Steel Shell Research Articles

Study on thermal response characteristics of encased propellants under laser irradiation

The laser safety of small and medium-sized flying units, exemplified by missiles, is crucial for ensuring their operational stability. In this regard, the response process of an encased propellant system comprising PBT propellant, stainless steel shell, and thermal insulation layer (EPDM) was meticulously captured during laser irradiation. The temperature distribution within the shell and insulation layer was determined through high-speed infrared thermography and finite element calculation. Results show that at a laser heat flux density of 2100 W/cm2, when the contact surface of the propellant reaches its ignition temperature, introducing a 1 mm insulation layer allows dissipation of 48.6-60.1% of the heat in the 0.5-1.6 mm shell beyond the laser irradiation range, significantly higher than the 3.1-12.2% observed without thermal insulation. Simultaneously, the ignition delay time increases from 0.45-0.75 s to 1.31-14.46 s. Theoretical calculations and experimental results confirm that replacing a portion of the shell with a thermal insulation layer achieves a lower heating rate of propellant with a thinner overall thickness, resulting in a longer ignition delay time. These findings have practical implications for enhancing the resistance of thin-shell targets, like rocket engines, against laser weapon interception.

Shell Deformation During the Construction of Record Span Soil-steel Buried Structure in Ras-Al-Khaimah (UAE)

Abstract The algorithm presented in this paper concerns the processing of data in the form of coordinates of measurement points located around the structure periphery, obtained from the geodetic measurements. The geometric parameter used here to study the deformation of the steel shell is the change of curvature. It is used to estimate the bending moment and hence the normal stress in the corrugated steel shell. The results given in the examples of calculations of the analyzed structure show the possibility of determining places with extreme values. For this purpose, a dense layout of measuring points and use the precision geodesy technique is necessary. Of significant importance in stress estimation is the correction of the geodetic measurement base. This is due to the fact that the points in the initial measurement do not lie on a section of the circle as a reference curve, used to determine the deformation of the shell.

Study of the Stress-Strain State of the System “Thin-Walled Steel Shell – Infill – Soil Base”

Study of the Stress-Strain State of the System “Thin-Walled Steel Shell – Infill – Soil Base”

Experiment‐based statistical distribution of buckling loads of cylindrical shells

AbstractA silo structure is usually constructed in the form of a cylindrical steel shell. It has the advantages of being lightweight, having a short construction period, and possessing a large storage space. It has been widely used in many fields of industry. Thin‐walled cylindrical shells often exhibit buckling failure and the experimental buckling load is usually lower than calculation results from classical theory and simulation without geometrical imperfection. Besides, test results with carefully conducted similar specimens still have substantial scatter due to imperfection sensitivity. The nonlinear analysis with FEM can obtain a high‐precision result comparing the experiment if the geometric parameters of the shell are fully known. However, this is almost impossible in practical engineering. The initial geometric imperfections and shell thickness of cylindrical shells are complex and random properties. Theoretically, these geometric imperfections can be described using a random field. This paper presents the experimental investigation of buckling analysis of cylindrical shells under axial compression considering the randomness of geometric imperfections and thickness. A total of 12 cylindrical shell specimens were fabricated and tested. Based on the test results, the optimal statistical distribution is obtained by the maximum entropy fitting method and the obtained results were compared with geometric imperfections based on laser scan measurements.

Research on explosive damage effects of tungsten fiber-reinforced Zr-based bulk metallic glass matrix composite shell

To expand the application range of explosive fragmentation projectiles, tungsten fiber-reinforced bulk metallic glass matrix composite (WF/Zr-MG) is used as the warhead shell in static explosion experiments, and is compared with 40CrMnSiB steel shells. The experimental results showed that, compared with 40CrMnSiB steel shells, the fragments produced by the WF/Zr-MG shell exhibit a larger aspect ratio, smaller average size, and a greater number of fragments at distances of 3 m and 5 m, with an equal number of fragments at a distance of 8 m. Theoretical calculations showed that the initial velocity of the fragments produced by the WF/Zr-MG shell is lower, but their velocity decay is slower, resulting in a greater determined damage range. The research results showed that WF/Zr-MG can be used as a shell material for explosive fragmentation projectiles, which can enhance their destructive power.

