Numerical Simulation of Pre-Crack Propagation in ZrB2-SiC-AlN Ceramics Subjected to Thermal Shock

2013 ◽  
Vol 833 ◽  
pp. 154-158
Author(s):  
Xiao Yang Wan ◽  
Jun Liang ◽  
Guo Dong Fang ◽  
Ling Ling Wang
Keyword(s):  
Numerical Simulation ◽  
Thermal Stress ◽  
Crack Propagation ◽  
Thermal Shock ◽  
Dimensionless Parameter ◽  
Experimental Results ◽  
Force Model ◽  
Quenching Temperature ◽  
Depth Direction ◽  
Good Agreement

The present work examines the pre-indented crack propagation in ZrB2-SiC-AlN ceramics subjected to thermal shock under different temperature differences. A cohesive force model is applied according to the shape and characteristics of the crack in the indentation - quenching experiments. A dimensionless parameter is introduced to characterize the effect of depth on thermal stress which considers the cracks propagate along both the surface and the depth direction. The modified numerical results are 11.3%, 16.6%, 20.8% 27.1% and 64.6% at the quenching temperature differences of 240°C, 280°C, 320°C and 360°C, respectively, which are in good agreement with the experimental results.

scholarly journals Numerical Simulations of V-Shaped Plates Subjected to Blast Loadings: A Validation Study

2016 ◽  
Vol 10 (11) ◽  
pp. 203
Author(s):  
Mohd Zaid Othman ◽  
Qasim H. Shah ◽  
Muhammad Akram Muhammad Khan ◽  
Tan Kean Sheng ◽  
M. A. Yahaya ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Variable Mass ◽  
Blast Loading ◽  
Experimental Results ◽  
Average Difference ◽  
Simulation Results ◽  
Blast Loadings ◽  
Carrier Vehicle ◽  
Good Agreement

A series of numerical simulations utilizing LS-DYNA was performed to determine the mid-point deformations of V-shaped plates due to blast loading. The numerical simulation results were then compared with experimental results from published literature. The V-shaped plate is made of DOMEX 700 and is used underneath an armour personal carrier vehicle as an anti-tank mine to mitigate the effects of explosion from landmines in a battlefield. The performed numerical simulations of blast loading of V-shaped plates consisted of various angles i.e. 60°, 90°, 120°, 150° and 180°; variable mass of explosives located at the central mid-point of the V-shaped vertex with various stand-off distances. It could be seen that the numerical simulations produced good agreement with the experimental results where the average difference was about 26.6%.

scholarly journals A Luenberger-Like Observer for Multistable Kapitaniak Chaotic System

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
J. Humberto Pérez-Cruz ◽  
Jacobo Marcos Allende Peña ◽  
Christian Nwachioma ◽  
Jose de Jesus Rubio ◽  
Jaime Pacheco ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Chaotic System ◽  
Estimation Error ◽  
Lipschitz Constant ◽  
Experimental Results ◽  
Good Agreement

The objective of this paper is to estimate the unmeasurable variables of a multistable chaotic system using a Luenberger-like observer. First, the observability of the chaotic system is analyzed. Next, a Lipschitz constant is determined on the attractor of this system. Then, the methodology proposed by Raghavan and the result proposed by Thau are used to try to find an observer. Both attempts are unsuccessful. In spite of this, a Luenberger-like observer can still be used based on a proposed gain. The performance of this observer is tested by numerical simulation showing the convergence to zero of the estimation error. Finally, the chaotic system and its observer are implemented using 32-bit microcontrollers. The experimental results confirm good agreement between the responses of the implemented and simulated observers.

Simulation of Fracture Behavior of Elastomer Modified Polypropylene Based on Elastoviscoplastic Constitutive Equation With Craze and Tensile Softening Law

2005 ◽  
Author(s):  
Hiroyuki Mae
Keyword(s):  
Constitutive Equation ◽  
Crack Propagation ◽  
Strain Rate ◽  
Fracture Behavior ◽  
Experimental Results ◽  
Experimental Result ◽  
Load Displacement ◽  
Macroscopic Crack ◽  
Tensile Softening ◽  
Good Agreement

