The lecture focuses on understanding and describing within the multiscale modelling frameworks the void growth and coalescence leading to the ductile damage of polycrystalline metals and alloys deforming by slip and twinning. Our motivation stems from solids with a high plastic anisotropy, like magnesium with hexagonal close packed (HCP) lattice, which are known to suffer from reduced...
We explore experimentally and computationally an unconventional class of fractures in elastomers: sideways cracks. Under certain conditions, a crack propagates in a (sideways) direction parallel to the loading direction rather than perpendicularly in the (forward) direction of the notch. Then, the crack arrests, and the material ahead of the crack can be further deformed enabling giant...
Metamaterials are artificial and architected materials, offering various possible designs for achieving peculiar mechanical properties thanks to their structural arrangement. Although promising, with potentially broad applications in, e.g., medicine [1] or mobility [2], apprehending their geometry is challenging due to their complex and often disordered configuration. In this regard, applied...
Diffusion chronometry is an important tool in understanding various aspects of geological processes, e.g., processes in magma reservoirs [1]. However, the timescales which can be accessed by diffusion chronometry are restricted by recrystallization. While the coupling of mechanical and chemical processes has not been explored in a quantitative framework yet, it has been shown in both...
In this talk we introduce some urban transport networks that we can analyze using multilayer complex networks. For these we show several multilayer centrality measure and how they can be computed efficiently.
Concrete and cement-based materials are known to describe a brittle failure. Thus, fiber reinforcement is used to enhance the post-cracking properties of the material. In this regard, the polymer fibers arise as an environmentally friendlier alternative to steel fibers. However, the effect of their characteristic viscoelastic behavior on the performance of fiber-reinforced concrete requires...
We study the behaviour of a given volume of liquid confined between two rough solid plates. When the separation between the plates is small relative to the liquid volume, capillary bridges are expected to form, which minimise Gauss' capillary energy locally. We derive aΓ-expansion for the energy as the plate separation approaches zero, yielding a dimensionally reduced problem in terms of the...
In this research talk, we delve into the intricacies of selected optical measurement techniques applied to experimental mechanics of complex and big (in relation to the actual field-of-view) objects. The focus is on two major approaches: multimodal measurements and synthetic aperture. We explore the challenges faced by two groups of experimental methods: (i) digital image correlation (or...
Simulation-based, patient-specific risk assessment via a digital liver twin has enormous potential in clinical applications such as personalized drug dosing or evaluation of the status and impairment of liver grafts before transplantation [1]. We present a flexible software framework for coupling tissue-scale and cellular-scale processes using FEniCS [2], libRoadRunner [3], and preCICE [4]....
A new arbitrary Lagrangian-Eulerian (ALE) formulation for area-incompressible Navier-Stokes flow on evolving surfaces is presented. The new formulation extends the surface ALE formulation of [1] to more general surface motions. It is based on a new curvilinear surface parameterization that describes the motion of the ALE frame. Its in-plane part becomes fully arbitrary, while its out-of-plane...
Multi-objective optimization for a hydraulic turbine blade is a significant challenge due to the high computational cost of performing the number of computational fluid dynamics (CFD) simulations. It becomes more challenging while dealing with a high number of parameters. This research addresses this issue by proposing an innovative approach that leverages Autoencoder techniques to reduce the...
Topology optimization is a valuable tool in engineering, facilitating the design of optimized structures. However, topological changes often require a remeshing step, which can become challenging. In this work, we propose an isogeometric approach to topology optimization driven by topological derivatives. The combination of a level-set method together with an immersed isogeometric framework...
Ropes are used in modern structures as load-bearing elements for various applications, e.g. the main cables or cross-ties in cable-stayed bridges, cable roof structures, or high-voltage transmissions lines. Guy lines are designed to stabilize the structure and keep it in the right position against external loads.
Since the ropes do not transfer compressive forces, they require significant...
Lie group integrators help to avoid singularities in the dynamical simulation of multibody systems with large rotations by solving initial value problems for (ordinary) differential equations on manifolds with Lie group structure.
For one-step methods, the application of classical ODE time integration methods to a locally defined equivalent ODE in terms of local coordinates has become a...
