Thermo-mechanical Finite Element Analysis Research Articles

Coupled thermomechanical finite element analysis of ultrasonic hot embossing process

Ultrasonic Hot Embossing of polymers is one of the most attractive manufacturing methods of high-quality and complex microparts needed for biological and chemical processes. A little simulation work has been done to study the deformation mechanism and the required load in the Ultrasonic Hot Embossing of polymethyl methacrylate (PMMA). This paper developed a 2D coupled thermo-mechanical finite element model to simulate the forming behavior of the ultrasonic embossing process of PMMA, optimize the mold microfeature corner, and predict the embossing load as well. VDISP ABAQUS subroutine has been used to describe the downward motion of the mold assisted with ultrasonic vibration. The Arbitrary Eulerian-Lagrangian re-meshing technique has been implemented to refine the deformation zone during simulation to avoid divergence due to localized excessive deformation. Embossing load, temperature, stresses, strains, and energy dissipation have been recorded and analyzed. Simulation results revealed that the coupled thermo-mechanical FE Model efficiently captures the deformation behavior and Embossing load. It also proved that a Mold microfeature corner of 20 μm filet radius is recommended to adequately fill out the area around the mold and maintain uniform temperature and strain distributions.

Additive Manufacturing of Composite Polymers: Thermomechanical FEA and Experimental Study.

This study presents a comprehensive approach for simulating the additive manufacturing process of semi-crystalline composite polymers using Fused Deposition Modeling (FDM). By combining thermomechanical Finite Element Analysis (FEA) with experimental validation, our main objective is to comprehend and model the complex behaviors of 50 wt.% carbon fiber-reinforced Polyphenylene Sulfide (CF PPS) during FDM printing. The simulations of the FDM process encompass various theoretical aspects, including heat transfer, orthotropic thermal properties, thermal dissipation mechanisms, polymer crystallization, anisotropic viscoelasticity, and material shrinkage. We utilize Abaqus user subroutines such as UMATHT for thermal orthotropic constitutive behavior, UEPACTIVATIONVOL for progressive activation of elements, and ORIENT for material orientation. Mechanical behavior is characterized using a Maxwell model for viscoelastic materials, incorporating a dual non-isothermal crystallization kinetics model within the UMAT subroutine. Our approach is validated by comparing nodal temperature distributions obtained from both the Abaqus built-in AM Modeler and our user subroutines, showing close agreement and demonstrating the effectiveness of our simulation methods. Experimental verification further confirms the accuracy of our simulation techniques. The mechanical analysis investigates residual stresses and distortions, with particular emphasis on the critical transverse in-plane stress component. This study offers valuable insights into accurately simulating thermomechanical behaviors in additive manufacturing of composite polymers.

A finite element thermomechanical analysis of the development of wheel polygonal wear

Polygonal wear is a type of damage commonly observed on the railway wheel tread. It induces wheel-rail impacts and consequent train/track components failure. This study presents a finite element (FE) thermomechanical wheel-rail contact model, which is able to cope with the three possible generation and development mechanisms of polygonal wear: initial defects, thermal effect, and structural dynamics. The polygonal wear-induced impact contact and further development of wear are simulated. The simulated elastic contact solutions are verified against the program CONTACT. Different material properties (elastic, elasto-plastic and elasto-plastic-thermo, i.e. with thermal softening) and initial polygonal profiles are then applied to the FE model to investigate the influence of wheel/rail material and wear amplitude on wheel-rail contact stress and wear development. The simulations indicate that the wheel-rail impact-induced temperature may reach up to 362 ℃ at the contact interface, and the high temperature at the contact area influences wheel-rail contact stress and wear depth.

Improved Finite Element Thermomechanical Analysis of Laminated Composite and Sandwich Plates Using the New Enhanced First-Order Shear Deformation Theory

This paper proposes a simple yet accurate finite element (FE) formulation for the thermomechanical analysis of laminated composites and sandwich plates. To this end, an enhanced first-order shear deformation theory including the transverse normal effect based on the mixed variational theorem (EFSDTM_TN) was employed in the FE implementation. The primary objective of the FE formulation was to systematically interconnect the displacement and transverse stress fields using the mixed variational theorem (MVT). In the MVT, the transverse stress field is derived from the efficient higher-order plate theory including the transverse normal effect (EHOPT_TN), to enhance the solution accuracy, whereas the displacement field is defined by the first-order shear deformation theory including the transverse normal effect (FSDT_TN), to amplify the numerical efficiency. Furthermore, the transverse displacement field is modified by incorporating the components of the external temperature loading, enabling the consideration of the transverse normal strain effect without introducing additional unknown variables. Based on the predefined relationships, the proposed FE formulation can extract the C0-based computational benefits of FSDT_TN, while improving the solution accuracy for thermomechanical analysis. The numerical performance of the proposed FE formulation was demonstrated by comparing the obtained solutions with those available in the literature, including 3-D exact solutions.

