Parametric Finite Element Analysis Research Articles

Eccentric compressive performances of circular steel-reinforced concrete-filled stainless steel tubular column

Steel-reinforced concrete filled stainless steel tube (SRCFSST) columns are predicted to offer excellent durability, load bearing capacity, ductility, fire resistance, impact resistance, and seismic performance. Therefore, eccentric compressive tests of 18 circular SRCFSST columns were carried out to investigate the effects of the slenderness ratio, load eccentricity, and embedment of carbon-profiled steel (CPS) on circular SRCFSST columns. The ultimate strength and ultimate deflection of the composite columns were improved significantly after the CPS was embedded. A finite element (FE) model was established and the FE analysis indicated that the CPS was proved to be an effective means of constraining concrete. Based on the FE parametric analysis, it was shown that the stability coefficient decreased with increasing concrete strength, proof strength of stainless steel, and CPS yield strength, but increased with increasing rotation radius-diameter ratio. The greater the concrete strength, the more similar the N∼M interaction curves of the SRCFSST columns and reinforced concrete columns. The higher the CPS yield strength, stainless-steel ratio, slenderness ratio, carbon steel ratio, or proof strength of stainless steel, the more similar the interaction curves of the SRCFSST columns and profiled steel columns. Finally, the simplified model was refined to forecast the carrying capability of a circular SRCFSST specimen under the eccentric compression.

Failure mechanism and bearing force of CFRP strengthened square hollow section under compressive load

Carbon fibre-reinforced polymer (CFRP) plates can efficiently repair or enhance the mechanical properties of the square hollow section. However, the loading end of such a CFRP-strengthened member is prone to local bearing failure under compressive load. Given this limitation, an innovative CFRP-plate-strengthened square hollow section composite member (CFRP-SHSCM) was raised, and the thick-walled section was welded on both ends of the thin-walled steel column. The mechanical properties of CFRP-SHSCMs were investigated through parameter finite element (FE) analysis, focusing on the influence of the amount of CFRP layers (nc), the slenderness ratio (λ), the initial geometric imperfections (v0), the CFRP layouts (2S and 4S) and the length of the exposed steel column (Le). The load–displacement curves, the bearing force, and typical failure modes were also acquired. Results indicated that with increasing nc and v0, and decreasing λ, the conventional CFRP-SHSCMs were prone to local bearing failure with poor ductility, leading to the insufficient use of the CFRP plate, in contrast, the improved CFRP-SHSCMs primarily underwent overall buckling failure and exhibited better bearing force and ductility. Finally, the modified Perry-Robertson formula was put forward to predict the ultimate load of the CFRP-SHSCMs. The coefficients of variation between the FE simulation and the theoretical results were 0.00436 and 0.0292, respectively.

Tensile strength of girth weld joint of linepipe with softened HAZ

In seismic-active area, the buried pipeline is subjected to the axial tensile load exceeding the yield stress of pipe material due to the lateral flow induced by soil liquefaction. Designing a girth weld joint that does not fracture at girth weld but base metal which has high elongation capacity is feasible to ensure adequate ground displacement absorbing capacity of the girth weld joint. However, as for fine grain steel, the heataffected zone (HAZ) is softened by welding heat input, and then, the zone of softened HAZ can be the origin of fracture under tensile load. The apparent strength of softened HAZ is affected by the plastic constraint from the surrounding weld metal and base metal during tensile loading, and the fracture location depends on the apparent strength of HAZ. This study investigates the tensile strength and fracture location of girth weld joints with softened HAZ in the static tensile test. The effect of geometric and mechanical heterogeneity of HAZ, strength overmatching of weld metal, and the width-thickness ratio of tensile test specimen on tensile strength are elucidated using parametric finite element analysis. Subsequently, an equation is proposed to predict the tensile strength and fracture location of the welded joint. Using the proposed equation, the condition of geometric and mechanical heterogeneity of the weld to confirm the girth weld joints that fracture at base metal under tensile load is clarified. The proposed equation can be used to design a girth weld joint with liquefaction earthquake resistance.

