Arbitrary Lagrangian Eulerian Technique Research Articles

Numerical prediction of ground-borne vibrations due to continuous vibratory driving of circular closed-ended piles

Various types of pile driving work may induce high-intensity ground-borne vibrations. Predicting vibration intensity before adopting mitigation measures is vital for minimizing the impact of vibration on nearby structures and occupants. Vibratory pile driving is a commonly applied foundation construction method. However, numerical simulation models for ground vibrations during a complete process of vibratory driving have rarely been studied. This study introduces an axisymmetric finite element model that utilizes the arbitrary Lagrangian-Eulerian technique to simulate the continuous vibratory driving of a circular closed-ended pile penetrating from the ground surface to a target depth. The model validity was confirmed by assessing the calculated ground vibrations against the findings documented in earlier research. The results showed that the critical penetration depth of piles, at which the maximum peak particle velocity (PPV) occurs, varied with the radial distance and depth of points of interest, contradicting a common preconception. Moreover, the maximum PPV did not always occur on the ground surface across all radial distances. Parametric analysis revealed that an increase in the soil cohesion strength, pile diameter, or soil-pile friction, or a decrease in the driving frequency or soil damping ratio would increase ground vibrations due to vibratory pile driving.

Prediction of wear of short glass fiber reinforced polyamide 66 composite sprocket

The wear of a polymer composite sprocket primarily depends on contact pressure and sliding velocity that vary significantly during service. The sliding distance and contact pressure at the sprocket/roller interface were estimated for a pristine polymer composite sprocket engaged with a standard and a 3% extended steel chain by employing the explicit finite element method. A set of experiments was executed to find the friction and wear coefficients of sprocket material using polyamide 66 composite pins and standard steel disc at sliding speeds of 1, 2, and 3 m/s and normal loads of 10, 20, 30, and 40 N. The wear depth is estimated after getting friction and wear coefficients experimentally, and contact pressure and sliding distance numerically. Archard wear model was executed using the UMESHMOTION subroutine with the Arbitrary Lagrangian-Eulerian technique in ABAQUS. The peak contact pressure on the sprocket is increased approximately by 1.5 times as the chain elongates from 0% to 3%. A pristine sprocket engaging a 3% extended chain after one lakh cycles experienced an approximate wear depth of 90 µm.

Effects of using magnetic field and double jet impingement for cooling of a hot oscillating object

Efficient cooling system design with impinging jets becomes an important topic due to its higher cooling performance applicable to engineering systems such as in electronic cooling, photovoltaic panels and material processing. In the present study, cooling of an oscillating hot object is considered by using a double slot jet impingement system in the presence of a uniform inclined magnetic field. The oscillation of body and magnetic field can be present in the system or they can be considered as methods for flow and convective heat transfer control for the slot-jet impingement system. Analysis is done for a range of values for the jet Reynolds number (Re ranging from 100 to 500), Hartmann number (Ha, ranging from 0 to 10), inclination of magnetic field (γ, ranging from 0 to 90), and oscillation amplitude (Amp, between −3 and 3) by using finite element method with Arbitrary Lagrangian–Eulerian technique. It is observed that due to the hot object’s oscillating nature, cooling is either increased or worsened for different time steps based. When Re is raised from the lowest to highest value, average Nusselt number (Nu) increases by a factor of 2.4. In the cooling system with impinging jets, strength of magnetic field and its inclination may be employed to regulate the vortex size and distribution. In comparison to the absence of magnetic field, the average Nu falls by around 73% to 75.5% at the greatest magnetic field strength. When oscillation is enabled, cooling performance is increased adopting the time step. By comparing the oscillating object with stationary one, cooling performance improvements of 28% and 8.3% are obtained at (Re, Ha)=(500, 0), and (500, 10) parametric combinations.

Numerical Study on Electromagnetic Hydraulic Forming Process to Overcome Limitations of Electromagnetic Forming Process.

