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In this study, a number of numerical simulations have been performed to analyze the distribution characteristics of residual stress (RS) in the wire and arc additive manufacturing (WAAM) components made of aluminum alloys. Experiments have been performed to measure temperature results (thermal cycles, etc.), residual stresses, and deformation for v...
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![Fig. 1c. For further details on the set-up, the reader can refer to [25].](profile/Thaneshan-Sapanathan/publication/353272218/figure/fig1/AS:1047063852765184@1626650884794/c-For-further-details-on-the-set-up-the-reader-can-refer-to-25_Q320.jpg)
Residual stresses are investigated for the first time in a dissimilar AA1050–DP450 steel magnetic pulse weld using neutron diffraction. Close to the joint interface, tensile residual stresses are observed in the Al sheet and compressive residual stresses are identified in the steel sheet. At the interface, longitudinal tensile stresses are dominant...
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... The RS is in tension at the bottom location for all the walls formed by different weaving strategies, with no significant variation (22-24 MPa) among the walls. This tensile RS arises because the bottom layers, located near the substrate, cool more rapidly than the surrounding substrate material [36], resulting in uneven shrinkage and causing the substrate to exert a pulling force on the bottom layers of the wall, leading to tension. Additionally, except for the helix, the residual stress value at the top for all the walls is nearly zero. ...
Arc weaving is a feasible technique for making thick-walled components in the arc-based directed energy deposition process (DED-Arc). In the current study, four different arc weaving strategies, namely, triangle, square, semi-circle, and helix, are used to fabricate the walls. For this, gas tungsten arc welding (GTAW) based DED-Arc set-up using aluminium alloy wire (ER4043) as a filler material is used for different printing strategies. The fabricated walls were investigated for their surface characteristics, microstructure, mechanical properties and residual stress. The weld-bead and wall geometry study revealed that for the same number of layers, the semi-circular arc-weaving strategy had the maximum height among all, with an effective area of 65.77 %. The waviness of the side surface of the walls was maximum for the semi-circle (714 ± 35 µm), indicating the semi-circle will require almost twice the amount of machining than the helix, square, and triangle in postprocessing operation. The optical micrographs showed that the semi-circular weaving pattern exhibited a coarser gain with thicker grain boundaries with an average grain size of 46.4 ± 23.7 µm as compared to other weaving patterns. The triangle weaving pattern demonstrated the smallest grain size among all, resulting in high hardness and superior wear resistance. The residual stress (RS) results revealed that the RS is in tension (22–24 MPa) in the bottom layers for all the walls and becomes almost zero (−1.5 to −2.5 MPa) in the top layers except for the walls formed by helix strategy. The square weaving strategy strikes a balance between surface characteristics, microstructure, and mechanical properties, making it a highly viable option for thick wall fabrication.
... To comprehend more details on the axial stress distribution due to thermal load, the σ x and σ y values from four elements at the centre of the deposition volume were consider and used to calculate the maximum principal stress (σ max ) using the following expression (Eq. 15) [44][45][46] where, σ x and σ y are the x-stress and y-stress respectively, τ xy shear stress in orthogonal direction. The τ xy can be further expressed by the following expression (Eq. ...
This study explores the numerical analysis of effective stress and distortion (dimensional variations) in bulk deposited structures of Inconel 625 alloy with seven different deposition strategies using wire arc additive manufacturing (WAAM) process. Due to the challenges in detecting in-situ stress changes during bulk deposition, numerical analysis is employed to approximate stress distribution. The goal is to investigate stress and distortion (dimensional variations) in the build direction (BD), longitudinal and transverse directions, and understand their impact on anisotropy and asymmetry. The findings reveal distinct patterns in effective stress, with initial decrease in bottom, followed by a gradual increase at the middle and rapid increase thereafter, regardless of deposition strategies. Parallel and contour deposition strategies exhibit lower effective stress compared to spiral strategies. Distortion (dimensional variations) along the BD increases with height, and parallel strategies result in higher distortion. The parallel strategies show increasing distortion from one edge to the other, while spiral and contour strategies lead to high distortion at the center. The parallel and contour deposition strategies exhibit higher compressive stress at the bottom and middle compared to the spiral strategies. Anisotropy analysis indicates higher stress anisotropy in parallel and contour patterns, but lower distortion anisotropy compared to spiral patterns. Empirical equations are developed to understand the relationship between stress, distortion (dimensional variations) and hardness. The study suggests that higher effective stress can adversely affect material yielding behavior. This study undertakes a comparison between FEA and analytical model which reveals a close alignment in the residual stress distributions in the build direction.
