Thin-walled Cylindrical Steel Research Articles

Investigation of buckling capacity behaviours of corroded tanks

The use of thin-walled steel shells is rapidly becoming widespread. Depending on their purpose, they can be susceptible to corrosion in the environments they are used in. This leads to metal loss and consequently a decrease in buckling strength. In this study, the effect of corrosion and CFRP reinforcement on thin-walled cylindrical steel tanks was experimentally investigated. Six samples with a length and diameter of 400 mm were tested; two samples were not subjected to corrosion, two samples were subjected to 2.5 % HCl corrosion, and two samples were subjected to 5 % HCl corrosion. The effect of CFRP usage was examined in both corroded and non-corroded samples. The results show that as the corrosion rate increases, the buckling strength decreases, and CFRP reinforcement recruitments the loss in buckling strength.

Numerical investigation of blast loading effects on a thin-walled cylindrical steel storage tank

Cylindrical storage vessels with thin walls are extensively utilized across various industrial sectors, including oil, gas, and petrochemicals, serving as crucial repositories for substances relevant to these industries. However, their susceptibility to fire and explosions underscores the need for comprehensive understanding and mitigation strategies. Amidst the escalating frequency of subversive attacks, regional conflicts, and other destabilizing events, a thorough comprehension of blast loading dynamics becomes paramount. These imperatives are compounded by recent occurrences, notably the cataclysmic explosion at the Beirut port in 2020 and the conflagration at a chemical plant in Texas in 2019, which starkly emphasize the pressing necessity for enhanced safety protocols. Thin-walled structures are particularly vulnerable to explosions, making the prediction of their response crucial. This study focuses on developing a computational model tailored for a horizontally oriented, simply supported, thin-walled water storage tank, utilizing advanced Abaqus/Explicit software. The primary objective is to investigate the impact of water when exposed to the explosive load generated by a 50 kg-TNT detonation at a distance of 0.50 m. The novelty of this work lies in the integration of advanced computational techniques, including the use of ConWEP 2.0, a sophisticated software framework developed by the U.S. Army, which integrates established formulations outlined by Kingery and Bulmash, as well as the employment of the Jones-Wilkins-Lee (JWL) Equation-of-State (EOS) alongside a sophisticated Smoothed-Particle Hydrodynamics (SPH) technique. The results reveal a significant reduction in deformation and damage inflicted upon the storage tank when subjected to explosive forces, attributed to the presence of water. This crucial finding highlights the effectiveness of water inclusion in enhancing the structural resilience of these tanks against potentially catastrophic blasts, thereby providing valuable insights for improved safety and durability in industrial environments.

A coupled SPH-FEM analysis of explosion-induced blast wave pressure on thin-walled cylindrical steel liquid storage tank and corresponding structural response

A coupled SPH-FEM analysis of explosion-induced blast wave pressure on thin-walled cylindrical steel liquid storage tank and corresponding structural response

Piezo-based flexural vibration suppression for an annular rotor via rotating-frame H2 control optimization

Elastic vibration can arise in annular and thin-walled rotor structures, impacting on operating performance and the risk of failure. Feedback control to reduce flexural vibration can be realized using lightweight actuators and sensors embedded in the rotor structure. To design optimal controllers, rotating-frame models of both the structural dynamics and sources of excitation are required. This paper describes a solution to this problem for the case of an annular rotor equipped with piezo patch actuators and sensors. To account for space-fixed external excitation sources, a forcing function is considered involving specified spatial and frequency domain distributions. A model-based [Formula: see text] synthesis is used to compute optimal control solutions. These are tested experimentally on a thin-walled cylindrical steel rotor for cases with narrowband and broadband excitation sources, applied from the fixed frame. The results show that frequency-splitting within the rotating-frame dynamics plays a key role in predicting and controlling resonance. The effectiveness of the optimal control methodology in reducing circumferential vibration of the annular rotor is also confirmed.

