Arbitrary Lagrangian Eulerian Adaptive Meshing Research Articles

Prediction of the End-Bearing Capacity of Axially Loaded Piles in Saturated and Unsaturated Soils Based on the Stress Characteristics Method

This study proposed an analytical approach for predicting the end-bearing capacity of driven piles that are subjected to axial loads in saturated and unsaturated soils. This is a generalized approach in which the stress characteristic method is employed successfully for both saturated and unsaturated soils. An iterative technique computer code was developed for the proposed analytical approach extending the finite difference method to develop solutions with the aid of MATLAB (version 2019a) that provides graphical output to visualize the results. The results from the proposed approach were compared against measurements for 13 pile load tests that include 11 in saturated soils and 2 in unsaturated soils, with good agreement. In addition, numerical analyses were performed using ABAQUS (version 6.14) to simulate the driven pile penetration and pile loading by employing the arbitrary Lagrangian–Eulerian adaptive mesh methods. The comparisons between the numerical predictions and measurements from a published model pile test suggested that the ultimate bearing capacity is well predicted by the finite-element model in comparison to the proposed analytical method. However, the proposed analytical method was simple for use in engineering practice applications to estimate the end-bearing capacity of pile foundations in both saturated and unsaturated soils.

Wear modelling and sealing performance prediction of C/C composite finger seal

Due to the high speed and high pressure operating conditions, wear between the finger seal and the rotor is inevitable, and this leads to an increase of leakage clearance and becomes an important factor affecting the seal life. The theory of anisotropic elasticity was employed to describe the mechanical characteristics of the seal material. An improved Archard wear model was proposed to calculate the nodal wear rate, and the local wear direction was also determined. The wear simulation model and procedure were established based on the Arbitrary Lagrangian Eulerian adaptive mesh strategy. The effects of material density, fabric orientation, pressure differential and rotor speed on the wear characteristics of finger seal and the change of leakage clearance caused by wear loss were studied. The results show that the wear first occurs at the heel area of the finger foot bottom and gradually extends to the toe area. C/C (carbon fibre reinforced carbon matrix) composite finger seal with higher material density has smaller leakage clearance and wear depth. With the increase of fabric orientation angle, the wear depth in the heel area of finger foot is smaller, and the circumferential wear area is narrower. The average wear depth of finger seal decreases with the orientation angle. When the orientation angle is 0, the seal leakage clearance is smaller. The increase of pressure differential not only aggravates the seal wear, but also expands the wear area, and also increases the average contact pressure and leakage clearance. Increasing the rotor speed make the wear depth of the heel area of finger foot gradually increase, but the wear area becomes narrower. The average contact pressure decreases and the average leakage clearance increases. This study provides a theoretical method and basis for the prediction and evaluation of the wear life and performance of C/C composite finger seal.

Experiment-based numerical evaluation of the surface recession of C/C–SiC composites under the high-energy laser

In this paper, we developed a multi mechanism coupling finite element model to predict the surface recession of C/C–SiC composites on the basis of the ablation phenomena. In particular, we took into account temperature-dependent properties of component materials, heat convection, and radiation in the ultra-high temperature range. By combining a user-defined subroutine and arbitrary Lagrangian-Eulerian adaptive meshing technique, the surface recession of C/C–SiC composites was captured. The predicted ablation depth agreed well with experimental results. The trend of the ablation rate between simulations and experiments was almost the same. Meanwhile, the effects of the laser powers on ablation behaviors of C/C–SiC composites were investigated. It was found that low laser powers had little effect on the ablation rate while the ablation rate increased first and then decreased for high laser powers.

