Thermal Shock Effect Research Articles

Research on the Influencing Factors of Pulsed Hydraulic Fracturing Effects in Hot Dry Rock Based on Numerical Simulation

Geothermal energy, representing one of the five principal non-carbon-based renewable resources, is crucial in the global energy transition and in mitigating greenhouse gas emissions. Hot Dry Rock (HDR) reservoirs, rich in geothermal resources, predominantly utilize hydraulic fracturing, the most extensively researched and applied technology. However, fracturing these robust HDR formations poses significant challenges compared to traditional hydraulic fracturing in sedimentary rocks in the oil and gas industry. Cyclic pulse fracturing, an innovative mode of fracturing, has received limited academic attention, particularly regarding its permeability enhancement mechanism under varying thermal and pressure conditions, which remains largely unexplored. Building on prior laboratory experiments, this study employs the pore pressure cohesive zone model within ABAQUS software to elucidate the initiation and expansion of hydraulic fractures. Numerical simulations investigated the influence of critical parameters such as pulse pattern, temperature, geostress differential, and confining pressure on fracture propagation. The findings indicate that cyclic pulse hydraulic fracturing can significantly reduce the breakdown pressure in HDR, with reductions up to 37.68% under certain conditions. Notably, at constant amplitude, increased frequency exacerbates damage to hot dry rocks; conversely, at constant frequency, higher amplitudes result in greater damage. Additionally, pulse hydraulic fracturing improves the fracturing process, yielding a more intricate fracture network. In HDR pulse hydraulic fracturing, the temperature disparity between the fracturing fluid and the rock markedly impacts the breakdown pressure. Cold water interacting with a high-temperature geo-thermal reservoir triggers a thermal shock effect, diminishing initiation pressure and expediting fracture development and expansion. The impact of geostress differential and confining pressure on pulse hydraulic fracturing is complex, influencing not only the breakdown pressure but also the direction and extent of fracture expansion.

High-temperature transient-induced thermomechanical damage of fiber-reinforced ceramic-matrix composites in supersonic wind tunnel

This article is based on the supersonic directly connected wind tunnel. Through a specially designed experimental chamber, combined with infrared temperature measurement, high-speed camera, etc., in-situ monitoring of composite materials under airflow at Ma 3.0 with a total temperature of 950 ∼ 1473K was carried out. The dimensional analysis method was used to propose dimensionless parameters to characterize the thermal coupling caused by high-speed airflow thermal shock. Research has shown that the thermal coupling effect of supersonic airflow causes uneven temperature inside the material, and the thermal stress caused by temperature gradient changes (including increasing and decreasing processes) is the main reason for material damage. The damage of ceramic matrix composites under thermal shock mainly manifests as a decrease in surface roughness, surface fiber fracture and a decrease in elastic modulus. In addition, the study also found that there are damage thresholds for the thermal shock effect of airflow at different total temperatures, which helps to further understand the thermomechanical damage mechanism and degradation law of composite structure under high-temperature transient conditions.

Improved properties of in-situ MgAl2O4-TiO2 dense layer reinforced low-carbon MgO-based refractories