This paper provides a comparison between the conventional Electromagnetic Forming (EMF) technique and the novel Electromagnetic Hydraulic Forming (EMHF) approach. The EMHF involves the use of finite element analysis coupled with the EM and arbitrary Lagrangian-Eulerian techniques analyzed through LS-DYNA. In the free-bulge configuration, EMF is influenced by the forming coil, resulting in a dead zone and uneven forming. Additionally, EMF can only be used to shape materials with high electrical conductivity. In contrast, EMHF, driven by induced hydraulic pressure from the electromagnetic field-affected drive sheet, is independent of the electrical conductivity of the material and produces dome-shaped workpieces. For rectangular die shapes, EMF is prone to collision owing to the acceleration of the blank, which results in a reduced quality owing to bouncing. However, EMHF exhibits no bouncing effect and successfully achieves the target shape in most cases. The two techniques differ in the strain rate, with EMF at 4850/s, whereas EMHF operates at approximately 1250/s. Despite being slower, EMHF is still a high-speed forming technique. In conclusion, EMHF is a promising technique capable of addressing the shortcomings of conventional EMF and achieving improvements in forming processes.

Thermal and fluid aspects of dual piezoelectric jet pump of double chambers

The rapid development of electronics has led to a significant reduction in the size of electronic devices, while increasing their power consumption. This has resulted in the need for small-scale thermal management solutions. Piezoelectric pump is one of the efficient devices for local thermal management. This paper presents a novel configuration of a piezoelectric pump, which separates the pump chamber with a rigid wall to create two independent pulsating flows. This configuration aims to reduce eddies within each chamber. Furthermore, the proposed design incorporates two pairs of open-sided channels to guide the pulsating flow towards the hot target. The electrostatics physic of the piezoelectric patches along with energy and momentum equations in three dimensions are manipulating mathematically and solved numerically using the finite element method (FEM) and the Arbitrary Lagrangian-Eulerian (ALE) technique. The implicit Large Eddy Simulation (iLES) turbulence model is adopted for this purpose. Several parameters, including frequency, voltage, and the radius of the piezoelectric patch are investigated to better understanding their influence on both the zero-net volumetric flow rate and the heat transfer process. The findings indicate that by separating the pump chamber, it becomes feasible to obtain a 3D solution with the iLES using a reasonable mesh size. Nusselt number increases with all the examined parameters, where it enhances by 42.48 % at V = 100 Volt when the pump is switched on compared to natural convection mode. The peak-peak volumetric flowrates rises by 50 % and 350 % when the applied voltage is raised from 50 to 100 Volts and the frequency is raised from 20 to 50.50 kHz, respectively.

Numerical Modeling of Critical Velocity and Deformation Behavior in Cold Spray Using Lagrangian and Arbitrary Lagrangian Technique

The cold spraying process is numerically modeled using Lagrangian and Arbitrary Lagrangian Eulerian (ALE) techniques. The simulations were performed to predict the critical velocity of spherical aluminum particles deposited on the aluminum substrate. ALE technique was found to be more suitable than the Lagrangian technique. Using Lagrangian and ALE techniques, the critical velocity for aluminum was predicted as 605 m/s and 770 m/s. Critical velocity was in between 770-775 m/s, as reported in the literature. The Lagrangian technique's capability is limited in capturing large deformations associated with cold spraying. However, this technique requires less computational ability and is quicker than the ALE technique. The jet formation was prominent in the case of the Lagrangian technique, and hence the difference between the numerically estimated value of critical velocity and experimentally measured velocity is more. The Compression ratio was found to increase with an increase in impingement velocity.

Self-Piercing rivet joining of multi-material including CFRP: Experiments and FE modeling

In this study, finite element (FE) analyses based on the arbitrary Lagrangian–Eulerian technique were used to investigate the complex deformation behavior and numerous process variables that arise during the self-piercing riveting (SPR) joining of multi-materials, including carbon-fiber-reinforced polymer, GA590DP, and Al5052-H32 sheets in two- and three-layer combinations. Tensile tests and inverse analysis were conducted to determine the mechanical responses of each joining material, including the rivet, and equivalent strain-based fracture modeling approaches were adopted for a simple but effective crack initiation prediction during the mechanical joining process. The damage distribution and joining characteristics during the SPR joining were then numerically investigated by considering different die profiles. The high predictability of the proposed FE modeling approach in terms of the cross-sectional profile with joint quality indicators, such as the interlock, residual distance between the rivet leg and die, minimum thickness of the bottom sheet, load history, and peak load during mechanical joining, was validated through comparisons between the experiments and FE simulations.

