Simulation Of Residual Stresses Research Articles

Sapphire optical fiber with (BN/SiBCN)n coating prepared by chemical vapor deposition for high-temperature sensing applications

To enhance the load-bearing capacity of sapphire optical fiber (SOF) in extreme environments, this study prepared SOF/(BN/SiBCN)n by optimizing the nanostructure through increased deposition temperature of BN using alternating chemical vapor deposition. Simulation results indicated an inverse correlation between the leakage loss of SOF/BN/SiBCN and BN thickness; at room temperature, the tendency for coating cracking along the radial direction of SOF/BN/SiBCN is positively correlated with BN thickness, whereas this trend reverses at 1500 °C. Mechanical testing revealed that the tensile strength of SOF/BN/SiBCN is inversely correlated with the tendency for interlayer cracking, aligning with the findings from residual stress simulations; under an air environment at 1500 °C, SOF/(BN/SiBCN)2 exhibited the highest tensile strength, indicating that the layered matrix design effectively mitigates the risk of BN oxidation by creating barrier layers. Optical test demonstrated that the BN coating functions as a total reflection layer to suppress the scattering of optical signals on the sapphire optical fiber surface. In conclusion, the coating design of SOF/(BN/SiBCN)n could meet the material requirements for sapphire optical fiber sensors in extreme environments.

AscentAM: A Software Tool for the Thermo-Mechanical Process Simulation of Form Deviations and Residual Stresses in Powder Bed Fusion of Metals Using a Laser Beam

Due to the tool-less fabrication of parts and the high degree of geometric design freedom, additive manufacturing is experiencing increasing relevance for various industrial applications. In particular, the powder bed fusion of metals using a laser beam (PBF-LB/M) process allows for the metal-based manufacturing of complex parts with high mechanical properties. However, residual stresses form during PBF-LB/M due to high thermal gradients and a non-uniform cooling. These lead to a distortion of the parts, which reduces the dimensional accuracy and increases the amount of post-processing necessary to meet the defined requirements. To predict the resulting residual stress state and distortion prior to the actual PBF-LB/M process, this paper presents the finite-element-based simulation tool AscentAM with its core module and several sub-modules. The tool is based on open-source programs and utilizes a sequentially coupled thermo-mechanical simulation, in which the significant influences of the manufacturing process are considered by their physical relations. The simulation entirely emulates the PBF-LB/M process chain including the heat treatment. In addition, algorithms for the part pre-deformation and the export of a machine-specific file format were implemented. The simulation results were verified, and an experimental validation was performed for two benchmark geometries with regard to their distortion. The application of the optimization sub-module significantly minimized the form deviation from the nominal geometry. A high level of accuracy was observed for the prediction of the distortion at different manufacturing states. The process simulation provides an important contribution to the first-time-right manufacturing of parts fabricated by the PBF-LB/M process.

Numerical Simulation and Analysis of Residual Stress in B91 Steel Deposition Using Wire Arc Additive Manufacturing

Numerical Simulation and Analysis of Residual Stress in B91 Steel Deposition Using Wire Arc Additive Manufacturing

Numerical Simulation of Residual Stresses and Structural Vibration of Welding Repaired Blades

Abstract Taking a typical aero-engine high-pressure compressor blade as the research object, the Gauss heat source was used to numerically simulate the repair process of blade surfacing welding. The temperature data and stress data of the blade were obtained when the heat source velocity was 1 mm/s, 2 mm/s, and 4 mm/s, respectively. The results showed that both the temperature and stress values decreased with the heat source velocity increasing. Then, the residual stress of the repaired blade is introduced into the modal analysis module as prestress, and the Campbell diagram is drawn to analyze the natural frequency and speed margin of the blade respectively. The results show that as the heat source speed increases, the frequencies of each order of the blade decrease. The speed margin of each resonance point is greater than 10%, and the modal dynamic stress corresponding to the resonance speed can be used as the primary criterion for blade failure.

