Papers by Keyword: ABAQUS

Abstract: Tailored welded and patchwork blanks are commonly used in the automotive field to locally tailor the mechanical response of sheet metal components, but conventional manufacturing approaches often introduce structural discontinuities, corrosion-prone interfaces and limited formability. Additive deposition of local reinforcements offers a more flexible alternative, enabling material to be placed only where it provides the greatest structural benefit and reducing overall material usage and environmental impact. This work investigates the flexural behaviour of additively reinforced blanks through finite element simulations. A numerical model was developed in Abaqus to reproduce three-point bending tests on 22MnB5 sheets locally reinforced by the wire-laser additive deposition of a 316L stainless steel. Metallographic cross-sections were used to define the reinforcement geometry and penetration depth, micro-hardness profiles to define the extent of the heat affected zone, and plastometric characterisation to obtain local mechanical properties. The simulations demonstrate that the proposed numerical model reliably reproduces the experimentally observed flexural behaviour of wire-laser additively reinforced blanks. The numerical force-displacement response is consistent with the experimental one, and within this agreement the increase in bending strength obtained with minimal added material is confirmed.

Abstract: Concrete, often conceptualized as an inert construction material, is fundamentally a dynamic composite that undergoes continuous physicochemical transformations throughout its service life, governed by natural degradation processes and mechanical aging. Despite its widespread utility, concrete’s quasi-brittle behavior, characterized by low tensile strength and susceptibility to abrupt failure under traction-dominated loading regimes, remains a critical limitation in structural engineering. To address these intrinsic vulnerabilities, the rehabilitation of concrete infrastructure has emerged as a pivotal research domain, with advanced retrofitting techniques focusing on enhancing tensile performance and transitioning failure modes from brittle to ductile. Among these, externally bonded reinforcement (EBR) using fiber-reinforced polymer (FRP) composites has gained prominence as a high-efficacy solution for augmenting load-bearing capacity and structural resilience. This study employs a parametric finite element analysis (FEA) framework in Abaqus/CAE to systematically evaluate the mechanical efficacy of two distinct carbon fiber-reinforced polymer (CFRP) retrofitting strategies: (1) externally bonded CFRP plates and (2) internally embedded CFRP reinforcement within the beam’s cross-section. The computational investigation quantifies the influence of reinforcement placement on critical performance metrics, including ultimate load capacity, deformation ductility, and failure mechanisms. Numerical results demonstrate that internally integrated CFRP reinforcement significantly enhances structural ductility and peak load resistance, while maintaining a marginal mass differential. These findings underscore the critical role of reinforcement topology in optimizing stress redistribution and crack mitigation, offering actionable insights for the design of next-generation retrofitting protocols that prioritize both strength and serviceability. The study advances the discourse on sustainable infrastructure rehabilitation by delineating a pathway for leveraging embedded composite systems to transcend the inherent limitations of conventional concrete matrices.

Abstract: This research investigates the penetration characteristics of single-nose blunt and double-nose blunt-blunt projectiles impacting thin aluminum plates using numerical analysis in ABAQUS. Finite element simulations model a 29.7g projectile impacting a 0.82mm thick aluminum plate at velocities ranging from 40 to 100 m/s. Results reveal distinct failure mechanisms, deformation profiles, and energy absorption behaviors influenced by projectile geometry. The blunt-blunt projectile exhibits a lower ballistic limit and two-plug failure, while the blunt projectile requires higher velocity for penetration, resulting in a single plug. The blunt-blunt projectile penetrates more efficiently, while the blunt projectile dissipates more energy at lower velocities. Analysis of residual velocity, impact duration, and deformation highlights the importance of projectile nose geometry in penetration performance. These insights contribute to the advancement of impact-resistant materials and structural designs for enhanced ballistic protection.

