Dynamic behavior and energy dissipation mechanisms of coral aggregate concrete under high strain rate impact loading

Microstructural characteristics, mechanical performance and constitutive modelling parameters of additively manufactured copper under quasi-static and dynamic loading conditions

The impact of crystallographic orientation, select grain boundaries, and vacancies on the shock response of aluminum was investigated using molecular dynamics simulations. Shock loading in the [001], [011], and [111] directions was explored, revealing anisotropic behavior in shock speed, generated dislocation density, and melting. The Hugoniot elastic limit (HEL) in the [100], [110], and [111] directions were calculated as 18.7 GPa, 17.8 GPa, and 22.5 GPa, respectively. These results were found to be an order of magnitude larger than the uniaxial compressive yield strengths computed at high strain rate using an affine loading scheme. Metastable melting in the [011] and [111] directions occurred around a pressure of 100 GPa and roughly 1000K below the observed metastable melting [001] direction and the equilibrium melt curve. The role of select twist and tilt grain boundaries was assessed. Differences in the wave speed profile were observed for most grain boundaries, but only for piston velocities [Formula: see text]1.5km/s. Additionally, the presence of vacancies, both randomly distributed and clustered, led to a decrease in shock speed with a larger decrease in shock speed recorded at higher vacancy concentrations. The change in shock speed, relative to a defect free cell, exhibited a dependence on the configuration of the defects. Melting was also found to occur at lower pressures for increasing vacancy concentrations. These results highlight key trends in the role of defects and crystallographic orientation in the behavior of FCC metals, such as aluminum, under extreme loading conditions.

Chronic Obstructive Pulmonary Disease (COPD) is a major global health burden, driving high rates of morbidity, mortality, and economic strain. Its prevalence is rising, especially among aging populations and in areas with heavy tobacco and pollutant exposure. Frequent comorbidities like cardiovascular disease and diabetes complicate care, necessitating multidisciplinary approaches beyond standard pharmacotherapy. This prospective randomized clinical trial investigated the impact of individualized care aligned with Global initiative for chronic obstructive Lungs disease (GOLD guidelines)-on clinical outcomes in COPD patients with comorbidities. 120 patients were randomly allocated to three arms: standard care, pharmacist counselling, and comprehensive pharmaceutical care. Participants were followed for 24 weeks, and outcome measures included assessments of symptom severity (via CAT and mMRC scores), lung function (FEV₁), exacerbation frequency, and quality of life. Arm 2 (Pharmaceutical Care) significantly lowered CAT scores to 18.82 ± 13.69 compared to 29.88 ± 13.69 in the Arm 0 (control group) (p < 0.001) and reduced mMRC ratings to 0.91 ± 0.39 versus 1.36 ± 0.39 (p < 0.001). Arm 2 experienced the smallest FEV₁ (% predicted) change (-2.76 ± 2.52) versus -9.73 ± 2.52 in the control group, with a post-intervention mean difference of -9.70 ± 2.83 (p = 0.001). The duration of moderate exacerbations was significantly shorter in Arm 2 (1.50 ± 1.49 weeks) compared to 3.23 ± 1.49 weeks in controls (p < 0.001). Disease progression scores were lower in Arm 2 (1.15 ± 0.36) versus 1.45 ± 0.44 in the Arm 0 (p = 0.016). Quality of life significantly improved in the Arm 2 compared to Arm 0 and Arm 1, as reflected by lower SGRQ scores (p < 0.001). In conclusion, implementing pharmaceutical care based on GOLD 2020 guidelines not only enhances symptom management and preserves lung function but also significantly improves quality of life in COPD patients. This study underscores the critical role of pharmacists in multidisciplinary care teams, focusing the patient education and individualized patient care, especially in resource-limited settings. This clinical trial has been registered in ANZCTR clinical trials registry: ACTRN12622000234718 (https://www.anzctr.org.au/ACTRN12622000234718.aspx). This clinical trial has been registered in Australian New Zealand Clinical Trials Registry: Trial ID (ACTRN12622000234718), Date of registration 09/02/2022 and updated at 02/03/2023. These protocols are the detailed version of the registered clinical trial that has been published in Heliyon 10.1016/j.heliyon.2023.e21539.

