Energy Propagation Research Articles

Typhoon‐Induced Near‐Inertial Waves Around Miyakojima Island in 2015

AbstractIn 2015, four typhoons traversed the regions surrounding the Ryukyu Island Chain, resulting in different near‐inertial waves (NIWs), the characteristics of which were investigated through in situ observations around Miyakojima Island and numerical simulations covering the East Asian marginal seas. The spatial distribution of typhoon‐induced near‐inertial motions was significantly correlated with the typhoon tracks and background currents. Typhoons Chan‐hom and Goni traversed the observation transect, resulting in different spatial patterns of NIWs owing to their different tracks. Observations on both the western and eastern sides of the Ryukyu Island Chain failed to capture NIWs after typhoon Chan‐hom, because they were positioned to the left of the typhoon track where near‐inertial motions were enhanced only in the upper 50 m. In contrast, NIWs were negligible on the left side and energetic on the right side of typhoon Goni. Despite being hundreds of kilometers from the observation transect, typhoons Soudelor and Dujuan induced NIWs with higher energy levels than those induced by typhoons Chan‐hom and Goni. The energy propagation of NIWs after typhoons Soudelor and Dujuan was significantly influenced by background currents. The western boundary currents, including the Kuroshio and Ryukyu Currents, create negative relative vorticity on their right, which works like a waveguide for the poleward advection of NIWs. However, the Ryukyu Current can be impeded by westward‐propagating cyclonic eddies from the North Pacific, which further disrupts the waveguide.

Influence of temperature and crack-tip speed on crack propagation in elastic solids.

I study the influence of temperature and the crack-tip velocity of bond breaking at the crack tip in rubber-like materials. Bond breaking is considered as a stress-aided thermally activated process and results in an effective crack propagation energy, which increases strongly with decreasing temperature or increasing crack-tip speed. This effect is particularly important for adhesive (interfacial) crack propagation but less important for cohesive (bulk) crack propagation owing to the much larger bond-breaking energies in the latter case. For adhesive cracks, the theory results are consistent with adhesion measurements for silicone rubber polydimethylsiloxane (PDMS) in contact with silica glass surfaces. For cohesive cracks, the theory agrees well with experimental results PDMS films chemically bound to silanized glass.

Dynamic response of rock landslides and avalanche debris flows impacting flexible barriers based on shaking table tests

Flexible barrier structures are commonly installed in mountainous regions to resist the impact effects of rock avalanches. Without reliable physical data, the study of rock landslide initiation and the impact mechanism of avalanche debris flow under seismic excitation remains poorly understood. In this study, a model of rock slope-flexible barrier system was developed to simulate seismic slope failure behavior and debris flow impact on flexible barriers. Seismic waves in shaking table tests were triaxially loaded to effectively simulate actual seismic responses. The results indicate that the response of the Acceleration Amplification Factor (AAF) is closely associated with seismic damage and deformation within the overlying rock layers and differential propagation of seismic energy on either side of the shear band triggers rockslide initiation. Furthermore, the progressive failure mode of modeled slopes under multiple seismic events is slip-compression cracking failure. Crushing spreading at the intersection of the cracking and slip surfaces is the source of the loose fractured rock mass. Finally, this paper examines the impact patterns and dynamic responses of large individual blocks and loose fractured deposits on flexible barriers. Large blocks cause localized strong acceleration in the steel wire nets, increasing the risk of local damage, whereas loose deposits tend to induce overall seismic deformation and instability of the supporting structure. The natural seismic damage mechanisms of the barrier structure are revealed. It is recommended that flexible barrier structures in earthquake-prone mountainous areas incorporate a reasonable footing design to ensure the columns can deflect out-of-plane in response to seismic activity.

Influence of Temperature and Bedding Planes on the Mode I Fracture Toughness and Fracture Energy of Oil Shale Under Real-Time High-Temperature Conditions

