scholarly journals DYNAMIC BIAXIAL STRESS ANALYSIS OF FLAT LAYERED CERAMIC COMPOSITES

2021 ◽  
Vol 55 (2) ◽  
pp. 195-200
Author(s):  
Milan Ambrožič ◽  
Anatolij Nikonov
Keyword(s):  
Dynamic Equation ◽  
Relaxation Method ◽  
Ceramic Composites ◽  
Biaxial Stress ◽  
External Loading ◽  
Biaxial Bending ◽  
Principal Stresses ◽  
Multilayered Plates ◽  
Kirchhoff Theory ◽  
Layered Ceramic

We study theoretically the biaxial bending of symmetric, flat layered ceramic composites (laminates) due to external loading. We focus on three-layered alumina/zirconia laminates. We compare the principal stresses in the samples in the case of static and harmonic dynamic loading. The dynamic equation within the Kirchhoff theory for thin homogeneous plates is first generalized to the case of multilayered plates. It is solved numerically with the relaxation method, which we have developed for this purpose.

Influence of the Interface and Residual Stresses on the Apparent Fracture Toughness of Layered Ceramic Composites Based on Alumina-Zirconia

2014 ◽  
Vol 606 ◽  
pp. 209-212
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composites ◽  
Layered Composites ◽  
Material Interfaces ◽  
Linear Elastic ◽  
Apparent Fracture Toughness ◽  
Elastic Fracture ◽  
Layered Ceramic ◽  
Good Agreement

This paper deals with the fracture behaviour of layered ceramic composite with residual stresses. The main goal is to investigate the effect of residual stresses and material interfaces on crack propagation by more complex 3D finite element models. The crack behaviour was described by analytical procedures based on linear elastic fracture mechanics (LEFM) and generalized LEFM. The influence of laminate composition with residual stresses on critical values for crack propagation through the laminate interfaces was also determined. Good agreement has been found to exist between numerical results and experimental data. The results obtained can be used for a design of new layered composites with improved resistance against crack propagation.

Damage Mechanics Implementation of Material Design Simulator for Layered Ceramic Composites

2006 ◽  
pp. 1083-1086
Author(s):  
Jae Myung Lee ◽  
Jung Kwan Seo ◽  
Dae Suk Han ◽  
Myung Hyun Kim ◽  
Hong Chae Park
Keyword(s):  
Damage Mechanics ◽  
Material Design ◽  
Ceramic Composites ◽  
Layered Ceramic

A Quick Computation of Factor of Safety for Biaxial Stress States

1998 ◽  
Vol 120 (4) ◽  
pp. 721-726
Author(s):  
K. Deb
Keyword(s):  
Factor Of Safety ◽  
Biaxial Stress ◽  
Principal Stresses ◽  
Design Charts ◽  
Failure Theory ◽  
Safe Stress ◽  
Design Activities ◽  
Stress States ◽  
Failure Theories

Determination of overall factor of safety of a design involves repeated calculation of factor of safety at critical points in the design. For a given stress state at a point, the factor of safety is calculated by first finding the principal stresses and then comparing them with the maximum safe stress that can be applied without causing failure of the material according to an appropriate failure theory. In this paper, we suggest quick and ready-to-use expressions and graphs for calculating factor of safety for biaxial stress states for a number of commonly-used failure theories. These graphs can be directly used as design charts for computing factor of safety in engineering design activities.

Diametral Compressive Testing Method

1979 ◽  
Vol 101 (2) ◽  
pp. 139-147 ◽  
Author(s):  
Hideo Awaji ◽  
Sennosuke Sato
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Biaxial Stress ◽  
Uniaxial Tensile ◽  
Principal Stresses ◽  
Uniaxial Tensile Strength ◽  
Contact Width ◽  
Wide Range ◽  
Mode Ii Fracture Toughness ◽  
Compressive Testing

