Critical Height Research Articles

Molecular dynamics simulation study on the wetting characteristics of carbon dioxide droplets on smooth and rough surfaces

A thorough investigation of the wetting behavior of carbon dioxide (CO2) is crucial for enhancing carbon capture efficiency and improving carbon storage and sequestration processes. This work investigates the wetting characteristics of CO2 droplets on smooth and rough Cu-like surfaces using molecular dynamics simulations. The results indicate that an increase in surface energy causes a linear decrease in the contact angle of CO2 droplets on smooth surfaces. An increase in temperature enhances the wetting tendency of the smooth surface toward CO2 droplets. On CO2-phobic surfaces, CO2 droplets tend to detach from the surface, causing the contact angle to increase. On neutral surfaces, CO2 droplets generally maintain wettability, with contact angles remaining almost unchanged. On CO2-philic surfaces, CO2 droplets rapidly wet and spread to form liquid film layers, causing the contact angle to decrease rapidly. In addition, constructing rough surfaces is beneficial for enhancing the surface CO2-phobic property, but the wettability of CO2 droplets varies slightly on different rough surfaces (cylindrical pillars, square pillars, and grooves), the fluctuation of contact angles of CO2 droplets on the grooved surface is relatively small. For square pillared surfaces, in contrast to smooth surfaces, as the surface energy increases, the CO2-phobic property of CO2-phobic surfaces is enhanced, and neutral surfaces can be transformed into CO2-phobic surfaces, with the CO2-philic property of CO2-philic surfaces enhanced. For CO2-phobic square pillared surfaces (α = 0.08), the wetting morphology and wetting modes of CO2 droplets on the square pillared surface are jointly influenced by both the pillar height and the interpillar spacing. When the interpillar spacing is constant, there exists a critical pillar height that can induce the transition of the wetting mode of CO2 droplets from Wenzel to Cassie state.

Analysis of swallowtail mutation instability of slope with weak interlayer under blasting disturbance

Abstract The stability analysis of slope under blasting disturbance is one of the important research topics in blasting engineering and geotechnical engineering. Based on the dynamic instabil-ity mechanical model of slope with weak interlayer, the mechanical effect of blasting dis-turbance on slope system is analyzed. The swallowtail mutation model of slope system under blasting disturbance is established. Two methods to determine slope stability under blasting disturbance are proposed: safety factor method and double judgment method. Through the analysis of the dynamic instability mechanism of the slope system under the effect of blast-ing disturbance, it is concluded that: (1) the greater the amplitude of blasting disturbance vibration, the worse the stability of the slope system, and the greater the possibility of land-slide disaster. The slope landslide disaster caused by blasting disturbance mainly occurs in the middle and late stage of blasting disturbance (0.17 ∼ 0.5s). (2) When the period of blast-ing vibration wave (T > 1s), the frequency of blasting disturbance wave can be appropriately increased, which is conducive to reducing the impact of blasting disturbance on slope stabil-ity. When the period of blasting disturbance wave (T < 1s), proper adjustment of blasting disturbance frequency will not have a direct impact on the stability of slope. (3) With the increase of the incident angle of blasting vibration wave, the change of the dynamic self-stability critical height of the slope system shows a trend of increasing, and the in-creasing rate is decreasing. The greater the incident angle of blasting vibration wave, the worse the stability of slope system. Proper reduction of the incident angle of blasting vibra-tion wave is beneficial to improve the stability of slope system. Finally, the rationality and applicability of thse proposed double judgment method are verified based on the actual con-ditions of the current slope in Laoyingzui.

CHARACTERISTICS ANALYSIS FOR HIGH-RISE BUILDINGS DURING TOP-DOWN CONSTRUCTION

New advances in top-down construction are developing with the construction of supertall buildings in China. This study presents a finite element analysis for high-rise structural construction with a top-down method (TDM) considering complex environmental conditions. Based on this analysis model, the forces and the deformation of the diaphragm wall, beams, and soldier piles at various stages of construction are computed. Taking a super high-rise building with a 5-story basement in Nanjing as an example, the reliability and accuracy of the model is verified by comparing the measured and simulated results of displacement and stress values at various locations. The research results reveal the relationship between excavation depth, soil settlement and pile displacement, which is convenient for finding the optimal construction critical surface. It lays a foundation for the study of the critical height of the subsequent construction and facilitates the prediction of the weak link in the process. At present, this project is under construction, so this study has reference value for subsequent construction projects.