Thermomechanical Analysis and Numerical Simulations of Fused Filament Fabricated Polylactic Acid Parts

This work aimed to investigate the thermal deformation of polylactic acid (PLA) samples 3D-printed by Fused Filament Fabrication. The irreversible thermal strain (ITS) and coefficient of linear thermal expansion (CLTE) of four sets of samples with various sizes and thicknesses of the layer in the three directions of the measurements were investigated. The thermomechanical analysis (TMA) was used for the investigation of thermal deformation. During the study, the dependencies of deformation on temperature were obtained. The samples' CLTE values at various ranges of temperatures were estimated using the obtained dependencies. ITS was observed after heating to 80 ℃ during the first TMA cycle. The values reached 8 – 9 %. The impact of layer thickness and the number of layers in the sample on ITS was noticed. Shrinkage in the X direction and expansion in the Z direction with almost the same values were observed. Finite element code ANSYS was used to simulate the distribution of temperature and accumulation of residual thermal stresses in the printed part. The correlation was obtained between the level of simulated residual thermal stresses for samples with different number of layers and layer thicknesses and measured ITS after annealing.

Evolution of 2-inch AlN single crystal grown on SiC seed via PVT method

The crystallization of aluminum nitride (AlN) hetero-epitaxial seeding on silicon carbide (SiC) by physical vapor transport (PVT), was systematically studied using XRD, UV–Vis, PL, SIMS, Raman and stress simulation. The evolution of crystal quality, transmittance, purity and residual stress of 2-inch AlN crystal in the growth process are described. The crystal quality of AlN growth layer gradually improves with the crystal thickness, as reflected in the decrease of XRD full width at half maximum (FWHM) from higher than 300 arcsec to 85 arcsec, SIMS yielded Si concentrations decreases from 1020 cm−3 to 1018 cm−3, absorbance coefficient @320 nm from 56 cm−1 to 9 cm−1, and simulated residual stress from 270 MPa to 50 MPa, indicating a comprehensively improved quality by simply increasing the crystal thickness of AlN crystal on SiC seed. Furthermore, a 2-inch crack-free AlN single crystal with high quality was successfully fabricated by inducing a layered structure.

Experimental and Numerical Study of Membrane Residual Stress in Q690 High-Strength Steel Welded Box Section Compressed Member.

High-strength steel (HSS) members with welded sections exhibit a notably lower residual compressive stress ratio compared with common mild steel (CMS) members. Despite this difference, current codes often generalize the findings from CMS members to HSS members, and the previous unified residual stress models are generally conservative. This study focuses on the membrane residual stress distribution in Q690 steel welded box sections. By leveraging experimental results, the influence of section sizes and welding parameters on membrane residual stress was delved into. A larger plate size correlates with a decrease in the residual compressive stress across the section, with a more pronounced reduction observed in adjacent plates. Additionally, augmenting the number of welding passes tends to diminish residual stresses across the section. Results showed that membrane residual stress adhered to the section's self-equilibrium, while the self-equilibrium in the plates was not a uniform pattern. A reliable residual stress simulation method for Q690 steel welded box sections was established using a three-dimensional thermal-elastic-plastic finite element model (3DTEFEM) grounded in experimental data. This method served as the cornerstone for parameter analysis in this study and set the stage for subsequent research. As a result, an accurate unified residual stress model for Q690 steel welded box sections was derived.

In situ measurements and simulation of residual stresses and deformations in additively manufactured thin plates

In situ measurements and simulation of residual stresses and deformations in additively manufactured thin plates

Comprehensive Distortion Analysis of a Laser Direct Metal Deposition (DMD)-Manufactured Large Prototype Made of Soft Martensitic Steel 1.4313

