Machining Residual Stresses Research Articles

An online prediction method of three-dimensional machining residual stress field based on IncepU-net

The magnitude and distribution of residual stress field inside thin-walled parts is a critical factor influencing machining deformation. Traditional methods relying on offline data struggle to rapidly and accurately predict evolutionary state of residual stress fields, due to the time-varying and nonlinear characteristics in machining. This paper presents an online prediction method for residual stress in machining thin-walled parts based on deep learning. The multi-channel vector model is proposed to incorporate geometric, physical, and process information as input for deep learning models. A deep learning framework utilizing the IncepU-net network is developed and trained using both experimental and finite element simulation data. Results indicate a mean error of 6.2 MPa compared to experimental values, with an overall prediction time of 0.17 s. The proposed method can online predict the magnitude and distribution of residual stress field in machining, which offers cost-effectiveness and strong generalization capabilities.

Research on distortion in boring process of large-size main bearing holes in marine diesel engine body

Machining-induced residual stress (MIRS) in thin-walled components affects their machining accuracy, especially for large-size thin-walled components. This study focuses on the bodies of marine diesel engines, exploring the distribution of MIRS and distortion caused by the gravity-coupled machining residual stress during the boring process of the main bearing hole. The research obtained the distribution of MIRS and the machining distortion based on the finite element method and the mapping method. It examined the influence rules of various parameters, such as the cutting speed, feed, and depth of cut, on MIRS and machining distortion. The study shows that cutting speed, feed, and depth of cut are vital factors affecting MIRS and machining distortion. For the machining distortion of large-size and thin-walled components, their own weight is an essential factor that cannot be ignored. By optimizing the wall thickness, the distortion range can be effectively controlled, supporting the lightweight design of the structure.

Inverse analysis of machining residual stress based on hybrid model

Machining-induced residual stress significantly impacts the fatigue life and service performance of machined components. Appropriate compressive residual stress can enhance resistance to crack initiation, while tensile residual stress may be detrimental. In this study, an inverse analysis is conducted to optimize the cutting parameters for achieving desired residual stresses. The analysis begins by predicting the machining-induced thermal-mechanical loads in the primary shear zones using analytical methods. Subsequently, an Arbitrary Lagrangian-Eulerian (ALE) based numerical model is proposed to calculate the resulting residual stresses by incorporating the determined thermal-mechanical loads. This analytical-numerical hybrid method facilitates rapid and accurate modeling of residual stresses. Then, the Newton’s method is employed to deduce cutting parameters iteratively, ensuring a proper residual stress. Finally, the results of inverse analysis are compared with experimental measurements to validate its efficacy.

Effect of cutting fluids on surface residual stress in machining of waspaloy

Effect of cutting fluids on surface residual stress in machining of waspaloy

Accurate Prediction of Residual Stresses in Machining of Inconel 718 Alloy through Crystal Plasticity Modelling

This study presents the dynamic and buckling analysis of the laminated composite thin arch plate frame structures employing Classical Plate Theory with Finite Element Analysis. For this purpose, the effects of the radius of curvature, aspect ratio, and stacking order of such structures on the first ten natural frequencies, mode shapes, critical buckling load, and the first unstable regions are investigated. Besides, the two-bay curved plate frame structure is investigated. In order to perform dynamic and buckling analyses, a computer code is developed and executed via MATLAB. The results are compared and validated with those of ANSYS. It is concluded that the aspect ratio or the stacking order affects the dynamic characteristics of the curved plate frame structure considerably while the radius of curvature relatively has less impact on such dynamic properties of the structure.