Estimation of spudcan penetration in variable sand deposits with the Arbitrary Lagrangian Eulerian Finite Element Method

Offshore jack-up rigs are most commonly founded on large-diameter conical “spudcan” foundations, which are frequently designed using traditional analytical methods for shallow footings. This paper presents the design of a spudcan installed off the coast of Tunisia. The maximum penetration depth of the footing under the available preload is predicted by a combination of analytical techniques, 2-dimensional axisymmetric modelling and 3-dimensional Finite Element Methods (FEM) using large strain arbitrary Lagrangian-Eulerian (ALE) techniques. Spudcan penetration based on FEM simulation of CPT soil profiles forms the basis of a comparison with results from the Society of Naval Architects and Marine Engineers (SNAME) guidelines. Particular attention is given to model calibration using the limited site investigation data available. Results are presented for the effect of penetrating footings on the behaviour of neighbouring footings, showing good agreement with conventional prediction methods.

A numerical study on mitigation of sloshing in a rectangular tank using floating foams

In this paper, the feasibility of using floating foams as a mitigation device to suppress water sloshing in a rectangular tank is numerically investigated. The sloshing in the tank is initiated using a harmonic excitation. To perform 3D numerical simulations, the Arbitrary Lagrangian-Eulerian technique (ALE) in the commercial software ABAQUS is utilized. The results of the model are validated by comparing the results of simulations with those of the experiments both quantitatively and qualitatively. Next, the efficacy of floating foams in suppressing water sloshing is evaluated for different cases with various layers of foam ranging from zero to three layers. In addition, the effects of various parameters on the wave height and kinetic energy variations are comprehensively analyzed. These parameters include water depth, density, friction factor, diameter of plastic foam spheres, frequency, amplitude and type of excitation. The numerical results show that the interactions between floating foams play a major role in mitigating water sloshing. Furthermore, the effects of plastic foam densities on decreasing the wave height are minor. A twofold increase in the foam density decreases the maximum kinetic energy by 9.68% and an almost threefold increase in the foam density reduces the maximum kinetic energy by 29.03%.

The response of a steel-ceramic composite structure to dynamic loading: comparison between air and water explosions

In this paper, by utilizing LS-DYNA hydrocode, the simulation of the explosion phenomenon was performed by the Load Blast Enhance method and the Arbitrary Lagrangian-Eulerian technique for air and water environment, respectively. The composite armor consists of three layers of alumina ceramic, hot rolled armor steel, and polymethyl methacrylate polymer as the face, back, and target layers, respectively. The deformation and effective stress of the target layer for two kinds of the test were compared. Utilizing the response surface methodology and analysis of variance, it was revealed that the ceramic layer thickness has the most influence on the displacement of the target layer in both environments. Moreover, by defining the destruction ratio, it was specified that in the underwater explosion, this ratio is much higher versus air blasting due to the incompressibility and higher density of the water vs. the air. Since, more incredible energy will be transmitted to the structure in the water explosion, accordingly, more severe deformation occurs within the water-submerged structure versus the air medium.

Impact Deposition Behavior of Al/B4C Cold-Sprayed Composite Coatings: Understanding the Role of Porosity on Particle Retention.

This study explores the role of porosity in the impact deposition of a ceramic-reinforced metal-matrix (i.e., Al/B4C) composite coating fabricated via cold spraying. The Johnson-Holmquist-Beissel constitutive law and the modified Gurson-Tvergaard-Needleman model were used to describe the high strain-rate behavior of the boron carbide and the aluminum metal matrix during impact deposition, respectively. Within a finite element model framework, the Arbitrary Lagrangian-Eulerian technique is implemented to explore the roles of reinforcement particle size and velocity, and pore size and depth in particle retention by examining the post-impact crater morphology, penetration depth, and localized plastic deformation of the aluminum substrate. Results reveal that some degree of matrix porosity may improve particle retention. In particular, porosity near the surface facilitates particle retention at lower impact velocities, while kinetic energy dominates particle retention at higher deposition velocities. Altogether, these results provide insights into the effect of deposition variables (i.e., particle size, impact velocity, pore size, and pore depth) on particle retention that improves coating quality.