Abstract: Trees' consistent shape and robust structure can withstand massive loads, which has influenced numerous architects and design engineers. Tree shape support structures are considered one of the most suitable alternatives to long-span roof-truss systems. Limited research has been undertaken on the structural efficiency of the columns with geometric subdivisions. This study investigates the Y-shape tree column's failure mechanism and damage index under static and lateral load. The variables considered are the external moment, subdivision element angle (θ), and joint failure volume of material (V_dj), investigating buckling and yielding behaviour. SAP2000 and ABAQUS are used in numerical modelling. The results revealed that when sliced half into branches, a symmetric column (prone to local buckling) switches the failure behaviour from buckling/ yielding to joint failure. Furthermore, V_dj has been found more in branches than stems, which increases with branch inclination (96.72% for θ =75^o). Considering both static and lateral load simultaneously resulted in a slight reduction (less than 35 %) in total V_dj but made the areas with high-stress asymmetric, making the support structure unfunctional comparatively at lesser load. The sliced column behaved like a single beam/column element for pure lateral load. To brace tree-shaped structures, this study recommends using a triangular wedge by welding the erected branches together just above the joint with the stem, increasing the overall affected joint area and making it resilient by reducing the stress intensity. Yet numerous areas need more exploration, such as integrating nonlinear behaviour and using a multilayer multi-material system utilizing high-fidelity modelling approaches.

Abstract: The presence of web openings in the shear span significantly impacts the structural behavior of reinforced concrete (RC) beams, affecting both shear capacity and crack propagation. This study explores the feasibility of strengthening web openings in the shear zone of RC beams using iron-based shape memory alloy (Fe-SMA) bars through numerical analysis with ABAQUS software. The investigation considered various web opening shapes; diamond, circular, and square strengthened with pre-stressed Fe-SMA bars. Results showed that web openings notably decrease the ultimate loads of beams by 53%, 44%, and 39% for square, circular, and diamond shapes, respectively. However, pre-stressed Fe-SMA bars enhanced the shear capacity of beams with unstrengthened web openings by approximately 60%, making their behavior comparable to solid beams. The proposed strengthening technique was most effective for diamond web openings, nearly restoring both shear strength and stiffness, while circular openings recovered nearly 90% of shear capacity and square openings about 75%. Additionally, Fe-SMA bars effectively controlled cracking at the corners of the openings. This study highlights the importance of strengthening web openings in RC beams, especially in shear zones, and provides significant insights into enhancing such beams, contributing to safer structural designs. Further laboratory experiments are recommended to validate and extend these numerical findings.

Abstract: The friction stir welding (FSW) process was developed by the Welding Institute (TWI) in 1991. The idea started from the need to use materials with high strength and low density in the aerospace and automotive industries to increase their performance. The FSW process enables the welding of dissimilar metals such as Al/Mg, Al/Cu, Cu/Mg, etc., without melting the base metal and avoiding the defects seen during fusion welding. FSW joining leads to a core and heat-affected zones with a behaviour different from that of the base metal. The behaviour of these zones influences the global behaviour of the welded structure and for this reason it is important to define the local behaviour. The present study focuses on identifying the local behaviour of a weld using numerical simulation. For this, the global model of the welded joint is created, by defining the specific areas of friction welding with rotating active element (the base material-MB; the thermally affected zone from the retreating side of tool- HAZ RS; the thermo-mechanically affected zone from the retreating side of the tool - TMAZ RS; the core of the weld - N, the thermo-mechanically affected zone from the advancing side of the tool - TMAZ AS; the thermally affected zone from the advancing side of the tool - HAZ AS) and the simulation of the tensile test is carried out. The local behaviour obtained after the simulation is compared with the behaviour obtained experimentally in the specialized literature. Next, the correlation of Abaqus and Matlab programs is presented to analyze and compare experimental data from the literature with those obtained from the simulation by applying the reverse method. This consists of introducing experimentally identified parameters into the numerical simulation, determining an eloquent comparison criterion, defining the error function and minimizing it. The inverse method presented in this paper opens new opportunities for its use in much more in-depth analyses.

Abstract: The integration of local metal structures into polymer components using Laser Powder Bed Fusion (PBF-LB/M) offers great potential regarding multifunctional lightweight structures. However, such process hybridization involves huge challenges. In order to reduce the temperature input into the less temperature-resistant materials, the use of lower laser powers in the interfacial region is essential. The resulting local sintering of the metal powder affects the thermal properties in the interfacial region, leading to a change in heat dissipation in the temperature-unstable material. A modeling approach oriented to selective laser sintering is presented for predicting the degree of sintering and associated thermal properties in the context of PBF-LB/M process simulation.