Research on hydration-caused thermal cracking risk of steel-concrete composite bridge pylons

Due to the large volume and different material of composite bridge pylons, a significant cracking risk has not yet been verified during concrete hydration. To clarify the hydration-caused temperature characteristics of concrete in composite pylons, based on an actual cable-stayed bridge, a 3D thermal-mechanical coupling model was established, demonstrating a good agreement between the FEM and measurements. On this basis, the temperature field and effects of pylon segments were analyzed. The key parameters influencing the temperature field, including the pouring sequences, hydration heat release, cement content, initial temperature, and convective coefficient，were analyzed. Results indicate that the temperature evolution can be divided into three stages: rapid warming, sharp cooling, and fluctuation. The temperature distributions exhibit high inside, low outside, and single-peak along the thickness direction. During the hydration process, the growth rate of the concrete elastic modulus is higher than its tensile strength. The maximum stress of concrete is 5 MPa, considerably higher than its tensile strength, leading to a significant cracking risk. Additionally, the maximum stress of the steel shell reaches 50 MPa. Adjusting the constructional parameters and environmental effects are the most effective improvement measure. The cracking risk of concrete can be reduced by 20% and 25% for every 20 kg/m3 and 50 kJ/kg reduction in the cement content and the cement heat release, respectively. Furthermore, reasonable methods for reducing unfavorable thermal effects are provided, which can facilitate the rational design and construction of composite bridge pylons.

Axial and radial thermal conductivity measurement of 18,650 Lithium-ion battery

Thermal conductivities of lithium-ion batteries are critical for the thermal management of battery packs. In this work, a novel method and experimental apparatuses are developed to measure the axial and radial thermal conductivities of the 18,650 LiNiCoAlO2 (NCA) lithium-ion battery. For the axial conductivity measurement, the one-dimensional steady conduction principle considering uniform heat loss is used, while the combined method of experiment and computational fluid dynamics (CFD) simulation is used for the radial conductivity measurement. By measuring the conductivity of the stainless steel cylinder, the errors are estimated to be less than 1.45 % and 1.37 % for the axial and radial measurement methods respectively. The axial and radial conductivities of the battery are measured at different open circuit voltage (OCV) and temperatures. Under the experimental conditions, the axial conductivity of the battery ranges from 10.26 to 14.20 W/m/K, and the axial conductivity generally increases with OCV and temperature. The radial conductivity ranges from 2.14 to 2.87 W/m/K if the battery core and the steel shell are considered as a whole; and the radial conductivity of the core ranges from 1.84 to 2.55 W/m/K if the core and the shell are considered separately. In the normal OCV range, there is no obvious relationship among the radial conductivity, temperature and OCV, whether the core and the shell are treated separately or not. This work may contribute towards improved thermal simulation of Li-ion cells.

Research on Solid Shell Growth during Continuous Steel Casting.

The continuous steel casting process must simultaneously meet the requirements for production performance, quality and safety against breakouts. Knowing the thickness of the solidified shell, particularly at the exit of the mould, is useful for the casting process control and breakout prevention. Shell thickness is difficult to measure during casting; in practice, it is predicted by indirect methods and models. But after undesired rupture of the shell and leakage of the liquid steel, it is possible to measure the shell thickness directly. This article is focused on the problem of the growth and measurement of the solid shell obtained after the breakout of a round block with a diameter of 410 mm. An original methodology was developed in which a surface mesh of points was created from the individual scanned parts of the block using a 3D laser scanner. Research has shown differences of up to 6 mm between the maximum and minimum shell thickness at the mould exit. A regression function of the average shell thickness on time was found. The results of the real shell growth were further used for the verification of the original numerical model of cooling and solidification of the round block.

Experimental study on fireproof board insulation technique for steel-concrete-steel immersed tunnel

Fireproof board insulation schemes applicable to steel-concrete-steel immersed tunnel elements were proposed, and then the thermal insulation effect of those schemes was examined by conducting fire tests under RABT standard fire curve, and the influence of the thickness, the material, the installation method and joint treatment method of fireproof boards on thermal insulation effect was discussed. It is found that fireproof boards can be fixed on the surface of the steel shell through keel and angle lifting, and it can play an obvious fire insulation effect in the fire. The thicker the fireproof board, the more obvious the effect of thermal insulation, the maximum temperature of steel shell has quadratic relationships with the thickness of fireproof boards. Thermal insulation effect of calcium silicate fireproof boards is slightly better than vermiculite fireproof boards. After the fire, vermiculite fireproof boards are more complete and do not cause obvious corrosion to the steel shell, calcium silicate fireproof boards warps, breaks, and is easier to fall, and causes corrosion to the steel shell. Vertical joints, L-type joints and double-layered boards staggered joints, which sealed with expansive fireproof sealant, can effectively stop the hot smoke of fire.

