Documents published in Scipedia

• A finite deformation micropolar peridynamic theory and its application to metamaterials

  . Sajal, P. Roy

  WCCM2024.

  
  

  Abstract

  Metamaterials with engineered microstructures exhibit exceptional properties such as negative Poisson’s ratio, energy absorption, and bandgap. These materials can prevent propagation of elastic waves in certain range of frequency called bandgap. The microstructure of these materials affects the overall response of the structures. Microstructures may undergo significant rotations and their rotary inertia needs to be considered along with deformation. As the metamaterials in the study involve cracks, we develop a finite deformation micropolar peridynamics (PD) theory. The proposed PD micropolar theory is validated by comparing the results obtained from the boundary element solutions of plate with a hole. The response of metamaterials with periodic arrangement of holes and cracks is studied under static and dynamic loads and the results are compared with the nonpolar PD theory.

  Abstract
  Metamaterials with engineered microstructures exhibit exceptional properties such as negative Poisson’s ratio, energy absorption, and bandgap. These materials can prevent [...]

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• Generative model to predict the deformation field of CFRP laminates with geometric deviations in wing assembly

  Y. Liu, Y. Zhao, Q. Lin, W. Pan

  WCCM2024.

  
  

  Abstract

  Thin-walled structure of CFRP laminates is widely utilized in the assembly of aircraft wings. The deformation field generated during the assembly process can impact the assembly performance of the structure, thereby influencing the product quality and operational performance of the wings. The geometric deviations on the critical mating surfaces of the laminate and physical parameters are key factors influencing the deformation fields during the assembly process. Analyzing the mapping relationship between fusion assembly data and deformation field plays a crucial role for assessing the assembly results. The traditional analysis methods only consider the impact of simple directional deviations on assembly results and do not comprehensively account for the multi-source input. This paper proposes a multi-source assembly input -deformation analysis framework for CFRP bolted joints in aircraft wing assembly. Taking the parameters representing the geometric deviations and physical parameters as input and deformation field as output, a conditional generative model is employed to learn the influence pattern of the geometric deviations on the deformation field. The framework establishes a prediction model from the deviation field to the deformation field and introduces specific accuracy metrics. Corresponding simulations demonstrate that the proposed method can predict assembly deformation field more efficiently than traditional numerical methods.

  Abstract
  Thin-walled structure of CFRP laminates is widely utilized in the assembly of aircraft wings. The deformation field generated during the assembly process can impact the assembly [...]

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• A fast prediction method for bearing strength of aircraft composite bolted structures considering initial assembly deviation

  Q. Lin, Y. Zhao, Y. Liu, W. Pan

  WCCM2024.

  
  

  Abstract

  Bearing limitation is a key performance indicator for composite bolted joints. Assembly process parameters such as washer structural parameters, interfacial friction coefficients and tightening process parameters have a significant effect on the bearing limitation. In the actual production process, there are inevitably deviations between the assembly process parameters and their design values. The accumulation of assembly process deviations leads to an obvious dispersion of the bearing limitation, which makes it difficult for composite bolted joints to be reliably in service. In this paper, the dispersion of assembly process parameters is experimentally tested to quantitatively characterize its uncertainty. Then, based on the high fidelity finite element analysis method, a data set of bearing limitation under different assembly process parameters is prepared. A data-driven algorithm is used to establish a fast prediction model for bearing limitation. The fast prediction model is used to realize the uncertainty analysis and the reliability evaluation for the bearing limitation. The established analysis method and the obtained conclusions can provide a reference for the reliability design and analysis of composite bolted joints.

  Abstract
  Bearing limitation is a key performance indicator for composite bolted joints. Assembly process parameters such as washer structural parameters, interfacial friction coefficients [...]

  • 14
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• Hybrid quantum algorithm for the Lattice-Boltzmann method

  D. Wawrzyniak, J. Winter, S. Schmidt, T. Indinger

  WCCM2024.