The strong strain-rate dependence, neck propagation and craze evolution characterize the large plastic deformation and fracture behavior of polymer. In the latest study, Kobayashi, Tomii and Shizawa suggested the elastoviscoplastic constitutive equation based on craze evolution and annihilation and then applied it to the plane strain issue of polymer. In the previous study, the author applied their suggested elastoviscoplastic constitutive equation with craze effect to the three dimensional shell issue and then showed that the load displacement history was in good agreement with the experimental result including only microscopic crack such as craze. For the future industrial applications, the macroscopic crack had to be taken into account. For instance, an airbag deployment simulation needed the macroscopic crack prediction. Thus, the main objective of this study was to propose the tensile softening equation and then add it to the elastoviscoplastic constitutive equation with craze effect so that the load displacement history could be roughly simulated during the macroscopic crack propagation. The tested material in this study was the elastomer blended polypropylene used in the interior and exterior of automobiles. First, the material properties were obtained based on the tensile test results at wide range of strain rates: 10−4 – 102 (1/sec). Next, the fast compact tension test was conducted and then the tensile softening parameters were fixed. Then, the fast bending test and the dart impact test were carried out in order to obtain the load displacement history and also observe the macroscopic crack propagation at high strain rate. Finally, the fracture behavior was simulated and then compared with the experimental results. It was shown that the predictions of the constitutive equation with the proposed tensile softening equation were in good agreement with the experimental results.

scholarly journals Thermal Shock Effect on the Glass Thermal Stress Response and Crack Propagation

2013 ◽  
Vol 62 ◽  
pp. 717-724 ◽  
Author(s):  
Qingsong Wang ◽  
Haodong Chen ◽  
Yu Wang ◽  
Jinhua Sun
Keyword(s):  
Thermal Stress ◽  
Stress Response ◽  
Crack Propagation ◽  
Thermal Shock ◽  
Shock Effect

Flexible chiral metamaterials with dynamically optical activity and high negative refractive index

2015 ◽  
Vol 29 (18) ◽  
pp. 1550087 ◽  
Author(s):  
Furkan Dincer ◽  
Muharrem Karaaslan ◽  
Emin Unal ◽  
Oguzhan Akgol ◽  
Cumali Sabah
Keyword(s):  
Numerical Simulation ◽  
Refractive Index ◽  
Numerical Analysis ◽  
Optical Activity ◽  
Negative Refractive Index ◽  
Experimental Results ◽  
Polarization Converter ◽  
Dynamic Design ◽  
Chiral Metamaterials ◽  
Good Agreement

We demonstrate numerically and experimentally chiral metamaterials (MTMs) based on gammadion-bilayer cross-wires that uniaxially create giant optical activity and tunable circular dichroism as a result of the dynamic design. In addition, the suggested structure gives high negative refractive index due to the large chirality in order to obtain an efficient polarization converter. We also present a numerical analysis in order to show the additional features of the proposed chiral MTM in detail. Therefore, a MTM sensor application of the proposed chiral MTM is introduced and discussed. The presented chiral designs offer a much simpler geometry and more efficient outlines. The experimental results are in a good agreement with the numerical simulation. It can be seen from the results that, the suggested chiral MTM can be used as a polarization converter, sensor, etc. for several frequency regimes.

scholarly journals Assessment of different turbulence models in simulating axisymmetric flow in suddenly expanded nozzles

2018 ◽  
Vol 7 (3.29) ◽  
pp. 243
Author(s):  
Sher Afghan Khan ◽  
Mir Owais Ali ◽  
Miah Mohammed Riyadh ◽  
Zahid Hossen ◽  
Nafis Mahdi Arefin
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Mach Number ◽  
Numerical Simulations ◽  
Axisymmetric Flow ◽  
Turbulence Models ◽  
Experimental Results ◽  
Nozzle Flow ◽  
Axisymmetric Nozzle ◽  
Good Agreement

A numerical simulation was carried out to compare various turbulence models simulating axisymmetric nozzle flow past suddenly expanded ducts. The simulations were done for L/D = 10. The convergent-divergent nozzle has been modeled and simulated using the turbulence models: The Standard k-ε model, The Standard k-ω model and The SST k-ω model. Numerical simulations were done for Mach numbers 1.87, 2.2, and 2.58 and the nozzles were operated for NPRs in the range from 3 to 11. From the numerical analysis it is apparent that for a given Mach number and effect of NPR will result in maximum gain or loss of pressure. Numerical results are in good agreement with the experimental results.  

