Energy Release Research Articles

Experimental and numerical study on the mechanical behavior of layered rock anchored by CRLD anchor cable

The study of the mechanical behavior of layered anchored rock is essential for addressing the stability control challenges of surrounding rock of the roadway in layered rock masses. This paper focuses on a novel constant resistance large deformation (CRLD) anchor cable and conducts a comparative study on the uniaxial compressive mechanical behavior of unanchored rock, conventional high-strength (HS) anchor cable, and CRLD anchor cable anchored rock under different bedding dip angles α (30°, 45°, 60°, 75°, and 90°). The strength characteristics, failure characteristics, and acoustic emission characteristics of various specimen types were analyzed with emphasis. The results indicate that with the increase of bedding dip angle, the elastic modulus, peak strength, and residual strength of all specimen types exhibit a trend of decreasing first and then increasing. Compared to unanchored and HS anchored rock, the values of various mechanical parameters for CRLD anchored rock show varying degrees of improvement. The failure modes of various specimen types under different bedding dip angles can be classified into five categories based on the characteristics of the crack distribution. Through comparison, it was found that the CRLD anchor cable can effectively restrict the occurrence of bedding shear failure within the anchored zone in layered rocks with smaller dip angles (30°, 45°). It also transforms the failure mode of layered rocks with larger dip angles (60°, 75°) from a single mode of bedding shear failure to a mixed mode of bedding-bedrock failure. However, under a bedding dip angle of 90°, the two types of anchored rocks exhibit similar failure forms. Comparing the acoustic emission characteristics of the two types of anchored rocks, it is observed that under different bedding dip angles, CRLD anchored rocks exhibit a more uniform distribution of acoustic emission counts, a smoother energy release process, and significantly lower peak count and cumulative energy values. Finally, a numerical model for layered CRLD anchored rocks was constructed based on the discrete element method. The reliability of the experimental results from the physical model in this study was verified by statistically analyzing the quantity evolution process and orientation distribution of microcracks in the numerical model.

Energy store & release facilitating movement in stick & slip friction, animal jump, and earthquake

Nature abounds in examples of evolutionary designs (bio and non-bio) that evolve freely into configurations that provide easier and greater access for movement. The present article considers three seemingly unrelated phenomena that appear to obstruct flow: stick–slip friction, animal jump, and earthquake. The analysis is based on simple models of rhythmic energy store & release motion. In each case, the rhythm is the sole degree of freedom. The analyses show that stick–slip friction facilitates movement because the coefficient of static friction is greater than the coefficient of sliding friction. Next, all forms of animal locomotion under gravity consist of cycles of energy storage (jump to a height) and energy release (forward fall). The rhythm of the cycle is natural such that the forward advance of the animal is economical. Finally, the onset of the earthquake is modeled the same way, as shear stresses at the rock-on-rock interface, which are matched by bending stresses in the bent ‘blades’ of rock contained between fissures perpendicular to the interface. In sum, naturally evolved store & release rhythm facilitates the movement, contrary to the commonly held impression.

A New Brittleness Evaluation Index for Reservoir Rocks Based on Fuzzy Analytic Hierarchy Process and Energy Dissipation

Summary Accurate and quantitative evaluation of rock brittleness is essential for optimizing hydraulic fracturing parameter design. Specific aspects of rock brittleness can be characterized based on mineral composition, strength parameter, stress-strain, and elasticity parameter. However, in characterizing the effect of high confining pressure on rock brittleness, these advantages have not been shown for various reasons. The essence of rock fracture resides in the accrual and dissipation of energy, concomitant with the transformation of three distinct energy modalities: elastic energy, dissipated energy, and post-peak release energy. In this study, we proposed a new brittle index for reservoir rocks considering the interactions of the energy evolution process in different stages. The associated Bii values are computed through the analysis of energy evolution based on the fuzzy analytic hierarchy analysis process (FAHP) method. Tri-axial compression tests were conducted on granite, shale, and sandstone specimens under different confining pressures for the validation of the proposed brittleness evaluation (BE) index. The results indicate a decreasing trend in the brittleness index with increasing confining pressure. Comparative analysis with other existing brittleness evaluation indexes demonstrates that the new brittleness evaluation index offers a more precise evaluation of the brittleness of various rock types.

