Shot Peening Simulation Research Articles

Shot peening simulation oriented to residual stress interaction with gear grinding

The current study proposes a shot peening model which enables the residual stress interaction with grinding, a typical combination for gear finishing. The effect of the interaction on the stress state development was addressed by comparing the residual stress state from a standalone shot peening procedure, against the residual stress state arising from a manufacturing route where the interaction of shot peening and grinding takes place. In the interaction model, the grinding procedure generates a pre-loaded condition on the material, modifying the internal strain system of the gear tooth. This pre-loaded system, when disturbed by shot peening, reaches a new internal strain equilibrium. In the interaction model, a 24% less compressive stress state was attained when compared with the standalone shot peening process. A significant shift in the depth and magnitude of the peak compressive stress was also observed. On account of the numerical study of the processes’ interaction, the developed model substantially contributed to understanding the residual stress formation during manufacturing chains.

Investigating the effect of shot peening parameters on the peened surface damage using FEA

Shot peening is a cold working process that generates compressive residual stresses on the surface by blasting a numerous of shots at a very high speed, also it is considered a complex process to be simulated. In this study, a simulation of a single spherical shot on stainless steel 410 martensitic target was implemented utilizing a finite element software (ANSYS Explicit), to study the contact parameters, surface damage, and the generated residual compressive stresses (RCS) just beneath the surface. Several conditions were conducted varying the speed of the shot and the angle of incidence. Two prior made empirical models based on vertical shooting were used to calculate the depth and the diameter of indentation, then the calculated values were compared with the simulation's results. The novelty of this work is to test the validity of these quasi-static empirical models which are based on vertical actual shot peening and indentation experiments and use them to support inclined shot peening simulation as substitution for experiments. The results show that the validity for the empirical models which are utilized in prediction of inclined shot peening contact parameters was proved, inclined impact gives a better RCS beneath the surface, and less geometrical deformation which keep the surface roughness in an acceptable range, however, shooting at angles lower than 45° can cause material removal, a rough surface, and less RCS.

Simulation Analysis with Randomly Distributed Multiple Projectiles and Experimental Study of Shot Peening

Shot peening technology is used to improve the fatigue strength of materials and parts, and is one of the most effective surface engineering techniques to prolong fatigue life. In this paper, according to the finite element simulation analysis of shot peening, a randomly distributed multiple-shot finite element model was established. The superimposed effects of multiple projectile impact craters in shot peening are fully considered. The effects of shot velocity, shot peening angle and shot coverage on the residual stress field and surface roughness were studied. The alloy steel 20MnTiB, widely used in the automotive industry, was used as the raw material to process the specimens. The shot peening tests of different process parameters were carried out. The test results verified the correctness and accuracy of the random distribution model of multiple-shot. The shot-peening simulation model proposed in this paper allows a more accurate analysis of the effect of shot-peening parameters on the surface residual stress field and helps to quickly set the correct shot-peening process parameters. This paper further investigates the effect of shot peening parameters on fatigue life, providing a basis for the rational development of shot peening solutions.

Simulation and Experiment Research on the Surface Deformation and Residual Stress of Fractal Rough Surface Single-Shot Peening

In order to study the influence of workpiece surface topography on deformation and residual stress during shot peening, the paper built a rough surface single-shot peening simulation model and designed a rough surface workpieces shot peening experiment to verify the correctness of the built simulation model, which differed from the smooth surface simulation model and was closer to the actual processing situation. Based on the W-M fractal dimension theory, the shot peening model of the target with a rough surface is established, and the simulation analysis is carried out by finite element software. The effect of different impact positions of the pellet on surface residual stress and surface displacement were also simulated. The simulation found that with the increase of surface complexity, the surface deformation and residual stress would both increase after shot peening. Through shot peening tests on workpieces with different surface roughness, it is found that the error between simulation and experiment results on surface deformation and residual stress are both less than 20%, which verifies the validity of the rough surface single-shot peening model and that the established model could provide a new method on shot peening simulation analysis.

Dynamic Hardening of AISI 304 Steel at a Wide Range of Strain Rates and Its Application to Shot Peening Simulation