The anisotropic fracture characteristics of oil shale are crucial in determining reservoir modification parameters and pyrolysis efficiency during in situ oil shale pyrolysis. Therefore, understanding the mechanisms through which temperature and bedding planes influence the fracture behavior of oil shale is vital for advancing the industrialization of in situ pyrolysis technology. In this study, scanning electron microscopy (SEM), CT scanning, and a real-time high-temperature rock fracture toughness testing system were utilized to investigate the spatiotemporal evolution of pores and fractures in oil shale across a temperature range of 20–600 °C, as well as the corresponding evolution of fracture behavior. The results revealed the following: (1) At ambient temperature, oil shale primarily contains inorganic pores and fractures, with sizes ranging from 50 to 140 nm. In the low-temperature range (20–200 °C), heating primarily causes the inward closure of inorganic pores and the expansion of inorganic fractures along bedding planes. In the medium-temperature range (200–400 °C), organic pores and fractures begin to form at around 300 °C, and after 400 °C, the number of organic fractures increases significantly, predominantly along bedding planes. In the high-temperature range (400–600 °C), the number, size, and connectivity of matrix pores and fractures increase markedly with rising temperature, and clay minerals exhibit adhesion, forming vesicle-like structures. (2) At room temperature, fracture toughness is highest in the Arrester direction (KIC-Arr), followed by the Divider direction (KIC-Div), and lowest in the Short-Transverse direction (KIC-Shor). As the temperature increases from 20 °C to 600 °C, both KIC-Arr and KIC-Div initially decrease before increasing, reaching their minimum values at 400 °C and 500 °C, respectively, while KIC-Shor decreases continuously as the temperature increases. (3) The energy required for prefabricated cracks to propagate to failure in all three directions reaches a minimum at 100 °C. Beyond 100 °C, the absorbed energy for crack propagation along the Divider and Short-Transverse directions continues to increase, whereas for cracks propagating in the Arrester direction, the absorbed energy exhibits a ‘W-shaped’ pattern, with troughs at 100 °C and 400 °C. These findings provide essential data for reservoir modification during in situ oil shale pyrolysis.

Modeling the Effects of a Light Bridge on Properties of Magnetohydrodynamic Waves in Solar Pores

Solar pores are ideal magnetic structures for wave propagation and transport of energy radially outwards across the upper layers of the solar atmosphere. We aim to model the excitation and propagation of magnetohydrodynamic waves in a pore with a light bridge modeled as two interacting magnetic flux tubes separated by a thin, weaker-field layer. We solve the three-dimensional magnetohydrodynamic equations numerically and calculate the circulation as a measure of net torsional motion. We find that the interaction between flux tubes results in the natural excitation of propagating torsional Alfvén waves but find no torsional waves in the model with a single flux tube. The torsional Alfvén waves propagate with wave speeds matching the local Alfvén speed where wave amplitude peaks.

The comparative analysis of energy dissipation behaviour of woven and UD para-aramid fabrics

This research examines how impact energy spreads across para-aramid fabrics, comparing woven and unidirectional types, using 2-D Thin Plate Spline analysis. The experiment involved dropping a weighted hemisphere onto fabric samples and measuring their deformation across different layer counts. To assess how yarn orientation affects energy dispersion, panels with 0º/90º and 0º/90º/±45º configurations were tested. By analysing the fabric's shape changes under impact, the study revealed patterns of energy propagation. Calculations of bending energy and expansion factors provided insights into this behaviour. The findings indicate that unidirectional fabrics outperform woven structures in distributing impact energy across their surface. Moreover, incorporating ±45º fibre reinforcements in both fabric types enhances energy dispersion and mitigates impact effects.

Influence of cold plasma on material removal behavior during diamond grit scratching single crystal silicon

As a typical brittle crystal material, single crystal silicon has high hardness and brittleness, which makes the machined surface prone to microscopic cracks and other subsurface damage. In addition, the anisotropic crystal structure may cause large differences in the material removal behavior along different crystal orientations. To solve these problems, researchers have proposed the methods of machining along the easy-to-cut direction and inducing external energy fields assisted machining, but there remain problems like cracks and surface thermal damage. In this study, we propose to modulate the deformation process of single crystal silicon by atmospheric pressure cold plasma and elucidate the influence of plasma on the material removal behavior based on diamond grit scratching experiments along different directions. The results show that before plasma treatment, the toughness along <110> direction is higher than that along <100> direction, and plasma has significant improvement effects on the plastic deformability in both directions. The critical load for plastic-brittle transition along <110> direction can be increased from 76.2 mN to 107.1 mN, and from 69.6 mN to 109.8 mN along <100> direction. The plasticity regulation mechanism is that the interaction of multiple shear bands dissipates the energy of crack propagation and inhibits the premature generation of cracks. Compared with the conventional scratching along <110> direction, the material removal rate of plasma-assisted scratching under normal loads of 20 mN, 40 mN and 80 mN can be increased by 30.2 %, 24.2 % and 21.9 %, respectively; while that along <100> direction can also be increased by 33.7 % and 19.5 % under 20 mN and 40 mN, respectively. This study may provide a novel approach for realizing high-quality and efficient processing of hard and brittle materials.

