In recent years, more and more metal oxides have been finding critical tribo-catalytic applications. Presently, we have explored the tribo-catalytic conversion of H₂O and CO₂ using Co₃O₄ nanoparticles and obtained some surprising results. In an as-received 150 mL glass reactor enclosed with 10 mL H₂O, 0.10 g Co₃O₄ nanoparticles, 1 atm CO₂, and a Teflon magnetic rotary disk, we observed the production of as much as 57.41 µmol/L of H₂, and 0.15 µmol/L of CH₄, 0.21 µmol/L of CO after 5 h magnetic stirring. Metallic coatings of Cu, Ni, SUS316, Ti, Nb, Mo, and W were further introduced on reactor bottoms separately. For those coatings of Ni, SUS316, Ti, and Nb, the reduction of CO₂ was dramatically enhanced and C₂₊ products of C₂H₆ and C₂H₄ were observed. Especially for Ti coating, the amounts of H₂ and CH₄ were increased by 2 and 26 times from those for the glass bottom, respectively, and the amounts of C₂H₆ and C₂H₄ were very impressive. Co₃O₄ nanoparticles were proven chemically stable under magnetic stirring in water, and hydroxyl radicals and superoxide radicals have been detected for Co₃O₄ nanoparticles under magnetic stirring through fluorescence spectroscopy and electron paramagnetic resonance spectroscopy analyses. These findings not only reveal an outstanding capability of Co₃O₄ to generate multicarbon products from H₂O and CO₂ through tribo-catalysis but also highlight a promising potential of tribo-catalysis as a whole to harness mechanical energy for addressing energy shortages and environmental pollution.

All solid-state lithium-ion batteries based on polymer electrolytes have higher safety and energy density, but the low conductivity of lithium ion restricts its application. This study proposes a new method to promote the ionic conductivity of polyethylene oxide (PEO)-based solid electrolytes. In this method, the PEO-based solid electrolyte was first prepared by casting, and then power ultrasound was exerted on the electrolyte by a sandwich structure to modify the electrolyte structure. Through analysis of the performance and microstructure of the electrolyte, it was found that the ultrasonic treatment increased the ionic conductivity by 78%, improved tensile strength and plastic deformation ability, but did not affect the thermal stability and the chemical composition. The ultrasonic vibration, exerting high energy to the solid electrolyte through high-frequency vibration, broke PEO grains and melted them with the frictional heat at boundary. Due to the slight melting and fast solidifying produced by the pulsed ultrasonic treatment, the crystallization was suppressed. The crystallinity was thus reduced by 6.2%, which increased the migration channels of lithium ions and reduced the tortuosity effect. Furthermore, the ultrasonic vibration compressed the electrolyte to produce plastic flow of the material, which made the electrolyte structure more compact. The density of ethylene oxide (EO) units thus increased in the amorphous phase, providing multiple electron-donor coordination sites for the Li⁺. The hopping distance of the ion between donors decreased, which also facilitated the migration. In addition, the mechanical performance of the electrolyte membrane improved. This study provides a reference for the improvement of polymer based all-solid-state batteries.

The main objective of this article is to exploit a phantom paired element based discrete crack network toolkit for predicting the damage progression and residual strength of laminated composites without and with a hole under tension and compression. Both intra-ply matrix cracking and inter-ply delamination are considered under a co-simulation framework in the discrete crack network toolkit. A mesh-independent kinematic description of discrete matrix cracks is accomplished via user-defined phantom paired solid elements to capture the initiation and evolution of fiber orientation dependent matrix cracking. In-ply matrix crack initiation is realized by inserting a crack along the fiber direction when a matrix driven failure criterion is satisfied and a cohesive injection along the matrix crack interface is applied to account for energy dissipation during matrix crack opening. The delamination failure mode is characterized by applying Abaqus’ cohesive interaction at ply interfaces. The non-linear shear behavior is introduced by employing a power law based curve-fit model and the fiber failure is described using a continuum damage mechanics based model. Both the blind and recalibrated predictions are performed for specimens of three different layups under the Air Force Tech Scout 1 program. The predicted damage progression and the load displacement curves are compared with the testing results provided by the Air Force Research Laboratory.

All-solid-state polymer lithium batteries have good safety, stability, and high energy densities and are employed in wireless sensors. However, the solid contact between the polymer electrolyte and the cathode leads to high interface resistance, limiting the broad application of solid-state lithium batteries. This paper proposes an ultrasonic fusion method to reduce the interface resistance between the polymer electrolyte and the cathode. The method applied a high-frequency ultrasonic vibration technique to impact the polymer electrolyte/cathode structure, melting the electrolyte at the interface and thus generating good contact at the interface. The experimental results showed that the ultrasonic fusion method decreased the interface resistance between the polymer electrolyte and the cathode by 96.2%. During the ultrasonic fusion process, high-frequency ultrasonic vibrations generated high temperatures at the interface, and the polymer electrolyte became molten, improving the contact between the electrolyte and the cathode. The ultrasonic fusion method eliminated the gaps at the interface, and the interface became more compact. Furthermore, ultrasonic vibrations made the molten electrolyte fill the holes in the cathode, and the contact area was enhanced, providing more Li⁺ ions transmission paths.

View Video Presentation: https://doi.org/10.2514/6.2022-0531.vid The paper presents a combined experimental and numerical study of multiaxial fatigue damage accumulation in scarf-repaired cruciform specimens subjected to fatigue loading. The existing fatigue analysis module is improved by including the local stress ratio and mode mixity dependent fatigue damage initiation description to capture the change in fatigue damage accumulation rate due to stress redistribution. Multiple stress ratios defined in the local ply material system are used to account for the distinct rate of fatigue damage accumulation under mixed-mode loading. A three-stage cycle jumping approach is implemented to characterize the local stress ratio dependent fatigue damage accumulation: 1) conducting FE analysis for one full cycle to establish a trendline, 2) extrapolating the trendline spanning many cycles, and 3) using the extrapolated state as the initial state for subsequent full-cycle calculation. A static analysis associated with the first cycle of the loading block is performed based on a mechanism-driven progressive damage accumulation model under multiaxial loading. The minimum and maximum stress components associated with the matrix, fiber, and delamination failure are determined for each element at the critical zone along with its corresponding stress ratios. A constant life diagram (CLD) is constructed to determine the S-N curve at a given stress ratio (R) based on the limited test data associated with a few applied load ratios. The interpreted S(N) data at a given R ratio and fatigue growth data are used to determine the evolved cohesive properties where the cohesive strength is degraded based on S-N and the shrunk post-peak cohesive behavior is driven by the fatigue damage growth model. The fatigue tests of cruciform specimens with and without repair are performed under biaxial fatigue loading. The cruciform specimens with and without scarf repair are fabricated and tested under biaxial fatigue loading of different levels of applied peak loads. The detected fatigue damage accumulation data and measured stiffness against cycle curves are compared with the model predictions for the cruciform specimens.

View Video Presentation: https://doi.org/10.2514/6.2022-2601.vid The failure mechanism of composite bolted joints was investigated using an in-situ X-ray CT technique with SSB test. A physics-informed modeling approach was proposed based on the traditional CDM method and a static bearing model. Residual stress in the longitudinal and transverse direction is considered due to the out-of-plane constraint in the bearing region. Meanwhile, a micromechanics model was adopted to predict the fiber kinking behavior of composite laminates under different constraints. The effects of the constraint on the compressive strength and kinking band angle were studied. The modeling approach was validated using SSB tests by comparing the stress-strain response and corresponding failure patterns.