With the increasing severity in the service environment of secondary refining furnaces, traditional refractories cannot meet the high requirements. MgO-based fired refractories are subject to the thermal shock effect and slag penetration which are detrimental to their performance. In this study, low-carbon MgO-based refractories are reinforced by an in-situ MgAl2O4(MA)-TiO2 dense layer with the addition of low-cost self-prepared titanium carbonitride [Ti(C, N)]. The influence of the addition of as-prepared Ti(C, N) on the properties of low-carbon MgO-based refractories was investigated. The reinforced refractories had no cracks after 190 thermal shock cycles, demonstrating the highest hot modulus of rupture (HMOR) with excellent thermal shock resistance (TSR). After 2.5 h of rotary immersion in a steel slag, the corrosion depth of the composites was only 26.3% of that of commercial MgO-CaO refractories. Based on the thermodynamic analysis, the Ti(C, N) reinforcement mechanism for the low-carbon MgO-based refractories was studied. A MA-TiO2 dense layer formed during the oxidation process of the composites which enhanced the oxidation resistance. The volume expansion caused by the partial oxidation of Ti(C, N) prevents the penetration of the molten slag to refractories and Ti(C, N) powders forming a protective layer to further effectively protect the composites from slag corrosion owing to its high surface area. In addition, 3CaO·2TiO2 formed by the reaction between the steel slag and Ti(C, N) further increased the slag corrosion resistance (SCR) of the composites. This research offers a new idea for the material selection for secondary refining furnaces to achieve a green and effective steel-making production route and enriches the understanding of the phase behaviour in the Mg-Al-Ti-C-O-N system under high temperatures.

Progress on the Microwave-Assisted Recycling of Spent Lithium Battery Graphite

The robust development of electric vehicles has driven a surging decommission stream of lithium-ion batteries (LIBs) owing to their limited service life. The recycling of spent LIBs has become an urgent and essential task for the sustainable development of the LIB industry. However, the prevailing recycling methods focus only on recycling valuable metal, whilst the graphite anode materials are usually discarded or burned as fuels, leading to great waste of valuable carbon material. A facile strategy to obtain value-added products in an efficient manner is of great significance for the recycling of spent graphite. As graphite has excellent microwave absorption capability and electrical conductivity, microwave radiation on spent graphite can induce a Joule heat–discharge–plasma coupled effect, leading to a rapid heating process, especially when discharge occurs, exhibiting a thermal shock effect with the generation of a large number of high-energy electrons and active materials. This special feature facilitates microwave heating that is tailored for assisting the removal of impurities, structure repair, and graphite intercalation and exfoliation in an efficient manner. Therefore, different from the conventional graphite recycling route that is associated with energy/solution-intensive processes, this paper reviews the progress on microwave-assisted removal of impurities, repair of damaged graphite structure, and innovatively discusses the breakthroughs in microwave-assisted preparation of graphite intercalation compounds, expanded graphite, graphene and graphene-based materials, and porous graphene, with an aim to provide a scientific reference for the value-added resource utilization of spent graphite and preparation of new energy storage materials.

Wetting and spreading behavior of molten CMAS on the laser textured thermal barrier coatings with the assistance of Pt-modification

Gadolinium zirconate (Gd2Zr2O7, GZO) is a promising next-generation material for thermal barrier coatings (TBCs). The molten CMAS (calcium-magnesium–aluminium silicates) will react with GZO and quickly produce dense Ca4Y6(SiO4)6 phase, which can prevent the further penetration of the molten CMAS. However, the large thermal expansivity difference between the dense reaction production and the GZO substrate leads to the delamination of the production layer when encountering the thermal shock effect. Therefore, it is essential to reduce the accumulation of molten CMAS. In this paper, the surface texture was fabricated on the surface of EB-PVD (electron beam physical vapor deposition) GZO-TBCs. And then a thin layer of Pt film was deposited on the laser-textured surface. The purpose is to increase the wetting contact angle between the molten CMAS and TBCs, thus decreasing the accumulation of the CMAS. The results show that the stable contact angle of the molten CMAS on the laser-textured GZO-TBCs increased from the original 16° to 66.3°, but the surface texture was completely corroded after high-temperature wetting. By introducing a thin layer of Pt film over the laser-textured coatings, a stable contact angle of 111.6° was achieved. This is because Pt film successfully prevents the molten CMAS react with GZO.