  
  

  Abstract

  We present a quantum algorithm for computational fluid dynamics based on the Lattice-Boltzmann method. Our approach involves a novel encoding strategy and a modified collision operator, assuming full relaxation to the local equilibrium within a single time step. Our quantum algorithm enables the computation of multiple time steps in the linearized case, specifically for solving the advection-diffusion equation, before necessitating a full state measurement. Moreover, our formulation can be extended to compute the non-linear equilibrium distribution function for a single time step prior to measurement, utilizing the measurement as an essential algorithmic step. However, in the non-linear case, a classical postprocessing step is necessary for computing the moments of the distribution function. We validate our algorithm by solving the one dimensional advection-diffusion of a Gaussian hill. Our results demonstrate that our quantum algorithm captures non-linearity.

  Abstract
  We present a quantum algorithm for computational fluid dynamics based on the Lattice-Boltzmann method. Our approach involves a novel encoding strategy and a modified collision [...]

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• On the iterative solution of saddle point problems using a symmetric positive definite preconditioner

  P. Devloo, G. Avancini, M. Meneghel

  WCCM2024.

  
  

  Abstract

  Saddle point problems frequently appear in many mathematical and engineering applications. Most systems of partial differential equations with constraints give rise to saddle point linear systems. Typical examples include mixed finite element formulations to solve fluid flows and/or elasticity problems under full incompressibility. The inversion of saddle point problems is challenging due to inherent numerical instability in the direct inversion methods. Many direct and iterative methods have been proposed to overcome this challenges, such as the Schur complement and the Uzawa’s method. In the context of mixed finite element for incompressible flows using stable H(div)-L2 spaces for velocity and pressure, we propose an iterative method that can effectively solve a saddle point problem iteratively by summing a small compressibility to the original matrix. The preconditioning matrix is symmetric positive definite, which allows the usage of Cholesky decomposition and/or CG-like iterative solvers to compute the incremental solution for the velocities unknowns. A procedure to compute the average pressure of each element of the incompressible problem is developed using the unbalanced fluxes caused by the compressibility perturbation. The average is updated during the iterative process as a function of the velocity increment at each iteration.

  Abstract
  Saddle point problems frequently appear in many mathematical and engineering applications. Most systems of partial differential equations with constraints give rise to saddle [...]

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• Effect of the capillary force on the repose angle of granular materials

  W. Ziye, T. Yong

  WCCM2024.

  
  

  Abstract

  The angle of repose does affect the behavior of granular materials and has a wide range of applications. The addition of a small amount of liquid can dramatically change the properties of granular media, leading to an increase in the repose angle. This change is mainly attributed to the capillary force resulting from the liquid bridge when the small amount of water was introduced. The capillary force as an attractive force increases the interaction between particles and becomes a dominant factor affecting the angle of repose because it is usually stronger than gravity. In this paper, a new discrete element method (DEM) model was developed in which the capillary force was calculated by the liquid bridge model based on toroidal approximation. The developed DEM model linked the microscopic liquid bridge volume to the macroscopic water content and it also considered the effect of liquid bridge breakage and formation on capillary force. The numerical model was first validated by comparing the experimental and numerical results. Then, the effects of surface tension, volume of the liquid bridge, and the contact angle are studied numerically. Finally, the empirical equation between water content and angle of repose is given under the present simulation conditions. This work will provide a deep understanding for the effect of capillary on the angle of repose.

  Abstract
  The angle of repose does affect the behavior of granular materials and has a wide range of applications. The addition of a small amount of liquid can dramatically change the [...]

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• Model-based design approach finding optimal liquid cooling flow path for electric vehicle battery

  D. Aketo, K. Ono

  WCCM2024.

  
  

  Abstract

  Today many electronic devices that generate significant heat are required to be equipped with liquid cooling systems to reduce their temperature. Since the liquid flow path in the cooling system affects cooling performance, determining flow path in the early development phase can improve the efficiency of the downstream development process and reduce the total cost. In this paper, we propose a model-based analysis system for thermo-fluid phenomena based on CFD results and demonstrate the parametric optimization of flow path.