A phase-field length scale insensitive mode-dependent fracture model for brittle failure

This article presents a consistent phase-field length scale insensitive mode-dependent fracture model for brittle failure by proposing mode-factor dependent degradation functions that incorporate the effect of two additional fracture parameters, namely the mode-II critical energy release rate and mode-II fracture strength, on the overall mechanical response. Using the proposed mode-factor dependent degradation functions and employing a recently proposed modified strain decomposition scheme, we provide analytical expressions for the mode-I and mode-II fracture strengths corresponding to the mode-dependent parts of the elastic energy. Adopting a modified Benzeggagh–Kenane (B–K) criteria, we propose mode-dependent driving forces by deriving expressions for the critical energy release rate corresponding to individual fracture modes. The proposed model provides a consistent coupling between the different fracture modes and can thus predict fracture for all possible mode-mixity ratios. A parametric study is carried out to unravel the effect of mixed-mode fracture parameters on the mechanical response of isotropic materials by considering a few representative numerical examples. The numerical results from the proposed model show an excellent agreement with experimental results reported in the literature.

A Numerical Scheme and Validation of the Asymptotic Energy Release Rate Formula for a 2D Gel Thin-Film Debonding Problem

A Numerical Scheme and Validation of the Asymptotic Energy Release Rate Formula for a 2D Gel Thin-Film Debonding Problem

Pressure Characteristics and Secondary Ignition Effects of Gas Produced in RDE Using Lignite and Anthracite/CH4 Fuel.

This study aims to address the energy efficiency release and environmental impact of coal dust in rotating detonation engines (RDEs) by monitoring the detonation characteristics of lignite and anthracite in methane gas-solid mixtures using high-precision sensor technology. Experimental results indicate that the peak detonation pressure of anthracite is 1.4% higher than that of lignite, and its detonation wave propagation speed is at least 5.5% faster, suggesting that anthracite exhibits more stable and efficient fuel energy release characteristics during detonation. Additionally, the sensor technology enabled detailed recording of pressure fluctuations and gas composition changes during the detonation process, providing accurate data for assessing and controlling emissions of harmful gases such as carbon monoxide and carbon dioxide. These data are crucial for designing more efficient and environmentally friendly coal dust detonation systems, enhancing mine safety and environmental protection. The outcomes of this research not only advance technological progress in the field of energy science but also address efficiency and environmental issues in industrial applications, offering significant support for achieving safer and more sustainable energy production methods.

Unlocking Power: Impact of Physical and Mechanical Properties of Biomass Wood Pellets on Energy Release and Carbon Emissions in Power Sector

Abstract This study investigates the physical and mechanical properties of 12 biomass wood pellet samples utilised in a power generation, focusing on their implications for energy release and carbon emissions during combustion. Through comprehensive analysis involving bulk density measurements, compression tests, moisture analysis, calorimetry and controlled burning experiments, significant correlations among key properties are identified. Pellets with densities above 1100 kg/m3 demonstrate superior mechanical durability and strength, achieving maximum strengths of 0.6 to 0.8 kN with durability exceeding 99.4%. Optimal moisture content, typically between 6 and 7% is crucial for maximising density, bulk density, mechanical durability and fracture resistance, ensuring robust pellet structure and performance. The research underscores the impact of pellet dimensions, highlighting those longer lengths, > 12 mm enhance durability, while larger diameters > 8 mm exhibit reduced durability. Elemental analysis focusing on calcium, silicon and potassium plays a critical role in predicting and managing combustion system fouling, potentially reducing operational costs. Moreover, the study emphasises the significant influence of oxygen levels during combustion on CO2 emissions, achieving optimal results with moisture content in the 7–8% range for maximum higher heating value (HHV). The moisture content in the 14–15% range represents the lowest CO2 emission. The findings underscore the intricacy of the system and the interplay of parameters with one another. In accordance with the priority of each application, the selection of parameters warrants careful consideration. Graphical Abstract