The role of Carica papaya latex bio-catalyst and thermal shock in water on synthesizing rice husk

A bio-catalyst made of natural resources, such as Carica papaya latex, is very challenging for nanoparticle separation. In addition, differences in thermal conditions between nanoparticles affect the movement of substances in the separation process. The study experimentally investigated the role of Carica papaya latex bio-catalyst and thermal shock in water on synthesizing rice husk (RH). The synthesis retained the Mg and C elements attached to SiO2, which were generally neglected during the process. The study's objective was to evaluate the effectiveness of biocatalysts and thermal effects on the separation of Mg-SiO2-C from rice husk carbon nanoparticles (CNPs-RH). The research involved various treatment processes, such as RH pyrolysis in obtaining charcoal, High energy milling (HEM) to have carbon particles, and washing to get nano-sized carbon particles. The bonding of elemental compounds to rice husk carbon particles (CPs-RH) was released using NaOH and coagulation using a bio-catalyst. Coagulated CPs-RH was injected into water at a temperature of 60–70 °C to have a thermal shock effect for H2O clusters in Na+ and Mg2+ ions attached to the surface of the nanoparticles. Several tests were carried out, such as the SEM-EDX, TEM, XRD, and FTIR tests, to investigate the two nanoparticle clusters formed up to the nanometer scale. The results indicated that CNPs-RH nanoparticles consist of spherical particles with a diameter of 1.2 nm, while Mg-SiO2-C nanoparticles have a diameter of 0.6 nm. Both are classified as amorphous. Based on the FTIR test, CNPs-RH is hydrophilic, while Mg-SiO2-C is hydrophobic. Thermal shock in water strengthens the ion's mobility, increasing the interfacial dipole forces between nanoparticles and accelerating the separation process.

Interface Characteristics, Erosion Behavior, and Thermal Shock Resistance of Al–Ta Alloy Coatings Produced by Arc Spraying

The pure aluminum coatings of physical vapor deposition chambers used in current semiconductor processes offer insufficient protection against ion bombardment. In this study, the arc spraying process was used to produce Al–Ta alloy coatings to replace pure aluminum coatings. The microstructure, mechanical properties, and particle erosion properties of these coatings were investigated at 1% and 3% Ta content and compared with those of pure Al. The surface and surface morphologies of the three coatings were similar. However, Ta was uniformly dispersed to form a supersaturated solid solution in the 1Ta and 3Ta coatings. The tensile results indicated that the adhesion of the three coatings was similar. According to particle erosion results, cohesive strength and erosion resistance apparently increased. Moreover, the thermal shock effect caused by the extreme thermal cycle in these chambers causes coating degradation. So, this study compared the thermal shock properties of the Al–Ta alloy coatings with Y2O3 ceramic coating. The 1Ta and 3Ta coatings did not differ considerably from pure Al coating in terms of thermal shock resistance, and all three were higher than that of the Y2O3 coating. The aforementioned results indicate that the produced Al–Ta alloy coatings can offer superior chamber protection ability.

Effect on microstructure of Fe80B13Si7 metallic glass irradiated by high intensity pulsed ion beam and He ions

Metallic glasses (MGs) are regarded as promising radiation-resistant materials due to their unique long-range disordered structure and abundant free volume. However, temperature sensitivity limits their application in complex irradiation environments, for example, in the fusion environment there are multiple irradiations such as He and strong thermal shock irradiation acting together on the service materials. In this work, the effects of thermal shock and He ions irradiation on the microstructure of Fe80B13Si7 MG were investigated using high intensity pulsed ion beam (HIPIB), He ions and HIPIB + He ions irradiation. It was found that Fe80B13Si7 MG remained amorphous as the main phase structure under all irradiation conditions, and no extensive surface damage occurred even at dose of up to 1.6 × 1018 He2+/cm2. Due to the strong thermal shock effect of HIPIB irradiation, the surface layer of Fe80B13Si7 MG remelted and solidified rapidly, which increased the free volume content. At the same He dose, the HIPIB induced increase in free volume content slightly promoted He bubbles growth and reduced the bubble layer depth, while it had no obvious effect on bubble layer width. As the dose increased, He bubble size and bubble layer width increased significantly. The addition of HIPIB also significantly suppressed the crystallization of Fe80B13Si7 MG induced by He ions irradiation: crystallization occurred within the He bubble layer after 4 × 1017 He2+/cm2 irradiation, while no crystallization was observed after HIPIB + 6 × 1017 He2+/cm2 irradiation. Fe80B13Si7 MG showed good resistance against HIPIB, He ions and HIPIB + He ions irradiation, and perhaps offer some unique advantages in complex irradiation environments.