The Residual Stress and Deformation Control of TC4 Thin-Walled Outer Ring Components by Ultrasonic Regulation

The deformation problem caused by the excessive residual stress has brought great challenges to the high-precision machining and geometrical stability of thin-walled components. Aiming to ensure the verticality within 0.012 mm after the processing and forming of a certain type of outer ring components, this paper firstly employs the ultrasonic critical refraction longitudinal wave (LCR wave) detection method to test the residual stress distribution in the key process. Additionally, the stress elimination effect of cryogenic stress relief treatment and the effect of residual stress on vertical deformation are analyzed. After that, combined with the self-developed ultrasonic stress relief (USR) equipment, the ultrasonic regulation treatment was used to replace the heat treatment stress relief process for the processing. The results show that after wire cutting and milling, excessive residual stress induces deformation of components, and USR method can eliminate machining residual stress more efficiently and quickly. As the whole component has torsional deformation along the cross section, the hole position at the upper and lower end faces is changed, which leads to the change in verticality. Finally, based on the results of X-ray diffraction (XRD), the potential microscopic mechanism of stress relief by ultrasonic treatment is analyzed. This study provides guidance for ultrasonic residual stress regulation to achieve the high-precision outer ring thin-walled components.

Research on the Residual Stress of the Machined Surface of Cutting Superalloy under High Pressure Cooling

High pressure cooling assisted cutting has certain advantages in cutting difficult materials such as superalloy. Therefore, the residual stress on the machined surface of superalloy is studied with the application background of high pressure cooling cutting. Firstly, the formation mechanism of the machined surface residual stress was analyzed. Then, the influence mechanism of high pressure coolant on the residual stress of machined surface was studied. Finally, it is concluded that the maximum residual compressive stress in cutting depth direction of cutting superalloy under high pressure cooling should be less than that of dry cutting by theoretical analysis and experimental research.

Finite element simulation and experimental investigation of machining induced residual stresses in ultrasonic elliptical vibration-assisted turning

In this study, an experimental study and three-dimensional finite element simulation of ultrasonic elliptical vibration-assisted turning (UEAT) are investigated. In addition, the comparison of this process with ultrasonic-assisted turning (UAT) and conventional turning (CT) is also provided. First, a three-dimensional FEM has been developed to study the cutting forces, friction coefficient, and residual stresses in CT, UAT, and UEAT. For the experimental tests, a special design of elliptical vibration tool with two bending modes (along feed and cutting speed) is proposed and fabricated. Then, the effect of vibration amplitude, cutting speed, and feed on the machining residual stresses during hard turning of AISI4340 steel has been explored. Finally, the developed FEM is validated with the experimental test results. According to the obtained results, by applying elliptical vibrations on the cutting tool in UEAT, machining residual stresses became more compressive on averagely by 49%. Moreover, the application of elliptical ultrasonic vibrations with amplitudes of 6 and 12 μm had made machining residual stresses 34 and 64% more compressive, respectively.

Modelling the effect of feed rate on residual stresses induced due to milling using experimental and numerical methods

The surface integrity of any manufactured product produced in machining process has proved to have a significant impact on the performance of the product. Many parameters influence the integrity of the surface, few of which are microstructure of the material, surface roughness, residual stresses etc. Out of which the present work focuses on the residual stress of the machining, which majorly effects the fatigue strength of the product. Understanding the significance of residual stresses in machining, and influencing it using three basic parameters: feed, cutting speed and depth of cut to increase the products performance and life by optimizing these measures to best possible combination. It is done using both experimental and numerical methods and authors have compared the numerical and experimental values. For experimental purposes AISI 1045 steel was used and the residual stresses measurement was done using X-ray diffraction method.

The effects of machining residual stresses on springback in deformation machining bending mode

Hybrid machining-forming technology is a combination of two thin-structural machining and incremental forming manufacturing processes. A group of complex geometry parts in which a thick region is connected to a thin-wall region can be manufactured through this technology with certain advantages. The parts made by this technology require less raw material compared to the ones created by means of machining. The major problem with this technology is the dimensional and geometric inaccuracy of its products which is mainly due to springback. The main purpose of this research was to study the effects of machining parameters and residual stresses induced by the machining primary stage on the subsequent springback after the forming stage. It was found by experiments that the parameters of cutting speed, axial depth of cut, mode of milling, and milling path had a minor effect on springback. However, the workpiece fracture during the forming stage was observed to be sensitive to the prior machining feed rate. Both finite element simulations and experimental results confirmed that the compressive machining residual stresses increased with an increase in the machining feed rate. The compressive residual stresses postponed the onset of fracture at the workpiece lower end during the forming stage. Therefore, we could approach the forming tool closer to the bottom of the wall during forming and, as a result, springback decreased considerably.