Residual stress computation in direct metal deposition using integrated artificial neural networks and finite element analysis

Direct Metal Deposition (DMD) as a part of additive manufacturing processes, utilizes a laser heat source to deposit metallic material to construct components layer by layer, allowing for controlled manufacturing. DMD processes inherently induce residual stresses and distortions in the build part. While finite element (FE) analysis is one of the approaches to predict the residual stress, the high computational time required for the FE analysis makes it undesirable for the early stages of product development. This study extends a previously developed approach to more complex structures to evaluate the accuracy and computational efficiency of predicting residual stresses. For the present study, six different metallic structures with various complex shapes made from AISI 304 L were considered. Comparing the residual stress fields predicted by the integrated ANN-FE with thermomechanical FE analysis, the results demonstrated consistent distributions for all stress components across structures. Although localized regions exhibited higher errors, these areas coincided with low-stress zones, posing no critical concerns. Despite higher errors in some areas, most structures displayed prediction errors below 15%. Moreover, the analysis achieved a substantial computational efficiency enhancement of approximately 6 times for all structures analyzed.

In-service welding of X70 steel gas pipeline: Numerical and experimental investigations

The in-service welding process is widely used to repair defective gas pipelines, which allows the damaged section to be repaired without interrupting gas flow. In this way, consumers and gas transportation companies will be able to minimize losses. In this study, a thermomechanical finite element analysis model was developed to examine the effects of pipe pressure, thickness, diameters, and welding heat input on temperature history and residual stress. The results were analyzed using the design of the experiment method (DOE). According to the results, these parameters significantly affect the thermal distribution and pipe yield stress at the welding point by 48.8%, 29.4%, 15.1 and 6.9%, respectively. On the basis of optimal conditions, in-service welding is conducted. Investigations were conducted on the microstructure, temperature distribution, and residual stresses induced during the in-service welding of API 5L X70 steel pipelines. As a result, it was determined that the HAZ microstructure consists primarily of ferrite, bainite, and M/A constituents, whereas the pipe microstructure undergoes fewer phase transformations. In order to validate the numerical model, mechanical tests, as well as hole drilling, were conducted to gather data, and a combination of equivalent carbon and T8/5 was used to determine hardness at various locations in the HAZ in order to determine which areas are susceptible to cold cracking. The numerical results and the experimental results were highly concordant.

Efficient ultrafast photoacoustic transduction on Tantalum thin films

Nano-acoustic strain generation in thin metallic films via ultrafast laser excitation is widely used in material science, imaging and medical applications. Recently, it was shown that transition metals, such as titanium, exhibit enhanced photoacoustic transduction properties compared to noble metals, such as silver. This work presents experimental results and simulations that demonstrate that among transition metals tantalum exhibits superior photoacoustic properties. Experiments of nano-acoustic strain generation by femtosecond laser pulses focused on thin tantalum films deposited on Silicon substrates are presented. The nano-acoustic strains are measured via pump-probe transient reflectivity that captures the Brillouin oscillations produced by photon–phonon interactions. The observed Brillouin oscillations are correlated to the photoacoustic transduction efficiency of the tantalum thin film and compared to the performance of titanium thin films, clearly demonstrating the superior photoacoustic transduction efficiency of tantalum. The findings are supported by computational results on the laser-induced strains and their propagation in these thin metal film/substrate systems using a two-temperature model in combination with thermo-mechanical finite element analysis. Finally, the role of the metal transducer-substrate acoustic impedance matching is discussed and the possibility to generate appropriately modulated acoustic pulse trains inside the crystalline substrate structures for the development of crystalline undulators used for γ-ray generation is presented.