Experimental and numerical investigation on wear behavior of carbon-fiber-reinforced carbon matrix composite used in rotary gas seals

This paper presents a numerical method for simulating progressive wear of the carbon-fiber-reinforced carbon matrix composite used in rotary gas seals due to high experimental cost. In this study, the carbon-fiber-reinforced carbon matrix composite wear rates are experimentally measured, and a formula for the carbon-fiber-reinforced carbon matrix composite wear rates and material design parameters (orientation angles and densities) and operating parameters (load and velocities) is fitted as an input to the wear simulation. A finite element incremental wear simulation procedure for the pin-on-disk wear problem is presented by calculating the local nodal wear rate and wear direction and by introducing the Arbitrary Lagrangian Eulerian adaptive meshing method. In the procedure, the relation between the anisotropy of carbon-fiber-reinforced carbon matrix composite and the varied orientation angle is considered. Results show that the calculated wear volume agrees well with the experimental data. And then the numerical methodology is utilized to investigate the effects of time, orientation angle and operating conditions on the disk wear. The developed numerical methodology could be applied to other sliding wear problems in engineering machinery.

Dynamic spherical cavity expansion in Gurson materials with uniform and non-uniform distributions of porosity

This paper investigates both theoretically and using finite elements the elastoplastic field induced by a pressurized spherical cavity expanding dynamically in an infinite medium modelled using the Gurson–Tvergaard–Needleman porous plasticity approach. The theoretical model, which assumes that the porosity is uniformly distributed in the material and the cavitation fields are self-similar, incorporates artificial viscous stresses into the original formulation of Cohen and Durban (2013b) to capture the shock waves that emerge at high cavitation velocities. The finite element calculations, performed in ABAQUS/Explicit (2013) using the Arbitrary Lagrangian Eulerian adaptive meshing available in the code, simulate the cavity expansion process in materials with uniform and non-uniform distributions of porosity. The finite element results show that the distribution of porosity has small influence on the cavitation velocity, as well as on the location of the shock wave, which are primarily determined by the cavity pressure and the average material properties. In contrast, it is shown that the intensity of the shock wave, evaluated based on the maximum value of the plastic strain rate within the shock, depends on the local material porosity. The ability of the theoretical model to reproduce the numerical results obtained for the various distributions of porosity used in this work is exposed and discussed.

A numerical model for continuous impact pile driving using ALE adaptive mesh method

Pile installation through consecutive hammer impacts is called impact pile driving which has increasingly exploited as the most efficient method, though the generated ground vibrations have great potential to undermine its surrounding structures. However, correct numerical simulation of pile driving process to credibly predict the ground vibrations has been the main problem to date. Hence, to significantly improve the predictions of ground vibrations, a continuous pile driving model from the ground surface to final installation depth, unlike previous common discontinuous pile driving, was employed using an arbitrary Lagrangian-Eulerian (ALE) adaptive mesh method, accurate simulation of the pile-soil interaction, and elimination of previous researchers simplified assumptions. The results were verified with field measurements which indicate a remarkably better match compared to the previous numerical studies. Moreover, an elastic pile consideration rather than rigid conditions was led to a better consistency of the ground vibration results with field measurements.

Stability and efficiency studies in the numerical simulation of cone penetration in sand

This paper evaluates the effect of analysis parameter choices on the stability and efficiency of modelling cone penetration into sand. This very large deformation quasi-static boundary-value problem is modelled here using the arbitrary Lagrangian–Eulerian adaptive mesh technique available within Abaqus/Explicit. The sand response is captured using a hypoplastic constitutive model. It is demonstrated that many choices of analysis parameters lead to spurious results, some of which show clear instability, while other combinations show reasonable stability but over-estimation of the cone resistance. The accuracy of the numerical solution is shown through comparison against centrifuge experimental data for two different relative densities of the sand.

Progressive wear prediction of C/C composite finger seal based on ALE adaptive meshing strategy

Leakage clearance between the finger seal and the rotor is influenced by the seal wear, and a large leakage clearance may cause sealing failure. The aim of this study is to develop a predictive method to simulate the progressive wear of C/C composite finger seal. A finite element model is presented for the finger seal dynamic motion. A wear model is built by calculating the local wear rate for the nodes on finger foot bottom and by introducing an Arbitrary Lagrangian Eulerian adaptive meshing strategy. Progressive wear analysis is implemented by integrating the finger dynamic motion and the wear model. The results show that the contact pressure of finger seal is decreased and the leakage clearance is increased with operating time due to progressive wear. Compared to the case that the non-woven cloth is parallel to rotor surface (O1) and the case that the non-woven cloth is perpendicular to rotor surface but the laminated direction is perpendicular to sliding direction (O2), low leakage and low wear are obtained when the non-woven cloth is perpendicular to rotor surface and the laminated direction is the same as sliding direction (O3). In addition, the wear depth of finger foot and the leakage clearance between the finger seal and rotor are both increased with pressure differential and rotor speed.