Relocation of the 2021 MW 7.4 Maduo, Qinghai, China earthquake sequence and implications for seismogenic structure

An MW 7.4 earthquake struck Maduo County, Qinghai, China on 22 May 2021. To better understand the seismogenic structure of this region, we collect local earthquake arrival time data at the MAD station in the China Earthquake Networks Center observational bulletins during 1 June to 20 September 2021, and manually pick P and S wave arrival times from high-quality seismograms recorded at 34 recently deployed MaduoArray portable seismic stations. Using these arrival times, we relocate the Maduo earthquake sequence using earthquake association, absolute location and relative location methods. Our results show that the 2021 Maduo earthquake sequence occurred along the Kunlun Mountain Pass-Jiangcuo fault zone in the NWW-SEE direction and the aftershocks are located on both sides of the mainshock, showing characteristics of bilateral rupture. Vertical cross-sections of the aftershock distribution illustrate a nearly vertical shape of the seismogenic fault that tilts toward the northeast and southwest in different sections, reflecting a complex geometry of the fault plane. There is a horsetail bifurcation phenomenon at the eastern end of the fault zone. A sparse area of aftershocks appears at about 30 km east of the mainshock epicenter, which may be associated with a uniform fault friction and sufficient release of rupture energy caused by super-shear rupture of the mainshock. Taking into account many geophysical results including seismic tomography and magnetotelluric soundings, we speculate that the occurrence of the Maduo earthquake could be affected by crustal fluids in the fault zone. The fluids may ascend from the lower crustal flow beneath northeastern Tibet.

Which Insights Can Gas Diffusion Electrode Half-Cell Experiments Give into Activity Trends and Transport Phenomena of Membrane Electrode Assemblies?

In order to push the energy turnaround forward, research and development on technologies enabling storage and release of renewable energies, such as water electrolysis and fuel cells is vital in the current decade. For both processes it is essential to collect meaningful data for catalyst activity in terms of transferability to the industrial application already on the lab-scale and at an early stage of material development. Gas diffusion electrode (GDE) half-cell setups were recently presented as a fast and cost-effective tool to characterize oxygen reduction reaction (ORR) catalyst layers at fuel cell relevant potentials and current densities (3 A cm-2) [1]. An Inter-lab comparison demonstrated that GDE testing with various, slightly differing setups can deliver data that is both reliable and comparable if standardized measurement protocols are followed [2]. On the way to widespread application, it is essential to evaluate to which extend GDE half-cell measurements can provide reasonable trends of how catalyst layer properties influence ORR activity in membrane electrode assembly (MEA) applications, despite the major influence of the active metal itself. Elucidating possibilities and limitations of GDE half-cell measurements to study catalyst layer influences is scope of this study.The transferability of trends was studied for i) an ionic liquid modified and unmodified Pt/C catalyst (following our previous work [3]) and ii) employing nitrogen modified carbon support at different ionomer to carbon ratios (following the work of Ott et al. [4]). Regarding the activity increase due to IL modification we will show that rotating disk electrode (RDE) and GDE results at low current densities show the same trend. GDE testing also shows a maximum activity depending on the IL loading at slightly elevated current densities. In the high current density regime, however, MEA testing showed a negative effect of the IL modification, which was also obtained correctly within the GDE testing at the same current densities. For the N-doped Pt/C catalyst a positive effect was observed in MEA characterization with low ionomer content under dry conditions, where proton transport losses are dominant for the unmodified catalyst. However, at higher I/C ratio and under wet conditions, where proton transport is sufficient for both unmodified and N-doped catalyst, worse performance after N modification is observed in the high current density regime. During GDE evaluation only the latter phenomenon could be capture and the unmodified catalyst showed a superior performance over the N-doped material at any I/C ratio in the ohmic and in the mass transport limiting regime.In summary, we showed that GDE half-cell experiments, where the catalyst layer is in direct contact with the liquid electrolyte, can be used to reliably predict trends in catalytic activity for real MEAs at high current densities that are related to differences in oxygen mass transport [5]. However, differences in catalytic activity being related to proton accessibility especially at lower relative humidities cannot be captured completely, as the catalyst layer is always wetted fully. An introduction of an ionomer membrane between catalyst layer and liquid electrolyte might be necessary during GDE evaluation for a reliable description of all transport phenomena in real fuel cells. Nevertheless, our results indicate that GDE measurements without the utilization of an ionomer membrane allow for the study of oxygen mass transport properties independent of other transport phenomena at fuel cell relevant current densities.Literature:[1] Schmitt et al. Electrochemistry Communications 2022, 141, 107362 [2] Ehelebe et al. ACS Energy Lett. 2022, 7, 816-826. [3] Zhang et al. Advanced Functional Materials 31.28 (2021): 2010977 [4] Ott et al. Nature materials 19.1 (2020): 77-85. [5] Schmitt et al. Energy Adv. 2023, 2, 854.

