy Agency

Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. SCC crack growth of a surface crack at inner suface of a pipe under thermal residual stress is simulated in three-dimensional filed. Distributions of residual stress is not axi-symmetric along pipe wall, and it affects the crack growth behavior. Ttwo cases, for axi-symmetric and non-symmetric thermal stress distributions, are assumed and crack growth behaviors are obtaiend and discussed.

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