Rock slope stability analysis under Hoek–Brown failure criterion with different flow rules

The stability analysis of homogeneous rock slope following the Hoek–Brown failure criterion under the hypothesis of different flow rules is performed based on limit equilibrium and finite element methods. The applied failure criterion is the generalized Hoek–Brown that can be introduced as a shear/normal function in analysis applying different flow rules. The results are compared with those obtained by the application of equivalent shear strength parameters of the Mohr–Coulomb criterion, considering that this is still the most widely used criterion in rock slope stability analysis and is still the base for the shear strength reduction method applied in finite element modelling. Different proposals for estimating the equivalent strength parameters based on confining stress level are evaluated. The limitation of stress-dependent linear Mohr–Coulomb parameters is emphasized by analysing the vertical cut problem, for which, depending on the chosen stress level, different critical heights are obtained for the same material. Sensitivity analysis of geotechnical parameters used as input for failure criterion is performed to determine their influence on slope stability. Probabilistic analysis is conducted to determine the probability of failure when different flow rules are applied. If slope stability analysis is performed with an assumption of associative flow rule, the probability of failure is within the acceptable limits for the considered case study, while employing non-associative flow rule, the probability of failure is rather high. The chart is presented that could be readily used to estimate the combination of σci, GSI, and mi values that produce failure for the analysed case study.

Novel evaluation method based on critical arch height as instability criterion for sustaining arch locked-segment-type slopes

In sustaining arch locked-segment-type slopes, natural soil arches play a key anti-sliding role in the slope's evolution. In this study, a self-developed model test device was used to simulate the whole process of deformation evolution of sustaining arch locked-segment-type slopes, and the formation of natural sustaining arch and its locking control effect on slope stability were studied. The test results show that the continuous formation and progressive destruction of the sustaining arch were observed. The sustaining arch formed in the second time has the best locking effect, and the anti-sliding force reaches its stress peak point. However, the slope is not in a critically unstable state, instead, the stress is continuously adjusted to form a larger range of soil arch to resist the slope thrust. Consequently, the slope destabilizes until the ultimate shear strength of arch foots is exceeded, at which point the critical arch height of the arch is reached. The critical arch height mechanical model for slope stability analysis was developed based on the soil arching effect and limit equilibrium theory. The applicability of the model was demonstrated by the physical test and Xintan slope data, which can provide some guidance for early warning of landslides.

Vortex bifurcation and air entrainment mitigation using multi-point intakes

Air entrainment is a concern of paramount importance in the process industries, including nuclear power plant, hydraulic machines, water treatment plants, hydrocyclones, and power generation turbines. The ingression of the air into the equipment results in the reduction of the hydraulic efficiency. In the current paper, a combined experimental and numerical investigation has been performed using the commensurate high-speed photography and volume of fluid-based numerical simulations. The mitigation strategies for the reduction of the air ingression include the reduction of the critical height by increasing the number of intakes and changing the intake configuration. The viability of these solutions and the hydrodynamics behind the interfacial evolution leading to the air entrainment have been studied in detail. The air ingression progresses with the establishment of the flow patterns ranging from bubbly flow, slug flow, to the annular flow. The reduction of the critical height can be accomplished by increasing the number of intakes for the same cross-sectional area leading to the reduction in the Froude number Fr=Vdown/gHlocal<1. Further increasing the number of intakes beyond four leads to the minimal reduction in the critical height in the tank.

Effect of Wavelength on Turbine Performances and Vortical Wake Flows for Various Submersion Depths

When tidal turbines are deployed in water areas with significant waves, assessing the surface wave effects becomes imperative. Understanding the dynamic impact of wave–current conditions on the fluid dynamic performance of tidal turbines is crucial. This paper aims to establish a fundamental understanding of the influence of surface waves on tidal turbines. OpenFOAM, an open-source computational fluid dynamics (CFD) library platform, is utilized to predict the performance of current turbine under waves and currents. This research investigates the effects of two critical wave parameters, wave height and wavelength, on the fluid dynamics and wake structures of current turbine. Additionally, this study explores the influence of various submersion depths on turbine performance. The findings indicate that, under various wave conditions, the turbine’s average power coefficient remains constant, but significant fluctuations are shown. Increasing submersion depth can mitigate the impact of waves. However, in regions characterized by longer wavelengths, altering the submersion depth has limited effects on turbine performance.

