scholarly journals Numerical Simulation and Experimental Investigation of Laser Ablation of Al2O3 Ceramic Coating

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5502
Author(s):  
Shuang Liu ◽  
Zongjun Tian ◽  
Lida Shen ◽  
Mingbo Qiu
Keyword(s):  
Laser Ablation ◽  
Solid Mechanics ◽  
Ceramic Coating ◽  
Element Model ◽  
Laser Damage ◽  
Damage Analysis ◽  
Mechanism Analysis ◽  
Continuous Irradiation ◽  
Al2o3 Ceramic ◽  
Micro Cracks

This paper presents an evaluation of the molten pool laser damage done to an Al2O3 ceramic coating. Mechanism analysis of the laser damage allowed for a 2D finite element model of laser ablation of the Al2O3 ceramic coating to be built. It consisted of heat transfer, laminar flow, and a solid mechanics module with the level set method. Results showed that the laser damage mechanisms through laser ablation were melting, gasification, spattering, and micro-cracking. The ablation depth and diameter increased with the increasing laser ablation time under continuous irradiation. The simulation profile was consistent with the experimental one. Additionally, the stress produced by the laser ablation was 3500–9000 MPa, which exceeded the tensile stress (350–500 MPa), and fracturing and micro-cracks occurred. Laser damage analysis was performed via COMSOL Multiphysics to predict laser damage morphology, and validate the 3D surface profiler and scanning electron microscope results.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Study of Influence of Residual Stresses on Crack Propagation in Particulate Ceramic Composites

2016 ◽  
Vol 258 ◽  
pp. 178-181 ◽  
Author(s):  
Zdeněk Majer ◽  
Luboš Náhlík ◽  
Kateřina Štegnerová ◽  
Pavel Hutař ◽  
Raúl Bermejo
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Element Model ◽  
Ceramic Composites ◽  
Particulate Composites ◽  
Micro Cracks ◽  
Dimensional Finite Element ◽  
Density Factor ◽  
Energy Density Factor

The aim of the present work is to analyze the influence of residual stresses in the particulate ceramic composite on the crack propagation. The crack propagation direction was estimated using Sih’s criterion based on the strain energy density factor. A two-dimensional finite element model was developed for determination of crack path. The residual stresses resulting from the mismatch of coefficients of thermal expansion during the fabrication process of the composite were implemented to the computational model. The effect of the particles shape on the crack propagation was investigated. Conclusions of this paper can contribute to a better understanding of the propagation of micro-cracks in particulate composites in the field of residual stresses.

Finite Element Model of Granite Ablation with UV Laser

2012 ◽  
Vol 730-732 ◽  
pp. 519-524
Author(s):  
Emilio Saavedra ◽  
Ana J. López ◽  
Javier Lamas ◽  
Maria Paula Fiorucci ◽  
Alberto Ramil ◽  
...  
Keyword(s):  
Finite Element ◽  
Laser Ablation ◽  
Finite Element Model ◽  
Element Model ◽  
Uv Laser ◽  
Stone Surface ◽  
Ablation Process ◽  
Laser Ablation Process ◽  
Cleaning Treatment ◽  
Molten Region

This work presents 3-D Finite Element Model of the heat transfer inside granite during pulsed laser ablation with the aim of achieving laser cleaning treatment without damaging the stone surface. The model is focused on biotite, the most affected granite-forming mineral, owing to its low melting temperature. The model predicts sizes of the molten region that are consistent with experimental results. Moreover, the effects of different irradiation parameters; i.e., fluence, laser repetition frequency, and speed of scan have been investigated through the size of the biotite molten region. This model may be considered as the first stage of a comprehensive model of the laser ablation process in granite.

A water-based Al2O3 ceramic coating for polyethylene-based microporous separators for lithium-ion batteries

2016 ◽  
Vol 315 ◽  
pp. 161-168 ◽  
Author(s):  
Hyunkyu Jeon ◽  
Daeyong Yeon ◽  
Taejoo Lee ◽  
Joonam Park ◽  
Myung-Hyun Ryou ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Ceramic Coating ◽  
Lithium Ion ◽  
Al2o3 Ceramic ◽  
Water Based

Damage Analysis Model for RC Members Based on Level of Material

2010 ◽  
Vol 163-167 ◽  
pp. 1262-1267
Author(s):  
Zuo Hua Li ◽  
Jun Teng ◽  
Xue Feng He
Keyword(s):  
Statistical Analysis ◽  
Damage Index ◽  
Three Dimensional ◽  
Element Model ◽  
Damage Analysis ◽  
Analysis Model ◽  
Damage Behavior ◽  
Beam Elements ◽  
Column Element ◽  
Numerical Strategy

This paper presents a numerical strategy to model nonlinear damage behavior of RC members based on level of material. The first part of the paper presents a numerical model of the RC member based on the Timoshenko multifiber beam elements and non-linear damage constitutive laws for concrete, and the effective three dimensional fiber beam-column element model is developed for the nonlinear damage analysis of RC members with VUEL subroutine based on ABAQUS/Explicit platform. In the second part, a nonlinear damage analysis for RC members is established by analyzing the sections of fiber beam column elements, and the member damage index through statistical analysis of concrete fibers damage is defined in the extreme section of beam elements, which can describe the nonlinear damage behavior of RC members under any loadings. Accuracy of the model is identified preliminarily by comparing with the analysis results of solid elements, the results shows that it seems now possible to use this approach to investigate numerically the nonlinear damage behavior of RC members based on level of material.