FEM modelling of the three stages of friction stir spot welding

A three-dimensional modelling of the Friction Stir Spot Welding process was carried out by means of a two-dimensional continuum with symmetry of revolution around the tool axis. The model included the plunging, dwelling and withdrawal stages of two [Formula: see text] mm thick AA6061 alloy plates joining process. A highly viscous flow model was adopted, as well as the hypothesis of full stick contact between tool and material. The model was solved by means of the Finite Element Method (FEM) and Arbitrary Lagrangian Eulerian (ALE) techniques in an axisymmetric domain with mesh tracking and algorithms to account for contact and free flow. Numerical results were compared to experimental data found in literature. The maximum temperature for the pin front face was found within less than [Formula: see text]% of the experimental value. The velocity field were found close to those reported in literature and the final shape of the weld flash was similar to its experimental counterpart.

Energy harvester using two-phase flow conditions

Single-phase flow-induced vibration energy harvesting approaches, such as vortex-induced vibration, galloping, and flutter, have received considerable attention from researchers in recent years. However, the challenges and potential applications of multi-phase flow-induced vibration energy harvesting have rarely been explored. To bridge the research gap in the present energy harvesting studies based on two-phase flow, we investigated in detail the mechanism and potential benefits of the fluid–structure interaction between smart structures and two fluid phases (water and air) on the vibration energy harvesting performance. A piezoelectric energy harvester using air–water two-phase flow conditions is proposed for potential multifunctional applications. A T-shaped piezoelectric cantilever was used to harvest liquid sloshing energy in the proposed structure. A fluid–structure interaction containing two fluid phases (water and air) was theoretically modelled using the arbitrary Lagrangian-Eulerian technique. The experimental results showed that a prototype of the proposed structure can be used as a smart water bottle that simultaneously performs human-motion energy collection and acts as a drinking water bottle. The prototype achieved its maximum peak-to-peak voltage value (12.08 V) at 5 km/h for powering wireless IoT (Internet of Things) nodes. Furthermore, it can be used as an energy regenerative shock absorber to perform the dual functions of vibration damping and energy harvesting. Therefore, multi-phase flow-induced vibration energy harvesting shows great application potentials.

A monolithic, ALE finite-element-based strategy for partially submerged solids in an incompressible fluid flow using the mortar method

This work presents a two-dimensional monolithic finite-element-based strategy for fluid–structure interaction problems involving hyperelastic solids floating in an incompressible fluid. This monolithic strategy is based on the Arbitrary Lagrangian–Eulerian (ALE) formulation for the fluid domain, and the Lagrangian framework for the solid domain. The flexibility of the ALE technique permits us to treat the free surface of the fluid as a Lagrangian entity. The continuity requirements at the fluid–structure interface have been satisfied in a weak sense using the mortar method. The use of a monolithic strategy gives an robust and stable algorithm, and allows the user to take large time steps. The consistent linearization ensures a quadratic rate of convergence of the non-linear iterations at each time step. The robustness and accuracy of the proposed method are demonstrated by solving benchmark problems from the literature.

Numerical study on the installation effect of a jacked pile in sands on the pile vertical bearing capacities

The installation effect of a jacked pile in silica sand is investigated numerically. A simplified state-dependent dilatancy model is used to model the sand behavior and the sand grain crushing effect is considered by modifying the critical state line at large confining pressures. The Arbitrary Lagrangian-Eulerian (ALE) technique is adopted to model the pile penetration and the load-displacement behavior at the operational loading stage is simulated using standard finite element method with the initial states being the equilibrium of the pile-jacking-disturbed soil stress and void ratio fields and a free pile head. The numerical procedure has been verified against some calibration chamber tests and centrifuge tests. Simulations of wished-in-place piles are performed for the quantitative study of the installation effect. The results show that the capacity ratios between the jacked and wished-in-place piles become higher for long piles in dense sand. Linear fittings have been applied to obtain the capacity ratios as functions of the relative density and the penetration length-to-diameter ratio, which can be used for a quick estimation of the bearing capacity difference between jacked and wished-in-place piles.

Accumulated wear degradation prediction of railway friction block considering the evolution of contact status

In this work, a simulation methodology with the combination of finite element modeling, Archard theory, and Arbitrary Lagrangian-Eulerian (ALE) technique is proposed for the accumulated wear degradation prediction of railway friction block. The validation is conducted with a test bench from the perspectives of tribological and dynamic behaviors during the running-in and formal testing processes. The friction pair comprises a forged steel brake disc and a Cu-based powder metallurgy friction block. The results indicate that the contact area increases during the running-in process and the average contact pressure decreases first and then fluctuates around a stable value. In the formal testing process, although the accumulated wear mass and the wear mass per cycle increase with the number of braking cycles, the increase rate of friction block wear mass decreases rapidly in the first few cycles and then decreases slowly. The prediction error of the proposed method for the accumulated wear mass is less than 5%. The research in this work is helpful to have a deep understanding of the wear degradation mechanism of friction block and can provide an effective method for the prediction of friction block wear degradation.