Dinoflagellates, a group of marine unicellular algae, are known for the fascinating glowing effects in coastal waters. While this natural mechanoluminescent phenomenon has been explored in pressure sensors and optical transducers, technologies to shape dinoflagellate-containing materials into more complex, engineering-relevant geometries remain limited. Here, we report a three-dimensional printing strategy to manufacture complex-shaped mechanoluminescent objects using dinoflagellates embedded in biocompatible hydrogels. The growth and mechanoluminescence of the entrapped dinoflagellates were investigated by optical microscopy, emission spectroscopy, and mechanical testing of cell-laden gels. Dinoflagellate-laden gels showed strong bioluminescence when compressed at sufficiently high strain and strain rates. By incorporating the dinoflagellates into a photo-curable hydrogel, we shaped such living material into complex geometries using a widely available light-based printing technique. The ability to print dinoflagellate-laden gels into intricate shapes broadens the design space available for the creation of mechanoluminescent living objects for applications in soft robotics, self-powered sensing, and optical transduction.

AlxCr30Fe30Ni20Ti(20-x) (x = 10, 12, 14 at%) high-entropy alloys with varying Al and Ti contents were prepared to investigate the effects of the element composition on the phase structure, mechanical properties, and fracture morphology of the alloy. Quasi-static compression and dynamic impact tests were performed to examine the mechanical properties and fracture behaviors of the alloy under different strain rates. The results showed that all three alloys had dual-phase FCC/BCC structures. Among them, the Al10Cr30Fe30Ni20Ti10 alloy exhibited the highest yield strength under both quasi-static and dynamic conditions. However, the Al12Cr30Fe30Ni20Ti8 and Al14Cr30Fe30Ni20Ti6 alloys showed better ductility. The fracture morphology observations revealed that all the alloys developed a fish-scale-like ductile dimple structure after quasi-static compression fracture. In contrast, under dynamic impact loading, the alloys formed tearing-type ductile dimples and cleavage planes, indicating a significant reduction in ductility at higher strain rates.

The welding of dissimilar metallic assemblies produced by high-velocity impact occurs at high strain rates ( i.e. , impact velocities) and various dynamic collapsing angles. However, the quality of the resulting weld surface depends on several parameters, one of which is the jet formation and particle cloud formation upon impact. This phenomenon arises from intense heat and pressure upon impact, playing a decisive role in determining the resulting weld quality. Here, the jet formation of such welds is described, providing new insights into the understanding of cold-welding methods. Jet formation plays a key role in generating the necessary conditions required to weld two dissimilar metal surfaces. Copper (Cu) and aluminum (Al) samples were subjected to high strain-rate loading using the single-stage gas gun available at ID19 beamline (ESRF, France) coupled with ultra-fast synchrotron X-ray radiography in order to investigate, in situ , the production, propagation, and evolution of jets upon impact of dissimilar metals. Several impact conditions (impact angle and material configuration) were investigated at an approximate impact velocity of 500 m/s. The results reveal that the jet size, speed, and morphology evolve differently as a function of the initial impact conditions. These results demonstrate, for the first time, a direct in situ investigation of jet dynamics and weld quality in impact welding of dissimilar metallic materials. • Synchrotron X-ray imaging reveals jet dynamics in dissimilar metal impacts. • Impact angle strongly influences jet morphology and propagation behavior. • Flyer–target material configuration controls jet angle and jet velocity. • Jet growth shows a linear relationship between jet length and time.

Genetic algorithm-based optimization for deriving traction–separation laws of CFRPs translaminar fracture at high strain rate

Experimental study on the bond between CFRP rod panels (CRPs) and steel under static and high strain rates

Dynamic tensile behavior of ultra-high performance concrete reinforced with steel fibers under quasistatic to high strain rates

Abstract The Marangoni flow with a soluble and diffusive surfactant in a deep layer of a non-Newtonian fluid is numerically analyzed. We have solved the momentum equations considering inertial effects and the components of the stress tensor based on the Carreau model using the modified vorticity-stream function formulation. A tangential stress balance at the interface relates the surface tension to the surface surfactant concentration using the Langmuir’s non-linear equation. The convective-diffusion equations for surface and bulk surfactant concentrations, taking diffusive effects into account, were solved using the one-dimensional Crank–Nicolson method and the alternating-direction-implicit method, respectively. Due to solubility, the mass exchange between the interface and the bulk fluid is driven by adsorption–desorption kinetics, leading to a coupled system of highly nonlinear equations. The main parameters controlling the temporal evolution of the initial surfactant distribution on the interface are the following: the fluid behavior index ( n ), the Carreau number ( C u ), the Biot number ( B i ), the solubility parameter ( β ) and the dimensionless surfactant depletion depth ( α ) . Our findings indicate that, for a shear-thinning fluid, a decrease in the power-law index leads to a faster decrease in the surface surfactant concentration when soluble surfactants are present. The associated high strain rates amplify convective effects, which significantly enhance mass transport and diminish interfacial non-uniformities by reducing surface tension gradients. The surfactant is transported more effectively into the bulk phase, leading to a more homogeneous distribution and preventing localized accumulations within a shear-thinning fluid. In addition, under fully adsorptive conditions, the strain rates are sufficiently low that shear-thinning fluids exhibit their maximum Newtonian viscosity as predicted by the Carreau model, so the fluid rheology does not influence the relaxation process.