Experimental Study and Optimization of Residual Stresses in Machining of Ti6Al4V Using Titanium and Multi-layered Inserts

Residual stresses are those types of stresses that are preserved in the material even after the applied force has been removed. These stresses have a direct influence in characteristics of superalloy along with the exterior finish of the same which plays a very pivot role in industrial applications especially aerospace. In this paper, the consequence of the residual stress has been given importance alongside the knowledge of machined part finish, tool wear, machining force, the heat generated and chip morphology. Superalloy commonly used aeronautical material Titanium (Ti6Al4V) workpiece has been taken and machined using CNC turning lathe with the help of titanium nitride (TiN) coated insert and multilayer-coated insert. The residual stress is obtained through the use of XRD technique. On the opposite side material removal rate, surface roughness and chip thickness have been also determined using defined machines and compared with various machining constraints like machining speed, depth of cut and feed rate. The tool wear was also interpreted and analysed. The machining parameters has been designated through the use of Taguchi Technique where L4 array have used to define the cutting constraints. Grey relational analysis has also been done to get optimal metal removal constraints and to get the optimal result. ANNOVA analysis is also used in this paper to acknowledge the best optimum result.

Prediction of Residual Stress on Cold-Formed Curvature Plates by Elastoplastic Material Model

To meet the demand of automatic production, the multisquare punch forming has been improved to process complex curved plates. However, the improved forming equipment improves the processing quality to the maximum extent, and springback and residual stresses are inevitable phenomena in the cold bending process. Residual stress is an important factor that causes fatigue crack and stress corrosion crack. And the residual stress in machining will seriously affect the fatigue life of cold-pressed parts. Therefore, it is necessary to quantitatively and qualitatively analyze the residual stress caused by the cold forming equipment. Through theoretical derivation and finite element simulation methods, the residual stress distribution for thick plates in the cold forming process was analyzed and compared in this article. Meanwhile, the variation law of residual stress peak with thickness and forming radius was further discussed. The results show that the residual stress distributions obtained by the two theoretical models are in good agreement with the numerical results. The maximum error of peak residual stress is about 10%, which verifies the reliability of theoretical formulas. 1. Introduction A large number of complex curved sheet metal parts are used in aerospace, marine structure, automobile, and other manufacturing industries, which makes the processing and forming of complex curved sheet metal parts attract much attention. In the process of ship construction, the forming and processing of hull plates is an important part of the low intelligence, time-consuming, and serious constraint on shipbuilding automation. Strictly speaking, most of the parts in the hull plate are three-dimensional curved surfaces, most of which are composed of complex undevelopable spatial curved surfaces. It is a very difficult and urgent key technology to process a ship's steel plate into complex three-dimensional curved surface shapes. such as saddle shape or sailed shape (see Fig. 1A), to create a streamlined outer body of the ship. For many years, bending of plates with complex curvatures has been carried out by manual operation, i.e., the combination of heat line forming and rolling bending (see Fig. 1B). However, the production efficiency of the thermoforming process is relatively low, and environmental pollution is relatively serious with bad working conditions and high labor intensity. Moreover, the forming quality depends more on the experience of technicians, and quality cannot be guaranteed. With the increasing demand for automation, the multipoint forming equipment was developed and used for stamping and forming of curved plates.

Study on Cutting Force, Cutting Temperature and Machining Residual Stress in Precision Turning of Pure Iron with Different Grain Sizes

Pure iron is one of the difficult-to-machine materials due to its large chip deformation, adhesion, work-hardening, and built-up edges formation during machining. This leads to a large workpiece deformation and challenge to meet the required technical indicators. Therefore, under varying the grain size of pure iron, the influence of cutting speed, feed, and depth of cut on the cutting force, heat generation, and machining residual stresses were explored in the turning process to improve the machinability without compromising the mechanical properties of the material. The experimental findings have depicted that the influence of grain size on cutting force in the precision turning process is not apparent. However, the cutting temperature and residual stress of machining fine-grain iron were much smaller than the coarse grain at all levels of cutting parameters.