Study of the Critical Safe Height of Goaf in Underground Metal Mines

The empty-space subsequent filling mining method is the main mining scheme for underground metal mines to achieve large-scale mechanized mining. The stage height, one of the main parameters of this method, affects the various production process aspects of the mine and influences the stability of the goaf. In order to determine the stage height scientifically and rationally in the empty-space subsequent filling mining method, a formula for the stabilized critical safe height of a high goaf in an underground metal mine was derived based on Pu’s arch equilibrium theory, Bieniawski’s pillar strength limit theory, and the Kastner equation and combined with the results of an orthogonal analysis to rank the importance of the main factors in the formula. A copper mine in Jiangxi Province was used as a case study, with the reliability of the formula verified by numerical simulation and industrial testing. The factors in the formula influencing the critical stabilized safe height of the goaf were, in descending order, the compressive strength of the rock body, the width of the two-step mining pillar, the width of the one-step mining room, the mining height, and the depth of mining. Based on the calculation results, the recommended stage heights are 30 m (−378 m middle section) and 25 m (−478 m middle section) in the area of poor rock body stability and 50 m in the area of better rock body stability. The simulation results show that the goaf is significantly affected by the compressive stress under the condition of a certain rock body stability and that the compressive stress increases with increasing goaf height. The minimum recommended values of the sidewall safety coefficients in areas of poor and better rock stability are 1.04 and 1.06, respectively. The volume deviation coefficients of the three industrial test mines were all controlled within 3%, indicating that no obvious collapse and destabilization phenomenon occurred in the goaf. This paper provides some theoretical and applied guidance for the stage height design of similar underground metal mines using the empty-space subsequent filling mining method.

Study on the Stability of Cut Slopes Caused by Rural Housing Construction in Red Bed Areas: A Case Study of Wanyuan City, China

The red beds that are widely distributed in hilly areas in eastern Sichuan Province are inevitable rock and soil masses in engineering construction. In order to obtain a larger building area, engineering slope cutting is quite common in red bed hilly areas. Engineering slope cutting destroys the inherent stability of a slope and causes geological disasters. In order to practice the concept of sustainable development and explore ways to develop and utilize land resources reasonably and reduce the possibility of geological disasters caused by engineering slope cutting, this paper took the slope cutting sites caused by rural housing construction in the red bed area of Wanyuan City as research objects. The internal and external factors affecting the stability of the cut slopes were summarized through a field investigation, and two typical slopes were selected for analysis. Sampling and indoor tests were conducted to obtain the geotechnical parameters. Geo Studio software (2018 R2) was employed to establish numerical models, simulate the stress and strain distributions, and compute stability coefficients under different slope cutting conditions at the same time. Based on field investigations and numerical simulations, the three main failure modes of shallow landslides caused by slope cutting were summarized, and the evolution process of slope landform accelerated by slope cutting activities was deduced. In an engineering application, the functional relationship between the cutting height and the stability coefficient was fitted. It was found that the critical cut height values of soil slope were 6.3 m, 6.2 m, 5.2 m, and 2.6 m at slope of 10°, 20°, 30° and 40°, respectively; the critical cut height values of rock–soil mixed slope were 9.3 m, 6.5 m, 5.9 m, and 2.2 m at slope of 10°, 20°, 30° and 40°, respectively. The research findings can be used to prevent and manage the hazards caused by slope cutting in this study area.

Climatology of atmospheric solar tidal mode effects on ionospheric F2 parameters over the American sector during solar minimum between cycles #23 and #24

This work presents the contribution of solar atmospheric tides (diurnal, semidiurnal, and terdiurnal modes) to the variability of the parameters critical frequency (foF2) and peak height of the F2-layer (hmF2) in the American sector during the transition of solar cycles #23 and #24, a period considered one of the lowest solar activities of the modern era. The Digisonde data available in the GIRO data center were analyzed (12 stations), and the solar tide modes were evaluated regarding their amplitude, latitude, and seasonal dependence. The results showed that the hmF2 and foF2 strongly depend on latitude and seasonality, being more intense in the stations located in the south hemisphere. The same behavior is seen for the tidal amplitude fitted in these parameters, except for hmF2 diurnal tide, which is more intense at latitudes farther from the equator. Moreover, the seasonal variability of the amplitude of hmF2 in most cases presented an annual and semiannual component. A terannual component was also observed in 8 h tide mode in the height and frequency parameters. Likewise, what was observed in foF2, the variability in the mean amplitude and different modes of tides of hmF2 are higher over the sectors located in the southern hemisphere.