Investigating the influence of geometric parameters on the deformation of laser powder bed fused stents using low-fidelity thermo-mechanical analysis

Maintaining dimensional accuracy is a major challenge of laser powder bed fusion (L-PBF) preventing its application for more complex and filigree L-PBF structures in industrial practice. Previous studies have shown that residual stresses and distortion of benchmark L-PBF components may be predicted by sequential thermo-mechanical analyses. However, the reliability of these analyses for more complex structures must be critically questioned, as comprehensive validation and sensitivity analyses are scarce. In this paper, we present a calibrated and validated low-fidelity sequential thermo-mechanical finite element analysis (FEA) of a tubular L-PBF lattice structure, i.e., an aortic stent, where pronounced local deformation is expected. As a first step, the finite element model was extensively calibrated using experimental data to ensure reproducibility of the simulation results. Thereupon, geometric features critical to the distortion of L-PBF lattice structures and measures to compensate for the distortion, such as inversion of the distorted L-PBF structure, were investigated. It was found that the distortion of the L-PBF lattice structures can be reduced, but not completely prevented, by increasing the strut angles, increasing the strut thickness, and decreasing the transition radius in the area of merging struts. FEA-based inversion of the numerically predicted deformed structure minimized distortion, resulting in the L-PBF aortic stent approximating the intended CAD geometry even with a small strut thickness. This work shows that low-fidelity sequential thermo-mechanical FEA can be used not only for the analysis and deformation compensation of reference structures, but also for the analysis of more complex filigree structures with pronounced local deformation.

Viscoplastic model-based analysis of in-service oscillation temperature and thermal stress in a rotating component

The thermal gradient in the rotor is a key influential factor in thermal stress. Steam temperature fluctuations cause temperature oscillations in the rotor, leading to variation in the thermal gradient and finally changing the rotor's thermal stress behavior. This study aimed to identify the influence of steam temperature fluctuations on the rotor's oscillation temperature and thermal stress behavior. Thus, the extent to which the rotor temperature is influenced by steam temperature fluctuations and the associated temperature change behavior in the rotor could be predicted in detail. The convective heat transfer between the steam and the rotor is characterized by the third boundary condition, and the thermal stress is described with a viscoplastic constitutive model with damage. Realistic in-service operating data during startup and steady-state operation phases were chosen to investigate the oscillation temperature and thermal stress induced by steam temperature fluctuation in a steam turbine rotor. With the benefits to the rotor design and power plant operation, the temperature fluctuating amplitude range was categorized into four groups by transient thermomechanical finite-element analysis, and the temperature differences in the rotor between sets of two adjacent locations are listed to demonstrate the heat congestion.

Thermomechanical and Material Flow Analysis during Friction Stir Welding of Marine Grade Aluminum Alloy 5083

_ This research aims to depict the thermal history, residual stress distribution, axial force applied, and material flow behavior on aluminum alloy 5083 (AA5083) plates, during the friction stir welding (FSW) process. This alloy finds most its use in shipbuilding industries and for marine constructions. It has been developed using an explicit, fully coupled thermomechanical nonlinear finite element (FE) analysis approach. The analysis was performed to simulate the effect of three stages, namely plunging, dwelling, and welding, of the FSW process. The ABAQUS/Explicit program was used for the computational modeling. To build a reliable and computationally efficient FE model, features such as arbitrary Lagrangian-Eulerian (ALE) formulation, adaptive meshing/ remeshing approach, mesh sensitivity analysis, and mass scaling have been introduced. The interaction between the tool bottom surface and the plate top surface was defined using a finite sliding and a sticking property. A Coulomb friction model with a temperature-dependent coefficient of friction (COF) was used to describe the tool-workpiece interaction. In addition, a small experiment was done with the following process parameters; a rotating tool speed of 875 rpm, a traverse speed of 60 mm/min, and a tool tilt angle of 0° to produce a defect-free butt joint to validate the numerically generated thermal profiles. The temperature was found slightly higher on the advancing side (AS). Residual stress distribution created over the whole width of the plates was also investigated. Introduction The introduction of friction stir welding (FSW) process by The Welding Institute in 1991 (Thomas 1991) drew much attention. During fusion welding of 5 mm AA5083 plates, the heat input should be very high. Because of this high input, a higher thermal gradient is produced, which leads to the formation of several intermetallic compounds (IMCs). Because of this IMC formation, the strength of the welded joint is reduced. However, the steep thermal gradient produced leads to the formation of finer microstructure near the weld bead and coarser along the base metal region. These results in the heterogeneity of the weld bead microstructure leading to less efficiency and accuracy of the weldment.