Rutting and fatigue behavior of neat and nanomodified asphalt mixture with SiO2 and TiO2

Modern asphalt technology has adopted nanomaterials as an alternative option to assert that asphalt pavement can survive harsh climates and repeated heavy axle loading during service life and prolong pavement life. This work aims to elucidate the behavior of the modified asphalt mixture fracture model and assess the fatigue and Rutting performance of Hot Mix Asphalt (HMA) mixes using the outcomes of indirect Tensile Strength (IDT), Semicircular bend (SCB) and rutting resistance; for this, a single PG (64−16) nanomodified asphalt binder with 5 % SiO2 and TiO2 have been investigated through a series of laboratory tests, including: Resilient modulus, Creep compliance, and tensile strength, SCB, and Flow Number (FN) to study their potential role of these nanomaterials to improve the rutting characteristics and fatigue life of wearing asphalt mixture at different temperatures. The outcome of this study revealed the positive role of these materials in enhancing mixture IDT characteristics, fracture energy, and viscoelastic deformation component of crack propagation; on the other hand, at higher temperatures, the modified mixture exhibited a superior performance in reducing the permanent deformation of asphalt mixture with SiO2 followed by TiO2 as compared to neat asphalt mixture.

Temperature dependence of the deformation behavior and mechanical properties of a Fe–Mn–Al–C low-density steel for cryogenic application

The temperature dependence of the deformation behavior and mechanical properties of a Fe–20Mn–6Al-0.6C-0.15Si austenitic low-density steel was studied by tensile test and Charpy impact test at −196 °C, −77 °C and room temperature (RT), followed by microstructure analyses. The results indicate that the decreased tensile temperature, which is corresponding to reduced stacking fault energy (SFE), promotes the planar glide of dislocations. This led to larger fraction of low-angle grain boundaries (LAGBs) at lower tensile temperature. Consequently, both the tensile strength and elongation were improved as temperature decreased. At lower impact test temperature, the load and energy of crack initiation were larger, indicating a higher resistance to crack initiation. However, the transition from stable to unstable crack propagation occurred more rapidly at lower temperature, resulting in lower crack propagation energy and reduced resistance to crack propagation. This is because less region experienced planar glide. Due to the rapid unstable crack propagation, the Charpy absorbed energy at −196 °C was the lowest. The smaller fracture surface area, larger fibrous zone and more obvious ductile fracture characteristics in radial zone suggest that the toughness is better at higher temperature. Additionally, the presence of secondary cracks at RT delayed fracture, therefore benefitting toughness.

Mid-frequency propagation path analysis on vehicle body using structural intensity

With the penetration of electric vehicles, reduction of structure-borne road noise gets important issue to realize comfortable vehicles for customers.Sound generation mechanism of structure-borne road noise on vehicle body is analyzed basically by modal analysis in low-frequency range. On the other hand, as frequency increases, modal analysis cannot clarify vibration mechanism because vibration wavelength gets shorter, mode density gets high and mode shape gets complicated. Therefore, it is difficult to identify efficient countermeasure parts and inefficient damping materials are added to response panels in mid-frequency range. So alternative analytical methods in mid-frequency range are under research to understand vibration mechanism. In this paper, Structural intensity (SI) analysis is introduced to clarify sound propagation mechanism. This analysis method makes it possible to clarify the main energy propagation path from input point to vibrating panels on vehicle body. The results show that SI analysis unveils the main energy propagation path and gives the opportunity to reduce the panel vibration efficiently by controlling the energy propagation path in body frame structure without damping materials.