Thin Film Extensional Flow of a Transversely Isotropic Viscous Fluid

Many biological materials such as cervical mucus and collagen gel possess a fibrous micro-structure. This micro-structure affects the emergent mechanical properties of the material, and hence the functional behaviour of the system. We consider the canonical problem of stretching a thin sheet of transversely-isotropic viscous fluid as a simplified version of the spinnbarkeit test for cervical mucus. We propose a novel solution to the model constructed by Green & Friedman by manipulating the model to a form amenable to arbitrary Lagrangian-Eulerian techniques. The system of equations, reduced by exploiting the slender nature of the sheet, are solved numerically and we discover that the bulk properties of the sheet are controlled by an effective viscosity dependent on the evolving angle of the fibres. In addition, we confirm a previous conjecture by demonstrating that the centre-line of the sheet need not be flat, and perform a short timescale analysis to capture the full behaviour of the centre-line.

오일러리안 무격자법을 이용한 진동하는 2차원 원주주위 점성 유동 해석

In this study, a newly developed Eulerian gridless solver for the simulation of a two-dimensional unsteady incompressible viscous flow around a moving body is introduced. A moving domain method based on the Arbitrary Lagrangian Eulerian(ALE) technique is adopted to implement the moving body. The spatial derivatives of the governing equation are solved by weighted moving least square(WMLS) interpolation over the point cloud. The fractional time step method is adopted and the Poisson equation for pressure is solved successively in the WMLS sense. Simulations of flows around a cylinder moving with constant speed and in harmonic motion are solved for validation and the results are compared with experiments and other CFD simulations.<BR> For the constant speed cases, the drag, lift and pressure coefficients estimated by present method were well matched with other results. From the computational results under the harmonic motion with changing main parameters such as Keulegan-Carpenter and Reynolds numbers, the drag and inertial force coefficients using the Fourier series approach were obtained and compared with other results. Even small discrepancy exist, the coefficients were good agreement with other ones.

Effects of charge relaxation on the electrohydrodynamic breakup of leaky-dielectric jets

The breakup process of a charged, leaky-dielectric jet subjected to an axial perturbation is computationally analysed from the perspectives of linear and nonlinear dynamics using the arbitrary Lagrangian–Eulerian technique. The linear dynamics of the leaky-dielectric jet is quantitatively predicted by the dispersion relation from the linear stability analysis. Regarding the nonlinear dynamics, it is found that the charge relaxation is responsible for the radial compression of satellite droplets, which is validated by experiments. Two types of charge relaxations, namely, ohmic conduction and surface charge convection, define the pinching process into three breakup modes, i.e. ligament pinching, end pinching and transition pinching. In the ligament-pinching mode, the ohmic conduction dominates the jet breakup since the charge relaxes to the jet ligament instantaneously. In contrast, the surface charge convection takes effect in the end-pinching mode since the surface charge is convected to the jet end via fluid flow. When the ohmic conduction is comparable to the surface charge convection, the breakup occurs simultaneously at the end and the ligament. Finally, the influences of the perturbed wavenumber, the electric field intensity and the viscosity on the breakup mode and the local dynamics at pinch-off are comprehensively discussed.

Aeroacoustic simulation of flexible structures in low Mach number turbulent flows

This work deals with the numerical simulation of aeroacoustic sound generated by flexible structures in low Mach number turbulent flows. A partitioned computation scheme is investigated to solve the coupled fluid-solid problem. A hybrid method based on the acoustic/viscous splitting technique is applied for aeroacoustic computation using large eddy simulations (LES) to resolve the incompressible turbulent flow field. Combining the acoustic/viscous splitting approach with a Kirchhoff wave extrapolation method enables an efficient evaluation of the far-field noise. The arbitrary Lagrangian-Eulerian (ALE) technique is applied for both the incompressible flow field and the acoustic field to take moving boundaries into account. Validation of the acoustic computation process is presented for stationary and moving surfaces. Finally, the approach described in this work is applied to study the aeroacoustic characteristics of a membrane airfoil.