The hardening behavior of AISI 304 steel is investigated at various strain rates, from the quasi-static state to ultra-high strain rates, because it is necessary for numerical simulation of high-speed deformation problems. This kind of testing at a wide range of strain rates has not been yet reported in the literature although it is indispensable for accurate numerical analyses where deformation takes place with a wide spectrum of strain rates. AISI 304 steel is a kind of austenitic stainless steel used in various engineering fields, which does not harden by heat treatment, but by cold working such as shot peening. In order to obtain hardening properties at each strain rate, tensile tests were carried out using a universal testing machine of the INSTRON 5583 for the quasi-static state, a high speed material testing machine of a servo-hydraulic type for intermediate strain rates, and a tensile split-Hopkinson bar for high strain rates with a digital image correlation method. The hardening properties at the ultra-high strain-rate region were obtained from Taylor impact test results by calibration with an experimental–numerical hybrid inverse optimization for reliable extrapolation results. Finally, the hardening flow stress curves were obtained at various strain rates from the quasi-static state to ultra-high strain rates by interpolating the data with the extended Lim–Huh model. The result shows that the yield stress of 759 MPa at the quasi-static state increased to 1429 MPa at a strain rate of 106 s−1, which is about 1.9 times of the quasi-static yield stress. As a demonstration example, the dynamic hardening properties obtained were applied to a shot peening simulation that required hardening curves at a wide range of strain rates from the static state to 106 s−1. The simulation result with the dynamic hardening properties is compared to that with the quasi-static properties. The comparison shows a notable difference in the maximum compressive residual stress by 32%, demonstrating that it is important to consider the dynamic hardening properties in such high strain rate simulation as shot peening for accurate simulation results.

Numerical modeling and experimental verification of residual stress distribution evolution of 12Cr2Ni4A steel generated by shot peening

Shot peening is a widely used surface strengthening technique which can improve the fatigue life of metal components by introducing reasonably distributed compressive residual stress. The accurate prediction of residual stress distribution of parts is a tough challenge in the simulation of shot peening. In this paper, the numerical calculation of the residual stress of shot peening is investigated with 12Cr2Ni4A steel as the target. A two-dimensional Gaussian distribution model is proposed to calculate the number of impact shots. A method is proposed to calculate shot peening coverage using displacement and displacement gradient, which increases the identification accuracy of peened surface topography and provides a scientific method for coverage calculation. A random multi-shot finite element model for high strength steel is established considering the elastoplastic of shot. The effects of the process parameters, initial surface morphology and initial residual stress on the residual stress distribution after shot peening are investigated. The accuracy of the proposed method is verified by comparing the measured and simulated results. • A two-dimensional Gaussian distribution model is proposed to calculate the number of impact shots. • An improved model for predicting the residual stress distribution in shot peening is developed. • A method to calculate the shot peening coverage using displacement and displacement gradient is proposed. • The effects of treatment parameters and initial state on residual stress are studied. • The experiment is used to verify the proposed model.

Shot Peening Simulation Oriented to Residual Stress Interaction in Gear Manufacturing Chain

Shot Peening Simulation Oriented to Residual Stress Interaction in Gear Manufacturing Chain

Investigation of the effects of shot overlap and rigid body assumptions on surface layer characteristics in shot peening simulation

As an important mean of shot peening (SP) research, finite element simulation has been widely and successfully employed in estimating the surface characteristic and residual stress distribution after SP treatment. In this study, the effects of shot overlap and rigid body assumptions on dimple geometry and residual stress distribution in depth were discussed via the validated ordered dimple pattern and stochastic dimple pattern SP models for quenched and tempered 42CrMo steel. The results show that shot overlap assumption has a great influence on the surface plastic deformation of peened material. The simulated value of plastic deformation is much larger than the experimental value, which results in the residual stress of the overlapping shot SP model deviating from the actual result seriously. For the prediction of the residual stress distribution, the shot must be set as an elasto-plastic body when the number of shot is large. The shot can be set as a rigid body for the aim of reducing the calculation time when the number of shots is small. In addition, the influence of material hardness on residual stress and equivalent plastic strain (PEEQ) was investigated via simulating the residual stress and PEEQ of different hardness materials treated by SP process . • It is necessary to choose the non-overlapping shot in SP simulation when the dimple geometry and residual stress distribution is predicted. • It is more accurate to choose elasto-plastic shot in SP model for the dimple geometry prediction. • The shot can be set as a rigid body when the number of shot is small.

Stress-Shot-Peened Leaf Springs Material Analysis through Nano- and Micro-Indentations.

Heat-treated and shot-peened lightweight steels with demanding requirements for durability are applied in high-performance automotive leaf springs. Due to their heat-treatment they exhibit degraded properties in the surface-near area compared to the core. This area, which may extend until 300 μm from the surface to the core, experiences the highest bending stresses at operation. The microstructure in the surface and sub-surface layers determines the mechanical performance as well as the wear resistance. The present study refers to the material properties of a stress shot-peened 51CrV4 steel at various depths from the surface. The effect of the manufacturing process has been captured both by Vickers micro-hardness measurements and nanoindentation. The latter combined with a Fine Element Method (FEM)-based algorithm enables the determination of variations in the material’s stress–strain curves over the affected layers, which translate to internal stress changes. The nanoindentation technique has been applied here successfully for the first time ever on leaf springs. The combination of microstructural analysis, microhardness and nanoindentation captures the changes of the treated material, offering insights on the material characteristics, and yielding accurate elastoplastic material properties for local, layered-based analysis of the components’ mechanical performance at operational loading scenarios, i.e., in the framework of stress shot-peening simulation models.