Investigating thermal conduction dynamics in ternary Carreau–Yasuda nanofluids under convective boundary conditions and exponential heat source/sink effects

The analysis of the Carreau–Yasuda nanofluid (CYNF) across a stretching surface has practical applications in several fields, such as heat exchange, engineering, and material science. Scholars may discover novel perspectives for increasing heat transfer performance, establishing advanced materials, and enhancing the efficiency of multiple engineering systems by studying the behavior of CYNF in this particular instance. The energy transfer through trihybrid CYNF flow with the effect of magnetic dipole across a stretching sheet is examined in the present study. The ternary hybrid nanofluid (THNF) has been prepared by the addition of ternary nanoparticles (NPs) in the water (50%) and ethylene glycol (50%). Titanium dioxide (TiO2), silicon dioxide (SiO2), and aluminum oxide (Al2O3) are used in base fluid. The fluid velocity and heat transfer are examined under the impact of Darcy–Forchheimer, chemical reaction, convective condition, activation energy, and exponential heat source. The fluid flow has been stated in form of velocity, energy, and concentration equations. The set of modeled equations is simplified to non-dimensional form of ordinary differential equations (ODEs) by using similarity substitutions. Numerically, the system of lowest order ODEs is calculated through the parametric continuation method. It has been noticed that the temperature field augments against the variation of viscous dissipation and heat source term. Furthermore, the magnetic dipole has significant impact to enhance the thermal curve of THNF whereas falloffs the velocity profile. It can be noticed that the energy propagation rate enhances with the rising numbers of ternary NPs, from 1.22% to 5.98% (nanofluid), 2.30% to 9.61% (hybrid nanofluid), and 3.23% to 11.12% (trihybrid nanofluid).

Fracture toughness and fracture mechanism of Al-Mg-Si alloy sheet subjected to pre-cryorolling and subsequent bake hardening

The fracture toughness of AA6061 sheets subjected to pre-cryorolling and room-temperature pre-rolling with varying reductions (5 %, 10 %, 15 %, and 20 %) followed by bake hardening was investigated. In the direction parallel to the rolling direction (R-T), the unit crack initiation energy (UIE) of the pre-cryorolled samples after bake hardening exhibited an increase of 0.8–6 % compared to samples without pre-rolling. In contrast, the UIE of the room-temperature pre-rolled samples displayed a varying degree of decrease. This difference can be attributed to the smaller mean grain size in the pre-cryorolled samples compared to the room-temperature pre-rolled samples. Due to work hardening, the crack propagation resistance of the pre-rolled samples was diminished, as evidenced by a decrease in crack propagation energy (UPE) with increasing reduction. The variation trends of UIE and UPE in the direction perpendicular to the rolling direction (T-R) were similar to those observed in the R-T direction. The fracture mechanism of the samples during the tearing process involves a combination of intergranular and transgranular fractures. However, samples in the R-T direction exhibit higher resistance to crack propagation compared to those in the T-R direction, which is reflected in the larger UIE and UPE. The greater resistance in the R-T direction can be attributed to the significant elongation of grains prior to fracture, resulting in a higher degree of plastic deformation in the region near the crack. Additionally, the proportion of transgranular fracture along the crack propagation path is greater in the R-T direction.

Effect of carbon content on the microstructure and mechanical properties of Ti2AlC/TiAl composites with network architecture

In the present work, using pre-alloyed Ti-48Al-2Cr-2Nb powders and graphite powders with different contents as raw materials, the Ti2AlC/TiAl composites with network architecture were fabricated by spark plasma sintering (SPS). The effect of carbon content on the microstructure and mechanical properties of Ti2AlC/TiAl composites with network architecture was investigated. The results have shown that with the increasing carbon content from 0.5 wt% to 2 wt%, the network continuity of Ti2AlC particles gradually transforms from semi-continuous network into quasi-continuous and nearly-continuous network, and the network thickness transforms from 5 to 10 μm into 10∼15 μm and 20∼30 μm. The Ti2AlC/TiAl composite with 1 wt% C shows a better balance of compressive strength and ductility, which the room-temperature compressive strength is 2051 MPa and compressive strain is 30.9 %. The quasi-continuous network structural Ti2AlC particles in Ti2AlC/TiAl composite with 1 wt% C could effectively deplete the crack propagation energy by deflecting the crack, and passivate the crack to hinder further propagation, which facilitates the improvement of the strength and ductility in the Ti2AlC/TiAl composite.