Influence of Mineral Admixtures on the Performance of Polymer Modified Porous Concrete

2009 ◽  
Vol 87-88 ◽  
pp. 92-97 ◽  
Author(s):  
Fang Xu ◽  
Ming Kai Zhou ◽  
Wei Guo Shen ◽  
Bei Xing Li
Keyword(s):  
Functional Performance ◽  
Element Model ◽  
Structural Features ◽  
Resistance Coefficient ◽  
Mineral Admixtures ◽  
Test Results ◽  
Strength Performance ◽  
Porous Concrete ◽  
Optimum Dosage ◽  
Micro Cracks

In order to improve the performance of polymer modified porous concrete (PMPC), the mineral admixtures (MAs) including fly ash (FA) and silicon fume (SF), are added in the concrete. In this paper, the optimum dosage of the MAs, the influence of the MAs on the strength performance, permeability performance and the surface functional performance of PMPC are studied. The microscopic test of SEM is used to explore the microscopic structure of PMPC. The test results indicate that: the dosage of 10% FA or of 6% SF is the optimum dosage, while the 28d compressive strength can reach 24MPa and 43MPa, respectively, the 28d flexural strength can reach 5.2MPa and 5.3MPa, respectively, and the permeability coefficient can reach 0.36cm/s and 0.32cm/s, respectively. The surface structural depth can reach more than 1mm and the slide resistance coefficient can reach more than 40BPN, which can conform to the standard of JTG F30-2003. The Contact Element Model is proved to conform to the structural features of PMPC. With the microscopic test, as the addition of the polymer and MAs, the internal micro-cracks and non-hydrated cement particles in the interfacial transition zone (ITZ) are covered by the cement paste and polymer films. The contact area, the mechanical property and durability of PMPC can be improved.

scholarly journals Unilateral contact and damage analysis in masonry arches

2009 ◽  
Vol 31 (3-4) ◽  
Author(s):  
M. Campo ◽  
G. A. Drosopoulos ◽  
G. E. Stavroulakis
Keyword(s):  
Failure Load ◽  
Damage Model ◽  
Unilateral Contact ◽  
Collapse Mechanism ◽  
Elastic Model ◽  
Damage Analysis ◽  
Load Bearing Capacity ◽  
Micro Cracks ◽  
Ultimate Failure ◽  
Comparison Of The Results

In the present work the ultimate failure load and the collapse mechanism of a stone arch bridge are estimated by the usage of (a) a multi - part elastic model with unilateral contact frictional interfaces and (b) a continuous damage model. According to the contact model, contact interfaces simulating potential cracks are considered and their opening or sliding indicates crack initiation. The second model deals with the material damage consisting in the development of internal micro cracks that affect the load bearing capacity of the material. Satisfactory comparison of the results is reported here.

Fatigue Life Prediction Under Biaxial FALSTAFF Loading Using Statistical Volume Element Based Multiscale Modeling

2012 ◽  
Author(s):  
Jinjun Zhang ◽  
Kuang Liu ◽  
Aditi Chattopadhyay
Keyword(s):  
Fatigue Life ◽  
Root Mean Square ◽  
Life Prediction ◽  
Element Model ◽  
Fatigue Tests ◽  
Volume Element ◽  
Fatigue Life Prediction ◽  
Mean Square ◽  
Damage Criterion ◽  
Micro Cracks

This article presents the fatigue life prediction in a cruciform specimen of 2024-T351 aluminum alloy subjected to biaxial FALSTAFF loading. An energy- and slip-based multiscale damage criterion is developed to capture the fatigue crack formation in crystalline metallic materials. In these materials, there are two stages in crack initiation: nucleation of micro cracks and coalescence of micro cracks into major cracks. In the first stage, micro cracks generate from intermetallic particles and extend into surrounding grains. For the FCC crystalline structure, fatigue damage increments in four dependent slip planes are calculated and accumulated to measure micro crack. In the second stage, the micro cracks grow and coalesce into major cracks. Subsequently, a meso-statistical volume element model is developed to represent the microstructure of the material. Finally, a root mean square method is introduced to take into account FALSTAFF loading. Using the root mean square (RMS) method, the loading history for tests is analyzed to determine the RMS maximum and minimum stresses. The multiscale damage criterion, statistical volume element and RMS method were validated using previously conducted fatigue tests on cruciform samples. The fatigue life and crack direction predicted using the developed model correlate well with the experiments.

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