Additive manufacturing (AM) by using direct metal deposition (DMD) often causes erratic distortion patterns, especially on large parts. This study presents a systematic distortion analysis by employing numerical approaches using transient–thermal and structural simulations, experimental approaches using tomography, X-ray diffraction (XRD), and an analytical approach calculating the buckling distortion of a piston. The most essential geometrical features are thin walls situated between massive rings. An eigenvalue buckling analysis, a DMD process, and heat treatment simulation are presented. The eigenvalue buckling simulation shows that it is highly dependent on the mesh size. The computational effort of the DMD and heat treatment simulation was reduced through simplifications. Moreover, artificial imperfections were imposed in the heat treatment simulation, which moved the part into the buckling state inspired by the experiment. Although the numerical results of both simulations are successful, the eigenvalue and DMD simulation cannot be validated through tomography and XRD. This is because tomography is unable to measure small elastic strain fields, the simulated residual stresses were overestimated, and the part removal disturbed the residual stress equilibrium. Nevertheless, the heat treatment simulation can predict the distortion pattern caused by an inhomogeneous temperature field during ambient cooling in an oven. The massive piston skirt cools down and shrinks faster than the massive core. The reduced yield strength at elevated temperatures and critical buckling load leads to plastic deformation of the thin walls.

Analysis of the Thermal Residual Stress and Parametric Simulation in Laser Cladding Using COMSOL Multiphysics

Analysis of the Thermal Residual Stress and Parametric Simulation in Laser Cladding Using COMSOL Multiphysics

Multi-scale simulation of residual stress and deformation of large-size hollow parts fabricated by laser-based powder bed fusion

Hollow structures are widely used in aerospace, automotive, and other fields. Laser-based powder bed fusion (LB-PBF) enables the fabrication of complex parts. However, residual stresses and deformations present challenges for manufacturing high-quality components. This study proposes a modified inherent strain method (MISM) coupled with shear strain and dynamic mechanical properties to capture the asymmetric deformation behavior of the parts. The asymmetric deformation behavior was verified by two typical geometric structure parts, which demonstrated the generality of the phenomenon. The excellent agreement between the experimental and predicted results proved the validity of the extended model. Based on the asymmetric deformation, the effect of different geometries on the stresses was investigated. The results showed that the geometry of the parts affects the stress distribution and magnitude. The proposed numerical model can accurately predict the stress components of the parts, which is helpful to further investigate crack extension and damage in complex thin-walled parts.

Residual Stress Generation in Additive Manufacturing of Complex Lattice Geometries

Residual stresses developed during additive manufacturing (AM) can influence the mechanical performance of structural components in their intended applications. In this study, thermomechanical residual stress simulations of the laser powder bed fusion (LPBF) process are conducted for both simplified (plate and cube-shaped) geometries as well as five complex lattice geometries fabricated with Inconel 718. These simulations are conducted with the commercial software package Simufact Additive©, which uses a nonlinear finite element analysis and layer-by-layer averaging approach in determining residual stresses. To verify the efficacy of the Simufact Additive© simulations, numerical results for the plate and cube-shape geometries are analyzed for convergence and compared to experimental residual stress results available in the literature. Numerical residual stress results are subsequently compared for five complex lattice geometries. Results suggest that lattice geometry can play a significant role in the distribution and magnitude of residual stresses, which are significant in some applications.

A Numerical Simulation of the Seismic Performance and Residual Stress of Welded Joints in Building Steel Structures Based on the Finite Element Method

With the development of society and urbanization, higher requirements have been put forward for the safety and seismic resistance of building structures. The fatigue strength and seismic performance of welded joints have received close attention, especially as a crucial part of building steel structure. This study used the finite element simulation method to analyze the stress-strain of welded joints in building steel structures, and explore the influence of residual stress on their seismic performance. A stress-strain calculation model for welded joints in building steel structures was studied and constructed, and the accuracy of the model was verified through numerical calculation methods. The results showed that the residual stress peaks of the horizontal and vertical directions of the V-groove welded joint structure were 475 MPa and 325 MPa, respectively, and the longitudinal residual stress peaks were 525 MPa and 425 MPa, respectively. The seismic performance of four different steel structural plates was Q960>Q690>Q460>Q345. In summary, the numerical simulation of residual stress in the seismic performance of welded joints in building steel structures, when based on the finite element method, makes a contribution of clear value to the field of seismic performance of welded joints in building steel structures.