SEPS functionalized PEG copolymer for improved toughness without obvious plasticization in epoxy resin

AbstractThe effects of grafting level of polyethylene glycol (PEG) grafted styrene ethylene propylene styrene (SEPS) on the intrinsic brittleness of epoxy thermosets were studied. The SEPS‐g‐PEG block copolymer (BCP) was synthesized by grafting various grafting degree of PEG (i.e., 10%, 20%, 30%, and 40%) on polystyrene (PS) blocks of SEPS following Williamson ether synthesis method. A total of 10 wt% of the BCP modifiers were dispersed in epoxy thermosets. PEG side chains were miscible in the epoxy which formed a uniform BCP dispersion within the epoxy thermoset matrix. As the degree of PEG grafting was increased, the BCP phase was absorbed in the epoxy matrix. This absorption occurred because the increase in PEG grafting provided more miscible PEG chains to bind the BCP and epoxy nanostructures together. The differential scanning calorimeter and dynamic mechanical thermal analysis analyses indicated that BCP toughened epoxy exhibited an improved glass transition temperature (Tg). At a 40% PEG grafting degree in the BCP, the critical stress intensity factor (KIC) and critical strain energy release rate (GIC) increased up to 80% and 180%, respectively. This trend suggested that the energy associated with fractures could be absorbed through the deformation of the softer phases when a load was applied to them.

Mesoscale formation and energy release characteristics of PTFE/Al reactive jet

AbstractIn order to investigate the mechanical formation, the mechanical‐thermo coupling mesoscale mechanism and the corresponding energy release characteristics of PTFE/Al composite material reactive jet, a mesoscale discretization model of PTFE/Al reactive liner with a mass ratio of 73.5 %/26.5 % is developed on the basis of the random delivery principle. The mesoscale numerical simulation is used to perform PTFE/Al reactive jet formation, obtaining the relative distribution characteristics of material, pressure, and temperature. The overpressure experiments for the energy release of reactive jets are conducted. The results show that there is an increasing tendency in the amount of Al particles from the jet's tip to its tail due to the velocity variance between PTFE and Al. The high temperature zones are found to be concentrated on the tip and axis of the jet, with particle deformation, collision and friction in the reactive jet accounting for the temperature rise. Moreover, the Al particle size has a significantly influence on the particle distribution and the mechanical‐thermo coupling behavior in the reactive jet, and the decrease of particle size is beneficial to the chemical reaction among the components of the reactive jet. To be more specifically, under the conditions of Al particle size of 400 μm, 600 μm and 800 μm, the overpressure peaks of reactive jet in 13 L chamber are 3.32 MPa, 2.86 MPa and 2.61 MPa, respectively. The variation of the overpressure with Al particle size obtained by experiment is consistent with the analysis of the mechanical‐thermo coupling characteristics of mesoscale numerical simulation.