An innovative contactless finite element simulation of the shot peening process

Shot peening is a major finishing treatment aiming to enhance parts’ life. However, the recourse to simulation to master the process and its effects still suffers from problems due to its complexity. The current paper presents a finite element-based approach that considers the random aspect of the shot peening process in association with a large number of shots, making it more realistic. The developed method is found to allow a computing time gain up to 70 % with comparable results to those obtained by the discrete element method, which has been reported as the most suitable for shot peening simulation. The comparison of both simulations results to experiment returned a good agreement. Simulations and experiences were concerned with C75 Almen-like strips.

Formulation of a Generalized Unit Cell and its Application to Shot Peening Simulation

The simulation of the residual stress field achieved by shot peening cannot be carried out on component-large models. Hence, an efficient unit cell model for the simulation of the shot peening process is developed. The model allows both, the simple inclusion of a pre-stress and the evaluation of the up-arching of the Almen strip. For this purpose, generalized coupling constraints for the periodic boundaries of the unit cell are developed. These allow for displacement and rotation of the coupled boundaries relative to each other. In the coupling constraints, this is accomplished by respective variables, which can either be prescribed to the analysis or read out as a result from the analysis. Hence, the unit cell can expand, shear, bend and twist under driving forces like, e. g., residual stresses or thermal effects. At the same time, deformations of the cell’s periodic boundary pairs are kept congruent by the generalized coupling. The ability to cover expansion is novel regarding known periodic boundary conditions. Also, the application of a generalized unit cell to shot peening is new.Results obtained with the generalized unit cell are displayed, demonstrating its capabilities: A fundamental analysis of the residual stress field from shot peening shows inhomogeneities at a fatigue relevant level to be inevitable. A validation of the model was done by comparison with experimental Almen strip shot peening tests reported in literature. Shot peening under pre-stress is demonstrated and its results in terms of residual stress are evaluated. The application of the generalized unit cell is not limited to shot peening.

Dynamic characterization of Ti-4Al-1.5Mn titanium alloy and a simplified approach for shot peening simulation

To predict the residual stress distribution of the Ti-4Al-1.5Mn (TC2) alloy in the manufacturing process, quickly and accurately, a precise dynamic constitutive model for rheological behavior and a new simplified approach for numerical simulation were proposed. The dynamic stress-strain curves indicate that the enhancement effect and plasticizing of the TC2 alloy are sensitive to high strain rates. The dispersed β particles play an important role in the formation of the adiabatic shear band and not widened significantly. The average relative error of 1.04% and the correlation coefficient of 0.9949 indicate that the modified Johnson-Cook constitutive model well describes the rheological behavior. Then, with the help of the Almen test, an efficient but simplified approach was proposed to achieving coverage and uniform loading in simulation. At last, the residual stress contribution of the TC2 alloy in the shot peening test is in a good agreement with the simulation results by random multipellet model.

Coupled finite and discrete element shot peening simulation based on Johnson–Cook material model

Shot peening is an essential treatment that produces a beneficial compressive layer on the material’s surface, which significantly improves its fatigue life. To minimizes the cost and resources used in determining the finest shot peening parameters based on the experimental approach, a numerical model capable of computing the induced compressive residual stress accurately is required. Hence, the numerical simulation of the shot peening process with multiple random shots that depict the actual shot peening is presented in this paper. The model is developed using the coupled finite and discrete element methods. The two numerical tools were coupled via code in ABAQUS, whereby shot–shot and shot–target interaction behaviors were accurately included. The induced compressive residual stress was computed due to the multiple random shots impact based on the Johnson–Cook material model. The model was experimentally validated and applied to evaluated the influence of shot velocity, shot size, and angle of impact on the final compressive residual stress.

3D Finite Element Simulation of Shot Peening Using a Sequential Model with Multiple-Shot Impacts

A sequential model of multiple-shot impacts has been established to investigate the shot peening process. Shot groups are proposed and designed with different patterns to obtain full surface coverage in the impacted region and a satisfactory computational efficiency. The sequential model was applied for the prediction of residual stress on a GH4169 alloy specimen. The results showed that uniform and saturated states of residual stress along the surface and depth profile were obtained in the impacted region when the numerical order of shot patterns reached 4. Furthermore, the numerical results of compressive residual stress in the subsurface were compared with the experimental results obtained using the X-ray diffraction (XRD) analysis and the incremental hole drilling method. The maximum relative error between the numerical results and XRD measurement was 11.6%. Furthermore, the stress profile measured using the incremental hole drilling method was consistent with the numerical results. The established finite element model demonstrated its robustness and effectiveness for the evaluation of residual stress in the shot-peened GH4169 alloy, and it may be applied to other metallic materials with simple modifications.