Effect of backfilled stone/brine media on the long‐term free corrosion and electrochemical performance of an aluminum sacrificial anode

AbstractAn Al–Zn–In–Si–Sn–Ti sacrificial anode, utilized to protect steel shells of subsea‐immersed tunnels, works in a backfilled stone (6–10 mm)/brine (40 Ω cm) media (125 Ω cm). This paper investigated its impact on the anode's long‐term free corrosion and electrochemical performance. After prolonged free corrosion, the anode's general corrosion rate is minimal. Although its capacity (Q) and current efficiency (η) increase slightly, it shows a nonuniform dissolution state. Over a long‐term working period, a significant amount of Al(OH)3 deposits and diffuses between the backfilled stone toward the cathode surface, creating distinct stone impressions and a thick product layer. These effects considerably increase the media ρ around the anode and continuously decrease the brine's pH, decreasing Q and η values and output currents. Nonetheless, the current distribution within the media gradually becomes uniform with time, resulting in a homogeneous potential distribution along the cathode.

Evaluation of blast mitigation performance of cylindrical explosion containment vessels based on water containers

Using liquid materials with specific geometries can enhance the explosion-proof properties of confined structures. This approach is promising because bulk water has multiple blast mitigation mechanisms and adds almost no extra mass. In this study, a method of using water-filled containers to reduce both the peak and permanent deformation of cylindrical explosion containment vessels (CECVs) is investigated through experiments and numerical simulations. Several explosion experiments were performed to evaluate the blast mitigation of the empty containers and the bulk water with multiple thicknesses and heights in terms of dynamic deformation and afterburning suppression. The experimental results indicated that the bulk water with a larger thickness and a smaller height had better protective performance, which provided up to an 80.1% reduction in permanent deformation compared with no mitigant. Numerical models were established using LS-DYNA and verified by the deformation-time history curves measured in the experiments. The energy conversion process during the explosion was analyzed through the numerical simulations, and the results showed that water absorbed most of the detonation energy that should have been transferred to the steel shell, proving that momentum extraction of water was a significant mitigation mechanism for the internal blast in CECVs. Another significant mitigation mechanism was the shadowing effect of water, which changed the spatial distribution of the blast loading acting on the steel shell, especially for water containers with larger thickness and smaller height.

Nondestructive millimeter-scale void detection for thick steel-shell–concrete interface of immersed tube tunnel: case study

The structural form of sandwich-structured immersed tunnel (SSIT) can be complex. During the casting of self-compacting concrete, creating void defects between the steel shell and concrete interface is not difficult, which can adversely affect the overall safety and service life of the structure. However, detecting millimeter-scale voids covered by a thick steel plate is a technical challenge for current engineering industries. In this study, we proposed a nondestructive millimeter-scale void detection method for SSITs with thick steel shells by combining impact imaging and neutron methods. First, based on the near-source wavefield theory and count rate of thermal neutrons, the void area and depth calculation methods were derived theoretically, and then the coupling detection method and grading criteria for void severity were proposed. Additionally, the void detection performance was validated for a full-scale SSIT model test by blind detection. Finally, the proposed method was applied to the SSIT of the Shenzhen–Zhongshan bridge. The results showed that the proposed method could quantitatively determine the location and distribution pattern of a void; however, it could not accurately determine the void depth. In contrast, the neutron method could accurately calculate the void depth but had a large minimum detectable unit area. The proposed method could effectively compensate for the limitations of both methods. Statistically, the coincidence rate of the model test was 95%, 89%, and 87.5% for the void location, void area, and void depth, respectively, when the error range was ±2 mm. Using this method, 30 tubes in the Shenzhen–Zhongshan bridge were inspected, and by summarizing the void law, suggestions to improve the casting process were proposed, such as adjusting the casting speed. Meanwhile, the void probability decreased significantly. The proposed method provides an important basis for high-quality construction in SSIT projects.