Experimental studies on the effect of cyclic thermal shock and cooling methods on the mechanical properties and fracture behavior of prefabricated fissured sandstone

The construction of sandstone thermal storage systems and the evaluation of their long-term stability are of great significance to the development of geothermal energy. In this study, the effect of the number of thermal shocks and cooling methods on the mechanical properties and fracture behavior of sandstone containing a single prefabricated fissure was investigated. The experimental results show that as the number of thermal shocks increases, the peak stress and elastic modulus of the fissured sandstone gradually decrease, and show a very good exponential functional relationship. The first thermal shock weakens the mechanical properties of fissured sandstone most severely, and the deterioration effect of mechanical properties is significantly slowed down when the number of thermal shocks exceeds 4. In addition, compared with water cooling, the reduction of the mechanical properties of fissured sandstone by air cooling is lower. As the cooling water temperature decreases, the thermal shock effect of the fissured sandstone is more severe, resulting in more significant damage. An empirical formula considering the number of thermal shocks and cooling water temperature is proposed to characterize the damage to the fissured sandstone. The crack initiation of fissured sandstone under uniaxial compression subjected to different thermal shocks is dominated by tensile failure (wing crack). As the number of thermal shocks increases and the cooling water temperature decreases, the initial crack modes gradually change from T1 to T2, or a more complex pattern. Subsequently, the thermal shock process of fissured sandstone is simulated in COMSOL Multiphysics. The effect of heat transfer coefficient and cooling water temperature on the temperature field and stress field in fissured sandstone are discussed, and the reasons for the thermal cracking of the fissured sandstone under thermal shock are revealed.

Thermal-shock-induced surface softening and conductivity evolution of hydraulic fracture in enhanced geothermal system

To reveal the thermal shock effect on micromechanical properties and conductivity evolution of hydraulic fracture in enhanced geothermal system, nanoindentation tests and fracture conductivity tests were performed on granite samples after different thermal treatments. Experimental results show that the hardness and the Young's modulus of fracture surface decreased with the increasing thermal treatment temperature. This degradation of micromechanical properties indicates the softening of fracture surface due to thermal shock effect which further influence the conductivity evolution. For propped fractures, the higher thermal treatment temperature, the lower fracture conductivity under the same closure stress. Particularly, at the thermal treatment temperature of 300°C, the dominant mechanism of quick fracture conductivity loss transformed from the proppant crushing under high closure stress (>50 MPa) to the enhancement of proppant embedment under low closure stress (<30 MPa). For self-propped fracture with small roughness, the thermal shock effect enhanced the conductivity under in-situ closure condition, while reduced that in case of shear slip. When the rough fracture was characterized by a local hump, it increased the flow resistance of in-situ closed fracture under high closure stress and reduced the fracture conductivity, but may form an effective flow channel with ultra-high conductivity once shear slip occurred.