Buckling Behavior of Sulfate-Corroded Thin-Walled Cylindrical Steel Shells Reinforced with CFRP

In this study, the buckling behavior of thin-walled cylindrical tanks exposed to sulfuric acid corrosion was investigated, and the buckling performance losses were recovered by reinforcing with Carbon fiber reinforced polymer (CFRP). Experiments were planned for three groups: Control samples without corrosion, full CFRP models and variable CFRP application group. The experiments were performed with 12 models of 800 × 400 × 0.45-mm dimensions. The prepared solutions were applied to the sealed test models as full and ½-filled and then exposed to sulfuric acid solution for 24 h, after which the experiments were performed. The mass losses were determined from the weights of the cylindrical samples, which were discharged after 24 h. After the corrosion, CFRP was applied to the cylinder, at ½ height of the cylinder and at 10 cm from its midpoint. The prepared model samples were placed in the test apparatus and sealed. In the experiments, vacuum was made using the vacuum pump, and data were recorded using the load cell. Deformations were measured by strain gauges and LVDT and transferred to the computer using a data collection device (datalogger). After data collection, vacuum-displacement plots were made. We aimed to recover a material that has undergone acid corrosion. The main goal of this work is to use the theoretical model, which is evaluated for limited geometrical ratios and for the perfect models, for the prediction of buckling behavior of sulfuric acid corroded thin-walled steel shells. We observed that the samples exposed to corrosion recovered 20–60% of their lost strength by CFRP application.

A design approach for the ring girder in elevated steel silos

Silos in the form of the thin-walled cylindrical steel shells are commonly supported on a ring girder, which rests on a limited number of columns to discharge the content by gravity flow into transportation systems. Local supports in the elevated steel silos produce a significant circumferential non-uniformity in the axial membrane stresses in the silo shell. One way of reducing the non-uniformity of these stresses is to use a very stiff ring girder which partially or fully redistributes the stresses from the local support into uniform stresses in the shell. Previous works that attempt to produce design expressions only address isolated ring girders and ignore the key role of the interaction between the cylindrical shell and the supporting ring girder. The aim of this study is to achieve a more efficient and realistic design of ring girders resting either on four supports, or on four supports with secondary beams, or on eight supports. Pursuant to this goal, variations of the stress resultants and displacements in the ring girder which rests on different support conditions are derived for the first time using Vlasov's curved beam theory. These expressions have been evaluated with finite element analyses for an isolated ring girder. Subsequently, a complementary finite element parametric study was conducted to investigate the variation of the stress resultants and displacements caused by the connection of the shell and ring girder resting on different supporting conditions. These variations were plotted as a function of the shell-ring girder stiffness ratio (ψ) for each support condition. Finally, considering lower bound limits for the stress resultants and displacements, design equations were proposed for ring girders which rest on different support conditions. These expressions may easily be placed in a practical spreadsheet, which could be used with different data to give realistic predictions.

3D wind buckling analysis of steel silos with stepped walls

Thin-walled cylindrical steel silos are one of the key structures for storage of materials in many industries and agricultural sectors. They are susceptible to instability under wind pressure when they are empty or partially filled. This paper investigates numerically the wind buckling behavior of three sample steel silos with stepped walls composed of isotropic rolled shells. Wind load vertical and circumferential distributions were adopted from Eurocodes. Two proposed circumferential pressure distributions for an isolated silo and a silo in a group with a closed roof were taken into consideration. Moreover, the effect of additional inward pressure, proposed by Eurocode, on buckling capacity of vented silos with a small opening was evaluated. Accordingly, comprehensive 3D finite element models were used and detailed linear and non-linear buckling analyses were conducted. The wind buckling capacity of sample structures considering multiple amplitudes of initial imperfections was also assessed. The results obtained suggest a considerable decrease in the buckling resistance of imperfect silos. Finally, Eurocode provisions for the wind buckling stress design of unstiffened cylinders with step-wise variable wall thickness were examined and the relevant conclusions have been made.