Comparative numerical study of rate-dependent continuum-based plasticity models for high-velocity impacts of copper particles against a substrate

The problem of high-rate elastic-plastic deformation of micro-sized copper particles impacting against a copper substrate was investigated by applying the continuum-based formulation and finite element thermomechanical analysis. Comparative study of selected plasticity models was performed. The aim of the paper was to study strain rate-dependant plasticity for a wide range of strain rates. The strain-rate-dependant Johnson-Cook and Cowper-Symonds models were studied by comparing displacements, velocities, strains, strain rates, stresses, contact forces, and temperatures and their contribution to material yield stress. The study shows the importance of the high-strain rate yielding model and its adequacy for experimental data. Both models complement each other and may be regarded as soft and hard bounds of the solution. A new, combined, two-function model, containing two independent functions for each of the two ranges, is suggested. The proposed model describes a low strain rate sensitivity range using the Johnson-Cook expression, while allows fitting of the model for experimental results in a high strain rate sensitivity range, using a modified Cowper-Symonds expression. This combination is capable of describing both low and high strain rate regimes, giving the minimum deviation from experimental results.

Novel Tube Design for Superheater Heat Exchanger Enabled Via Additive Manufacturing

Abstract Superheater tubes are critical boiler components that operate at relatively higher temperatures and pressure. Amongst the primary concerns for these tubes is the deposition of ash particles on the tube surface, leading to the reduced thickness of the tube due to material corrosion, consequently causing early creep failure of the component. In this research, a novel tube design has been proposed which resembles a teardrop or ogive shape to reduce the drag and concurrently improve the creep life of the superheater tubes. To administer the practicality of novel tubes, metal additive manufacturing (AM), for instance, laser-powder bed fusion (L-PBF), has been proposed. These unconventional designs were assessed and compared with the baseline circular tube design for mechanical design requirements (hoop stress and creep life) and the particle and flue gas flow characteristics around the differently shaped tubes. A thermomechanical finite element (FE) analysis was performed for hoop stress calculations. This study also emphasizes on effect of circumferential thermal variation on hoop stress distribution in tubes. Therefore, a detailed two-dimensional (2D) thermal simulation has been performed to report the circumferential thermal variation on the tube. A computational fluid dynamics (CFD) analysis coupled with particle tracing was performed for gas flow visualization and particle tracing around the proposed shapes and baseline circular-shaped tube design. The Schlieren optic setup was built and leveraged for qualitative validation of the proposed design. The complete design methodology established in the paper shows teardrop-shaped tubes better in terms of drag and creep life in contrast to the circular-shaped tube.

A semi-passive beam dilution system for the FCC-ee collider

The operation modes for the proposed FCC-ee collider foresee a very small beam spot size and stored beam energies of up to 20.6 MJ in Z production. This necessitates a dedicated beam dumping system. To reduce the complexity of the system as well as to minimize the required space, an optimized, semi-passive system has been designed and is presented here. The beam dilution is done with a defocusing triplet structure, followed by passive beam diluter elements (spoilers). This greatly reduces the risk of possible dilution failure scenarios compared to an active dilution kicker-magnet system. The dump core itself is located {sim}70~text{m} downstream of the spoilers and is designed following the experience gained from the LHC dump.The dilution performance as well as the interaction effects responsible for the energy deposited in the spoiler, are directly related to the radiation length and the dimension of the device in beam direction. Materials for these spoilers have been studied extensively and key requirements have been identified using both Monte Carlo shower simulations and thermo-mechanical Finite Element Analysis. Even though the maximum temperature reached in the spoilers is well within the working temperature range of the material, the induced mechanical stresses can lead to material failure. Thermo-mechanical simulations have shown that the transversal beam shape plays a key role in the magnitude of mechanical stresses as a result of the beam impact and the abrupt temperature change. This problem is addressed in this paper and an optimized solution is presented.

Thermo-mechanical finite element analysis of a fused cast AZS block applied to a glass melting furnace during the heating step