The fundamental cause of coal mine dynamic disasters lies in microstructural failure under dynamic loading. This study employed molecular dynamics simulations to investigate the uniaxial tensile mechanical behavior and failure mechanisms of bituminous coal macromolecules under different strain rates. The results indicate that when the strain rate is below 1 × 1010s-1, coal exhibits ductile failure. The stress-strain curve comprises four stages: elastic, plastic, strain hardening, and unstable crack propagation. When the strain rate exceeds 5 × 1010s-1, the strain hardening stage disappears, and the failure mode transitions to brittle, with a critical transition interval between 1 × 1010 and 5 × 1010s-1. Porosity shows a positive correlation with strain. At low strain rates, pores with a diameter less than 0.5nm reversibly close, which is conducive to the progressive damage of toughness failure. Pores with a diameter greater than 0.5nm irreversibly expand at high strain rates, directly causing brittle failure. The combined influence of hydrogen bonding and π-π stacking contributes to strain hardening during ductile deformation. After fracture, the planes of aromatic ring align parallel to the tensile direction, and aliphatic chains are straightened along it. The overall change in the potential energy of the system is primarily governed by van der Waals energy. At low strain rates, energy is gradually dissipated through molecular structural adjustments, manifesting as plasticity. At high strain rates, energy accumulates rapidly and cannot be dissipated in a timely manner, resulting in sudden brittle failure. This study provides a theoretical microscopic basis for understanding the disaster mechanisms induced by dynamic disturbances in coal mines.

Dynamic response and fracture of B₄C/6061 Al composites: experiments and simulations

Shear impact resistance of nanoparticle-incorporated ultra-high-performance fiber-reinforced concrete at high strain rates

The increasing number of taller timber structures, which require the use of mass timber panels, demands a thorough understanding of the dynamic response of such elements under simulated blast loads. This paper investigates the behaviour of glued-laminated timber panels (GLT) subjected to simulated blast loading using the Shock Tube testing facility. A total of sixteen spruce-pine GLT panels were subjected to out-of-plane static and dynamic loading under four-point loading with simply-supported boundary conditions. The strength increase factor for GLT panels was found within the range of 1.6–1.9. The dynamic increase factor under a high-strain rate equal to 0.2 s −1 was found to be 1.1. Both static and dynamic failure behaviour were consistent and characterised as simple tension flexural failure. A single-degree-of-freedom model was used to predict the dynamic behaviour of the GLT panels and showed good agreement with experimental results when proper inputs were used.

Metallic micrometamaterials exhibit exceptional specific strength and energy dissipation capacity, yet their mechanical behavior under extreme thermomechanical conditions remains poorly understood. Here, we uncover deformation mechanisms in metallic microlattices subjected to combined thermal and mechanical extremes. Copper microlattices were fabricated via localized electrodeposition process with submicron spatial resolution and, for the first time, compressed at cryogenic (-150°C) and room temperatures under high strain rates up to 100 s -1 . The copper microlattices, characterized by micron-sized grains and randomly oriented growth twins, exhibit distinct temperature and strain rate dependent deformation responses that lead to enhanced energy dissipation. Compression tests on copper micropillars, which are dimensionally equivalent the microlattice struts, reveal substantial shifts in deformation mechanisms from dislocation slip to mechanical twinning as a function of temperature and strain rate. Together, these results provide a comprehensive framework for designing metallic micrometamaterials optimized for extreme thermomechanical environments.

Tensile response and dynamic constitutive modelling of cold-formed Q355B steel at high strain rates

Mechanical response and failure mechanisms of novel boron carbide ceramics under medium and high strain rates

Experimental and numerical characterization of Johnson–Cook plasticity and damage models for spheroidal graphite cast irons at high strain rates and elevated temperatures

Strain rate influence on mechanical behaviour of Ti-6Al-4V reinforced with TiC or TiB composites produced by sintering and hot isostatic pressure on compression