Innovative carbonization techniques for food waste: A comparative study of hydrothermal carbonization (HTC) and vapor-thermal carbonization (VTC)

This study addresses the pressing issue of global food waste (FW) by conducting a comprehensive comparison between two conversion methods: hydrothermal carbonization (HTC) and vapor-thermal carbonization (VTC) for the production of hydrochar. The analysis encompasses physicochemical characterizations, Fuel characteristics, and surface properties. Under identical reaction conditions (180–250 °C, 30 minutes), both processes significantly elevate the carbon content of hydrochar. VTC-hydrochar with a carbon content ranging from 54 % to 62 %, while HTC-hydrochar with a slightly higher range of 55–63 %. Notably, hydrochar derived from both methods results in higher heating values (HHV) of 24.04–27.40 MJ/kg for HTC and 22.85–26.60 MJ/kg for VTC, indicating enhanced fuel quality. But with less volatile matter, VTC-hydrochar shows lower HHV. Moreover, HTC-hydrochar demonstrates superior attributes for rapid ignition and energy release, while VTC-hydrochar proves more suitable for applications requiring higher combustion temperatures and stability. In terms of surface properties, VTC-hydrochar demonstrates a higher NH4+ adsorption capacity attributed to its superior pore structure and abundant key functional groups, making it an ideal choice for adsorption applications. Most notably, through comparative analysis, finding that VTC-hydrochar with a more uniform structure from the complex and diverse FW feedstock. This study establishes a robust scientific foundation for selecting appropriate hydrochar production technologies.

Solar thermal energy and CO2 storage in saline aquifers for renewable energy space heating

There are a large number of abandoned oil and gas wells and corresponding depleted oil/gas reservoirs (DOGR) throughout the world, which are recognized as one of the best geological formations of saline aquifers for thermal energy storage and CO2 sequestration and however, the lack of innovative technique limits the efficient use of underground storage space. Here a novel scheme of storing solar thermal energy and concomitantly sequestrating CO2 in DOGR for renewable energy heating is proposed, which uses CO2 as thermal energy storage working fluid. The process of thermal energy storage and release as well as CO2 sequestration in DOGR are simulated, and thermal performance and CO2 dissolution in DOGR are analyzed. The results for twenty years of operation show that the thermal recovery efficiency reaches up to 82.93 %, which is 76 % higher than the traditional high temperature aquifer thermal energy storage. Energy storage capacity per heating season, energy storage density per unit volume of underground space and energy efficiency are respectively 57,222.27 GJ, 22,943.01 kJ/m3 and 96.19 %. Furthermore, the dissolved CO2 during thermal energy storage and extraction is 54.76 % larger than that of mere CO2 sequestration due to the repeated expansion and contraction of gas and water interface caused by the periodically injection and extraction of CO2, indicating that energy storage accelerates CO2 sequestration. To sum up, the new scheme is a high value-added technical route for solar thermal energy storage and CO2 sequestration as well as renewable energy heating.

Location preference of boron and nitrogen dopants at graphene/copper interface

Controlling the placement of dopants can significantly tailor graphene's properties, but this process is influenced by copper substrates during vapor deposition. Understanding the influence of interfacial atomic structures on the preference for dopant locations is crucial. In this work, we conducted a systematic first-principles study of boron- and nitrogen-doped graphene on copper {111}, considering both sublattice and superlattice configurations. Our calculations revealed that the formation energy is minimized at the top-fccb site (−0.60 eV) for boron and the hcp-fcca site (1.94 eV) for nitrogen, suggesting a possible selective distribution of dopants in both sublattice and superlattice arrangements at the graphene/copper interface. Furthermore, a lower formation energy indicates a higher release of energy during doping, resulting in a stronger interfacial binding. Since formation energy is closely associated with out-of-plane interactions, while in-plane interactions remain relatively stable, these differences offer potential avenues for modifying dopant distribution at graphene/copper interfaces.