Numerical Simulation of Dynamic Response of Planing Craft Sailing in Calm Water

2014 ◽  
Vol 590 ◽  
pp. 37-41
Author(s):  
Yu Min Su ◽  
Yun Hui Li ◽  
Hai Long Shen
Keyword(s):  
Numerical Simulation ◽  
Empirical Formula ◽  
High Speed ◽  
Evaluation Method ◽  
Simulation Method ◽  
Experimental Results ◽  
Planing Craft ◽  
Calm Water ◽  
Performance Evaluation Method ◽  
Good Agreement

In order to forecast the sailing response of planing craft at high speed rapidly and accurately, CFD code Fine/Marine solver was used to calculate the resistance and sailing attitude of a high-speed planing craft, then the numerical results were compared with experimental results and empirical formula results. The results showed that resistance error calculated by Fine/Marine was between 5% and 10%, trim and heave results were in good agreement with experimental results, and had greater accuracy compared with the empirical formula results. The feasibility of this numerical simulation method was validated and this method provided an effect performance evaluation method for new designing planing crafts.

Thermal Shock Testing of Ceramics for Circuit Substrates

2006 ◽  
Vol 11-12 ◽  
pp. 31-34 ◽  
Author(s):  
Sawao Honda ◽  
Shinobu Hashimoto ◽  
Hideo Awaji
Keyword(s):  
Fracture Toughness ◽  
Thermal Properties ◽  
Thermal Stress ◽  
Thermal Shock ◽  
Alumina Ceramics ◽  
Radiation Heating ◽  
Ambient Temperatures ◽  
Shock Testing ◽  
Experimental Values ◽  
Good Agreement

Thermal shock resistances of commercially available aluminum nitride and alumina ceramics as used for the circuit substrate were evaluated by infrared radiation heating (IRH) technique. Thermal shock fracture toughness, R2c of these materials was estimated experimentally and theoretically using IRH technique at various ambient temperatures. Temperature dependence of thermal properties of the materials was taken into account for the temperature and the thermal stress analysis. Experimental values of thermal shock fracture toughness were in good agreement with the calculated values. Thermal shock fracture toughness decreased with elevated ambient temperature in both ceramics.

Numerical Simulation of Multi-Track Laser Cladding Process

2011 ◽  
Vol 399-401 ◽  
pp. 1802-1805 ◽  
Author(s):  
Jin Wu Kang ◽  
Tian You Huang ◽  
An Feng Zhang ◽  
Di Chen Li
Keyword(s):  
Numerical Simulation ◽  
Surface Roughness ◽  
Heat Source ◽  
Laser Cladding ◽  
Experimental Results ◽  
Laser Spot ◽  
Laser Cladding Process ◽  
Clad Layer ◽  
Overlap Ratio ◽  
Good Agreement

Multi-track laser cladding is necessary in the forming of parts. The overlap between neighbor tracks plays an important role, which determines the quality and surface smoothness of the clad layer. In this paper, numerical simulation of the multi-track laser cladding process is studied. The heat source of laser spot is applied by updating the profile of clad region and the location of the moving laser spot. The clad profile of overlapped track was obtained, from which the surface roughness was analyzed by the variation of overlap ratio. Meanwhile, experiments were carried out to evaluate the effect of overlap ratio. The simulated and the experimental results are in good agreement; both show that there is an optimal overlap ratio to achieve best surface roughness.

Bond-Slip Numerical Simulation of Concrete and Gypsum Board

2011 ◽  
Vol 255-260 ◽  
pp. 3133-3136
Author(s):  
Quan Bin Zhao ◽  
Xin Liang Jiang
Keyword(s):  
Numerical Simulation ◽  
Constitutive Relation ◽  
Simulation Analysis ◽  
Experimental Results ◽  
Gypsum Board ◽  
Bond Slip ◽  
Pull Out ◽  
Simulation Results ◽  
Research Situation ◽  
Good Agreement

The characteristics and research situation of bond-slip performance at the inter face of concrete and other materials are introduced, and the bond-slip constitutive relation models are summarized at the same time. Through the load-slip curves obtained from the pull-out experiment of CFFP, the proposed bond-slip constitutive relation models are presenting, including the simple one. With the numerical simulation analysis of CFFP is carried out by the use of the proposed constitutive relation, while the numerical simulation results are in good agreement with the experimental results conducted before, which is feasible and can be applied to further research on CFFP.

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