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An accurate simulation of gas networks has been the objective of the last decades in numerical analysis, provided that this could later bring improvements on the operation of the network and reduced costs. However, when considering real-world application networks, simulating the gas network becomes computationally expensive due to the scale, complexity, and dynamic nature...
In shape memory alloys, the competition between interfacial and elastic strain energy contributions leads to twin branching, i.e., to refinement of the twin laminates close to the macroscopic interface between twinned martensite and austenite. We have developed a 1D model of twin branching in which the average twin spacing is a continuous function of the distance from the austenite-twinned...
The presentation will outline the activities of the PSNC, the challenges addressed with the use of cutting-edge data processing infrastructure (including quantum computers), as well as the scope of the project under which the tutorial is being delivered.
The presentation will address two topics. First, a brief introduction to quantum computing to capture its current landscape. Second, an overview of gate-based quantum algorithms and their applications in mechanical design, optimization, system dynamics, and machine learning.
The hands-on session on the basis of quantum computing will introduce participants creating quantum circuits, and with using this framework basic quantum phenomena such as superposition, entanglement will be explained.
Large deformations cannot be neglected in many engineering dynamics applications due to their significant contribution to the overall system dynamics. For instance, human gait analysis often employs multibody models that conventionally represent body segments as rigid bodies. However, bones are covered with muscles and other soft tissues that are not rigidly connected with the bones but act as...
Solid-state processing techniques like friction extrusion (FE), friction stir welding (FSW), and friction surfacing (FS), represent advanced methods for processing Al alloys. These techniques utilize frictional heat and intense mechanical deformation to induce microstructural evolution without reaching the melting point. This study focuses on Al-Cu-Li alloys, which are widely employed in the...
The pressure to reduce greenhouse gas emissions is growing, which demands new and innovative technologies to produce mobile as well as stationary energy. The CO2 methanation offers a pathway to reduce greenhouse gas emissions by directly converting CO2 to CH4. This also plays a crucial role in "power-to-gas" (P2G) technologies by providing an approach to store excess renewable energy in the...
The second part of the hands-on session will dive deep into the realm of quantum algorithms. The participants will be shown how some quantum and hybrid algorithms work and can be used in real-world applications and use-cases such as factoring, optimization and machine learning.
The pseudopotential method [Shan, Chen (1993), https://doi.org/10.1103/PhysRevE.47.1815] is a popular multiphase extension to the lattice Boltzmann method (LBM). Several improvements to the method have been proposed, allowing for better thermodynamic consistency, surface tension control, or stability for high density ratios [Czelusniak et al. (2020),...
In lightweight bar-membrane structures, it is essential to shape their joints properly. Especially in tensegrity structures, the reliability of such a connection plays a key role. This work aims to perform numerical and experimental analysis of selected bar-membrane joints that can be used in tensegrity systems. Despite the textile used for the membrane is a nonlinear material it can be...
The Swift-Hohenberg equation arises as a basic pattern forming model. We consider the dynamics of a space fractional version of this model near instability using amplitude equations. More precisely, we prove that there exists an approximation by a Ginzburg-Landau equation near the first bifurcation point.
Traumatic spinal cord injury (SCI) in humans and many mammals is a non-regenerative condition that can lead to motor function loss and disability. Mechanical factors are increasingly recognized to be influencing spinal cord regeneration, yet accurate characterization of the mechanical behavior of spinal cord tissue is lacking. To address this gap, we employ a multimodal approach that combines...
In engineering practice, epistemic uncertainty widely exists due to imperfect modeling, simplifications, and limited data. Among these uncertainties, uncertainty in distribution parameters has drawn significant attention. To comprehensively evaluate structural reliability under the distribution parameter uncertainty, often referred to as conditional failure probability, several methods have...
Thin-walled composite structures are widely used in weight-critical applications such as aircraft and spacecraft. However, ensuring the stability of such structures under various load cases remains a key challenge in their design and optimization. For omega-stringer stiffened panels, the local buckling and postbuckling behavior is investigated using closed-form analytical solutions. The...
Composite materials often exhibit complex anisotropic mechanical responses governed by their microstructural geometry and material phase distributions. Capturing these responses and their dependence on microstructural parameters is thus a critical challenge. In this work, we address this problem through a data-driven model-discovery framework that infers interpretable constitutive...
