Documents published in Scipedia

• Modeling the effect of backbone instabilities and guest occupancies on interfacial and structural processes and dynamics of sII gas hydrate systems using molecular dynamics

  S. Mathews, P. Servio, A. Rey

  WCCM2024.

  
  

  Abstract

  Gas hydrates are inclusion compounds that form in conditions of low temperature and high-pressure systems with water and gaseous molecules. Their potential use in carbon capture and storage, energy exploitation, and flue gas extraction makes them prime candidates for various engineering applications and climate change mitigation technologies. However, their nucleation is poorly understood and the effect of guest molecule interactions with the host on macroscale properties has yet to be elucidated. Herein we study the optimal positions of a point mass, linear molecule, and planar triangular guest molecule using a distance minimization technique that can replicate preliminary density functional theory results. The linear molecule shows strong alignment to hexagonal phases of cages, while the triangular guest molecule shows very distinct positions. These positions indicate a lower number of degrees of freedom, which in turn affect the molecules’ ability to move and vibrate in heat absorption, for example. Additionally, it shows that hydrate formation may only be possible when the guest is oriented a certain way, providing an avenue to control nucleation by adjusting guest molecule position with external fields.

  Abstract
  Gas hydrates are inclusion compounds that form in conditions of low temperature and high-pressure systems with water and gaseous molecules. Their potential use in carbon capture [...]

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• Beyond lubrication flow for thin-film manufacturing

  R. Secor, R. Rao, W. Ortiz

  WCCM2024.

  
  

  Abstract

  Reynolds’ hydrodynamic lubrication theory has been used extensively to analyze and quantify thin film manufacturing1 . Applications span liquid flows in bearings, coatings, and molds, and gas flows between rigid or elastic surfaces. To enable further applications of efficient, reduced-order modelling, we pursue streamlined algorithms for non-Newtonian liquids in marginally “thin” geometries with multiple phases and capillarity. The goal is expanded use of “modified”, non-traditional lubrication methods to bring physics-based knowledge to bear in process design, optimization, and control methods.

  Abstract
  Reynolds’ hydrodynamic lubrication theory has been used extensively to analyze and quantify thin film manufacturing1 . Applications span liquid flows in bearings, coatings, [...]

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• Towards a multiscale computational framework for simulating flow-mediated crystallization based on phase-field crystal formalisms

  L. Willis, R. Rao, L. Liu

  WCCM2024.

  
  

  Abstract

  We lay the foundation and framework for a multiscale approach for studying crystallization in the presence of flow by coupling the Structural Phase Field Crystal (XPFC) formalism with the Navier-Stokes equations. We discuss the numerical techniques and verify the formalism against previous attempts with the vanilla Phase Field Crystal (PFC) formalism. Moreover, with this new Hydrodynamically coupled Structural Phase Field Crystal (HXPFC) method, we discuss unreported global and local crystal microstructural transformation induced by the flow. The HXPFC method establishes a framework to predict more complex crystal structures while incorporating physics relevant to film coating flows.

  Abstract
  We lay the foundation and framework for a multiscale approach for studying crystallization in the presence of flow by coupling the Structural Phase Field Crystal (XPFC) formalism [...]

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• Design of in-mold decoration mold for complex thin-walled parts

  J. Dong, D. Shi, J. Wang

  WCCM2024.

  
  

  Abstract

  In order to address the issues of warping deformation and long-term production of complex thin-walled parts during In-Mold Decoration (IMD) production, the structure design of the IMD mold was carried out with the humidifier top cover as the production object. To ensure the flow characteristics of molten plastic in the mold during the injection molding process, based on the technical contradiction analysis of TRIZ theory, the hot runner mold is improved to mix cold and hot runner, that is, the sprue is set as a hot runner, the branch runner is set as a cold runner, and use a multi-point injection cold gate solution. And construct a complex structure numbering method to arrange and design various complex structure undercut-forming side insert mechanism, design of special structure lifters along the same direction of motion the two inverted buckle at the same time undercut-forming. The lifter mechanisms are used to complete the molding, parting, demolding and ejection of plastic parts, multiple uses for one mechanism. In order to optimize product quality and improve production efficiency, providing theoretical and empirical support for the production of complex thin walled parts with IMD molds. Then design the cooling system and demolding mechanism separately. Finally, based on Moldflow software, the final flow of plastic part warpage analyzed. The maximum warping deformation of the product is 0.7055mm, while the maximum warping deformation of the traditional cold runner mold is 0.8519mm, reducing the warping deformation of the humidifier top cover.

