Ceramics Reliability: Statistical Analysis of Multiaxial Failure Using the Weibull Approach and the Multiaxial Elemental Strength Model

1988 ◽  
Author(s):  
Jacques Lamon
Keyword(s):  
Experimental Data ◽  
Structural Design ◽  
Mixed Mode ◽  
Bending Test ◽  
Second Step ◽  
Strength Model ◽  
Precise Evaluation ◽  
Ceramic Components ◽  
Stress States ◽  
Mode Failure

Methodology for designing reliable ceramic components requires a precise evaluation and correlation of strengths in different stress states. The present paper compares the merits of the Weibull approach and the Multiaxial Elemental Strength model on an experimental case involving mixed mode failure in the presence of bimodal flaw populations (surface and volume flaws). The experimental data were obtained using flexure specimens of Si3N4 tested at various spans, with the purpose of enhancing shearing effects. The analysis of data was refined by developing an advanced post-processor program to finite element codes, for failure probability determination based upon the Barnett-Freudenthal approximation of the Weibull approach and the Multiaxial Elemental Strength Model. In a second step, the strengths of the specimens exhibiting failures from the two concurrent populations of flaws (intermediate span) were predicted using both approaches from data obtained with different span lengths (long and short spans). Comparison with experimental data showed that the Multiaxial Elemental Strength Model is an improvement over the Weibull approach. It also allowed the short span bending test to be assessed. Finally, important implications for structural design with ceramics are discussed.

scholarly journals Evaluation of Fast Fracture Strength of Ceramic Components Under Multiaxial Stress States

1992 ◽  
Author(s):  
H. Uchimura ◽  
A. Kokaji ◽  
M. Kaji
Keyword(s):  
Experimental Data ◽  
Probability Distribution Function ◽  
Fracture Probability ◽  
Surface Cracks ◽  
Multiaxial Stress ◽  
Fracture Criteria ◽  
Ceramic Components ◽  
Stress States ◽  
Fast Fracture ◽  
Sintered Silicon

Several fracture criteria were studied under multiaxial stress states by Matsuo’s multiaxial fracture probability distribution function including effects of both volume and surface cracks. Tested material was a pressureless-sintered silicon nitride. Tensile (compressive)-torsional tests revealed that experimental data were satisfactorily described by Shitty’s empirical criterion for C=1.46. Good agreements for a spin and a thermal shock tests were obtained applying the Weibull parameters and the Shetty’s parameter.

scholarly journals An Improved Cohesive Zone Model for Interface Mixed-Mode Fractures of Railway Slab Tracks

2021 ◽  
Vol 11 (1) ◽  
pp. 456
Author(s):  
Yanglong Zhong ◽  
Liang Gao ◽  
Xiaopei Cai ◽  
Bolun An ◽  
Zhihan Zhang ◽  
...  
Keyword(s):  
Interface Crack ◽  
Cohesive Zone ◽  
Mixed Mode ◽  
Cohesive Zone Model ◽  
Complex Loading ◽  
Bending Test ◽  
Mixed Mode Fracture ◽  
Zone Model ◽  
Slab Track ◽  
Interfacial Cracks

The interface crack of a slab track is a fracture of mixed-mode that experiences a complex loading–unloading–reloading process. A reasonable simulation of the interaction between the layers of slab tracks is the key to studying the interface crack. However, the existing models of interface disease of slab track have problems, such as the stress oscillation of the crack tip and self-repairing, which do not simulate the mixed mode of interface cracks accurately. Aiming at these shortcomings, we propose an improved cohesive zone model combined with an unloading/reloading relationship based on the original Park–Paulino–Roesler (PPR) model in this paper. It is shown that the improved model guaranteed the consistency of the cohesive constitutive model and described the mixed-mode fracture better. This conclusion is based on the assessment of work-of-separation and the simulation of the mixed-mode bending test. Through the test of loading, unloading, and reloading, we observed that the improved unloading/reloading relationship effectively eliminated the issue of self-repairing and preserved all essential features. The proposed model provides a tool for the study of interface cracking mechanism of ballastless tracks and theoretical guidance for the monitoring, maintenance, and repair of layer defects, such as interfacial cracks and slab arches.

scholarly journals Mixed-mode evaluation of ductile adhesive joints by the single-leg bending test