Thermodynamic modeling and analysis of a Carnot battery system integrating calcium looping thermochemical energy storage with coal-fired power plant

Long-term energy storage and carbon capture technologies are pivotal in managing renewable energy surpluses and achieving carbon neutrality. This paper proposes a Carnot battery system integrating calcium-looping thermochemical energy storage with a coal-fired power plant. The system utilizes excess electricity from the grid for energy input, facilitating long-term energy storage, achieving carbon capture, and reducing coal consumption in the power plant. An optimization framework is developed, incorporating component thermodynamic models and optimization algorithms, to maximize the coal savings in plants and energy efficiencies of the Carnot battery system. During the energy release process, the carbonator partially replaces the reheat load of the boiler, necessitating retrofitting of the boiler’s heating surface to ensure normal operation. The base system demonstrates a CO2 capture capacity of 3.23 MJ/kg and a reduction in coal consumption by 7.07 %. The round-trip efficiency and comprehensive efficiency of the base system are 36.93 % and 37.91 %, respectively. The relatively low energy efficiency is primarily due to the deactivation of circulating adsorbents and the limited efficiency of the subcritical coal-fired power plant. By incorporating an additional recarbonation step to mitigate adsorbent deactivation, the system’s comprehensive efficiency is improved to 42.20 %. Further improvements in system efficiency can be achieved by using modified adsorbents with high cycling stability instead of natural limestone and by coupling the system with more efficient ultra-supercritical units instead of the investigated subcritical units. This study offers valuable insights into the development of long-term energy storage solutions and multifunctional Carnot battery technology.

The impact of energy releasing B-vitamin intake on indices of obesity and cardiac function: a cross-sectional study

Background B vitamins play a crucial role in the balance and metabolism of energy. Energy metabolism mainly benefits from the B-complex vitamins. Specifically, decarboxylation, transamination, acylation, oxidation, and reduction of substrates that are ultimately employed in energy intake require thiamin, riboflavin, niacin, and vitamin B6. Vitamin deficiency could lead to chronic disease occurrence. Objectives To assess the impact of energy-releasing B-vitamins intake (B1, B2, B3, and B6) on selected indices of obesity and cardiac function. Methods A cross-sectional study was performed on 491 apparently healthy adults (18-64 years old) between January and May 2019 at Hashemite University, Jordan. Anthropometric measurements were taken, lipid profiles were analyzed, and indices of obesity and cardiac function were calculated. The typical dietary intake of B1, B2, B3, and B6 vitamins was calculated. Results Conicity index (CI) and abdominal volume index (AVI) scores significantly decreased with the increased adjusted vitamin B1 and B6 intake. Also, body roundness index (BRI), weight-adjusted-waist index (WWI), lipid accumulation product (LAP), and atherogenic index of plasma (AIP) scores were decreased with the increase of adjusted B6 intake (p<0.05). The total sample showed a significant inverse weak correlation between energy-adjusted intake of B1 and AVI (r= -0.156, p=0.001) and BRI (r= 0.111, p=0.014). Similar correlations were detected among male participants between energy-adjusted B1 intake and BAI, AVI, and BRI. Female participants had a significant weak inverse correlation between BAI and energy-adjusted B2 (r= -0.180, p=0.029) and B6 intake (r= -0.212, p=0.010). Only B1, the vitamin, significantly explained 2.43 and 1.24% of changes observed in the AVI and BRI scores, respectively (p<0.05). Conclusions Increasing the consumption of B1, B2, and B6 may significantly lower values of indices of obesity and cardiac function regardless of sex differences. Thus reducing the occurrence of obesity and related coronary heart diseases.