Simulation of Residual Stress of V-Notch Specimen Treated by Ultrasonic Rolling

Simulation of Residual Stress of V-Notch Specimen Treated by Ultrasonic Rolling

High-precision simulation and experimental verification of residual stress and surface topography of cylindrical surface shot peening

Shot peening is commonly employed for surface deformation strengthening of cylindrical surface part. Therefore, it is critical to understand the effects of shot peening on residual stress and surface topography. Compared to flat surface, cylindrical surface shot peening has two significant features: (i) the curvature of the cylindrical surface and the scattering of the shot stream cause distributed impact velocities; (ii) the rotation of the part results in a periodic variation of the impact velocity component. Therefore, it is a challenge to quickly and accurately predict the shot peening residual stress and surface topography of cylindrical surface. This paper developed a high-precision model which considers the more realistic shot peening process. Firstly, a kinematic analysis model was developed to simulate the relative movement of numerous shots and cylindrical surface. Then, the spatial distribution and time-varying impact information was calculated. Subsequently, the impact information was used for finite element modeling to predict residual stress and surface topography. The proposed kinematic analysis method was validated by comparison with the discrete element method. Meanwhile, 9310 high strength steel rollers shot peening test verified the effectiveness of the model in predicting the residual stress and surface topography. In addition, the effects of air pressure and attack angle on the residual stress and surface topography were investigated. This work could provide a functional package for efficient prediction of the surface integrity and guide industrial application in cylindrical surface shot peening.

Research on analyzing and valuing residual stress for micro wire busbar

The electroplated diamond wire saw made from high-carbon steel wire busbar (busbar), which directly affects the quality of cutting monocrystalline silicon, polysilicon, sapphire and SiC. When the wire diameter is on the micro-scale, there is no equipment to precisely measure the distribution of residual stress at present. The free circle diameter (FC-diameter) is used as the quality index to measure the distribution of axial residual stress of the busbar post-drawing. The existing finite element simulation of residual stress of steel wire post-drawing is mainly aimed at steel wire diameter of millimeter, and most of it is two-dimensional finite element simulation. The effect of actual factors on residual stress of the busbar is not considered in the simulation. In this paper, finite element simulation is carried out for steel wire with diameter in micron scale. The influences of die deflection, die friction coefficient, die sizing band ellipse and steel wire ellipse on axial residual stress is considered. The relationship between residual stress distribution and FC-diameter is established, and the correctness of simulation results is verified by experiments.

Finite-element simulation of residual stresses induced by laser shock peening in TC4 samples structurally similar to a turbine blade

This study is devoted to the investigation of residual stresses distribution (RSD) in a TC4 sample treated with laser shock peening. The study placed special emphasis on analyzing the RSD at the part of the samples structurally similar to a turbine blade, which is more frequently subjected to damage during service according to the aircraft statistics. Results of simulation showed that low power density of 1.11 GWt/cm2 could not induce compressive residual stress on the surface of a treated object. Furthermore, increasing the overlapping of laser spots does not improve the situation and still fail to induce surface compressive residual stress at a laser intensity of 1.11 GWt/cm2. The compressive stresses occur only with the rise in power density. Reducing the spot size from 3 mm to 1 mm for the power density of 10 GWt/cm2 results in a 20% increase in the magnitude of compressive residual stress in the area of interest. Moreover, applying 35% overlapping further enhances this value. In addition to increasing the magnitude of residual stress, this approach also leads to a more homogeneous RSD of the treated material.