Numerical Simulation of Polyurethane Pad Punching Process

A numerical simulation was conducted to investigate the effect of the punching clearance, the thickness of sheet, and the hardness of polyurethane pad on the process of punching by finite element program ABAQUS which based on shear failure criterion and arbitrary Lagrangian-Eulerian adaptive meshing method. And the collapse height dimension and width dimension tendency of the sheet under different control parameters was analyzed after punching process according to this simulation result. The results show that the collapse height dimension and width dimension decreased with the increase of the polyurethane hardness, it means the cross section quality perspicuously has been increased; the collapse height dimension and width dimension decreased with the increasing of the sheet thickness; while the influence of the punching gap is indistinctive.

Laser ray tracing in a parallel arbitrary Lagrangian-Eulerian adaptive mesh refinement hydrocode

ALE-AMR is a new hydrocode that we are developing as a predictive modeling tool for debris and shrapnel formation in high-energy laser experiments. In this paper we present our approach to implementing laser ray tracing in ALE-AMR. We present the basic concepts of laser ray tracing and our approach to efficiently traverse the adaptive mesh hierarchy.

Modeling Aspects of High Velocity Impact of Particles in Cold Spraying by Explicit Finite Element Analysis

In this study, an examination of cold spray particle impacting behavior using the ABAQUS/Explicit program was conducted for typical copper material (OFHC). Various combinations of calculation settings concerning element type, Arbitrary Lagrangian Eulerian adaptive meshing, contact interaction, material damage, etc., were examined with the main focus on the element excessive distortion and its effect on the resultant output. The effect of meshing size on the impact behavior was also clarified compared to the previous results obtained by using the LS-DYNA code. Some fundamental aspects on modeling of cold spray particle deformation are discussed.

Some aspects on 3D numerical modeling of high velocity impact of particles in cold spraying by explicit finite element analysis

Three-dimensional modeling of particle impacting behavior in cold spraying by using ABAQUS/Explicit was conducted for copper and other materials. Various combinations of calculation settings concerning material damage, Arbitrary Lagrangian Eulerian adaptive meshing, distortion control and contact interaction were examined. The effects of meshing size and particle size on the impact behavior were analyzed compared to the previous results. The results show that the simulations with material damage cope well with the element excessive distortion and the resultant output is more reasonable than that obtained without material damage. In addition, the meshing size has less effect on the output with the material damage than without material damage. Although particle size has little effect on the morphologies of the deformed particles, it has some effect on the failure of elements at contact interfaces. The critical velocity for particle deposition could be estimated given the appropriate material properties.

Interface reconstruction in two- and three-dimensional arbitrary Lagrangian-Eulerian adaptive mesh refinement simulations

Modeling of high power laser and ignition facilities requires new techniques because of the higher energies and higher operational costs. We report on the development and application of a new interface reconstruction algorithm for chamber modeling code that combines ALE (Arbitrary Lagrangian Eulerian) techniques with AMR (Adaptive Mesh Refinement). The code is used for the simulation of complex target elements in the National Ignition Facility (NIF) and other similar facilities. The interface reconstruction scheme is required to adequately describe the debris/shrapnel (including fragments or droplets) resulting from energized materials that could affect optics or diagnostic sensors. Traditional ICF modeling codes that choose to implement ALE + AMR techniques will also benefit from this new scheme. The ALE formulation requires material interfaces (including those of generated particles or droplets) to be tracked. We present the interface reconstruction scheme developed for NIF's ALE-AMR and discuss how it is affected by adaptive mesh refinement and the ALE mesh. Results of the code are shown for NIF and OMEGA target configurations.