Abstract: The Cowper-Symonds relationship is the most common empirical equation used to model the influence of strain rates in steel structures subjected to blast loads. The simplicity of this relationship makes it as the preferred choice due to the minimum number of coefficients used in the equation. However, different coefficients were reported from experimental results where it was found that the coefficients could be influenced by the thickness of the specimens, types of materials and method of testing. Even so, the actual coefficients even for the same type of material such as for mild steel could be differ. It is known that strain rates effect increases the yield strength of steel, and this could reduce the maximum displacement of steel structures such as steel plates subjected to blast loads. This influence could be more significant if the steel plate was stiffened. Therefore, this study investigated the influence of Cowper-Symonds coefficients for steel plates with stiffeners subjected to close-in blast loads. The numerical investigations were performed using finite element software, Abaqus. The target plate was a 0.4 m x 0.4 m plate with 0.002 m of thickness subjected to a 0.012 kg of Plastic Explosive No. 4 (PE4) at 0.04 m stand-off distance. The influenced of stiffeners were investigate first where five stiffeners’ configurations were used and, in each configuration, the stiffeners come with different geometry ratios. Two best stiffened steel plates have been chosen to study the influence of different Cowper-Symonds coefficients. Different coefficient values of dominator, D and hardening coefficients, q was used. The results shows that any possible coefficient combinations of Cowper-Symonds relation are possible to use in predicting response of steel plates subjected to blast loads. From this study, the most ideal stiffened square steel plates for offshore platform could be identified.

Abstract: The creep response and stress relaxation of X20 CrMoV12-1 steam piping under diverse operating conditions were simulated using finite element analysis (FEA) code, Abaqus alongside fe-safe/Turbolife software. In the study, steady-state creep and creep analysis characterized by 24 hours daily cycle consisting of a total of 6 hours peak, 4 hours transient and 14 hours off-peak period was considered. Modified hyperbolic sine creep model used in the analysis was implemented in Abaqus via a special creep user-subroutine to compute the stress relaxation and creep behaviour, while the useful service life and creep damage was estimated using fe-safe/Turbolife. The optimum creep strain, stress, damage, and worst life were found at the intrados of the piping, with the steady-state analysis having a higher useful creep life and slower creep damage accumulation. Furthermore, slower stress relaxation with faster damage accumulation was observed in the analysis involving cycles. Finally, a good agreement was obtained between the analytical calculated and simulated rates of the piping.

Abstract: The Asymmetrical Castellated concavely – curved soffit Steel Beams with RPC and Lacing Reinforcement improves compactness and local buckling (web and flange local buckling), vertical shear strength at gross section (web crippling and web yielding at the fillet), and net section ( net vertical shear strength proportioned between the top and bottom tees relative to their areas (Yielding)), horizontal shear strength in web post (Yielding), web post-buckling strength, overall beam flexure strength, tee Vierendeel bending moment and lateral-torsional buckling, as a result of steel section encasement. This study presents two concentrated loads test results for seven specimens Asymmetrical Castellated concavely – curved soffit Steel Beams section encasement by Reactive powder concrete (RPC) with laced reinforcement. The encasement of the Asymmetrical Castellated concavely – curved soffit Steel Beams consists of, flanges unstiffened element height was filled with RPC for each side, and laced reinforced which are used inclined continuous reinforcement of two layers on each side of the Asymmetrical Castellated concavely – curved soffit Steel Beams web. The inclination angle of lacing reinforcement concerning the longitudinal axis is 45. Seven specimens with seven different configurations will be prepared and tested under two concentrated loads at the mid-third of the beam span. The tested specimen's properties are: unconfined Asymmetrical Castellated Steel Beams (Reference1), second model; Asymmetrical Castellated concavely – curved soffit Steel Beams (web and flange) confined with (RPC) only, third model; Asymmetrical Castellated concavely – curved soffit Steel Beams (web and flange) confined with (RPC) and laced reinforcement, fourth model; is same as the third model but it has one web opening with increase the depth of web post by 10 %, 20%, and 30 % as a gap between top and bottom parts of Asymmetrical Castellated concavely – curved soffit Steel Beams respectively. The results that have been obtained from the experimental part and the numerical analysis results by ABAQUS demonstrated that the increase of the gap leads to an increase in the load against the deflection curve. Sample CB8 with 122 mm gap has gained the highest load against deflection when compared with either reference sample without gap and other samples with 65 mm and 105 mm gap for concavely–curved soffit Steel Beams.