Numerical study of interface damage formation mechanisms in machining CFRP/Ti6Al4V stacks under different cutting sequence strategies

2022 ◽  
pp. 115236
Author(s):  
Jinyang Xu ◽  
Tieyu Lin ◽  
Linfeng Li ◽  
Min Ji ◽  
J. Paulo Davim ◽  
...  
Keyword(s):  
Numerical Study ◽  
Formation Mechanisms ◽  
Interface Damage ◽  
Cutting Sequence

A Numerical Study for the Relationship between Natural Manganese Dendrites and DLA Patterns

2016 ◽  
Vol 71 (3) ◽  
pp. 225-234
Author(s):  
Tugba Ozbey ◽  
Mehmet Bayirli
Keyword(s):  
Critical Exponent ◽  
Numerical Study ◽  
Formation Mechanisms ◽  
Diffusion Limited Aggregation ◽  
Density Correlation ◽  
Diffusion Limited ◽  
Crystalline Anisotropy ◽  
The Relationship ◽  
Good Agreement ◽  
Dla Model

AbstractThe formation mechanisms and the origin of manganese dendrites on the magnesite ore have been under discussion. The growth process of the manganese dendrites is statistically studied by comparing them to aggregations obtained according to the diffusion limited aggregation (DLA) model via Monte Carlo simulations. In this case, ten manganese dendrite patterns changing from the least dense to the densest aggregations on the surface are separately selected to determine the relationship between real and simulated patterns. The sticking parameter is ranged from 0.05≤t≤1. The density–density correlation functions C(r) (their critical exponent A), fractal dimension Df, critical exponent α, and critical exponent β pertaining to the root mean square (rms) thickness have been computed for both the ten manganese dendrites and the simulated aggregations representing them. The results indicate that manganese dendrites may be determined with the general DLA model. Analyses of manganese dendrites, both scaling and simulations, suggest the growth mechanism for the macroscopic expression of crystalline anisotropy for the dendritic patterns. These results are in good agreement with the values in other literature and can be helpful in comparing natural and simulated aggregations (both dendritic and compact deposits).

scholarly journals Experimental and numerical investigation of interface damage in composite L-angle sections under four-point bending

2020 ◽  
Vol 55 (2) ◽  
pp. 187-200
Author(s):  
Xi Zou ◽  
Shibo Yan ◽  
Mikhail Matveev ◽  
James P Rouse ◽  
I Arthur Jones
Keyword(s):  
Numerical Study ◽  
Cohesive Element ◽  
Interlaminar Stresses ◽  
Damage Initiation ◽  
Interface Damage ◽  
Four Point Bending ◽  
Initiation And Propagation ◽  
Bending Load ◽  
Modelling Strategies ◽  
Cohesive Surface

Curved laminates in aero-structures, such as the L-angle sections where webs and flanges meet, are prone to delamination due to high interlaminar stresses in these regions. Some efforts to investigate delamination in these structures can be found in the literature but commonly structures are limited to unidirectional layups or modelling approaches are constrained to the cohesive element based methods. In this work, multi-directional L-angle laminates were manufactured using unidirectional prepregs and tested under four-point bending load conditions to examine the interface damage. Acoustic emission technique was used to assist the capture of damage initiation and propagation. Three interface modelling strategies for predicting delamination, namely cohesive element, cohesive surface and perfectly bonded interface were used in the numerical study. The interface damage behaviour was successfully predicted by the simulation methods and differences among the strategies were compared.

Experimental and Numerical Study of Steady and Modulated Transverse Jets at Low Blowing Ratios

2010 ◽  
Author(s):  
Guillaume Bidan ◽  
Pierre-Emmanuel Bouladoux ◽  
Jeremiah E. Oertling ◽  
Dimitris E. Nikitopoulos
Keyword(s):  
Steady State ◽  
Numerical Study ◽  
Mie Scattering ◽  
Formation Mechanisms ◽  
Transitional Region ◽  
Vortical Structures ◽  
Coverage Metrics ◽  
Jet In Crossflow ◽  
Wide Range ◽  
Hotwire Anemometry

The effects of jet flow pulsation were investigated in the case of a fully modulated vertical jet in crossflow over a flat plate using Mie scattering visualizations, hotwire anemometry and Large Eddy Simulations (LES). A preliminary steady state study was conducted over a wide range of blowing ratios to provide a baseline comparison to pulsed results in terms of vortical structures and performance. Based on observation of the vortical structures and hotwire signatures, two distinct regimes were identified separated by a transitional region. LES using the dynamic Smagorinsky sub-grid model were carried out to provide additional insights on vortical structures formation mechanisms and their effect on heat transfer results, showing good agreement with the experimental observations and measurements. The influence of the pulsing parameters such as mean, high and low blowing ratios, forcing frequency and duty cycle was explored in terms of jet coverage metrics and spanwise adiabatic effectiveness. Average blowing ratios of 0.250, 0.350 and 0.450, duty cycles of 25, 50 and 70% and forcing frequencies of St∞ = 0.008, 0.016, 0.079, and 0.159 were investigated. While in most of the cases, forced jets show a decrease in average performance compared to steady state configurations, some improvement was found in part of the forcing cycle. Vortical structures formed at the jet onset are consistent with the classification given by previous studies in terms of stroke-ratio and high blowing ratio over an overlapping range of conditions. The dynamics of the vortical structures formed at the pulse rise are highly responsible for the decrease in performance observed under forced conditions.

scholarly journals NUMERICAL STUDY ON ACCUMULATION MECHANISM OF CORAL GRAVELS AROUND BALLAST ISLAND, THE CORAL CAY OFF THE COAST OF IRIOMOTE ISLAND