... Additionally, the layer-by-layer deposition characteristic of WAAM introduces unique mechanical interactions that influence the final shape and structural integrity of the manufactured object. Understanding and managing residual stresses and deformations is crucial, as they can adversely affect the dimensional accuracy, mechanical properties, and overall performance of WAAM produced parts [7]. Uncontrolled stresses can lead to warping, distortion, and even cracking of the fabricated components [8]. ...
The present paper introduces a novel temporal acceleration strategy for computationally efficient prediction of residual stresses and deformations in wire arc additive manufacturing (WAAM) components. It employs a semi-analytical approach, dividing temperature into the analytical and the complementary fields. The analytical field is obtained by a closed-form solution, and the complementary field is employed to solve the boundary conditions. A temporal acceleration factor for the heating period is applied. Meanwhile, the diffusion time in the analytical field is manipulated to guarantee accurate temperature prediction. Validation via WAAM experiments, including both a thin-wall structure and a practical engineering component with characteristic dimensions on the order of metres, indicates that the predicted stresses is 50 MPa lower than the experimental values. Moreover, the discrepancy of between the predicted deformations and the experimental measurements is less than 10%, demonstrating reasonable accuracy can be achieved with attractive computational efficiency.
... However, this technology encounters several challenges [4], [5]. Various issues may arise during manufacturing, including porosity [6], [7], [8], residual stress [9], [10], microstructure concerns [11], and dimensional defects [12], [13]. Developing pertinent sensors for in-operando monitoring of these defects is the subject of many papers [14]. ...
Wire Arc Additive Manufacturing (WAAM) is a metal arc welding additive process that allows the production of large parts. Managing the quality of produced parts is a key challenge to the adoption of this technology in the industry. A particular case of this is the production of aluminum thin walls and the management of their thicknesses. Literature supports that the use of a near-infrared camera is a good way to monitor the meltpool shape to predict the manufactured thickness. Nevertheless, the post-processing applied to the image has a big influence on the accuracy of the measure. That is why, this article proposes a method to qualify image post-processing for thin wall thickness prediction from near-infrared camera images of aluminum WAAM process. A dataset from the literature is used to evaluate the accuracy of different post-processes. First, a method is proposed to evaluate the accuracy of a given post-process. Secondly, two types of post-processing are presented: post-processing based on conventional image processing and post-processing based on neural networks. Their accuracy is evaluated with the proposed method. The article concludes that the proposed method is adapted to qualify post-processes and that the proposed post-processing based on neural networks gives significant results in terms of accuracy.
... With its high deposition rate and buy-to-fly ratio close to one, WAAM is a good candidate for printing medium to large-scale metallic components [7]. However, repeated thermal cycles during the WAAM process induce residual stress and distortion in the printed part [8,9]. While most studies have been reported on the WAAM of titanium and steel alloys, aluminium alloys have become the centre of focus in recent years due to their high strength-to-weight ratio and better resistance to corrosion [10][11][12]. ...
Additive manufacturing (AM) has emerged as a crucial element of Industry 4.0. In the pursuit of fabricating lightweight components, AM of aluminium alloys has become the centre of focus in recent years. This study investigates aluminium alloy (ER4043) components fabricated by arc-based directed energy deposition (DED-arc) for their corrosion and stress corrosion cracking (SCC) behaviour in 0.6 M NaCl solution at room temperature. Electrochemical characteristics in 0.6 M NaCl solution were investigated using open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests. Electrochemical results revealed that the DED samples fabricated using a tungsten inert gas (TIG) welder as the energy source demonstrated better resistance against corrosion when compared to those developed through cold metal transfer (CMT) based DED. The prolonged exposure of samples in 0.6 M NaCl facilitated the growth of a stable passive oxide film leading to enhanced corrosion resistance. Slow strain rate tests (SSRT) conducted in air and 0.6 M NaCl solution showed that DED samples are susceptible to SCC. The fractography of the fractured SSRT samples indicated the mode of failure to be intergranular.
