Aqueous zinc-ion batteries have gained significant interest, offering several distinct advantages over conventional lithium-ion batteries owing to their compelling low cost, enhanced battery safety, and excellent environmental friendliness. Nevertheless, the unfortunate growth of zinc dendrites during cycling leads to poor electrochemical performance of zinc batteries, primarily attributed to the diminished wet mechanical properties and limited electrolyte uptake of existing commercial separators. Herein, a bio-based separator was developed from sustainable resources using natural polymers derived from wood pulp to replace fossil-based polyolefin separators. The inherent hydrophilicity and swelling ability of cellulose fibers provide separators with superior electrolyte wettability and uptake. Notably, the structural reinforcement provided by lignin, especially after hot pressing, enhances the separator's wet mechanical integrity and performance during battery cycling. These improvements contribute to the separator's more stable electrochemical performance and improved ion transport properties. Separators composed of lignin-rich microfibrillated cellulose fibers showed superior dimensional stability under heat compared to Celgard, ensuring higher thermal safety and enhanced performance of aqueous zinc-ion batteries. Our results reveal the great potential of lignin-rich cellulose-based separators for future zincion batteries.

Post-disruption runaway electron (RE) kinetic energy K and pitch angle sin ϑ are critical parameters for determining resulting first wall material damage during wall strikes, but are very challenging to measure experimentally. During the final loss instability, confined RE K and sin ϑ are reconstructed during center-post wall strikes for both high impurity (high-Z) and low impurity (low-Z) plasmas by combining soft x-ray, hard x-ray, synchrotron emission, and total radiated power measurements. Deconfined (wall impacting) RE sin ϑ is then reconstructed for these shots by using time-decay analysis of infra-red imaging. Additionally, deconfined RE K and sin ϑ are reconstructed for a low-Z downward loss shot by analyzing resulting damage to a sacrificial graphite dome limiter. The damage analysis uses multi-step modeling simulating plasma instability, RE loss orbits, energy deposition, and finally material expansion (MARS-F, KORC, GEANT-4, and finally COMSOL). Overall, mean kinetic energies are found to be in the range ⟨ K ⟩ ≈ 3 − 4 MeV for confined REs. KORC simulations indicate that the final loss instability process does not change individual RE kinetic energy K. Confined RE pitch angles are found to be fairly low initially pre-instability, ⟨ sin ϑ ⟩ ≈ 0.1 − 0.2 , but appear to increase roughly 2 × , to ⟨ sin ϑ ⟩ ≈ 0.3 − 0.4 for both confined and deconfined REs during instability onset in the low-Z case; this increase is not observed in the high-Z case.

The thermo-mechanical response of an ATJ graphite sample to controlled runaway electron (RE) dissipation, realized in DIII-D, is modelled with a novel work-flow that features the RE orbit code KORC, the Monte Carlo particle transport code Geant4 and the finite element multiphysics software COMSOL. KORC provides the RE striking positions and momenta, Geant4 calculates the volumetric energy deposition and COMSOL simulates the thermoelastic response. Brittle failure is predicted according to the maximum normal stress criterion, which is suitable for ATJ graphite owing to its linear elastic behavior up to fracture and its isotropic mechanical properties. Measurements of the conducted energy, damage topology, explosion timing and blown-off material volume, impose a number of empirical constraints that suffice to distinguish between different RE impact scenarios and to identify RE parameters which provide the best match to the observations.

Virtual testing of helmets using finite element (FE) analysis can be a valuable tool during product development. Still, its usefulness is limited by the quality of the constitutive model of the energy-absorbing material, usually foam. Built-in constitutive models in commercial FE software are developed for traditional linear compression loading. However, modern oblique test methods load the foam in combined compression and shear. Therefore, we aim to evaluate to what extent built-in constitutive models in commercial FE software can represent Expanded Polystyrene (EPS) foam during combined compression and shear loading (CCSL). EPS foam is tested experimentally in a newly developed test rig for CCSL (V-test). The response is compared against the simulation using three different constitutive models available in LS-DYNA (M83, M126, and M181). The models are assessed by their ability to capture the correct response, focusing on how well the continuum models can capture the phenomenological events seen in the experiments. The results show that the models perform well in compression, as expected. However, we point out limitations in the shear response and significant limitations in the unloading response, both important for oblique helmet testing. Due to these limitations, we conclude that the existing models are inadequate for accurately simulating oblique helmet impacts. There is a clear need to develop and implement new constitutive models focused on capturing CCSL including the unloading. Additionally, frictional sliding was found to substantially influence the measured response in the V-test method. Minimizing interface sliding is therefore critical for isolating the material behavior.

The expanding field of lignin-containing nanocellulose offers a sustainable alternative to fossil-based substances in applications such as packaging, coatings, and composites. This has underscored the importance to explore the impact of raw materials due to the complexities of lignin structures and different raw fiber characteristics, which plays a significant role in determining the properties of the resultant lignin-rich cellulose materials. This study presents a detailed investigation and comparison on the production and structure-property relationships of lignin-containing microfibrillated cellulose (LMFC) fibers prepared from unbleached softwood and hardwood kraft pulps. The microfibrillation process was analyzed for both softwood and hardwood pulps, comparing the results across various stages of fibrillation. Distinguishing features of lignin structures in softwood and hardwood pulps were identified through Py-GC/MS analysis. Additionally, Digital Image Correlation was employed to investigate the varying failure patterns in LMFC films derived from different wood species. Softwood-derived LMFC films demonstrate less strain-concentrated regions and strain variation, attributed to the formation of more physical crosslinking joints by the elongated fibers. Consequently, softwood-origin LMFC films displayed superior load-sharing and enhanced tensile strength (287 MPa) compared to those derived from hardwood. Additionally, the denser lignin structures in unbleached softwood pulp further boosted the stiffness of resultant softwood-derived films. Upon recycling, LMFC films exhibited superior recovery of mechanical properties following drying, suggesting their significant potential for widespread commercial use.