Simulation and experimental study on surface residual stress of ultra-precision turned 2024 aluminum alloy

In order to reveal the influence of cutting parameters on the surface residual stress of 2024 aluminum alloy in ultra-precision cutting, the thermal coupling simulation of 2024 aluminum alloy ultra-precision cutting process was carried out based on ABAQUS software, and it was verified by the residual stress test of ultra-precision machined samples. The results show that the dominant factor of the machining residual stress of 2024 aluminum alloy ultra-precision with single crystal diamond tool is the plastic deformation caused by cutting force. With the normal ultra-precision machining parameters, the residual stress of the machined surface of 2024 aluminum alloy is mainly compressive stress. With the increase in distance to the machined surface, the residual compressive stress value decreases and gradually transforms into tensile stress, and the total residual stress depth is less than 8 μm. With the increase in cutting depth (0.01–0.03 mm), the reduction of cutting speed (150–50 m/min) and the increase of feed (0.01–0.024 mm/r), there is an increasing trend of the residual stress on the machined surface of 2024 aluminum alloy workpiece, and the influences of feed rate and cutting depth on residual stress are slightly greater than that of cutting speed.

Ultraprecision laser-assisted diamond machining of single crystal Ge

In this paper we present an experimental study on ultraprecision machining (UPM) of single crystal Ge using the μ-LAM process. The material is oriented with the cutting plane normal to the <111> direction. It is shown that increased hydrostatic pressures on the surface during cutting by increasing the tool radius and negative rake angle can aid in enhancing ductile material removal from the surface. It is shown that the cutting performance can be increased by approximately 400% using the optimal tool geometry. It is also shown that the optimal tooling geometry with a steep negative rake angle, i.e. −65°, is capable of producing repeatable surface form and finish over long cutting distances. Finally, it will be shown that the laser beam used for μ-LAM, with the right amount of power, produces surfaces that are under less post machining residual stresses.

Design of Broaching Tool Using Finite Element Method for Achieving the Lowest Residual Tensile Stress in Machining of Ti6Al4V Alloy

The aim of this study, is to use finite element simulation to achieve the optimal geometry of a broaching tool that creates the lowest tensile stress at the machined surface of the Ti6Al4V alloy. It plays a major role in reducing production costs and improves the surface integrity of the machined parts. The type and amount of residual stress determined by the thermal and mechanical loads transmitted to the workpiece. In this research, the two-dimensional simulation of the broaching process is done by finite element DEFORM-2D® software for the two end teeth of the tool that perform the cutting operation. In simulating the first tooth, Response Surface Method is used to select the desired controllable parameters of the process such as cutting speed, rake angle, clearance angle, rise per tooth and depth of cut. In order to establish low thermal and high mechanical load in workpiece, multi-objective genetic algorithm employed after perform simulation in the first tooth. In simulating the second tooth, Response Surface Method used to select desired controllable parameters of the process such as rake angle, clearance angle and radius of cutting edge. For the second tooth, a multi-objective genetic algorithm has been used. Ultimately, the geometry of the broaching tool utility has been designed to store the lowest tensile residual stresses in the machined surface for Ti6Al4V alloy.

Modeling the effects of Undeformed Chip Volume (UCV) on residual stresses during the milling of curved thin-walled parts

With the increasingly popularized curved thin-walled parts, the control of curved surface residual stress in machining has become more and more demanding. However, it remains to be a major challenge to predict and control curved surface residual stress in the present aerospace research areas. Amidst this backdrop, this paper introduces a residual stress volume model to evaluate the effects of sequential cuts for the generated surface and subsurface residual stresses. Additionally, based on the proposed modeling and calculated results, quantified method is used for superposition of residual stress under different machining conditions. The superposition rates in feed, vertical feed and depth of cut directions are about 10%, 11% and 7%, respectively. In addition, this paper presents a newly constructed mathematical model between the curved surface maximum tensile residual stress and the Undeformed Chip Volume (UCV) (fz, R, ap and ae) of the ball end milling cutter. Through polynomial fitting for the proposed mathematical model, the influence coefficients α and β can be obtained, which act as the influence factors of machining parameters on residual stress generation. The values of α vary from 0.0018 to 0.0087, while the values of β vary from −3.99 to 0.72. That means that the depth of cut and tool radius can exert the greatest influence on the curved surface maximum tensile residual stress. Finally, with larger tool radius and smaller depth of cut, an experiment of machining curved thin-walled part proves that curved surface residual stress and deformation can be effectively reduced.