Theoretical prediction for maximum residual cross-sectional deformation of thin-walled cylindrical steel tubes under pure plastic bending

Cross-sectional ovalization（ovalisation）usually occurs when thin-walled tube is subjected to large plastic bending. This paper is concerned with residual deformation of tube's cross-section in radial direction when external bending moment is removed. A combination of experiments and theoretical modeling is used to study this issue. Firstly the four-point pure bending experiments involving fifteen stainless steel specimens with a range of diameter-to-thickness ratios are carried out to observe the shape of the ovalized cross-section and to obtain the cross-sectional flattening (value of ovalization) along the circumferential direction. Secondly the theoretical modeling procedure is performed to derive a rational model for predicting the maximal residual cross-sectional flattening of the thin-walled tube subjected to pure bending after unloading process, employing the thin-shell kinematics, the principle of virtual work and the classic unloading rule. Finally the model is validated by comparing the theoretical results with the experimental ones with less than 10% error. And the relationships between the residual flattening and the bending radius as well as the wall thickness are also revealed by the numerical results. The application of this investigation will play a positive role in thin-walled steel tube bending operation.

The Effects of Carbon Fiber Reinforced Polymer Strengthening on Cylindrical Steel Storage Tanks under Bending Shear Load

Large thin-walled cylindrical steel storage tanks play important roles in the development of economy and infrastructures. Storage tanks subjected to internal pressure can cause buckling modes, especially elephant foot bulge at the bottom of the tanks. The design of tanks against buckling is very necessary. In this paper, the load-carrying capacity and the failure modes of the storage tanks subjected to internal pressure under bending shear load will be calculated by the finite element analysis. The results will be compared with the design method from Architectural Institute of Japan. Moreover, this paper will also consider the effects of the use of carbon fiber reinforced polymer layers to strengthen storage tanks against buckling and the increase of the load-carrying capacity of the tanks under bending shear load.

3D wind buckling analysis of long steel corrugated silos with vertical stiffeners

Abstract Thin-walled cylindrical steel silos are susceptible to instability under wind pressure when they are empty or only partially filled. This paper investigates numerically the wind buckling behavior of a real steel corrugated silo with 8.02 m diameter and 17.62 m height, strengthened by open-section vertical stiffeners. Accordingly, comprehensive 3D finite element models were used and detailed linear and non-linear buckling analyses were conducted. The effects of sinusoidal corrugated sheet profile dimensions on this issue were specially explored. Wind load vertical and circumferential distributions were adopted from Eurocode. Two proposed circumferential pressure distributions for an isolated silo and a silo in a group were taken into consideration. To investigate the material efficiency of corrugated steel silos, a comparison between a full-scale corrugated silo and an equivalent flat sheets one was performed. Additionally, imperfection sensitivity analyses for both structures were carried out.

Buckling of Thin-Walled Long Steel Cylinders Subjected to Bending

The present paper investigates structural response and buckling of long unstiffened thin-walled cylindrical steel shells, subjected to bending moments, with particular emphasis on stability design. The cylinder response is characterized by cross-sectional ovalization, followed by buckling (bifurcation instability), which occurs on the compression side of the cylinder wall. Using a nonlinear finite element technique, the bifurcation moment is calculated, the post-buckling response is determined, and the imperfection sensitivity with respect to the governing buckling mode is examined. The results show that the buckling moment capacity is affected by cross-sectional ovalization. It is also shown that buckling of bent elastic long cylinders can be described quite accurately through a simple analytical model that considers the ovalized prebuckling configuration and results in very useful closed-form expressions. Using this analytical solution, the incorporation of the ovalization effects in the design of thin-walled cylinders under bending is thoroughly examined and discussed, considering the framework of the provisions of the new European Standard EN1993-1-6.