Experimental studies on the physical and mechanical properties of heated rock by air, water and high-viscosity fluid cooling

A series of tests were conducted to study the thermal shock damage effect on the physical and mechanical properties of granite and limestone in different cooling media. The dry rock specimens were heated slowly to different target temperatures ranging from 25 °C–800 °C and then quickly cooled to room temperature in air, water, and high-viscosity liquid. After the heat treatment, physical and mechanical properties, such as P-wave velocity, mass, uniaxial compressive strength, elastic modulus and microstructure, were measured. The test results showed that the P-wave velocity, uniaxial compressive strength, and elastic modulus of the heated limestone and granite were all lower after thermal shock in the three cooling media. With increasing heating temperature, the changes in physical and mechanical properties became more pronounced. Air cooling has least influence on rock behavior among the three cooling media. Compared with water cooling, high-viscosity liquid cooling caused less degradation on the physical and mechanical parameters of rocks at any target temperature, which indicates that the thermal shock effect of high-viscosity liquid cooling on rocks was slightly lower than that of water cooling. The brittleness of the rock was affected by the treatment temperature and cooling media. When the treatment temperature was low, the brittleness of the rock was obvious. The brittleness of rock was maintained well by air cooling and was weakened by high-viscosity liquid cooling. Water cooling made the rock more ductility than the other two media.

Amorphous – Crystalline phase transition in nanostructural thin SiOx layers induced by pulsed laser radiation

The possibility of laser-induced structural transformation of amorphous SiOx thin layers into the SiOx -based nanocomposite layers with increased Si nanoparticles (NPs) has been studied. It was found that the average sizes of silicon NPs depend on the laser intensity (IL) and wavelength (λ). The NPs range of sizes d increase from 1 nm ≤ d ≤ 10 nm in initial films up to 1 nm ≤ d ≤ 35 nm with predominant of the single-crystalline Si NPs in modified SiOx after processing by pulses of the Nd+3: YAG laser (λ = 532 nm) with a pulse duration τ = 10 ns. The structural and topographic changes of SiOx films were studied using field emission scanning electron microscope (FESEM), Energy-Dispersive X-ray Spectroscopy (EDXS), and Raman spectroscopy. The high-frequency shift of the Raman band responsible for the crystalline phase of silicon NPs, caused by the quantum confinement effect, showed an increase in the average of the NPs size with the laser intensity (IL). This is correlated with a decrease of intensity Raman band with a maximum at a vibration frequency at 475 cm−1, which testifies for the decrease of the amorphous phase in the SiOx film with an IL increasing. The correlation between the increase of the average sizes of silicon NPs, the values growing of the stoichiometric index x in SiOx film, and the decrease of the percentage of amorphous silicon was established. The physical mechanisms that explain the growth process of Si NPs are based on the laser thermal shock effect with the following coalescence of Si atoms into NPs and recrystallization of a melted fraction of SiOx film into the NPs with changed sizes have been proposed.

Effect of Cyclic Thermal Shock on Granite Pore Permeability

Abstract Geothermal development requires an understanding of changes in pore permeability caused by repeated thermal shock fatigue damage in hot dry rock. Research on the subject can aid the evaluation of the longevity and mining value of enhanced geothermal systems (EGS). However, few relevant studies are currently available. In this study, the change characteristics of pore permeability in granite following different heating–cooling cycle temperatures (250°C, 350°C, 450°C, 550°C, and 650°C) and numbers of cycles (1, 5, 10, 15, and 20 cycles) were analyzed. Results show that with increasing temperature, the uneven thermal expansion and thermal shock effect of minerals promote crack development, leading to increases in the porosity and permeability of granite, particularly at temperatures above 450°C. When the heat treatment temperature was below 450°C, the number of cycles only slightly affected the porosity and permeability; meanwhile, when the temperature exceeded 450°C, the porosity and permeability increased significantly with an increase in the number of cycles. Moreover, three-dimensional nonlinear fitted relationships among porosity (or permeability), cycle temperature, and number of cycles have been established for the first time with correlation coefficients (R2) above 0.9, which reveals the change rules of pore permeability after quenching in hot dry rock. The results can be used to evaluate the efficiency of geothermal reservoir energy extraction and aid in geothermal reservoir design.