There is a great motivation to understand the best-operating practices for glass melting furnaces to improve their quality, increase the process energy efficiency and extend the working life of the refractory. Electrofused AZS (Alumina-Zirconia-Silica) refractories are used for furnace linings due to their good corrosion resistance and mechanical properties at high temperatures. Operating conditions can influence their performance, limiting the service life of the furnace. Computer simulations have proven to be useful for analyses wherein testing is difficult and involves certain risks for experiments and validations. Therefore, this work investigates the thermal and mechanical behavior of AZS blocks with a metal electrode support, which present cracks along the furnace heating-up. The simulations were carried out using the finite element method (FEM) to determine the AZS block temperature and maximum principal stress fields during furnace heating. Considering the refractory properties with the temperature, the results showed that the maximum principal stress reaches the modulus of rupture of AZS, after 42 h when the block hot face temperature is 145 °C. Analyses of the effects of a cooling system, heating curve and alternative hole designs to support the electrodes are also shown. In the case of cooling, there are no positive effects from the refractory behavior point of view, reaching the maximum allowable stress value after 40 h for the best scenario. Regarding the heating curves, the thermal and mechanical profiles and the location at it reaches the maximum principal stress were equivalent to that of the reference. Finally, changing the hole geometry showed that the crack initiation time was slightly longer than the reference, 43 and 44 h for the conical and single diameter holes, respectively. The critical region was observed closer to the hot face for the conical case, which can be interesting for further analysis to consider some post-cracking effects.

Adhesion strength of paraffin droplet impacted and solidified on metal substrate

Debonding of solidified splats is a crucial issue for thermal sprayed coatings, which greatly influences the performance and lifetime of industrial components. The purpose of this study is to provide an in-depth understanding of the effects of impact parameters as well as residual stress on the debonding behaviors, and the related adhesion strength and driving forces of single splats. In this study, debonding behaviors of molten paraffin droplets which were impacted and solidified on stainless steel substrates, were observed considering the effects of substrate pre-set temperature, drop height (impact velocity), and droplet temperature. It was found that the debonding is prone to take place at lower substrate pre-set temperatures, lower drop heights, and lower droplet temperatures. A scraping method was then employed to measure the adhesion strength of splats formed under various conditions. The results showed good accordance with debonding behaviors in the drop impact test. The scraping tests also indicated that the residual tensile stress in splats reduces the scraping forces and prevents the complete removal of splats during the scraping processes. Peeling stress and shear stress along the splat-substrate interface, which are driving forces for debonding, were calculated using coupled thermomechanical finite element analyses. The calculated driving forces were larger for lower drop heights and lower droplet temperatures under which the debonding was more easily to occur. The results of numerical simulations coupled with scraping tests provide reasonable explanations for observed debonding behaviors of single splats. This study provides a comprehensive understanding of the effects of several droplet impact variables and residual stress on the debonding behaviors, and the related adhesion strength as well as driving forces of single splats.

Improved tensile membrane action model of composite slabs at elevated temperatures

Previous fire testes have showed that tensile membrane action (TMA) between composite slabs and reinforced concrete slabs is different. An improved TMA model is proposed in this paper to accurately and reasonably determine the fire resistance of composite slabs exposed to ISO834 fire. It is assumed that the fracture of steel reinforcement in the long span is the governing failure mode of composite slabs at elevated temperatures. The slab is divided into four concrete rigid plates and one elliptic reinforcement net at centre considering TMA, and the contribution of rotation of concrete rigid plates on the deflection in short-span is taken into account. Meanwhile, coupling thermo-mechanical finite element analyses are carried out to simulate the TMA response of composite slabs at elevated temperatures. The accuracy of the proposed improved model is validated against experimental and numerical results, with a maximum error within 10%. It is found that the improved model has a better prediction of the mid-span deflection and fire resistance than Li’s model and Bailey’s model. It is important to consider the stress redistribution of the reinforcement in two directions in determining TMA in composite slabs under fire conditions.

Numerical and Experimental Investigation on the Surface Defect Generation during the Hot Extrusion of Al6063 Alloy.

The surface quality control of extruded products is a critical concern in the home appliance manufacturing industry owing to the increasing need for products with a high surface quality, in addition to the essential mechanical properties of the final product. The underlying issue with achieving high-quality extrusion products is that surface defects, especially those resulting in surface gloss differences, called white line defects, are only observed after surface treatment. In this study, we aim to investigate the cause of white line defect generation on the surface of an extruded product. Accordingly, an experimental extrusion program is established using an L-shaped die that has a noticeable change in its bearing length along the inner corner of its cross-sectional profile. Laboratory-scale experiments were performed for the L-shaped extrusion of homogenized Al 6063 alloy at various ram speeds, in order to induce surface defects, considering the production yield rate required for mass production. Subsequently, the microstructural changes near the surface failure region were investigated using an arbitrary Lagrangian–Eulerian (ALE) technique-based thermomechanical finite element (FE) analysis. To scale-up the defect observation method from laboratory-scale to production-scale manufacturing and confirm the reproducibility of the surface defect, scaled-up L-shaped extrusions were performed in an actual industrial production line. Finally, the potential cause of white line defect generation is discussed by comparing the numerical and metallurgical analyses, including the scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations.