Synthesis of boron-based High-Energy composite microspheres via the Co-Flow microchannel method

Boron-based metastable intermolecular composites (MIC), renowned for their swift energy release and elevated thermal output, exhibit significant promise for utilization in domains such as gunpowder, propellants, and powdered fuel ramjet fuels. The work successfully accomplished the safe and efficient preparation of B/Bi2O3 microunits by utilizing co-flow microchannel technology. The choice of the optimal binder, F2603, for this system was determined by simulation analysis. The practicality of the microchannel platform was then verified using Fluent. SEM analysis demonstrated that an amount of 10 % F2603 resulted in the formation of spherical particles. In terms of physical properties, boron treated with 10 % F2603 exhibits a reduction in its angle of repose from 35° of the raw material to 15°, along with a significant enhancement in hydrophobicity. Furthermore, the MICs lower the reaction temperature of raw boron from 840℃ to 770℃. In the constant volume combustion test, the MIC output pressure increased by 33.3 %. In the constant pressure combustion test, the MIC ignition delay time was reduced from 0.7262 s to 0.5566 s. The structural characteristics of the system decrease the distance for mass and heat transmission across components, resulting in improved overall performance. The study unequivocally demonstrates the efficacy of co-flow microchannel technology in swiftly, effectively, and securely producing energetic molecules. It establishes a solid foundation for future industrial manufacturing.

Signature of nano alumina condensation during metal combustion

The work is focused on thermal radiation originating from aluminum oxide nanoparticles formed during the combustion of an aluminum and copper oxide (Al/CuO) thermite. The light emission signature allows for the identification of condensation features important for the global energy balance of burning metal-containing systems. From a fundamental science perspective, identifying light emission signatures associated with phase changes, and in particular, with condensation that is accompanied by high energy release, will lead to new knowledge with widespread applications. The recently developed calibration-free pyrometry approach is used to isolate the radiation of interest during combustion. Processing the obtained spectra made it possible to detect the solidification of the resulting nano alumina. Knowledge of the phase transition temperature enabled the determination of the temporal behavior of the absolute temperature of aluminum oxide nanoparticles during their formation by condensation from gaseous metal suboxides. This ability to measure absolute temperature, as opposed to its reciprocal value available with the original calibration-free pyrometry approach, further enhances the diagnostic method's capabilities. The general implications of revealed peculiarities of nano alumina formation for detailed modeling of the combustion of metal-containing systems are discussed.

Effect of Bedding Angle on Energy and Failure Characteristics of Soft–Hard Interbedded Rock-like Specimen under Uniaxial Compression

To investigate how bedding planes affect the energy evolution and failure characteristics of transversely isotropic rock, uniaxial compression tests were conducted on soft–hard interbedded rock-like specimens with varying bedding angles (α) using the RMT-150B rock mechanics loading system. The test results indicate that throughout the loading process, the energy evolution shows obvious stage characteristics, and the change of α mainly affects the accelerating energy dissipation stage and the full energy release stage. With the increase of α, the ability of rock to resist deformation under the action of energy shows the characteristics of “strong–weak–strong”. The energy dissipation process is accelerated by medium angle bedding planes (α = 45°~60°). The precursor points of the ratios of dissipation energy to total energy (RDT) and elastic energy to dissipation energy (RED) can be used to effectively predict early failure. With the gradual increase of α, the difficulty of crack development is gradually reduced. The changes of energy storage limitation and release rate of releasable elastic energy are the immanent cause of different macroscopic failure modes of specimens with varying α.

Fatigue and delamination of 6061 aluminum cold spray on a similar wrought substrate

Fatigue crack growth and fracture of a thick 6061 aluminum cold spray coating on 6061-T6 aluminum substrate were studied through in-situ observation of fatigue crack growth through the coating to the interface in notched four-point bend samples. Mode I cracking was observed through the coating before delamination at the substrate. Crack tip strain fields during the delamination event were plotted with DIC. Interfacial steady-state strain energy release rates were measured using the bimaterial four-point bend solutions by Charalambides. The interfacial crack primarily spread cleanly along the coating/substrate interface, with a post-fracture surface morphology containing a wavy structure with an amplitude on the same order of magnitude as the cold spray particle diameters. The in-situ video of crack propagation and coating-substrate delamination provides lessons for improving the coating-substrate interfacial toughness and thus expands use cases for structural cold spray applications