Modification of Johnson–Cook Constitutive Parameters in Ball Burnish Simulation of 7075-T651 Aluminum Alloy

The Johnson–Cook model is widely used because of its ability to meet the simulation material requirements in various situations. However, under different working conditions, the accuracy of the model may have errors. In this work, based on Abaqus (Abaqus R2022 Education Edition, Dassault Systèmes, Paris, France) simulation software, Johnson–Cook (JC) constitutive model parameters and compression parameters were selected to simulate the improvement of surface roughness during the ball milling of a 7075-T651 aluminum alloy. In the numerical simulation of ball polishing, the changes in the residual stress field when the Johnson–Cook parameters change are analyzed. By comparing the numerically simulated residual stress fields under the JC parameters calculated at different strain rates, a set of parameters that agrees with the experimental values is selected. The results show that the residual stresses are in line with the experimental values when the strain rate is 10−4s −1. The changes in roughness corresponding to the selected parameters are analyzed. The results indicate that the simulated trend of roughness variation is consistent with the experimental values, and the optimal surface roughness value under a static pressure of 300 N is obtained.

Study on modelling simulation and distribution characteristics of residual stress during robotic weld end grinding of high strength modulated steel

Welding technology is widely used in the aerospace, construction, machinery, and rail transportation industries. After the welding process is completed, the weld seam is typically ground to improve the assembly accuracy and surface integrity of the structural part. However, residual stresses on the surface after grinding often affect the product performance and service life of structural components. Therefore, the formation mechanism and distribution of residual stresses after the robotic weld end grinding of high–strength modulated steel welds were investigated. First, a local contact geometric model of the grinding wheel and weld was established, and a grinding -force contact model was built based on this model. Next, a model of the heat-flow distribution in robotic end grinding was analysed, and the magnitudes of the heat flow in the contact and weld-width directions were calculated for the contact area. The results of these calculations were similar to the actual heat-flow distribution. Then, based on a theoretical analysis, the finite element method was used with a birth–death element to establish a force-thermal coupled residual stress prediction model, which could simulate the material removal process during actual grinding. Finally, the accuracies and reliabilities of the theoretical and simulation models were experimentally verified. The maximum error between the maximum simulated temperature and experimentally measured value was 10 %. The minimum error was 3 % when using the same process parameters, and the residual stress error was approximately 15 %. Based on the simulations, the variations in the temperature and residual stresses with time and position were explored. The highest weld-contact surface temperature of 417.75 °C was found when grinding using process parameters ap = 0.2 mm, vs = 23.55 m/s, vw = 20 mm/s. The residual tensile stresses could be up to +553 MPa in the longitudinal direction and −161 MPa in the transverse direction. The temperature in the zone of demarcation between the weld and base material was 212.8 °C, with maximum residual tensile stresses in both the longitudinal and transverse directions, of up to 352 MPa. The analysis revealed that the magnitude of the residual stresses was consistent with the temperature variation pattern, and that the grinding depth had the greatest influence on the residual stress distribution.

Numerical simulation and experimental study of residual stress in dissimilar aluminum alloy laser composite welding

The study combined experimental and numerical simulation methods to investigate the distribution of residual stress in laser composite welding of dissimilar aluminum alloys 6063 and 5083. Using the Simufact Welding simulation software and a combined volume heat source, the distribution patterns of transverse and longitudinal residual stress fields at different welding speeds were analyzed. The blind hole method was used to test the residual stress after welding. The results showed that the use of a combined volume heat source model for heat source calibration yielded ideal results, and the thermal cycle curve was basically consistent with the simulation and experimental results of residual stress. As the welding speed decreased, the longitudinal residual stress of the parent material on both sides significantly decreased, while the transverse residual stress increased. The majority of tensile and compressive stresses on both sides of the 5083 and 6063 aluminum alloys decreased with a decrease in welding speed. The Von Mises equivalent stress indicated that the cooling process is the main stage for residual stress generation. When the welding speed decreased, the peak value of longitudinal residual stress on the 6063 aluminum alloy side decreased from 230 to 90 MPa, while that on the 5083 aluminum alloy side decreased from 304 to 150 MPa. These findings provide an important basis for controlling and reducing the residual stress and deformation of dissimilar aluminum alloy laser arc composite welded components.