A new approach of diametral compressive testing with circular anvils is proposed. The circular anvils are used to select a suitable contact width or to avoid the collapse of the specimen in the contact edge. Furthermore, the statistical corrections on the diametral compressive strength for the effects of the size and stress distribution are explained by the application of Weibull’s statistical theory. The experimental results of the diametral compressive testing are compared with the uniaxial tensile strengths for some kinds of graphite and marble, and the discrepancies between the two strengths are discussed. According to our macroscopic brittle fracture criterion under biaxial stress state, which was proposed recently, the tensile strength can be deduced from the diametral compressive strength σHC* and the uniaxial compressive strength σC as follows, σt*=KICKIIC12σCσHC*(1+σx/σH)+σC{σHC*(1−σx/σH)−σC}+σC2 where σt* is the deduced tensile strength, σx/σH is the ratio of maximum and minimum principal stresses at the center of the disk, and KIC and KIIC are the values of Mode I and Mode II fracture toughness. The deduced values σt* are ascertained experimentally to agree very well with the uniaxial tensile strength in wide range of brittle materials, such as graphite and marble.

Lifetime and Reliability Assessment of AlN Substrates Used in Harsh Aeronautic Environments Power Switch Modules

2010 ◽  
Vol 112 ◽  
pp. 113-127 ◽  
Author(s):  
Adrien Zéanh ◽  
Olivier Dalverny ◽  
Moussa Karama ◽  
Arezki Bouzourene
Keyword(s):  
Finite Elements ◽  
External Loading ◽  
Principal Stresses ◽  
Ceramic Substrates ◽  
Ceramic Fracture ◽  
Bending Tests ◽  
Weakest Link ◽  
Power Switch ◽  
Finite Elements Modelling ◽  
Switch Module

This paper presents a Finite Elements Modelling (FEM) based methodology dedicated to the evaluation of the lifetime and the reliability of assemblies involving brittle materials under cyclic loading. It focuses on the particular case of metal bonded Aluminium Nitride (AlN) substrates used in power electronic switch modules. The ceramic fracture criterion was formulated according to the weakest link concept, under Weibull's approach. The material's parameters were determined by running three points bending tests. In order to check the relevancy of the proposed methodology, a non linear thermomechanical Finite Elements Model allowed computing the number of thermal cycles before substrate brittle fracture within a test vehicle, which was then compared to experimental results. Once validated, the methodology was applied to two different configurations of a power switch module, designed for harsh environment aeronautic applications. The corresponding external loading profile was considered to compute and monitor the evolution of the maximal principal stresses within the ceramic substrates whole volumes. Their lifetimes and reliabilities was finally assessed and compared to the applications requirements.

Principal Stress Separation Using a Combination of Photoelasticity and Thermoelastic Stress Analysis under Biaxial Stress

2005 ◽  
Vol 297-300 ◽  
pp. 1214-1219
Author(s):  
Akira Shimamoto ◽  
Hiroshi Ohkawara ◽  
Sung Mo Yang
Keyword(s):  
Principal Stress ◽  
Integration Method ◽  
Stress Measurement ◽  
Thermoelastic Stress ◽  
Uniaxial Stress ◽  
Biaxial Stress ◽  
Combined Method ◽  
Principal Stresses ◽  
Stress Separation ◽  
The Difference

Today, stress measurement methods by thermography and by photoelasticity are widely used to make stress distribution visible. However, it is difficult to separate principal stresses using only one of these methods because only the difference of principal stresses is measured in photoelasticity, and only the sum of the principal stresses is measured in thermograpy. Therefore, the inverse analysis problem must be solved to separate the principal stress in the thermoelastic method and the shear difference integration method must be used for the photoelastic method. Although there are some reports separation of the principal stresses under uniaxial stress by combining the two methods, little research under the biaxial stress has been reported due to the difficulty of experimentation. In this research, the principal stresses under biaxial stress are separated by a combined method. Moreover, it is verified that the thermoelastic stress measurement method is effective to evaluate the stress concentration factor.

Layered ceramic composites via control of electrophoretic deposition kinetics

2013 ◽  
Vol 33 (12) ◽  
pp. 2305-2312 ◽  
Author(s):  
Hynek Hadraba ◽  
Daniel Drdlik ◽  
Zdenek Chlup ◽  
Karel Maca ◽  
Ivo Dlouhy ◽  
...  
Keyword(s):  
Electrophoretic Deposition ◽  
Ceramic Composites ◽  
Deposition Kinetics ◽  
Layered Ceramic
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