A new counterweight design method for shaking table test models of single-layer spherical latticed shells

Shaking table test is one of the effective methods to study the dynamic behaviors of single-layer latticed shells, and the dynamic behavior of a shaking table test model is significantly affected by the size and installation way of the counterweight. Considering the characteristics of the single-layer latticed shells and the requirement of the test model similarity design, the size of the counterweight needed is normally large. To accommodate the counterweight in the test model, one way is to install the counterweight on the nodes directly and the other way is to enlarge the node size directly to account for the counterweight. Both the methods change the size and configuration of the nodes significantly, which brings additional bending moment and torque forces to the bars or causes a non-negligible reduction of the effective length of the bars. Those problems caused by the counterweight will have considerable influence on the evaluation of the seismic behavior of the single-layer latticed shells. A new counterweight design method is proposed by using multiple layers of upper and lower paired spherical steel shells assembled around a node, which improves the shortcomings of the traditional counterweight in the shaking table test model of single-layer spherical latticed shell (SLSLS). Thin rubber cushions are adopted between two layers of steel counterweight layers to help accommodate the local defects of the counterweight layers when they are not manufactured perfectly so that the counterweight layers can be tightly fixed to the node. With the new method, the improved counterweigh is installed around the node to avoid producing additional forces and keep the satisfaction with the design of the effective length of the bars. The effectiveness of the proposed counterweight design method is verified through theoretical analysis and numerical simulation of the test models. To carry out the finite element (FE) analysis of the test models, the seismic waves input way and the FE model updating method are improved. The static stability capacity of the bars and SLSLSs, and dynamic characteristics and dynamic stability capacity of SLSLSs are discussed to compare the improved counterweight with the traditional counterweight. The applicability of the new counterweight design method to the similarity ratios of the dynamic behaviors of the test models and the prototypes of SLSLSs is also studied under different rise-span ratios and grid-making.

Numerical study on damage effects of segmented reactive-core penetrator impacting double-layer steel targets

Reactive penetrator has stronger damage effects due to the combination of penetration and blasting. In this paper, numerical simulations are carried on by LS-DYNA to understand the penetration mechanism of a new type of segmented reactive-core penetrator. The primary core and secondary core are made of W/Zr reactive alloy and PTFE/Al reactive composite respectively, which are coated by a steel shell. Different from the Penetrator with Enhance Lateral Effect (PELE), the penetrator in this investigation performs a “self-sharpening” behaviour due to its high-density primary core and prefabricated groove. It is shown that the impact velocity of the penetrator has an influence on the fragmentation of targets, and there is a good balance between penetration ability and chemical reaction.

Artifacts from the Perspective of Effutu Masquerade Performance: An Aesthetic Album

Artifacts from the Perspective of Effutu Masquerade Performance: An Aesthetic Album

Intelligent initial model and case design analysis of smart factory for shipyard in China

At present, due to the lack of core technology and technological innovation ability, the design technology of traditional shipyards in China is backward. The operation mode of front-line workers in shipyards is highly dangerous. There are problems that endanger the physical and mental health of workers, such as noise and paint mist pollution, which lead to low production efficiency of workers and difficulties in personnel allocation. Under this background, “shipyard labor shortage” and other similar situations followed. If the concept of smart factory is introduced into traditional shipyards, the above problems can be effectively alleviated and solved. However, due to the complexity of ship product structure processing and manufacturing, the definition of smart shipyard in China is still vague, and the research process of smart shipyard is relatively slow. Aiming at the vague functional concept of smart shipyard, the lack of research on information design and management, smart production process and smart implementation process, this paper provides a conceptual architecture design model of civil smart shipbuilding factory. The functional definition of smart shipyard is discussed, and the initial conceptual model of smart shipyard is established, including information network platform model, smart production process model and smart implementation process model. The application case verifies the above model. Firstly, the information network platform model of α group is constructed, and the group brain control system is established. Secondly, the smart production process of shipyard A under α group is established. Finally, the smart implementation process of shipyard A is designed. The case study shows that: All ships completed 100% modeling, and the pre-outfitting rate increased to about 95%. By using the wire cutting robot, the production efficiency is increased by 70%. In the smart factory mode, the 60,000 tons bulk carrier can save 35thousand dollars labor costs and 11 million dollars in shipping fuel costs each year. The shell steel plate of the 300,000 tons ore carrier is reduced by 212 tons, and the weight is reduced by 10.5%. Case shipyard A under α group using the above smart factory model can save about 0.7 million dollars labor costs per year; reduce fuel costs by about 2.2 million dollars per year; saving 2.5 million steel usage per year. In total, shipyard A reduced expenditure by about 5.4 million dollars in one year.