2020 ◽  
Vol 28 ◽  
pp. 1106-1115
Author(s):  
J.P.S.M.B. Ribeiro ◽  
Raul D.S.G. Campilho ◽  
R.J.B. Rocha
Keyword(s):  
Mixed Mode ◽  
Adhesive Joints ◽  
Bending Test

scholarly journals A Study of Yielding and Plasticity of Rapid Prototyped ABS

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1495
Author(s):  
Dan-Andrei Șerban ◽  
Cosmin Marșavina ◽  
Alexandru Viorel Coșa ◽  
George Belgiu ◽  
Radu Negru
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Plastic Flow ◽  
Plane Stress ◽  
Yield Criterion ◽  
Numerical Analyses ◽  
Flow Potential ◽  
Stress States ◽  
State Configuration

In this article, the yielding and plastic flow of a rapid-prototyped ABS compound was investigated for various plane stress states. The experimental procedures consisted of multiaxial tests performed on an Arcan device on specimens manufactured through photopolymerization. Numerical analyses were employed in order to determine the yield points for each stress state configuration. The results were used for the calibration of the Hosford yield criterion and flow potential. Numerical analyses performed on identical specimen models and test configurations yielded results that are in accordance with the experimental data.

The Revised Universal Slope Method to Predict the Low-Cycle Fatigue Lives of Elbow and Tee Pipes

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Hiun Nagamori ◽  
Koji Takahashi
Keyword(s):  
Experimental Data ◽  
Internal Pressure ◽  
Low Cycle Fatigue ◽  
Experimental Studies ◽  
High Accuracy ◽  
Universal Method ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Slope Method ◽  
Stress States

The stress states of elbow and tee pipes are complex and different from those of straight pipes. The low-cycle fatigue lives of elbows and tees cannot be predicted by Manson's universal slope method; however, a revised universal method proposed by Takahashi et al. was able to predict with high accuracy the low-cycle fatigue lives of elbows under combined cyclic bending and internal pressure. The objective of this study was to confirm the validity of the revised universal slope method for the prediction of low-cycle fatigue behaviors of elbows and tees of various shapes and dimensions under conditions of in-plane bending and internal pressure. Finite element analysis (FEA) was carried out to simulate the low-cycle fatigue behaviors observed in previous experimental studies of elbows and tees. The low-cycle fatigue behaviors, such as the area of crack initiation, the direction of crack growth, and the fatigue lives, obtained by the analysis were compared with previously obtained experimental data. Based on this comparison, the revised universal slope method was found to accurately predict the low-cycle fatigue behaviors of elbows and tees under internal pressure conditions regardless of differences in shape and dimensions.

Strength Model Uncertainties of Burst, Yielding, and Excessive Bending of Piping

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Kleio Avrithi ◽  
Bilal M. Ayyub
Keyword(s):  
Structural Design ◽  
Design Method ◽  
Strength Model ◽  
Allowable Stress ◽  
Model Uncertainties ◽  
Reliability Based Design ◽  
Design Variables ◽  
Strength Models ◽  
Potential Use ◽  
Allowable Stress Design

Nuclear safety-piping is designed according to the ASME Boiler and Pressure Vessel Code, Sections III, NB-, NC-, and ND-3600 that use the allowable stress design method (ASD). The potential use instead of reliability-based design equations for nuclear piping could benefit the structural design by providing, among others, consistent reliability levels for piping. For the development of such equations, not only the probabilistic characteristics of the design variables are needed, but also the quantification of the uncertainties introduced by the strength models that are used in order to estimate the resistance of pipes subjected to different loadings. This paper evaluates strength models, and therefore provides necessary information for the reliability-based design of pipes for burst or yielding due to internal pressure and for excessive bending.

scholarly journals EXPERIMENTAL DATA AND NUMERICAL SIMULATION OF WAVE LOADING AND ITS REDUCTION ON SHELTERED BUILDINGS

2020 ◽  
pp. 21
Author(s):  
Joaquin Moris ◽  
Andrew Kennedy ◽  
Joannes Westerink
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Structural Design ◽  
Structural Damage ◽  
Wave Loads ◽  
Wave Loading

Wave loading from inundation events like storms and tsunamis can cause severe structural damage to buildings (Xian et al., 2015); therefore, it is important to predict wave loading as accurately as possible. One uncertainty in estimating wave loads during inundation events is the possible reduction of loads by sheltering from other buildings. Understanding and quantifying this effect could reduce overestimated loads in sheltered buildings and avoid over-conservative structural design. This work aims to quantify the reduction of wave loads in sheltered buildings through the analysis of experimental data and numerical simulations.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/89QblLjDBnI

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