Aurorally Driven Supersonic Gravity Waves in Saturn's Atmosphere

AbstractSimulations with the Saturn Thermosphere‐Ionosphere General Circulation Model have revealed global‐scale gravity waves in Saturn's upper atmosphere that have not been observed or predicted before. They are forced by diurnally varying zonally non‐uniform distributions of Joule heating and ion drag at the high‐latitude auroral regions in both hemispheres and propagate outward from the source region. The supersonic zonal phase speed imposed by Saturn's rotation and the subsonic meridional phase velocity of about 800 m form a distinct spiral wave structure. They exhibit features of gravity waves: vertical phase progression opposite to the propagation of wave energy and long vertical wavelengths consistent with the dispersion relation for gravity waves. The amplitudes of the perturbations grow with height, reaching 6%–10% for relative temperature variations and up to 350 m for the meridional velocity perturbations. The main effect of these waves is to accelerate the retrograde westerly jets.

Analysis of dynamic modeling and power flow of ABH laminated composite thin beam with elastic boundaries

To investigate the energy distribution characteristics of a laminated structure with an acoustic black hole (ABH), this study introduces the dynamic modeling and power flow analysis of an ABH laminated thin beam (ABH laminated beam) with elastic boundary conditions for the first time. ABH profile is defined by a power function in the dynamic modeling process. Utilizing the Euler-Bernoulli beam theory, the constitutive equation of ABH laminated beams is formulated by using the isogeometric method. Three sets of artificial springs are employed to replicate the elastic boundary conditions, incorporating the potential energy of the springs. Subsequently, the dynamic model of the ABH laminated beam is developed by solving the Lagrange equation concerning the total energy within the uniform region, ABH region, and boundary. Through numerical examples, the convergence and accuracy of the proposed modeling approach are validated by comparing the results with those obtained from COMSOL Multiphysics and experimental data. The analysis of power flow and structural intensity elucidates the energy propagation behavior in ABH laminated beams and the underlying mechanism of the ABH effect. The results demonstrate that the ABH laminated beam displays remarkable absorption and dissipation characteristics, introducing a new perspective for the design and application of ABH structures.

Enhancing charpy absorbed energy of aged duplex lightweight steel plates through TRIP and TWIP mechanisms

Ensuring toughness in thick hot-rolled plates remains a challenge for lightweight steels in automotive, shipbuilding, military, and construction industries despite improved tensile properties. This study investigated the Charpy absorbed energy of thick hot-rolled Fe-0.4C-15Mn-6Al duplex lightweight steel plates exhibiting TRIP and TWIP mechanisms, aged at 450–500 °C to precipitate κ-carbides. Fracture initiation and propagation energies measured from instrumented Charpy impact testing were analyzed through microstructural and microfracture analyses. The 500 °C-aged (A500) specimen showed the highest Charpy absorbed energy, composed of the highest fracture initiation and propagation energies across all test temperatures, particularly due to active TWIP and TRIP mechanisms along with significant κ-carbide precipitation strengthening. Despite predominantly ductile fracture modes, regardless of aging temperature and test temperature, deformation mechanisms were influenced by stacking fault energy (SFE). Aging resulted in κ-carbide precipitation, reducing C and Mn contents in austenite and lowering SFE. At 25 °C, the superior energy absorption of the A500 specimen (296 J) was attributed to its high flow stress and extensive roughness in the fracture surface due to crack deflection in the fracture initiation region and zigzag crack propagation. The Charpy absorbed energy decreased significantly at lower temperatures due to limited development of slip line field and less zigzag crack propagation. Despite this, the A500 specimen maintained the highest energy absorption due to its optimized TWIP and TRIP mechanisms and κ-carbide precipitation strengthening.

Mechanical property improvement of diffusion bonded ZrCx joints by chemical homogenization using Ta as the interlayer

In the present study, a transition metal Ta foil was used as the interlayer to diffusion bond ZrCx ceramics. A needle-like ζ-Ta4C3-x phase was initially formed at the interface and could be effectively dissolved into the base ceramic by reasonably tuning the bonding temperature and holding time, resulting in a chemically homogeneous joint when diffusion bonded at 1600 °C for 1 h under 20 MPa pressure. The composition of the homogeneous joints was composed of ZrCx(Ta), which is very similar to the base ceramic. The ζ-Ta4C3-x phase was found beneficial to the mechanical property of the joints due to its mechanically interlocking effect and the ability to absorb the propagation energy of microcracks. The chemically homogeneous joint had comparable four-point bending strength and nano-indentation hardness with that of the base ceramic, indicating that chemical homogenization of the joint has great potential to enhance the mechanical property of the ZrCx joints.