Finite element simulation of residual stress in machining of Ti-6Al-4V with a microstructural consideration

Machining-induced residual stress plays significant role in the corrosion resistance and fatigue life of the manufacturing end-product. The high temperature condition in the turning process could induce microstructure changes of titanium alloys, which would directly influence the residual stress generation in the machining process. A prediction model is proposed to calculate the microstructure evolution in orthogonal turning process. Based on the explicit calculation of grain size growth and phase transformation, a microstructure-sensitive Johnson–Cook model considering the material microstructural attributes is developed for the machining-induced residual stress prediction of Ti-6Al-4V. Grain size characterization with electron backscatter diffraction test is conducted on the machined workpiece surface. Experimental measurement on force and residual stresses are conducted for model validations. The predicted force value agrees well with the measurement data. The general trend of residual stress profile is captured by the prediction model. The mechanisms of how the residual stress would be influenced by the different machining conditions, such as surface cutting speed, and feed rate, are also studied. The proposed method provides an in-depth understanding on the machined workpiece residual stress distribution as influenced by material microstructural attributes evolution in the machining process.

Investigation of residual impact stress and its effects on the precision during milling of the thin-walled part

Residual stress has a lasting effect on the deflection of machined thin-walled parts, which also strictly restricts the use of products. This paper finds that there exists residual impact stress during the high-speed cutting machining of thin-walled parts, which is very unfavorable to the quality of thin-walled parts. Obvious residual impact stress exists during the cutting-in and cutting-out stages, while stable machining residual stress exists in the middle stage. At the cutting-in and cutting-out positions of tool, the residual impact stress generated by a parameter combination of low speed, large feed, and large depth of cut is much smaller than that generated by other combinations of process parameters. The residual impact stress on multiple machined surfaces can propagate on the surface to form distribution with equal stress energy areas. By increasing the linear cutting speed, the surface and subsurface residual stress values can be decreased to some extent. Although the cutting efficiency improves, the deflection caused by residual stress reduces. Based on these results, experimental verification is carried out on the thin-walled parts. And the evidence shows the presented approach is useful to reduce the residual impact stresses; therefore, distortion of thin-walled part is also within control.

Effect of hybrid wire EDM conditions on generation of residual stresses in machining of HCHCr D2 tool steel under ultrasonic vibration

This experimental examination exhibit a novel Hybrid Wire electrical discharge machining (H-WEDM) process of ultrasonic vibration combined with traditional Wire-EDM. The metal cutting for form tool and extrusion die with WEDM is liked to give better surface morphology. The effect of residual stresses has been dissected for H-WEDMed machined surface alongside the surface roughness and erosion rate to enhance surface integrity and longer service life of High Carbon High Chromium D2 tool steel. The process parameters chose for this investigation are type of vibration continuous/discontinues, amplitude of vibration, workpiece dimension, duty cycle, peek current and wire feed rate with objective to optimize the residual stresses and erosion rate. Portable X-ray Residual Stress Analyzer, a non-destructive X-ray analyzer is used to measure the residual stress efficiently by detecting the full Debye ring data from a single incident X-ray angle and Non goniometer stage influence on the measurements. An endeavor was made to compare the residual stresses for continuous/discontinues vibration and without vibration. The impacts of amplitude of vibration, peak current, duty cycle and wire feed rate variations on erosion rate was study using Taguchi method. From experimental study, it was observed that discontinuous vibration enhances the erosion rate and diminishes the resultant stresses. High Peak current and duty cycle altogether deteriorate the surface texture, which creates high tensile residual stresses because of debris and micro cracks. The optimum value of residual stresses 86.53 MPa and material erosion rate 6.45 mm/min was achieved using H-WEDM.