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The wear of backup rolls will have a great impact on the quality of the shape of hot rolled strip sheet. In order to overcome the limitations of the finite element method (FEM) in calculating backup roll wear in terms of efficiency and accuracy, this paper proposes a tandem FEM + ML hybrid model to optimise the predictive effect of the finite element method (FEM) on backup roll wear. Firstly, a backup roll wear model based on FEM is established. Secondly, in order to select the optimal machine learning (ML) algorithm as the finite element error compensation model, three types of finite element error compensation models were established based on the random forest (RF) algorithm, the radial basis function (RBF) neural network algorithm, and the particle swarm optimisation support vector machine (PSO-SVM) algorithm. Finally, the three types of finite element error compensation models were connected in series with the FEM model to compare the prediction performance of the three types of FEM + ML models on backup roll wear. The numerical experimental results show that the FEM + PSO-SVM model can better predict the wear of the backup roll, and the PSO-SVM algorithm is the most suitable for building the finite element error compensation model. It is proved that the FEM + ML model proposed in this paper can effectively improve the accuracy and computational efficiency of the FEM model for predicting backup roll wear without adding microelements. In addition, among the hot rolling parameters, the rolling force has the greatest influence on the backup roll wear, and excessive rolling force for a single pass should be avoided to slow down the backup roll wear. [ABSTRACT FROM AUTHOR]

This paper presents a computer-based methodology to support the design for additive manufacturing of metal components. Metal additive manufacturing, and in particular powder bed fusion systems, are playing a prominent role in the industry 4.0 scenario. The state of the art concerning design methods and tools to support design for additive manufacturing is reviewed by the authors. The key phases of product design and process design to achieve lightweight functional designs and reliable processes are deepened, and the computer-aided technologies to support the approaches implementation are described. Indeed, the state of the art design for additive manufacturing general workflow can be enriched by holistic approaches, use of numerical simulation, and integration and automation between the required tasks. The paper provides a methodology based on the systematic use of numerical simulation to achieve the optimization of both products and associated processes. To take advantage of the holistic perspective, the approach relies on the use of integrated product-process design platforms, allowing to streamline the digital process chain. Product design is based on the systematic integration of topology optimization and automatized tools for concept development and selection and subsequent product simulation driven design refinement. Process design is based on a systematic use of process simulation to prevent manufacturing flaws related to the high thermal gradients of metal processes and minimize residual stress and deformations. This is achieved by working on both the build cycles layouts and the 3D models' distortion compensation. An automotive use case of product and process design performed through the proposed simulation-driven integrated approach is provided to assess the actual method suitability for effective re-designs of additive manufacturing high-performance metal products. The bridged gaps are systematically outlined, and further developments are discussed. [ABSTRACT FROM AUTHOR]

Elastic deformation in thin-walled parts during machining is affected by the coupling of force and flexibility. Obtaining flexibility information along machining tool paths is crucial for online monitoring of this deformation. However, the current finite element method (FEM) is limited by mesh nodes, hampering its ability to accurately determine flexibility along tool paths. To overcome this limitation, this paper proposes a method that combines FEM with the surrogate model to predict flexibility accurately at any position on thin-walled parts' surfaces. The surrogate model is the hybrid model K-K-CNN based on two K-nearest neighbor (KNN-KNN) algorithms and a convolutional neural network (CNN) model. Initially, an initial dataset containing positions and flexibility of mesh nodes is generated automatically through secondary development of ABAQUS. Then, the K-K-CNN hybrid model is introduced and trained on this dataset to calculate flexibility accurately at any position on the surface of thin-walled parts. The hybrid model employs a CNN to address the nonlinear spatial correlation issue in flexibility prediction. Moreover, the hybrid model incorporates two KNN algorithms to alleviate the overfitting challenge stemming from the straightforward input features and extensive dataset size. In comparison to traditional deep learning models, the K-K-CNN hybrid model presents notable benefits in predicting flexibility for complex thin-walled parts at any given position, which affirms its robustness and accuracy. The proposed prediction method for flexibility can provide high-quality data-driven information for monitoring the elastic deformation of thin-walled parts. [ABSTRACT FROM AUTHOR]

Reliable prediction of the grinding force is essential for improving the grinding efficiency and service life of the grinding head. To better optimize and control the grinding process of the grinding head, this paper proposes a grinding force prediction method of the grinding head that combines surface measurement, statistical analysis, and finite element method (FEM). Firstly, a grinding head surface measurement system is constructed according to the principle of focused imaging. The distribution model of abrasive grains in terms of size, spacing, and protruding height has been established by measuring and counting the characteristics of abrasive grains on the surface of a real grinding head. Then, the undeformed chip thicknesses when the abrasive grains are cut are analyzed in depth, the material model of abrasive grains and workpiece is established, and the cutting process of abrasive grains with different characteristics on the surface of the grinding head is analyzed by finite element simulation. A single abrasive grain grinding force model is obtained. Finally, the grinding force prediction of the grinding head was realized by combining finite element simulation with grinding kinematics analysis. In addition, grinding experiments with different grinding parameters were conducted to verify the grinding force prediction model. The results show that the predicted grinding force of the grinding head is in good agreement with the experimental values. The average error of tangential grinding force is 7.42%, and the average error of normal grinding force is 9.77%. This indicates that the grinding force prediction method has good accuracy and reliability. [ABSTRACT FROM AUTHOR]