A key concept in comparison and classification of dynamical systems is the notion of topological conjugacy. In the talk we will consider a problem of testing topological (semi-)conjugacy of two trajectories coming from unknown dynamical systems when only finite samples of those trajectories are given. A number of tests and various numerical examples indicating their scalability and robustness...
Composite thin-walled shell and plate elements are indispensable components of modern critical structures and technical devices for various purposes. This is due to their efficient material usage and ability to provide the required stiffness in specific directions under operational conditions. Intense cyclic loads cause geometrically nonlinear vibrations in these elements. Preventing resonance...
Lattice structures have gained increasing popularity due to their remarkable strength-to-weight ratio. With advancements in material extrusion additive manufacturing (MEX), complex designs of lattice structures have become more accessible and widely applicable. However, their slender components face the challenges of elastic buckling at low densities.
A novel lightweight additive...
3D concrete printing (3DCP) aims to revolutionize construction by increasing automation, reducing material usage, and enabling customized designs. Despite its potential, the lack of regulations and reliance on trial-and-error methods result in significant waste and inefficiencies. Reliable models are needed to predict and control the complex printing process with its various influencing...
This paper presents a method for integrating base excitations into the harmonic balance method within the context of path continuation. Footpoint excitation can be applied via linear or non-linear elements to the mechanical system. First, a brief introduction into the harmonic balance method and the continuation procedure are given. Then, different types of base excitations are discussed:...
In recent years, 4D printing has gained significant attention in the material modeling community. Unlike classical 3D Fused Deposition Modeling (FDM), 4D printing incorporates the dimension of time to the printing process. Recent publications have focused on characterizing printed materials, predicting their time-dependent behavior, and investigating the influence of infill patterns on the...
We study the effective behavior of random, heterogeneous, anisotropic, second order phase transitions energies that arise in the study of pattern formations in physical-chemical systems. Specifically, we study the asymptotic behavior, as $\varepsilon$ goes to zero, of random heterogeneous anisotropic functionals in which the second order perturbation competes not only with a double well...
This study presents an optimization model for forced convection problems, aiming to determine the optimal location and size of inlet and outlet ports in a cavity flow field. The proposed approach integrates the localized meshless method, the generalized finite difference method (GFDM) for spatial discretization, the projection method for stable and accurate simulation, and particle swarm...
Numerical optimization has long been a cornerstone in engineering disciplines, underpinning areas such as optimal control and design optimization. The multi-objective nature of design optimization problems raises the interest in computing entire Pareto fronts of optimal compromises. By suitable scalarization techniques, this can be formulated as solving a family of parametric optimization...
The effect of the dielectrophoretic forces in convective flows under microgravity conditions were experimentally investigated to examine the onset and behavior of the hydrodynamic instability. A dielectric fluid confined within a differentially heated, vertically aligned cylindrical annulus was subjected to an alternating electric field at a frequency of 200 Hz during sounding rocket flight,...
According to the Nernst theorem or, equivalently, the third law of thermodynamics, the absolute zero temperature is not attainable. Starting with an initial positive temperature, we show that there exist solutions to a Kelvin-Voigt model for quasi-static nonlinear thermoviscoelasticity at a finite-strain setting [Mielke-Roubíček '20], obeying an exponential-in-time lower bound on the...
The repair and strengthening of reinforced concrete (RC) frames is of great importance in ensuring the structural safety and serviceability of buildings after seismic events. Beam-column joints are primary mechanisms for dissipating seismic energy within RC frame structures. During ground motions, these joints accumulate significant energy, which may result in plastic deformations [1]....
Anisotropic elasto-plasticity, sensibility to temperature and moisture, wrinkling and damage occurrence are some of the phenomena needed to analyse for a better insight on the performance of a material. Due to this complex material behavior, the usage of certain materials, like paper and paperboard, has been hindered. These materials are highly sustainable and are mostly used in the packaging...
The presentation we will describe the mathematical model of an oscillator with damping, whose vibrations were forced by a random series of impulses. Under appropriate assumptions regarding random variables, in the model, the vibrations of the system become a process which, in the limit as time tends to infinity, is stationary and ergodic. For value of the impulses, which are independent...