  Abstract
  In order to address the issues of warping deformation and long-term production of complex thin-walled parts during In-Mold Decoration (IMD) production, the structure design [...]

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• Numerical simulations of origami-based folded carbon-reinforced concrete shells

  H. Spartali, L. Mester, G. Kikis, S. Klarmann

  WCCM2024.

  
  

  Abstract

  The advantages of carbon-reinforced concrete (CRC) over traditional concrete elements reinforced with steel, including high strength, low weight, and corrosion resistance, make it a promising material for thin, efficient, and more sustainable designs. As the demand for less CO2-intensive materials such as concrete grows, a shift from simple massive elements to thin-walled elements with complex geometries is becoming increasingly necessary. However, to seek optimal design variants, efficient nonlinear numerical calculations that provide reasonable predictions of the structural behavior, including the stress-redistribution process and the failure mechanisms are essential. This paper presents FEM simulations of origami-based folded CRC shells that were experimentally investigated in a previous study. Two FEM modeling approaches were used, employing a smeared and a discrete representation of the carbon reinforcement. For both approaches a damage plasticity model for the concrete has been used. The load-deflection response from the discrete approach closely matches the experimentally obtained curves. Despite an overestimation of the load capacity, the computationally less expensive smeared FEM model qualitatively reproduces the structural response and the correct failure mechanism. Therefore, the quality of the results obtained from the smeared model is sufficient to determine preferable design variants in a typical design scenario. This is necessary to provide a deeper understanding of the structural behavior of these folded elements and to facilitate the sustainable design and application of thin-walled CRC elements in the future.

  Abstract
  The advantages of carbon-reinforced concrete (CRC) over traditional concrete elements reinforced with steel, including high strength, low weight, and corrosion resistance, [...]

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• Development of a design methodology for slender carbon-reinforced concrete columns in axial compression based on EC3

  Y. Ciupack, J. Giese, M. Curbach, B. Beckmann

  WCCM2024.

  
  

  Abstract

  Advancements in concrete construction, such as carbon-reinforced and ultra-high performance concretes, enable the creation of slender, high-capacity structures, enhancing resource efficiency and reducing CO2 emissions. Despite the clear advantages of such innovative material composites, challenging load-bearing and deformation behavior emerges in slender carbon-reinforced concrete components, indicating potential stability issues. To address this concern, current research is dedicated to experimental and analytical investigations of the structural behavior and failure of slender components in compression made of carbon reinforced concrete, aiming to enhance our understanding of stability-related aspects.

  Abstract
  Advancements in concrete construction, such as carbon-reinforced and ultra-high performance concretes, enable the creation of slender, high-capacity structures, enhancing [...]

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• Possibilities for numerical model validation through computed tomography generated data

  M. Pahn, C. de Sousa, S. Grzesiak, J. Giese

  WCCM2024.

  
  

  Abstract

  In order to make accurate predictions of the structural behaviour of non-metallic reinforced concrete elements, one of the key problems in the development of this type of new material system is the capacity of modelling the load transfer mechanisms between the concrete matrix and the reinforcement elements. To predict the load-deflection response up to ultimate limit state conditions, a wide range of numerical simulation approaches, with capability of modelling the bond behaviour between the different materials has been proposed over the years and compared to experimental results. This research work presents new possibilities for comparing numerical finite elements models with laboratory data generated by computed tomography, namely in the context of three-point bending tests performed on carbon-reinforced concrete specimens. The aim is to present the potential of in situ computed tomography for validation of numerical simulations. Examples of computed tomography generated quantitative results and data visualisation are shown, which focus on generated displacement fields and crack patterns.