Thermo-mechanical modeling of stacked die flash memory package EMI shielding layer crack under thermal cycling test

EMI (Electromagnetic Interference) shielding is widely used in electronic modules to reduce the coupling of radio waves, electromagnetic fields, and electrostatic fields to enhance electric performance (Liu et al., 2016). Some flash memory products are also equipped with EMI shielding for the desired electric requirements. In this paper, TCT (Thermal Cycling Test) reliability of metallic thin film EMI (Electromagnetic Interference) shielding layer, which is deposited on stacked die flash memory package top and sidewalls is studied. A crack in the EMI layer is observed under TCT (Thermal Cycling Test) experiment. Three-dimensional thermo-mechanical FEA (Finite Element Analysis) modeling is used to determine the root cause of EMI shielding layer crack, that is, the two stacks of stacked NAND dies causes stress concentration and plastic strain accumulation at the EMI centerline region where the local metallic EMI structure gets fatigued and finally cracks. In addition, simulation results explain the difference in EMI layer fatigue behaviors between two stacks and one stack NAND package, which is verified by experimental warpage test data and crack occurrence. Lastly, methods to improve EMI layer fatigue life under TCT for two NAND stacks package are suggested.

Experimental verification of computational and sensitivity analysis on substrate deformation and plastic strain induced by hollow thin-walled WAAM structure

PurposeThis paper aims to numerical and experimental analysis on substrate deformation and plastic strain induced by wire arc additive manufacturing.Design/methodology/approachThe component has the form of a hollow, rectangular thin wall consisting of 25 deposition layers of SS316L on an SS304 substrate plate. Thermo-mechanical finite element analysis was applied with Goldak’s double-ellipsoidal heat-source model and a non-linear isotropic hardening rule based on von Mises’ yield criterion. The layer deposition was modelled using simplified geometry to minimize overall pre-processing work and computational time.FindingsA new material modelling of SS316L was obtained from the chemical composition of the evolved component characterized by scanning electron microscope/energy dispersive X-ray and further generated by an advanced material-modelling software JMatPro. In defining heat-transfer coefficients, transient thermometric analysis was first performed in the bead and on the substrate, which was followed by an adjustment of the heat-transfer coefficients to reflect the actual temperature distribution. Based on the adjusted model and boundary conditions, sensitivity analysis was conducted prior to the ultimate simulation of substrate deformation and equivalent plastic strain. Furthermore, this simulation was verified by conducting a series of automated wire + arc additive manufacturing tests using robotic gas Metal arc welding with distortion measured by coordinate-measurement machine and equivalent plastic strain measured by optical three-dimensional-metrology measurements (Gesellschaft für Optische Messtechnik).Originality/valueIt can be concluded that a proper numerical computation using the adjusted model and property-evolved material exhibits a similar trend with acceptable agreement compared to the experiment by yielding an error percentage up to 30% for deformation and up to 21% for equivalent plastic strain at each individual measurement point.

Finite element simulation of residual stresses in welded steel butt joints and their experimental verification and mitigation

The localized, intense, and moving heat source existing in welded fabrication results in residual stresses and distortion. Residual stresses remain inside the material even after the external forces or thermal gradients are removed after welding. Residual stresses decrease fatigue life of the welded joint leading to premature failures and associated distortion cause problems in fitment during assembly. Estimation of residual stresses before actual fabrication is essential for elimination or mitigation after fabrication. In this work, finite element thermomechanical analyses are carried out to estimate the levels of residual stresses of thin welded similar butt joints of 1018 steel and SS 304 steel. The numerically obtained results of the joints are compared with experimental results of identical joint geometry, welding conditions, and material properties existing in the literature. The comparison of numerically obtained thermal histories with those from experiments yielded good agreements. Longitudinal residual stresses are found to be dominant and comparison of these longitudinal stresses with experimental data also found to be in good agreements. Further, the levels of residual stresses are computed with three different preheat temperatures (600°C, 700°C and 800°C) to study the effect of preheating temperature in the mitigation of residual stresses. It has been found that the peak value of longitudinal stress decreased considerably with preheat temperature. Increasing preheat temperature has a marginal reduction in the peak value of longitudinal stress.