On the relative importance of saltation and suspension for aeolian snow mass transport

AbstractSnow transport affects various hydrological processes significantly through reshaping the glacial landscapes. Snow particles that are transported in a turbulent flow are typically classified under the saltation and suspension states based on the inertia of the particles relative to the strength of the turbulence. In this study, snow transport in the turbulent boundary layer was simulated using the large‐eddy simulation with Lagrangian particle tracking method. Contrary to most previous studies in which saltation and suspension are defined by a specified critical height or particle size, hop time ratio Rt and particle Stokes number St were adopted to judge the state of saltating snow particles, and the contributions of pure saltation, modified saltation, short‐ and long‐term suspension particles were quantified appropriately. A threshold value of St≈5 for pure saltation was proposed through the particle trajectory comparison. The results show that the St criterion measures pure saltation particle appropriately but fails to diagnose long‐term suspension particles. Furthermore, although there are hardly any pure saltation particles in natural snow transport, the contribution of modified saltation cannot be neglected in the lowest centimetres of the atmosphere, which may also dominate the overall mass flux at the near surface under larger friction velocities. Rather, considerable short‐ and long‐term suspended particles spread over the entire vertical dimension of the snow cloud, contributing a major proportion of the overall mass flux, even within the saltation layer. Based on this, the suspension layer should be defined as the entire vertical dimension of the particle cloud. The results can improve our understanding of the motion dynamics of transported snow particles and further provide new ideas in modelling this process.

Smoke exhaust characteristics under stack effect of natural ventilation by shaft in high-altitude tunnel

The number of high-altitude tunnels is increasing year by year and natural ventilation of shafts is widely used as a critical component of the ventilation system. For the design of ventilation systems, it is particularly crucial to consider the smoke exhaust performance of shafts in low-pressure environment. Therefore, this study simulates tunnel fires with natural ventilation by shaft in high-altitude areas, aiming to analyze the impact of atmospheric pressure on smoke exhaust performance and smoke exhaust capacity by natural ventilated shafts at 50 to 100 kPa atmospheric pressure. It appears from the results that the increasing of ambient pressure can enhance the ability of air entrainment and natural smoke exhaust, and thus plug-holing is more likely. In which condition, fresh air can be expelled straight from the shaft, reducing smoke exhaust efficiency. As ambient pressure increases, the critical shaft height for plug-holing decreases. By analyzing the smoke exhausting process by shaft and smoke flow, smoke exhaust capacity can be evaluated by obtaining the mass flow rate of exhausted smoke and fresh air from the shaft under various atmospheric pressures and fire source power and. It could be said that increasing ambient pressure and shaft height can improve the smoke expulsion performance before plug-holing. However, once plug-holing happens, the increase of shaft height can no longer expel more smoke but much more air is exhausted by shaft. It is hoped that this work will serve as a guideline for ventilation systems design in high-altitude tunnels.

Intensifying the particle deposition from a colloidal solution for the purpose of liquid purification: Comparison of deposition mechanisms and rates

The deposition of particles from a layer of colloidal solution (water and microparticles) has been experimentally studied in the presence of laser heating. Instantaneous temperature and velocity fields are measured using a thermal imager and the Particle Image Velocimetry and the Particle Tracking Velocimetry methods. The unstable behavior of the velocity field in the presence of heating and a free liquid surface are assumed to be determined by the Bond number (Bo). Of interest is also an additional mechanism for the instability formation when the Peclet number (Pe) exceeds the critical value and when the ratio of characteristic velocities VT/Vavr > 1, where VT is the heat front velocity at the initial moment of laser heating, and Vavr is the average convection velocity. A new mechanism of particle deposition due to the use of local laser heating is proposed for the first time. The control over local heating and local deposition increases the particle deposition rate by 2–3 orders compared with that without convection. The particle deposition rate and the deposit area increase with increasing height of the liquid layer, reach maximum values at a critical height, and then decrease sharply with increasing height. The dependence for determining the area and mass of the deposit is proposed to take into account the deposition time, the height of the liquid layer and the rate of convection. The resulting particle deposition method and calculation method may be used in technologies related to the purification of liquid from solid impurities in small volumes, as well as in problems where deposition in a given direction is required to form an ordered nanocoating.