  Abstract
  In order to make accurate predictions of the structural behaviour of non-metallic reinforced concrete elements, one of the key problems in the development of this type of [...]

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• Examples of analysis methods for ultrasonic vibration-assisted machining

  S. Aoki

  WCCM2024.

  
  

  Abstract

  Ultrasonic vibration has been applied to many machining processes. It has been reported that the application of ultrasonic vibration to machining has improved machining efficiency and accuracy. In this report, ultrasonic vibration is applied to welding, drilling, and knurling, and its effects are shown through experiments and analyses. In welding, it is shown that ultrasonic vibration can reduce tensile residual stress. In addition, the simulation method using a simple model showed that residual stress is reduced by the plastic deformation caused by ultrasonic vibration. In the drilling process, it was found that the surface roughness of the machined surface was improved when ultrasonic vibration was used. The conditions under which the surface roughness is improved by the impulse due to cutting resistance were also determined. In knurling, it was found that the pressing and friction forces were reduced by the use of ultrasonic vibration. It was also shown that the reduction in pressing force is expressed as the product of the equivalent mass and the amplitude of ultrasonic vibration

  Abstract
  Ultrasonic vibration has been applied to many machining processes. It has been reported that the application of ultrasonic vibration to machining has improved machining efficiency [...]

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• Coupled twin conical funnels or conical hoses: an internal process of dynamic flow distribution

  R. Ferreyra

  WCCM2024.

  
  

  Abstract

  The first objective of this study is to revisit an analytical test by the author that helps now for a prediction and explanation for the likely physical existence of twin funnels in the fluid crossed by shock wave, under certain conditions. These funnels function like a conical hose within shock waves traveling through matter. In terms of the laws of continuity, momentum, and energy the classical shock wave model is empowered with a not widespread actual function that explains a nonlocal physical phenomenon of matter distribution. The second objective is the recognition and application of two almost new analytical boundary conditions V1S = −V1 and 1 1 M S = iM , provided in the recent past that open the theory to the, at least, analytical existence of hoses or coupled twin funnels. Finally, given that supersonic and hypersonic solid cones are related to theoretical, experimental, natural, aeronautical, astronautical, geophysical and industrial interests, among others, certain analytical regions derived from this recently characterized formulation are shown and hoses or twin funnels located among them. These regions can be visualized on the plot of cone angle, shock angle, and free-stream Mach number for analogy, comparison, and prediction.

  Abstract
  The first objective of this study is to revisit an analytical test by the author that helps now for a prediction and explanation for the likely physical existence of twin [...]

  • 244
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• Determination of high-order frequency response of nonlinear systems using the arc-length method

  L. Pini Tanabe, A. Serpa

  WCCM2024.

  
  

  Abstract

  While linear systems have been extensively studied in the past few decades, systems with strong nonlinearities are not as widely investigated. One of the reasons why these are less applied in engineering is due to the fact that solving nonlinear equations usually demands a steep increase in processing capacity and time when compared to their linear counterparts. As computers become more powerful, significantly more advanced nonlinear systems can be studied and analyzed, providing solutions that are more accurate for real-world applications. When it comes to frequency analysis, it is possible that nonlinear frequency response shows the phenomena of hardening or softening. In this case, the resonance peaks of the frequency response are tilted to the right or left, respectively, in comparison with linear frequency response. The consequences of these phenomena might prove essential to safety assessment of real-life structures as the resonance peak might greatly differ from those obtained in a linear analysis. In this study, the high-order frequency response of the Helmholtz-Duffing oscillator is analyzed in order to evaluate its influence on the system. The oscillator exhibits Duffing nonlinearities represented by cubic springs and Helmholtz nonlinearities represented by quadratic springs. The high-order harmonic balance method was used to determine the dynamic equation in the frequency domain. The nonlinearities were numerically integrated based on the coefficients of the Fourier series. Originally used to find the solution path of nonlinear static structural analyses, the arc-length method was adapted to determine the nonlinear frequency response

  Abstract
  While linear systems have been extensively studied in the past few decades, systems with strong nonlinearities are not as widely investigated. One of the reasons why these [...]

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