2018 ◽  
pp. 93
Author(s):  
Yoshimitsu Tajima
Keyword(s):  
Field Survey ◽  
Numerical Study ◽  
Formation Mechanisms ◽  
Physical Mechanisms ◽  
Iriomote Island ◽  
Characteristic Behavior ◽  
Protection Strategies ◽  
Accumulation Mechanism

Understanding the formation mechanisms of a coral cay or a coral beach is essentially important to consider better conservation and protection strategies and measures of coral coast. Ballast island is a coral cay formed on the isolated reef located off the coast of Iriomote island, Okinawa, Japan. While this small coral cay frequently alters its shape under the attacks of severe waves, coral gravels gather around the island and keep the island around the same location. This study carries out the field survey and the numerical study to investigate the physical mechanisms of above mentioned characteristic behavior of coral gravels.

A numerical study for determining the effect of raffia, alfa and sisal fibers on the fiber-matrix interface damage of biocomposite materials

2021 ◽  
Vol 14 ◽  
Author(s):  
Bouchra Achour ◽  
Allel Mokaddem ◽  
Bendouma Doumi ◽  
Abdelkader Ziadi ◽  
Lahcen Belarbi ◽  
...  
Keyword(s):  
Numerical Study ◽  
Natural Fibers ◽  
Numerical Data ◽  
Matrix Interface ◽  
Interface Damage ◽  
Automotive Technology ◽  
Fiber Matrix Interface ◽  
Sisal Fibers ◽  
Matrix Damage ◽  
Good Agreement

Background: : nowadays, the natural fibers are used in all industrial fields, particular in automotive technology and in civil engineering. this great emergence due to its biodegradability, recyclability and has no environmental effect. Objective: In this article, the effect of raffia, alfa and sisal fibers on the damage of biocomposite materials (raffia/PLA (polylactic acid), alfa/PLA and sisal/PLA), subjected to the same mechanical shear stress, has been investigated. Method: To calculate the damage to the interface, the genetic operator crossing are employed based on the fiber and matrix damage. Result: The results have shown that the raffia / PLA and alfa/PLA biocomposite materials are the better mechanical properties compared to sisal / PLA, this observation has been confirmed by the different values of interface damage of the biocomposite studied. Conclusion: The numerical results are similar and coincide perfectly with the results of Cox where he demonstrated that the Young's modulus of fibers improves the resistance of the interface. These conclusions are in very good agreement with our numerical data presented by the red cloud, and also in good agreement with the work presented by Antoine Le Duigou et al. and the work of Bodros et al. have shown that natural fibers greatly improve the physical characteristics of composite materials.

On steady and pulsed low-blowing-ratio transverse jets

2013 ◽  
Vol 714 ◽  
pp. 393-433 ◽  
Author(s):  
G. Bidan ◽  
D. E. Nikitopoulos
Keyword(s):  
Numerical Study ◽  
Cross Flow ◽  
Vortex Pair ◽  
Leading Edge ◽  
Mie Scattering ◽  
Formation Mechanisms ◽  
Transverse Jets ◽  
Vortical Structures ◽  
Blowing Ratio ◽  
Counter Rotating Vortex Pair

AbstractThe present experimental and numerical study focuses on the vortical structures encountered in steady and pulsed low-blowing-ratio transverse jets ($0. 150\leq \mathit{BR}\leq 4. 2$), a configuration hardly discussed in the literature. Under unforced conditions at low blowing ratio, a stable leading-edge shear-layer rollup is identified inside the jet pipe. As the blowing ratio is increased, the destabilization and evolution of this structure sheds light on the formation mechanisms of the well-known transverse jet vortical system. A discussion on the nature of the counter-rotating vortex pair in low-blowing-ratio transverse jets is also provided. Under forced conditions, the experimental observations support and extend numerical results of previous fully modulated jet studies. Large-eddy simulation results provide scaling parameters for the classification of starting vortices for partly modulated jets, as well as information on their three-dimensional dynamics. The counter-rotating vortex pair initiation is observed and detailed in both Mie scattering visualizations and simulations. The observations support a mechanism based on stretching of the starting vortical structures because of inviscid induction and partial leapfrogging. Two modes of cross-flow ingestion inside the jet pipe are described as the pulsed jet cycles from high to low values of blowing ratio.

Numerical Study on Two-Phase Flow Patterns in Vortex Dropshaft

2017 ◽  
Author(s):  
Xichen Wang ◽  
Jian Zhang ◽  
Xiaodong Yu ◽  
Sheng Chen
Keyword(s):  
Numerical Study ◽  
Flow Patterns ◽  
Structure Design ◽  
Structural Safety ◽  
Formation Mechanisms ◽  
Two Phase ◽  
Specific Flow ◽  
Fluent Software ◽  
And Control ◽  
Hydropower Stations

As one of the main types of dropshaft structure, vortex dropshaft is commonly used in hydropower stations, urban drainage systems and other water conservancy projects. Many scholars have conducted researches into hydraulic characteristics of this type of dropshaft. However, its flow patterns and mechanisms are still not clear. Consequently, a 3-D, steady, two-phase numerical model of vortex dropshaft is developed through FLUENT software, using volume of fluid (VOF) method to track the interface of air and liquid water. Four cases sharing the same geometry domain and boundary conditions with different inlet velocities have been studied. The specific flow patterns and formation mechanisms in the four cases are discussed in this study, and the influences of inlet velocity are investigated as well. The results show two negative pressure zones appearing at inlet and outlet connections threatening the structural safety, and it is important to optimize the structure design and control the inlet flow.

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