Finite element analysis of the seismic performance of PVC-CFRP confined concrete column-ring beam interior joints

This paper presents a finite element (FE) analysis of the seismic performance of PVC-CFRP confined concrete column-ring beam interior joints (PCCC-RBIJs) under low cyclic loading. Based on the constitutive relationship of materials, a FE model was established using ABAQUS and validated against the experimental results of ring beam joints found in the literature. Then, FE parametric analysis was performed to investigate the influence of studied parameters on the seismic performance of the PCCC-RBIJs. These studied parameters included the axial compression ratio, height-diameter ratio of the ring beam joint, column longitudinal reinforcement ratio, reinforcement ratio and stirrup ratio of ring beam, and joint concrete strength. The FE analysis showed that the seismic performance of PCCC-RBIJ specimens can be enhanced by increasing their axial compression ratio, column longitudinal reinforcement ratio, and ring beam reinforcement ratios or decreasing their height-diameter ratio of the ring beam joint. Although the joint concrete strength and ring beam stirrup ratio have little effect on the seismic performance of the joint, the ring beam stirrup ratio affects the stirrup utilization. The paper also provides design suggestions for PCCC-RBIJs.

Crack tip shielding and size effect related to parallel edge cracks under uniaxial tensile loading

The present work aims at investigating crack shielding and size effect related to a cracked slab under tensile loading. For this purpose, experimental tests are carried out on PMMA cracked samples. Three different geometries are taken into account, presenting one, two or three parallel edge cracks, and assuming their distance equal to their initial length. Results are interpreted through the coupled stress and energy criterion of Finite Fracture Mechanics (FFM). The approach is implemented numerically, and parametric finite element analyses are carried out to evaluate the normal stress field and the stress intensity factor for each configuration. It is found that asymmetric crack propagation has to be preferred according to the energy balance. The matching between FFM failure predictions and experimental data reveals to be satisfactory.

Bi‐stable cured shape of CFRP variant structures with asymmetric layup: Rapid prediction and inverse design

AbstractThis study aims to produce variant composite structures that can precisely maintain equilibrium after changing stable states. A rapid and precise prediction method for the cure‐induced bi‐stable warping was developed, and the inverse design for the required part's structural and material parameters was investigated. Firstly, the mechanism causing the warping was investigated. Then, in order to acquire basic data for a data‐driven model to achieve rapid and accurate warping prediction, a finite element analysis (FEA) was developed, with most of the prediction deviations being under 10%. Additionally, deformation forms of variant parts with various layups and shapes were studied to offer guidance for the different shape requirements. The structural and material parameters were analyzed using the response surface methodology and sensitivity analysis. After removing parameters like all rubbery properties with low influence, basic data from the parameterized FEA was utilized to build a precise proxy model. Finally, for the variant structures requiring reasonable shape forms, the inverse design of the material, layup, and sizes can be achieved using the proxy model and the non‐dominated sorting genetic algorithm II. All optimization results were validated using FEA or experiments. The deformation form in the two steady states of each case meets the specifications. The shape difference between the produced part and the required shape is less than 5 mm, and the design deviation for the maximum deformation is less than 10%. Consequently, the rapid prediction and inverse design methods for the bi‐stable shape of variant composite parts were effective and accurate.Highlights All the rubbery properties are almost uncorrelated to the bi‐stable warping. The proxy model can rapidly and precisely predict the bi‐stable shape. The inverse design can be achieved for a part requiring proper bi‐stable shapes. The design part can precisely maintain equilibrium with the required shapes.

A hybrid self-centering seismic damper: Finite element modeling and parametric analysis

This study presents a finite element model for a hybrid self-centering damper considering the rate and temperature effects and explores the effects of different design parameters on the damper response. The damper, called as superelastic friction damper (SFD), consists of superelastic shape memory alloy (SMA) cables and a frictional energy dissipation mechanism. The experimental response of the SMA cables, frictional unit and overall damper at different loading frequencies and temperature are used to develop numerical model of the damper. Once a validated numerical model is obtained, parametric studies are carried out to evaluate force-displacement response of the damper when the design parameters are altered. The effects of damper design parameters on the equivalent stiffness, dissipated energy, equivalent viscous damping and self-centering capabilities of the damper are analyzed. Based on the findings, the recommendations for the design of the damper are presented.