Fault slip and seismic source response characteristics under induced stress wave

As coal mining depth and structural complexity increase, the failure severity of mining-induced fault activation leading to rock bursts escalates. Fault fracture zones, consisting of various secondary structures, are essential for understanding tectonic evolution and seismic wave propagation. The interaction between mining-induced stress waves and in-situ stress complicates the dynamics and activation markers of fault fracture zones. This paper aims to clarify the patterns of stick–slip instability and stress evolution in these zones under coal mining-induced stress waves. Using theoretical models and continuous-discrete coupling simulations, the study explores the dynamic response of fault fracture zones in the meta-instability stage, the micro-scale fracture force chain structure, and the distribution and synergistic instability of fault plane seismic sources. The research shows that fault fracture zones changes stress wave propagation path and energy redistribution due to its heterogeneity leads to multiple times decomposition of wave field. Minor delamination between the hanging wall and footwall can trigger unstable slip. Tensional seismic sources with extensive failure drive fault slip. Dynamic stress waves disrupt force chains near seismic sources, increasing hazard levels. Static in-situ stress affects shear seismic sources by influencing porosity and crack angles. Seismic sources along the fault strike transition from divergent to concentrated, trending horizontally. In the meta-instability stage, the initial fracture area locks, with strong structures causing cohesive fractures in the middle of the fault zone, releasing strain energy and forming a sudden increase in slip intensity. These findings provide crucial insights into fault fracture-development-activation markers, fault region stress deformation evolution mechanisms, and risk control of fault-induced rock bursts.

The combined link of the Indian Ocean dipole and ENSO with the North Atlantic-European circulation during early boreal winter in reanalysis and the ECMWF-SEAS5 hindcast

Abstract During early boreal winter, the extra-tropical atmospheric circulation is influenced by Rossby waves propagating from the Indian Ocean towards the North Atlantic-European (NAE) regions, resulting in a North Atlantic Oscillation (NAO)-like pattern. The mechanisms driving these teleconnections are not well understood and are crucial for improving model skills. This study investigates these mechanisms using the ERA5 dataset and tests the predictive capabilities of the ECMWF-SEAS5 hindcast, exploring potential reasons for a weak model response. Linear regression methods are employed to examine the extra-tropical links with the Indian Ocean dipole (IOD), both in isolation and in combination with the El Niño-Southern Oscillation (ENSO). Our findings demonstrate a connection between October IOD sea surface temperature anomalies and December Indian Ocean precipitation patterns. Furthermore, a correlation between the October IOD and December NAO time series suggests a link between the IOD and NAE circulation. The early winter European response to a positive IOD is characterized by a north-south precipitation dipole and a large positive surface air temperature anomaly. Positive feedback from transient eddy forcing reinforces the wavenumber-3-like propagation across extra-tropical regions, with ENSO playing a minor role compared to the IOD. This phenomenon is particularly evident in regions such as the North Pacific and North Atlantic, where wave energy propagation is intensified. Although SEAS5 replicates the NAO response, its magnitude is significantly weaker. The model struggles to simulate the delayed rainfall dipole response to the IOD accurately and shows structural discrepancies compared to reanalysis data.

Thermal energy propagation characteristics and hazard effects of hydrogen cloud explosion

Hydrogen has advantages such as high energy density and zero carbon emissions, but it poses a risk of generating explosion fireballs in the air. The gas explosion process not only involves thermal radiation from the fireball but also heat conduction and convection caused by the diffusion of high-temperature products. In this work, the thermal parameters of hydrogen cloud explosion with different equivalence ratios and gas cloud radius in an unconfined space were investigated. The results show that the flame temperature-distance curve of a hydrogen explosion exhibited a ’Z’ type. The maximum distance of flame propagation is positively correlated with the peak thermal radiation flux and cloud radius and increases first and then remains steady with the equivalence ratio. When only considering thermal convection, the minimum injury distance of flame temperature is achieved, and the thermal radiation effect can promote the flame propagation speed. Under the q-t criterion, the effective thermal radiation radius of first-level damage at a gas cloud size of 1 m was 6.11 m at φ = 1.2, which was 1.89 times that of φ = 0.6. Compared with the thermal dose criterion, the thermal flux-time criterion results in a larger thermal injury radius. The propulsion effect of hydrogen explosion products can cause the hydrogen cloud in the premixed zone to diffuse outward. The critical distance of hydrogen diffusion within the lower explosion limit was also analyzed. This study provides significant guiding implications for preventing hazards in people and buildings.