Thermal Shock Effect on Acoustic Emission Response During Laboratory Hydraulic Fracturing in Laizhou Granite

Thermal Shock Effect on Acoustic Emission Response During Laboratory Hydraulic Fracturing in Laizhou Granite

Effect of thermal shock on laboratory hydraulic fracturing in Laizhou granite: An experimental study

This paper aims to investigate the effect of thermal shock on hydraulic fracturing in hot dry rock (HDR). To simulate the thermal shock effect caused during the injection of cold water, several natural granite specimens were slowly heated to various target temperatures and then rapidly cooled down by flowing water. Laboratory hydraulic fracturing experiments were performed on granite specimens under triaxial stress condition and room temperature. After that, computed tomography (CT) scanning technique, scanning electron microscope (SEM) observation, and surface profile scanning (SPS) tests were combined to analyze the influence of thermal shock on fracture morphology from micro-scale to macro-scale. Moreover, the characteristics of injection pressure curve were discussed. Experimental results show that a single main hydraulic fracture with large aperture is created and approximately propagates along the direction perpendicular to the minimum principal stress before 300 °C. When the thermal treatment temperature is higher than 300 °C, multiple hydraulic fractures with branches tend to be created due to the existence of thermally-induced damage zone near the well hole. Experimental results of SPS tests indicate that the maximum height difference of the hydraulic fracture surface increases with increasing thermal treatment temperature. The tortuosity of hydraulic fracture significantly increases when the thermal treatment temperature is higher than 300 °C. Additionally, the analysis of injection pressure response shows that apparent non-linear pressurization, and decrease in pressurization rate and breakdown pressure are observed after 300 °C.

Effects of Cryofrequency in the Different Swine Skin Tissue Layers: &amp;lt;i&amp;gt;In Vitro&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;in Vivo&amp;lt;/i&amp;gt; Study

Introduction: Cryofrequency is a novel therapy which was developed with the combination of cold (cryotherapy) and heat (radiofrequency) application, causing a thermal shock effect on skin tissue. The thermal shock is believed to alter local metabolism. Objective: To investigate the effect of cryofrequency on the skin tissue of a mini pig in an in vitro and in vivo experimental model. Methodology: A small swine of the S. domesticus species, a male mini-pig (30 kg weight) was elected for the in vivo procedure subject. The in vitro step was performed on the extracted abdominal part of another subject of the same species and breed. Then, after the application of cryofrequency in the monopolar and bipolar form in vivo, a histological analysis was performed. Results: A higher temperature variation was observed comparing the pilot study in vitro with respect to the experimental one in vivo. Microscopically, an increase of collagen fibers and blood supply and decreased adipose tissue was observed after cryofrequency application. Conclusion: With the bipolar cryofrequency, no reduction of adipose tissue was observed, but regarding the connective tissue, extensive areas of collagen deposition were observed, as well as a great amount of new-formed collagen fibers.

Thermal Behavior Assessment of Natural Stone Buildings in the Semi-Arid Climate

This paper aims to assess the effects of harsh climatic conditions’ interactions with natural stone on thermal inertia properties and the thermal performance of ancient residential buildings. As the type of stone differs, its thermo-physical components differ; therefore, its interactions with environmental factors vary. For this purpose, an experimental measurement was conducted on many buildings with different orientations in a semi-arid climate and validated by a simulation performed by the “EnergyPlus 9.3” software. Results showed that the important outdoor temperature gap between day and night influences the natural stone thermos-physical properties used in construction. The stone components affected by the thermal shock effect weathering are eroded over time, then saturated with water, and affect the thermal conductivity coefficient of stone; however, this directly changes the indoor thermal comfort and performance of buildings. Additionally, the high indoor relative humidity percentage and the absence of natural ventilation have an important influence on the ambient temperature values recorded. This paper discusses the experimental measurement results compared to the simulation results. KEYWORDS Thermal performance, building envelope, thermal inertia, limestone, Tébessa, Algeria