TC4 shot peening simulation and experiment

TC4 shot peening simulation and experiment

A sequential DEM-FEM coupling method for shot peening simulation

Shot peening is a cold-working process widely used to form and enhance the fatigue life of metallic components. The process consists of projecting high-velocity particles onto a metallic surface. This study introduces a new, and experimentally validated, sequentially coupled Discrete Element Model (DEM) - Finite Element Model (FEM) to predict the process' effects in terms of residual stresses and roughness. A shot stream was first simulated in DEM to obtain the velocity distribution of impacting shots. The target's progressive hardening was accounted for by adjusting the Coefficients of Restitution (CoRs) for shot-target interactions as the number of impacts evolved through a meshless method. The extracted impacting shots were then impinged onto a representative cell in a dynamic FEM model to evaluate the shot peening effects. The simulations were compared against experimentally measured roughness and residual stresses at full coverage. The study shows that using a constant average CoR yields results that are quite similar to those with an evolving CoRs, for a fraction of the computational cost. Moreover, cases where shot-shot interactions were accounted for yielded lower residual stresses and roughness than cases where such interactions were not accounted for. Nevertheless, all simulated cases delivered simulations that were in good agreement with the experiments, which validates the proposed approach.

Finite element simulation of shot peening of an aluminum alloy considering hardening models

Shot peening is a surface engineering process acknowledged for its potential to develop fatigue strength and erosion-corrosion resistance of metallic materials. In the present study, a 3-D finite element model is employed to predict the effective parameters through a single shot impact and the accuracy of the simulation is validated using previous literatures. In order to induce uniform compressive residual stress patterns across the specimen, processing parameters such as shot velocity, impact angle and friction coefficient should be controlled. It is observed that by increasing the shot velocity and the friction coefficient, the depth of compressive residual stress increases. Moreover, a comparative study between isotropic and kinematic hardening models is performed to evaluate the significant role of the hardening models on the compressive residual stress. It is observed that the kinematic hardening model shows better compatibility with the experimental results compared to the isotropic hardening.

Shot peening coverage effect on residual stress profile by FE random impact analysis

Shot peening is one of the most effective surface treatments for improving the fatigue strength of machine elements. In this paper, a new finite element-based model to predict the effect of coverage on the surface state is proposed and critically discussed. By this model, the effects of Rayleigh damping, mesh size, and target dimensions on residual stress profile are investigated using a random impingement simulation of shot peening. Moreover, the model enables the realistic simulation of shot peening process with an affordable computational time with respect of present approaches without reducing the number of impacts and analysis accuracy: the computational time was reduced by 25% in comparison with the conventional finite element models using the proposed method. In addition, the required RAM capacity was reduced up to 80% while the calculated residual stresses and the resulting surface roughness are in good agreement with the experimental results.

Simulation of shot peening: From process parameters to residual stress fields in a structure

Manufacturing industries perform mechanical surface treatments like shot peening at the end of the manufacturing chain to protect important working parts. This treatment modifies the near surface of the treated part with the introduction of compressive residual stresses due to the repeated impacts of the shot. Then, the treated part exhibits, not only a longer life, but also a better fretting behavior, an improved resistance to corrosion… The objective of the present paper is first to study the relation between the process parameters and the material state (residual stress and plastic variables…) for a complex geometry. Next, a numerical tool is proposed, able to predict this material state in a time frame that is consistent with industrial constraints. The originality of the proposed approach thus consists in the chaining of the different steps. The first step is to choose the process parameters for the shot peening process considering conventional or ultrasonic shot peening and model the shot dynamics for a complex geometry. Once the impact velocity field is known, the objective is to compute the local incompatible plastic deformation field due to the repeated impacts using analytical methods. Then, a finite element model is used to compute the residual and deformation fields in the considered mechanical part. The complete method has been performed on the model of a gear, a mechanical part that is most often shot peened and exhibits a complex geometry.

Shot peening optimisation by means of 'DOE': Numerical simulation and choice of treatment parameters

Shot peening is widely used to improve the fatigue properties of cyclically loaded mechanical components. The benefits of the treatment, which are mainly due to the compressive residual stress field induced in the surface layers of material, depend on the correct choice of the peening parameters. However, many times the choice of the treatment parameters is made by following empirical considerations, that do not make it possible, for the particular mechanical application, to set the most important factors at their best levels. So, an appropriate procedure, suitable for the different applications, would be necessary to optimise the treatment parameters and to address the choice of their best levels. 'Design of Experiment' (DOE) was applied to the results obtained from the numerical simulation of shot peening (impact of one or more spheres on an infinite smooth steel target), and permitted a choice to be made of the best levels of the treatment parameters in a cheap and fast way.