... Sun et al. [25] analyzed the residual stress distribution characteristics of aluminum alloy wire arc additive manufacturing (WAAM) components through numerical simulation. Zhao et al. [26] established a coupled finite element model for the thermal structure of selective laser melting (SLM) of 7075 aluminum alloy. ...
... The scanning path was in a reciprocating scanning mode along the X-axis. The software used for numerical simulation is ABAQUS, and the birth and death technique was used to simulate the forming process of the deposition layers [25,30]. Birth and death mean the activation and deactivation of the elements. ...
Electron beam additive manufacturing (EBAM) has broad application prospects in the preparation of large structural components such as those in aerospace structures. It is of great significance to have a deep understanding of the residual stress distribution and deformation of EBAM. A three-dimensional transient thermal–mechanical coupling model was established for the comprehensive investigation of the deformation and residual stress of aluminum alloy components prepared by wire-feed EBAM for the first time. The reliability of the simulation model was verified by comparing the predicted temperature, stress and deformation with experimentally measured values. The influence of heat input on residual stress distribution and deformation was studied using the verified model. The simulation results indicate that reducing heat input is an efficient approach to reducing deformation and residual stress. The developed model can be a powerful tool to optimize process parameters to reduce the residual stress and deformation of EBAM aluminum alloy components.
... While fusion-based AM processes often result in high residual stresses in as-manufactured condition (Sun et al. 2021;Kaess et al. 2023), residual stresses are relatively low and generally compressive for AFSD deposit as demonstrated in Fig. 2c. Furthermore, highest residual stresses, which were tensile, existed in the substrate near fusion zone. ...
Additive friction stir deposition (AFSD) is an emerging solid-state additive manufacturing technique where material is deposited layer-by-layer. Unlike fusion-based additive manufacturing processes, AFSD relies on a rotating tool to extrude and bond feedstock material through frictional heat, keeping the material below its melting point to eliminate fusion-related defects. It is suitable for large structure fabrication due to its high deposition rate. However, AFSD is still in development, with questions concerning hardness variation along the build height, defect formation, and residual stress distribution. In this research, an AFSD-manufactured structure is examined using optical microscopy, Vickers hardness testing, and neutron diffraction. Optical microscopy reveals defects at first layer and substrate interface as well as deposit edges, while hardness testing indicates deposit hardness decreases from final layer to first layer. Neutron diffraction shows tensile residual stress near the fusion zone in the substrate with compressive residual stress in majority of deposit.
... This work is an exploratory study for space exploration plans in the future. Wire-Arc Additive Manufacturing (WAAM) is an advanced fabrication technique that uses an electrical arc to melt a metal wire for layer-by-layer deposition [1][2][3][4][5], as shown in Fig 2. WAAM can be used to create near Solid Freeform Fabrication 2023: Proceedings of the 34th Annual International Solid Freeform Fabrication Symposium -An Additive Manufacturing Conference Reviewed Paper net shape part geometries, making it highly desirable for material savings relative to subtractive processes like machining [6][7][8]. WAAM can also be used for repairing existing components as an alternative to traditional processes such as MIG and TIG welding [6,[9][10][11]. ...
Countries all over the world are rushing into space exploration due to crisis of energy and resources exhaustion on the Earth. Mars is an obvious target because it has a thin atmosphere, good geological similarity, and is close by in the Solar system. As the satellite of the Earth, Moon is another target since it is very close to the Earth. For the large spacecrafts such as Mars rovers, periodic maintenance is necessary to ensure the completion of long-duration exploration missions. In-space wire arc additive manufacturing (WAAM) provides a potential solution towards sustainable maintenance with onsite repair or additive manufacturing. For in-space manufacturing, reduced gravity is an important factor. In this work, WAAM processes under reduced gravity conditions on the Mars and Moon were studied through a multi-physics modeling approach. The metal droplet transfer, deposition geometry, thermal dissipation, and other key physics in WAAM were simulated. To validate the modeling approach, an experimental case was conducted on an in-house WAAM platform under the Earth condition.