Bending of cylindrical steel tubes: numerical simulation using Grid computing

Crashworthy structural elements may be subjected to various types of loading, such as axial or lateral compression and bending; consequently, extensive theoretical and experimental research work has been performed exploring the collapse mechanisms occurred under such loading conditions. However, the designer needs theoretical tools ranging from simple analytical calculations to full finite element analysis using non-linear, large deformation codes. The main objective of this paper is to apply the explicit FE code LS-DYNA through a Grid computing platform in order to simulate the crash behaviour of thin-walled cylindrical steel tubes subjected to three-point bending test in various cases of the position and direction of the imposed load. The simulation has been carried out through the GRIA computing platform that advances the computational performance of the executed tests, and additionally enables the remote and collaborative conduction of the experiments. The results taken from the simulation allow in drawing useful concluding remarks pertaining to the design of the crushing process.

Buckling and post-buckling behavior of thin-walled cylindrical steel shells with varying thickness subjected to uniform external pressure

In the present paper, numerical and experimental investigation have been undertaken into the buckling and post-buckling behavior of thin-walled cylindrical steel shells with varying thickness subjected to uniform external pressure. For the experimental study, four different cylindrical steel shell specimens with varying thickness were tested to collapse. For the post-buckling analysis of these structures, material and geometric nonlinear collapse analysis are carried out. To trace the equilibrium paths through limit points into the post-critical range, the ‘Arc-Length-Type Method’ has been used. In order to verify the accuracy and validity of the finite element modeling, the numerical results, obtained from nonlinear finite element collapse analyses, have been compared with the results of the experimental study. The study shows that the theoretical behavior predicted by the nonlinear finite element collapse analyses followed closely the experimental behavior. Consequently, it has been found that the finite element model is reliable enough to be used to undertake nonlinear analyses for investigation into the buckling and post-buckling behavior of thin-walled cylindrical steel shells with varying thickness. Also it has been found that the buckling mode can be generated in whole length of the shell if the thickness variation is low. However, in the case of high variation of thickness, the buckling mode is formed in thinner part only. Also, the considerable effects of circumferential and vertical weld line on the buckling strength and mode shapes are verified.

Bending of cylindrical steel tubes: numerical modelling

Crashworthy structural elements may be subjected to various types of loading, i.e., axial or lateral compression and bending; consequently, extensive theoretical and experimental research work has been carried out exploring the collapse mechanisms that occur under such loading conditions. However, the designer needs theoretical tools ranging from simple analytical calculations to full finite element analysis using nonlinear, large deformation codes. The main objective of the present paper is to apply the explicit FE code LS-DYNA to the simulation of the crash behaviour of thin-walled cylindrical steel tubes subjected to three-point bending test in different positions and directions of the imposed load. The results obtained from the simulation allow us to draw useful conclusions pertaining to the design of the crash behaviour process.

Collapse analysis of thin walled cylindrical steel shells subjected to constant shear stress

Two principal possibilities for analyzing the structural response of quasi-statically loaded steel shell structures to different actions are available: the commonly used static path tracing and the dynamic analysis with slowly changing loads, i.e. quasi-static loading. However, the failure process of thin-walled shells can often not be traced into the deep post-buckling area with static methods. The current research is focused on a thin-walled circular cylindrical steel shell collapse analysis under constant shear loading. It is shown that it is possible to overcome the difficulties and inconsistencies of the static analysis by using quasi-static analysis. This method allows to distinguish local and global instability points and to determine too the experimentally observed post-buckling strength.

Impact On Liquid Filled Containers

The study summarizes experiments and theoretical investigations to explore the behavior of liquid filled containers under medium speed impact. Thin-walled cylindrical steel containers with different wall thickness were impacted by gun projectiles. To investigate the major difference of the container failure modes empty and water filled containers were used. In the case of the water filled containers the impact damages ranged from simple perforation of Front and rear wall to a catastrophic front wall rupture which started at the rim of the impact hole and an additional perforation of the rear wall. The development of the pressure distribution in the water starting at the point of penetration was followed through the container to the opposite wall and back to the point of entry of the projectile. Stresses and strains in the containment were registered. Also the impact velocity and the geometry of the container cause different failure modes. The primary and the reflected pressure fields interact with the wall creating specific crack patterns. Theoretical investigations by means of the Finite Element Method helped to explain the experimental findings.