  Abstract
  Today many electronic devices that generate significant heat are required to be equipped with liquid cooling systems to reduce their temperature. Since the liquid flow path [...]

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• Input-output reduced order modeling for public health intervention evaluation

  A. Viguerie, E. Jacobson, C. Piazzola, H. Islam

  WCCM2024.

  
  

  Abstract

  In recent years, mathematical models have become an indispensable tool in the planning, evaluation, and implementation of public health interventions. Models must often provide detailed information for many levels of population stratification. Such detail comes at a price: in addition to the computational costs, the number of considered input parameters can be large, making effective study design difficult. To address these difficulties, we propose a novel technique to reduce the dimension of the model input space to simplify model-informed intervention planning. The method works by first applying a dimension reduction technique on the model output space. We then develop a method which allows us to map each reduced output to a corresponding vector in the input space, thereby reducing its dimension. We apply the method to the HIV Optimization and Prevention Economics (HOPE) model, to validate the approach and establish proof of concept.

  Abstract
  In recent years, mathematical models have become an indispensable tool in the planning, evaluation, and implementation of public health interventions. Models must often provide [...]

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• Computational model for local buckling of compressively loaded omega-stringer-stiffened panels

  C. El Yaakoubi-Mesbah, C. Mittelstedt

  WCCM2024.

  
  

  Abstract

  Thin-walled composite structures are used in applications such as aircraft and spacecraft due to their low weight and corresponding high stiffness properties. To optimize the potential of these structures to the fullest extent, a complete understanding of their stability behavior is required. Thereby, uniaxial compression describes an important load case that is investigated. A closed-form analytical method based on the energy method for determining the local buckling load of omega-stringer-stiffened panels is presented. The stiffened panel under consideration consists of the skin plate with eccentrically attached stringer feet along the longitudinal sides of the panel, while the remaining part of the omega-stringer is modeled by corresponding elastically restrained edges. Due to the applied stringer feet, stiffness discontinuities occur in the stiffened panel. This is covered by the presented method, whereas in comparable studies in the literature, a homogeneous stiffness is often assumed across the entire panel. To evaluate the new analysis method, a comparison with the numerical solution of the corresponding Levy-type ´solution and the finite element analysis is being drawn.

  Abstract
  Thin-walled composite structures are used in applications such as aircraft and spacecraft due to their low weight and corresponding high stiffness properties. To optimize [...]

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• Developments in the use of the Bonded Particle Model to study ore fracture

  T. Oladele, D. Weatherley, L. Bbosa

  WCCM2024.

  
  

  Abstract

  In mineral processing, ore fracture is an essential first step for which the objective is to increase the exposed surface area of the valuable mineral, thereby increasing the likelihood of liberation in subsequent separation stages. This process is well known to be energy-intensive, and increasing scrutiny around sustainable practices has heightened the need to examine the efficiency of current industry approaches. Factors such as mineralogical structure and inherent weakening in the form of micro cracks are known to affect ore breakage mechanisms. However, isolating and investigating individual factors under experimental conditions is challenging and typically impractical. Numerical techniques such as the Bonded Particle Model-Discrete Element Method (BPM-DEM) have been developed as a means of investigating in isolation, the effects of different factors on ore breakage behaviour under closely controlled breakage conditions. In this work, the robustness of the BPM-DEM in predicting fracture characteristics during SILC impact breakage is evaluated. Thereafter, the BPM-DEM is used to analyse the internal mechanical response of a simulated rock specimen under impact loading commensurate with that of the SILC. The method is shown to be an insightful opportunity to study intrinsic and extrinsic rock properties during dynamic loading and breakage

  Abstract
  In mineral processing, ore fracture is an essential first step for which the objective is to increase the exposed surface area of the valuable mineral, thereby increasing [...]

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