Structural Behavior of a Fixed-End Arched Cellular Steel Beam without Lateral Support

The arched cellular beam has the advantages of both the solid-web arch and the straight beam with web opening, and has become increasingly admired by architects in recent years. In this paper, four arched cellular beam specimens are designed using an orthogonal test method (OTM) with a three-factor and two-level approach. Firstly, the static loading test is carried out to analyze the mechanical response of the arched cellular beam under concentrated load. Then, a numerical analysis based on ABAQUS finite element (FE) software is carried out. The results show that the simulation results agree well with the test results, which indicates the accuracy of the simulation analysis method. Finally, the buckling load of the arched cellular beam under three different loads is calculated using the variable parameter FE analysis. Combined with the range analysis in the OTM, the influence of the target factor on the buckling load of the arched cellular beam is determined. The results show that the order of the factors affecting the out-of-plane elastic buckling is rise–span ratio > web height–thickness ratio > diameter–depth ratio.

Development of a convolutional neural network model to predict the size and location of corrosion defects on pipelines based on magnetic flux leakage signals

This study employs the convolutional neural network (CNN) to predict the dimensions and locations of corrosion defects on steel pipelines based on magnetic flux leakage (MFL) signals. Extensive three-dimensional parametric finite element analyses are carried out to generate MFL signals corresponding to semi-ellipsoidal-shaped corrosion defects with different sizes and locations on a pipe model. The white noises characterized by different signal-to-noise ratios are considered in the analysis to represent the measurement errors in the real MFL inspection tool. The numerically generated MFL signals are used to train and validate the CNN model to predict the dimensions and locations of the corrosion defects. The results indicate that the developed CNN model achieves a high predictive accuracy. The study demonstrates the application of CNN model to improve the pipeline integrity management practice.

Novel cellular coil design for improved temperature uniformity in inductive heating of carbon fibre composites

Electromagnetic induction has great potential for energy efficient manufacturing of polymer composites. Carbon fibre can be directly heated inductively, achieving rapid, localised, and volumetric heating. The main obstacle to wider adaption of induction in composites processing is the non-uniformity of temperature distribution in-plane and through thickness of composite laminates. This study puts forward a new cellular architecture of the coil and examines the feasibility of addressing the problem of field uniformity. The geometrical parameters of the coil were examined in concurrent modelling and experimental work, aiming at reducing the effect of field cancellation in neighbouring cells and maximising both the coil efficiency and the field uniformity. The paper demonstrates good potential of the new coil designed with significantly improved uniformity of temperature field compared to traditional commercially available coils. This result has been further optimised with parametric finite element analysis to reduce the standard deviation in surface temperature by a further 37%.

A novel surrogate-based crack identification method for cantilever beam based on the change of natural frequencies

A novel crack identification method is presented in this paper for cantilever beam-type structures within the scope of vibration-based damage identification. Natural frequencies are more easily to be measured yet are weakly sensitive to damage in comparison to other dynamic parameters such as mode shape and damping ratio. Therefore, this paper develops a surrogate-based crack identification method in order to overcome the low sensitivity of frequency to damage. The surrogate model was constructed using radial point interpolation method (RPIM) and subsequently trained with the frequency shift database established from parametric finite element analysis (FEA) modeling of cracked/ non-cracked cantilever beams. On this basis, the crack identification problem had been converted to a standard optimization model with crack length and location as design variables. Subsequently, genetic algorithm (GA) was employed for solving the optimization model to achieve crack parameters. In the end, numerical examples and experimental test have been conducted to validate the developed method, revealing maximum relative errors within 0.5% and 2.5%, respectively.

Tensile behavior of parallel threaded couplers for reinforcements by natural cooling after elevated temperatures

Parallel threaded couplers (PTC) are increasingly being applied to prefabricated concrete (PC) structures owing to their excellent structural performance. To evaluate the effect of high temperatures on the tensile behavior of PTC, the specimens were cooled to natural temperature after the fire (400 ℃, 500 ℃, and 700 ℃), and monotonic and cyclic tests were carried out on PTC with two thread angles (60° and 75°). After the test, the failure mode, ultimate bearing capacity, load-displacement curve, and ductility of PTC were investigated. The results show that the failure mode of PTC is steel bar necking, and the ultimate load of PTC after the fire are reduced by 6.7 %, 7.3 %, and 11.1 % under the monotonic test, the connection performance of mechanical splices is excellent. Besides, the finite element model was established to simulate the mechanical properties of PTC. The load-displacement curves and the constraint effect of the sleeve obtained by the finite element simulation corresponded well with the tests. Based on this agreement, a parametric study was carried out to investigate the effect of the thread pitch and thread angle on the ultimate bearing capacity and ductility of PTC, and the constraint effect of the sleeve on the thread head was further investigated by the finite element parametric analysis.