Effect of Binder on Internal Resistance and Performance of Lithium Iron Phosphate Batteries

In this paper, a water-based binder was prepared by blending polyacrylic acid (PAA) and polyvinyl alcohol (PVA). The effects of the binder on the internal resistance and electrochemical performance of lithium iron phosphate batteries were analyzed by comparing it with LA133 water binder and PVDF (polyvinylidene fluoride). First, positive electrode sheets were prepared by using PVDF, PAA/PVA and LA133 as binders, respectively. and the effects of binders on the resistivity and compaction density of electrode sheets were analyzed. Secondly, the buckle battery and the 14500 steel shell full battery were prepared by using PVDF, PAA/PVA and LA133 as binders, respectively. The influence of the positive electrode materials prepared by different binders on the internal resistance of the battery and on the charge and discharge performance and cycle performance of the battery was analyzed. The results show that the internal resistance test of 14500 type whole cell prepared with PVDF, PAA/PVA and LA133 as the binder shows that the internal resistance of sample batteries LFP-F, LFP-AV and LFP-L are 40.5 mΩ, 33.2 mΩ and 35.7 mΩ, respectively. The internal resistance of the battery prepared by self-made PAA/PVA binder is the lowest.

Strength and stability of composite concrete and pipe-concrete structures under static load

The existing regulatory framework and imperfect calculation methods hinder the widespread use of pipe-concrete structures, which have great potential for industrial and civil facilities requiring small cross-sections of load-bearing elements. In order to solve this problem, a series of experiments is conducted to study the behavior of various combinations of steel and concrete materials under static load. Stress-strain state of composite and pipeconcrete structures is investigated. The analysis is given to the bearing capacity of test specimens. The critical load of specimen fracture is calculated, the bearing capacity loss and fracture are determined, deformation diagrams are suggested herein. The comparative analysis of bearing capacity of test specimens is conducted.The analysis of experimental investigations shows the non-linear increase of bearing capacity during the joint operation of steel shell and reinforced concrete core of the pipe-concrete element, and advantages of pipe-concrete structures over conventional structures.

Design and key construction technology of steel-concrete-steel sandwich composite pylon for a large span cable-stayed bridge

This paper introduces a new type of steel-concrete composite pylon that has been applied to Nanjing Fifth Yangtze River Bridge (a three-pylon cable-stayed bridge with a main span of 600 m). For this new type of pylon, the steel shells are connected with concrete through PBL shear connectors and studs, and the inner steel shells are connected with the outer steel shells by angle steels. Numerical analysis and full-scale model tests show that the pylon structure exhibits excellent mechanical properties and construction performance. The application of BIM technology, the research and development of special spreaders and construction platforms ensure the precise installation of structures. Highly factory-manufactured modular assembly of the reinforced steel shell structure can effectively reduce the intensity and difficulty of on-site operations, and improve the quality of the project, with low construction risks. Whereas, the successful application of this steel-concrete-steel sandwich composite pylon marks the formation of a complete set of construction technology of steel-concrete-steel sandwich composite pylon, which can be widely used in similar bridges.

Studying the Plastic Deformation of Cu-Ti-C-B Composites in a Favorable Stress State.

Composites with a copper matrix attract the attention of researchers due to their ability to combine high ductility, heat conductivity, and electrical conductivity of the matrix with the high hardness and strength of the reinforcing phases. In this paper, we present the results of studying the effect of thermal deformation processing of a Сu-Ti-C-B composite produced by self-propagating high-temperature synthesis (SHS) on its ability to deform plastically without failure. The composite consists of a copper matrix and reinforced particles of titanium carbide TiC (sized up to 1.0 μm) and titanium diboride TiB2 (sized up to 3.0 μm). The composite hardness is 60 HRC. Under uniaxial compression, the composite starts to deform plastically at a temperature of 700 °C and a pressure of 100 MPa. Temperatures ranging between 765 and 800 °C and an initial pressure of 150 MPa prove to be the most effective condition for composite deformation. These conditions enabled a true strain of 0.36 to be obtained without composite failure. Under higher strain, surface cracks appeared on the specimen surface. The EBSD analysis shows that dynamic recrystallization prevails at a deformation temperature of at least 765 °C; therefore, the composite can plastically deform. To increase the deformability of the composite, it is proposed to perform deformation under conditions of a favorable stress state. Based on the results of numerical modeling by the finite element method, the critical diameter of the steel shell is determined, which is sufficient for deformation of the composite with the most uniform distribution of the stress coefficient k. Composite deformation in a steel shell under a pressure of 150 MPa, at 800 °C, is experimentally implemented until a true strain of 0.53 is reached.