Review of World Rugby’s Test Method 01 head injury criteria: Procedure analysis and optimisation

Rugby is a close-contact sport in which players occasionally fall headfirst to the ground during scrums and tackles. Because head impacts represent an obvious threat to players’ integrity and safety, World Rugby, Rugby’s International Governing Body, developed a test method named Test Method 01 to evaluate the capacity of the playing surface to mitigate head impacts by determining the critical fall height (CFH). The aim of this study is to analyse World Rugby’s current Test Method 01 head injury criteria (HIC), which consider a field as unsafe if the CFH is below 1.3 m. To make this analysis, a pilot study was performed on seven artificial turf rugby fields. At each field, a three-drop procedure was performed to estimate the initial CFH (CFH0). Subsequently, the procedure was repeated on each surface at 50-mm intervals, from 0.6 m below to 0.6 m above CFH0. All possible combinations of four height–HIC data pairs with two height values below and above 1000 HIC were obtained. A comparison was performed between the linear adjustment, currently prescribed in Test Method 01 to calculate the CFH0, and the quadratic adjustment. In particular, the percentage of outliers obtained when applying both the linear and quadratic adjustment and the robustness of the regressions were investigated. The results show that the current Test Method 01 can be improved by applying two main modifications: first, replacing the linear adjustment with a quadratic adjustment, and second, adapting the current test restrictions by maintaining the maximum difference between the highest and the lowest drop heights in 1.00 m, increasing the minimum difference between consecutive drop heights from 0.15 to 0.20 m and removing the current prohibition on obtaining HIC values close to 1000.

Random field failure and post-failure analyses of vertical slopes in soft clays

This research investigates the spatial heterogeneity of cohesion within soft clay and its implications for slope stability and post-failure analysis. In-situ cone penetration tests were conducted in alluvial soft clays to calibrate probabilistic strength properties. Slope stability analyses employed deterministic, semi-deterministic, and comprehensive probabilistic approaches, while post-failure analysis utilised the nodal integration-based particle finite element method. The undrained shear strength (cu) demonstrated a log-normal distribution (mean: 19 kPa, standard deviation: 3 kPa), with correlation lengths modeled through Bayesian inference. Treating correlation lengths as distributions resulted in a negligible 2% difference compared to using a single value for the probability of failure. Semi-deterministic analyses exhibited results similar to probabilistic analyses, offering computational advantages. Nevertheless, probabilistic analysis, considering spatial variability, provided more comprehensive insights for post-failure analysis. For a vertical slope of critical height in the studied soft clay, probabilistic analyses predicted a range of runout distances from 0 m to over 125 m. Specifically, 89% of these distances were less than 80 m, and 82% were less than 40 m. The findings contribute to an enhanced understanding of spatial variations in soil strength within soft clay slopes, providing valuable insights for future geotechnical assessments and design considerations.

Subcritical transition of the Stokes layer induced by wall surface roughness

Wall defect is an important reason for the Stokes layer transition. The present study investigates the transition of the Stokes layer induced by wall surface roughness under subcritical Reynolds numbers, which is lower than the critical Reynolds number of the global neutral curve. A pseudo-spectral numerical method is utilized to simulate the interactive effects of different parameters related to surface roughness. Based on the cycle-average pulsation energy, a critical roughness height is defined for the flow transition. A characteristic curve, termed as the transition curve, is discovered to relate the most critical roughness height with the Reynolds number for a given wave number in the span-wise direction. This curve can provide a quantitative criterion to predict the transition of the Stokes layer caused by the surface roughness. The result demonstrates that the critical roughness height is lower for three-dimensional than for two-dimensional roughness. It is also shown that when the Reynolds number is close to the critical Reynolds number of the global neutral curve (R=600), even a roughness height in the order of one nanometre could significantly interact with the flow and causes the transition. Moreover, when the Reynolds number is around 300, the order of 1 roughness height could be sufficient for the transition. This offers a possible explanation as to why the transitions observed in most of the experimental findings usually occur when the Reynolds number is around 275.