Parametric topology optimization design and analysis of additively manufactured joints in spatial grid structures

This paper presents a complete computer-aided workflow for the parametric topology optimization (TO) design, numerical analysis and additive manufacturing (AM) of steel joints in spatial grid structures. A fully parametric TO design framework for steel joints in spatial grid structure was developed based on the Grasshopper platform. The joint models were parametrically established based on subdivision surface technology and further topology optimized through the bi-directional evolutionary structural optimization (BESO) algorithm with the support of cloud computing server. The structural performance of the optimized joints was thoroughly investigated via the parametric finite element analysis. Variables of loading conditions and TO parameters (target volume and filter radius) that affect the compliance, maximum displacement, maximum stress and stress distribution were taken into account. Analysis showed that the target volume governed the joint structural behaviour while the filter radius affected the geometric details of optimized joint. The practicability of proposed workflow was demonstrated through a parametric optimization design framework of a double-layer spatial grid structure with hundreds of steel joints. A typical optimized joint made of 316L stainless steel was additively manufactured using selective laser melting. This workflow is highly automatic and featured by high design flexibility and integration degree as well as good transplanted ability.

Investigation of the Defect Width Effect on the Burst Capacity of Composite-Repaired Pipelines With Corrosion Defects Using Finite Element Analysis

Abstract This study investigates the effect of the defect width on the burst capacity of corroded pipelines repaired with fiber reinforced polymer composite. Parametric finite element analyses are carried out to evaluate the burst capacities of composite-repaired pipes containing localized and full-circumferential corrosion defects. The analysis results indicate that burst capacities of composite-repaired pipes containing localized defects can be markedly lower than those of composite-repaired pipes with full-circumferential defects. The burst capacity model derived from the design equation recommended in the ASME PCC-2 code is found to be nonconservative for composite-repaired pipes with localized defects based on the parametric finite element analyses. An empirical equation for the defect width correction factor is then developed and shown to be highly effective in improving the predictive accuracy of the PCC-2 burst capacity model.

Finite element analysis for built-up steel beam with extended plate connected by bolts

Abstract Extended end-plate type connections are widely utilized in steel assemblies for easy production and assembly. The proper end-plate and bolt selection is paramount to confirming safety and economy in all connections and, consequently, steel buildings. This study presented an approach for refined parametric three-dimensional finite element analysis of bolted steel beam-to-beam extended end-plate connections. The model considers geometrical and material non-linearity to determine the impact of various factors on the connection’s performance. The proposed model was used to construct a parametric study. The study variables were bolt diameter and end-plate thickness, focusing on how thick and thin end plates affect connection conductivity. Numerical outcomes demonstrate that the connection's flexural strength and stiffness capability improved by increasing the end-plate thickness and bolt diameter. Finally, the analysis results were assessed, and the main conclusions were presented.

Anti-vibration Design of the Civil Aircraft’s Horizontal Tail Trailing Edge Compartment

The horizontal tail trailing edge compartment is a vital component of civil aircraft, situated between the horizontal tail beam and elevator. Its primary function is to connect the elevator and meet the aerodynamic sealing requirements of the unflapped elevator, and to transfer the aerodynamic and inertial load of the elevator to the outboard wing box of the horizontal tail in concentrated form. Under aerodynamic or other excitation, the horizontal tail trailing edge compartment may experience vibration, increasing the risk of structural damage. This study aims to enhance the anti-vibration capability of the horizontal tail trailing edge compartment via parametric finite element analysis. This analysis examines various design elements of the horizontal tail end cabin and compares the first-order modal frequency to deduce the influence of factors on the stiffness. The results provide a reference for the anti-vibration design of the horizontal tail trailing edge compartment in civil aircraft.