In this contribution, we present a robust and efficient computational framework capable of accurately capturing the dynamic motion and large deformation/deflection responses of highly-flexible rods interacting with an incompressible viscous flow. Within the partitioned approach, we adopt separate field solvers to compute the dynamics of the immersed structures and the evolution of the flow field over time, considering finite Reynolds numbers. We employ a geometrically exact, nonlinear Cosserat rod formulation in the context of the isogeometric analysis (IGA) technique to model the elastic responses of each rod in three dimensions (3D). The Navier–Stokes equations are resolved using a pressure projection method on a standard staggered Cartesian grid. The direct-forcing immersed boundary method is utilized for coupling the IGA-based structural solver with the finite-difference fluid solver. In order to fully exploit the accuracy of the IGA technique for FSI simulations, the proposed framework introduces a new procedure that decouples the resolution of the structural domain from the fluid grid. Uniformly distributed Lagrangian markers with density relative to the Eulerian grid are generated to communicate between Lagrangian and Eulerian grids consistently with IGA. We successfully validate the proposed computational framework against two- and three-dimensional FSI benchmarks involving flexible filaments undergoing large deflections/motions in an incompressible flow. We show that six times coarser structural mesh than the flow Eulerian grid delivers accurate results for classic benchmarks, leading to a major gain in computational efficiency. The simultaneous spatial and temporal convergence studies demonstrate the consistent performance of the proposed framework, showing that it conserves the order of the convergence, which is the same as that of the fluid solver.

Structural disorder induces energetic fluctuations, leading to variations in energy levels across different scales, with the spatial orientation of structural units playing a pivotal role in shaping the resulting structure-property relationships. In this communication, we derive expressions for higher-order nematic orientation parameters for planar materials analogous to the Hermans orientation parameter used for axially symmetric materials. The measure of anisotropy has been analyzed by integrating the widely used probability density functions representing the orientation distributions in nematic order parameters. These higher-order nematic orientation parameters are essential for accurately determining the ‘true’ orientation distribution function of macromolecules and understanding structure-property relationships in complex planar systems.

Highlights Fully coupled (electro-chemo mechanics) phase field approach to characterize the fracture behavior. Highly heterogeneous electrochemical and mechanical response of randomly oriented polycrystalline NMC active particle is predicted. Mechanical degradation of polycrystalline NMC particle caused by significant particle cracking in the first charge cycle. Quantifying the electrochemically active surface area due to intergranular and intragranular particle fracture. Electrochemical performance analysis of polycrystalline NMC particle during the first charge cycle considering particle cracking plus electrolyte penetration.

In this work we have investigated the effect of surface modification of fibres on the overall mechanical properties of high-density papers. Paper sheets were prepared by a combination of heat-pressing and polyelectrolyte Layer-by-Layer (LbL) modification of different softwood fibres. LbLs of Polyallylamine Hydrochloride (PAH) and Hyaluronic Acid (HA) were adsorbed onto unbleached kraft fibres and bleached Chemo-ThermoMechanical Pulp (CTMP) to improve the strength of the fibre–fibre joints in papers made from these fibres. Additionally, different sheet-making procedures were used to prepare a range of network densities with different degrees of fibre–fibre interaction in the system. The results demonstrate that interfacial adhesion within fibre–fibre joints plays a pivotal role in the network's performance, even at higher paper densities. Hygroexpansion measurements and fracture zone imaging with Scanning Electron Microscopy (SEM) further support the claim that stronger interactions between the fibres allow for a better utilisation of the inherent fibre properties. Surface treatments and network densification significantly improved the paper sheets' mechanical properties. Specifically, LbL-treatments alone increased specific stiffness up to 60% and specific strength by over 100%. This improvement is linked to the build-up of residual stresses during drying. Due to a high interaction between the fibres during water removal the fibres become constrained, leading to increased stretching of fibre segments. Strengthened fibre joints intensify this constraint, further increasing the stretch and, consequently, the paper's strength.

In this work, we predicted the gradient of the deformational moisture dynamics in a sized commercial paper by observing the curl deformation in response to the one-sided water application. The deformational moisture is a part of the applied liquid which ends up in the fibers causing swelling and subsequent mechanical response of the entire fiber network structure. The adapted approach combines traditional experimental procedures, advanced machine learning techniques and continuum modeling to provide insights into the complex phenomenon relevant to ink-jet digital printing in which the sized and coated paper is often used, meaning that not all the applied moisture will reach the fibers. Key material properties including elasticity, plastic parameters, viscoelasticity, creep, moisture dependent behavior, along with hygroexpansion coefficients are identified through extensive testing, providing vital data for subsequent simulation using a continuum model. Two machine learning models, a Feedforward Neural Network (FNN) and a Recurrent Neural Network (RNN), are probed in this study. Both models are trained using exclusively numerically generated moisture profile histories, showcasing the value of such data in contexts where experimental data acquisition is challenging. These two models are subsequently utilized to predict moisture profile history based on curl experimental measurements, with the RNN demonstrating superior accuracy due to its ability to account for temporal dependencies. The predicted moisture profiles are used as inputs for the continuum model to simulate the associated curl response comparing it to the experiment representing “never seen” data. The result of comparison shows highly predictive capability of the RNN. This study melds traditional experimental methods and innovative machine learning techniques, providing a robust technique for predicting moisture gradient dynamics that can be used for both optimizing the ink solution and paper structure to achieve desirable printing quality with lowest curl propensities during printing.