A novel model for directed energy deposition-arc based on in-order stacking of primitives

ABSTRACT To address the issue of low accuracy of directed energy deposition-arc (DED-Arc) and expand its use in producing large-sized components, a novel concept called “in-order stacking of primitives” has been proposed. This concept aims to simplify the additive manufacturing (AM) planning process and improve forming accuracy. Experiments at the weld, layer, and block levels examined relationships between process parameters and primitive dimensions, offset distance, and interlayer lift height. Increasing heat and mass transfer significantly increased primitive width and surface roughness but had little effect on height variation (1.95-2.27 mm). The impact of offset distance on the forming precision for layer-level components varied by the stacking path used, with Zig-Zig level parts showing more deterioration than Zig-Zag level parts. Thermal equilibrium in block components was achieved within a critical height range of 88.2 to 112.0 mm. The stacking path has a substantial impact on the surface temperature and is a crucial factor for ensure accurate workpiece formation. This study establishes a physical relationship between component forming quality and process parameters through mathematical expressions that are supported by experimental results. Future research will focus on optimizing the physical model and refining the mathematical expressions.

Numerical analysis of a monitored piled-supported embankment of an airport runway

This paper presents a 3D finite element analysis of deep soil mixing column-supported embankments (CSEs) with a geosynthetic platform. The numerical model simulated the CSE for the expansion (≈1.0 km) of the existing runway at the Salgado Filho International Airport, in the city of Porto Alegre. The numerical model using Abaqus software was calibrated by comparing numerical calculations with good quality instrumentation data. Deep Soil Mixing (DSM) columns were used to improve the soil foundation. A novel approach to modeling the geosynthetic is also presented based on the mechanical properties of this material. The load transfer mechanisms and deformation of the column-supported embankments were analyzed by means of numerical and field results. Additional aspects such as the critical height and the pattern of vertical stress distribution in the columns and embankment as well as the stress distribution in the geosynthetic reinforcement were also investigated. The numerical model reproduces the vertical stress measured by the total stress cells installed above the columns and between the columns. The numerical model shows that the soil reaction of the thick compacted layer used as a work platform reduced the arching and membrane effect in the embankment.

Analytical study on seismic performance of ECC shell-RC column and its plastic hinge forming mechanism

Engineered cementitious composites (ECCs) are a type of high-ductility material with excellent crack-control capacity and pseudo-strain-hardening behaviour. To improve the seismic performance and damage-tolerant capacity of traditional reinforced concrete (RC) columns, this paper proposes an innovative ECC-RC composite column with a cast-in-place or precast ECC shell in the plastic-hinge zone, namely the ECC shell-RC column. Based on finite element software ABAQUS, a comprehensive numerical and analytical study of the seismic performance of the ECC shell-RC column was conducted. First, three-dimensional (3D) nonlinear finite element models were developed and validated using previous experimental results. Subsequently, the influence of different design parameters on the seismic performance of this type of column was systematically investigated via finite element analysis, including the ECC height, ECC shell thickness, axial compression ratio, and material parameters. The seismic performance of the ECC shell-RC column with optimized design parameters subjected to actual ground motions was also preliminarily investigated. Notably, certain important design principles of ECC shell-RC columns were established. Furthermore, the theoretical critical height and thickness of the ECC shell were determined based on a theoretical analysis of the plastic-hinge (PH) forming mechanism.

The influence of helium-induced defects on the migration of strontium implanted into SiC above critical amorphization temperature

The presence of radiation-induced defects and the high temperature of implantation are breeding grounds for helium (He) to accumulate and form He-induced defects (bubbles, blisters, craters, and cavities) in silicon carbide (SiC). In this work, the influence of He-induced defects on the migration of strontium (Sr) implanted into SiC was investigated. Sr-ions of 360 keV were implanted into polycrystalline SiC to a fluence of 2 × 1016 Sr-ions/cm2 at 600°C (Sr-SiC). Some of the Sr-SiC samples were then co-implanted with He-ions of 21.5 keV to a fluence of 1 × 1017 He-ions/cm2 at 350°C (Sr + He-SiC). The Sr-SiC and Sr + He-SiC samples were annealed for 5 h at 1,000°C. The as-implanted and annealed samples were characterized by Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and Rutherford backscattered spectrometry (RBS). Implantation of Sr retained some defects in SiC, while co-implantation of He resulted in the formation of He-bubbles, blisters, and craters (exfoliated blisters). Blisters close to the critical height and size were the first to exfoliate after annealing. He-bubbles grew larger after annealing owing to the capture of more vacancies. In the co-implanted samples, Sr was located in three regions: the crystalline region (near the surface), the bubble region (where the projected range of Sr was located), and the damage region toward the bulk. Annealing the Sr + He-SiC caused the migration of Sr towards the bulk, while no migration was observed in the Sr-SiC samples. The migration was governed by “vacancy migration driven by strain fileds.”