... Therefore, in order to enable the unmanned vehicle chassis to adapt to the diverse and unknown loads encountered on actual roads, subdivision 1163 -Heat source parameters a f = a r , b, c(µm) 3,4,5 -Ambient and initial temperature T a , T 0 (K) 25,80 -Heat transfer coefficient h (W/(m 2 . K)) 0.02 -Density r w (T) = 2830 − 0.513 · T + 2 × 10 −4 · T 2 [28] Thermal conductivity (W/m·K) k w (T) = 130.5 + 0.0161 · T − 6 × 10 −6 · T 2 [28] Specific heat (J/kg·K) C w (T) = 960 +0.53 · T − 6 × 10 −6 · T 2 +6.2 × 10 −7 · T 3 [28] Young [31] algorithms are employed on the chassis structure. This ensures that the chassis structure has maximum loadbearing capacity in both two-dimensional and threedimensional spatial directions, as illustrated in Figure 2. ...
In the automotive industry, the extended design and iteration cycles for integrated chassis typically span 2–3 years, creating a misalignment with swiftly changing market demands. Wire arc additive manufacturing (WAAM) technology presents a viable alternative, overcoming the limitations of conventional chassis production. Our holistic framework significantly condenses the design, optimisation, and validation stages for automotive chassis. Initially, a ground structure method is utilised to outline and generate a skeleton chassis. We then utilise the OpenCV image processing method to select a hollow skeleton chassis with minimal material occupancy (0.476) and suspension printing. Subsequently, we assess the influence of printing radian variations by the robotic arm on the microstructure and stress, employing a cellular automaton-finite element (CA-FE) model at the 150th and 200th layer benchmarks. A Kalman filter (KF) is also implemented to fine-tune the printing radian in regions with coarse grain structures and elevated solute concentrations. The process concludes with collision and modal simulation verifications of the skeleton chassis, affirming the optimisation's success. This streamlined methodology allows the completion of the chassis design and manufacturing cycle within a remarkably condensed time frame of one week, accelerating the development process by a factor of 120.
... The finite element (FE) coupled thermo-mechanical analysis can reflect the transient thermodynamic information during the WAAM process in real time [8], which can provide internal details on distortion and residual stresses in the WAAMed part without considering the actual manufacturing process [9][10][11]. In particular, the dynamic thermal behavior, the evolution of stress, and distortion are analyzed to adjust the process parameters or select an optimal deposition strategy to formulate residual stress and deformation control strategies [12][13][14][15]. ...
... Eq. (14) illustrates that the average geometric deviation increases with the increase of the deposition beads. The maximum geometric deviation can be expressed by Eq. (15). ...
Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residual stress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layer multi-bead profile geometric modeling method through the isosceles trapezoid function is proposed to build the FE model of the WAAM process. Firstly, a straight-line model for overlapping beads based on the parabola function was established to calculate the optimal center distance. Then, the isosceles trapezoid-based profile was employed to replace the parabola profiles of the parabola-based overlapping model to establish an innovative isosceles trapezoid-based multi-bead overlapping geometric model. The rationality of the isosceles trapezoid-based overlapping model was confirmed by comparing the geometric deviation and the heat dissipation performance index of the two overlapping models. In addition, the FE-coupled thermal-mechanical analysis, as well as a comparative experiment of the single-layer eight-bead deposition process show that the simulation results of the above two models agree with the experimental results. At the same time, the proposed isosceles trapezoid-based overlapping models are all straight-line profiles, which can be divided into high-quality FE elements. It can improve the modeling efficiency and shorten the simulation calculation time. The innovative modeling method proposed in this study can provide an efficient and high-precision geometric modeling method for WAAM part FE coupled thermal-mechanical analysis.