CHARACTERISTIC ANALYSIS OF HOT DRY ROCK DAMAGE AND FAILURE UNDER THERMAL SHOCK

Wave propagation and thermal conduction properties can indicate structural damage to hot dry rock (HDR) caused by thermal shocks. Granite from the central paleo-uplift belt in the Daqing area in the northern Songliao Basin is the focus of this research. Wave propagation tests and thermal conduction tests were conducted on high-temperature specimens after natural cooling and water cooling. The influence of the cooling process with water on the apparent temperature and thermal shock velocity of rock masses is discussed. Changes in the P- and S-wave velocities, specific heat capacity, thermal diffusion coefficient, and thermal conductivity coefficient of specimens under different heat treatment conditions are analyzed and compared. The relationships between the wave propagation characteristics and the thermal conductivity values are established. The results indicate the following: (1) The apparent temperature and thermal shock velocity values of high-temperature rock masses show nonconstant rates of change from fast to slow. Rock masses with higher initial temperatures exhibit a continuous and strong thermal shock effect, and water temperature differences have only a limited effect on the thermal shock velocity over 20 s of cooling with water. (2) As the initial temperature increases or water temperature decreases, the P-wave velocity, S-wave velocity, thermal diffusion coefficient, and thermal conductivity coefficient values of high-temperature rock masses decrease overall, while the specific heat capacity values increase. The amplitude of change after water cooling is higher than that after natural cooling. When the initial temperature is below 100° C, the free water content is the main factor influencing the wave propagation characteristics and changes in the thermal conduction characteristics. When the initial temperature is greater than 300° C, the changes in both properties depend on the amount of thermal damage done to the rock mass. (3) The fitting results suggest that the wave propagation and thermal characteristics are closely related, and the damage factors are strongly consistent. The deviation of fitting coefficients is mainly due to the limited development of fractures in the small-sized specimens. The research results provide a reference for studies on thermal damage in HDR in the geothermal development process, and a method to determine the in situ thermal conductivity of reservoirs is proposed.

A developed energy-dependent model for studying thermal shock damage and phase transition of composite reinforced panel subjected to lightning strike

Lightning strikes generate large amounts of energy. Thus, composite structures subjected to lightning strikes undergo significant physicochemical changes. In this study, the thermal shock damage and three-phase transition of a composite reinforced panel were investigated through a numerical simulation, an experiment, and ultrasonic C-scanning. An anisotropic constitutive model and PUFF equation of state (EOS) were proposed to study the damage behaviors of composite materials. The dynamical damage behaviors and three-phase transition of the composite reinforced panel were simulated using the proposed constitutive model and PUFF EOS. Finally, a lightning experiment and ultrasonic C-scanning were conducted to validate the numerical results. Obvious fiber upwarping and swelling were observed in the numerical simulation. The melted and vaporized materials caused a reverse thermal shock effect, which led to concave pits, buckling and internal damages in the composite reinforced panel. The numerical results were compared with experimental results and scanning results to validate that the proposed constitutive model and modified PUFF EOS can be well used to simulate the dynamical damage behaviors of composite materials. The simulated damage behaviors of the composite reinforced panel agreed well with the behaviors observed in the experiment.

A Simple Method to Control the Growth of Copper Oxide Nanowires for Solar Cells and Catalytic Applications

Copper oxide nanowires (CuO NWs) were synthesized by thermally oxidizing copper foils at various heating rates. It has been shown that both monoclinic CuO and cubic Cu2O phases were grown on the copper surface with NW diameters of almost 200 nm for all samples. While NWs were shown to be dense for low heating rates, they end up being broken for quick heating. The underlying growth mechanism was described basing on a detailed comprehensive study, and the effect of the heating rate was explained by considering the thermal shock effect and in-plane tensile stresses on curved surfaces. This study contributes to the research for suitable methods for the use of recyclable metals in technological applications. In particular, copper oxide NWs were deposited, for the first time, on FTO/glass substrates, and the optical characterization revealed that this method is a promising way to improve the surface contact for solar cells and catalytic applications.