Nonlinear finite element modeling and parametric analysis for the design implication of expanded rib steel bars in RC beams

The quest for innovative design of reinforced-concrete to make it more durable, flexible, and sustainable has brought a transition from traditional methods of lap splicing to the use of anchor-head bars. One such innovation is the state-of-the-art Expanded Rib Steel Bar (ERSB) technique which reduces the conventional splice-length and also lessens the stress concentration at the concrete anchor-head contact areas to avoid brittle failure. Leveraging the four-point-bending experimental results of ERSB and two conventional designs, this paper investigates the performance of ERSB using a nonlinear 3D-Finite-Element Model. The results indicate that the proposed FEM reproduces the experimental behavior of ERSB in terms of maximum strength, displacement, ductility ratio, and crack pattern accurately. Moreover, the performance of ERSB is superior than the single-head-anchor bars and similar to that of the reinforced beams without joints. A parametric study then suggests design implications which can be adopted to develop guidelines for designing ERSBs.

Assessment of Eurocode 3 Shear Design Provisions for Cold‐Formed Steel Beams with Web Holes

AbstractCold‐formed steel beams are often provided with web holes to accommodate service conduits. These web holes result in reduced structural strength. Accurate estimation of the structural strength, including shear strength, is crucial during the design phase. There are a lot of studies available in the literature investigating the shear strength reduction in cold‐formed steel beams due to web holes. However, the experiments and parametric finite element results were not assessed against Eurocode 3 shear design provisions. Therefore, the shear design of cold‐formed steel beams with web holes is investigated herein. Existing experimental and parametric finite element analysis data on cold‐formed steel beams with circular web holes were collected from the literature. The accuracy of the current Eurocode 3 shear design provisions was then assessed using the collected data. The comparisons showed that the current Eurocode 3 shear design provisions were not suitable to estimate the shear strength of cold‐formed steel beams with web holes. Finally, Eurocode 3 shear design provisions are extended to capture the effect of web holes and verified against the available shear tests and finite element results. It was found that the new extended shear design proposal offers improved accuracy and consistency in shear strength predictions.

The response of diagrid structures to fire

The diagrid structural system has seen significant uptake in medium to high rise buildings because of the architectural and resource advantages that it provides. These arise mainly as a result of flexibility in the topology that this particular structural solution provides. However, as a result of the way in which diagrids carry both horizontal and vertical loading, the diagrid structure itself may be susceptible to fire in ways which are not immediately obvious on the basis of our understanding of more traditional rectilinear construction forms. This study addresses this to improve our understanding of diagrid structures' response to fire. A comprehensive structural analysis on 45 fire load cases is conducted, considering different fire locations and sizes, using parametric design tools and finite element analysis software. The results provide valuable insights into the load redistribution and collapse mechanisms of diagrid structures in fire conditions.

Artificial intelligence assisted optimization of rammed aggregate pier supported raft foundation systems based on parametric three-dimensional finite element analysis

The increased usage of rammed aggregate piers has demanded optimizing the design parameters of this technique. In this study, numerous parametric three-dimensional finite element analyses were conducted to optimize the parameters of the rammed aggregate pier-supported raft foundation with novel methods. Three-dimensional finite element simulations were validated using a field loading test for a single rammed aggregate pier at Neola, Iowa (USA). After the validation, elasticity modules of the rammed aggregate piers, raft foundation thicknesses, and column spacings were varied. The raft foundation-rammed aggregate pier groups system in 81 different combinations was subjected to parametric three-dimensional finite element analyses to provide data for the optimization study. The effect of the changes in the elasticity modulus of the rammed aggregate piers, the raft foundation thickness, and column spacing on the settlement was investigated. Optimization analyses were performed using the artificial intelligence-supported novel Goal Attainment Method and the Response Surface Method. The novel coding developed in this study, which automatically selects the most reasonable prediction function with the support of artificial intelligence, created a prediction function with a high correlation coefficient used in the optimization analyses. Two different optimization methods specified in the optimization study performed as multi-objectives were compared, and the solution system with the highest desirability value was selected. Therefore, optimum design parameters were reached by using novel methods for general raft foundation-rammed aggregate pier group systems to guide researchers.