The paper investigates the characteristics of the laser beam percussion micro-drilling (LBPMD) process in aerospace nickel-based superalloy Hastelloy X using microsecond pulses. The quality of the drilled hole is crucial in laser beam micromachining, and selecting appropriate process parameters significantly impacts the hole's quality. The objective is to achieve predefined hole dimensions with minimal taper angles. Additionally, the study focuses on the alteration of pulse width, which is a combination of laser pulse frequency and duty cycle. Laser power (P), duty cycle % (D), focal plane position (FPP), and laser frequency (f) are considered input parameters, while geometric features such as inlet and outlet diameters, hole taper angle, and inlet circularity are examined as process responses. ANOVA is employed to establish significant relationships between process parameters and response variations based on experimental tests. Creating a precise simulation model that accurately accounts for the moving boundary of the target material's receding surface is a crucial and challenging task in formulating the laser heat conduction problem. It is necessary to simultaneously capture the material's dynamic front movement and update the boundary conditions of the laser source. To model the micro-drilled hole with LBPMD, the UMESHMOTION and DFLUX subroutines, along with the arbitrary Lagrangian-Eulerian (ALE) adaptive remesh algorithm in the Abaqus™ software, are utilized. Notably, no previous numerical study has predicted the geometry of micro-drilled holes using this technique. The proposed procedure is validated through the predictions of inlet and outlet hole diameters. Special emphasis is placed on the validation of models. Consequently, the numerical model and statistical model are compared as well as the need to define model applicability. The study demonstrates that all input parameters significantly influence the inlet hole diameter, while the pulse width notably affects the taper angle and circularity. The interaction between high laser frequency and low duty cycle results in reduced pulse duration. Multi-objective optimization is performed to determine the optimal process parameter settings for desired quality characteristics, considering minimum hole taper angle, precise inlet diameter, and maximum inlet circularity of the hole as optimization criteria. The findings show that with the optimized predicted results obtained from the optimal input variables, a composite desirability of 92% can be achieved. [ABSTRACT FROM AUTHOR]

The working temperature of any 3D printer has a critical effect on process feasibility as well as the final quality of the product. In this respect, thermal analysis can provide a comprehensive understanding of operation parameters and optimization potential. This most certainly also is the case for the new layer-wise additive manufacturing system, selective thermoplastic electrophotographic process (STEP). In the present paper, we propose a 3D part-scale finite element thermal model for multi-materials which is developed in the commercial software Abaqus/CAE 2021. The reduced-order method, flash heating (FH), is adopted in the model to obtain good accuracy with acceptable simulation time. A specific analysis of the trade-offs between accuracy and CPU-time is carried out by varying the amount of lumping in the meta-layers in the FH method. Furthermore, we conduct an in-house experiment in which we use IR cameras for measuring temperatures during manufacturing, and the results are applied for model validation and calibration. We specifically compare measured and numerically predicted average surface temperatures when steady state is obtained after printing of each layer. Here we obtain a mean error up to 6% depending on the thickness of the meta-layers. Moreover, parametric studies show that pulse duration and heater intensity significantly influence both the surface and bulk temperature profiles, and this provides us with an increased understanding of the thermal behavior of the recently developed STEP process which in turn could make way for further process optimization. [ABSTRACT FROM AUTHOR]

For the rolling process from rectangular blank to profiled ring, there is a lack of simple and rapid prediction method for geometric size. Based on the constant volume principle and the discrete idea from slab method, a rapid prediction model (RPM) describing the exact geometry of ring is established, and a simplified prediction formula for the section shape of profiled ring in the rolling filling process is proposed. This method is used to analyze the rolling process of typical profiled ring, and the results are compared with the rolling experiment, the finite element model (FEM), and the formula model (FM). The results show that this method has higher prediction accuracy than the constant volume formula method and higher calculation efficiency than the finite element method. The rapid prediction method proposed in this paper is of great significance for improving the analytical efficiency of profiled ring rolling. [ABSTRACT FROM AUTHOR]

Cold hole expansion is a crucial technology for enhancing the fatigue life of hole structures. This paper presents the design and optimization of a novel multi-convex hulls expansion tool for deep small holes in Inconel 718 superalloy using the finite element method (FEM) and experimental techniques. The results from the FEM model, which was used to investigate the compressive residual stress (CRS) distribution and contact force during the expansion process, indicate that the curved single convex hull (CSCH) structure is more suitable for deep small hole expansion (DSHE). However, accounting for the strength limitations of the actual expansion tool, a multi-convex hulls expansion tool structure was proposed. The FEM model was employed to compare the effects of various tool structures on the hole wall CRS distribution and the contact force during the expansion process. The obtained optimal parameters for enhancing deep small holes in Inconel 718 superalloy under high temperature and high load conditions are as follows: expansion section hull spacing l1 = 0.4 mm, taper ratio C = 0.008, number of convex hulls in the sizing section n = 10, and sizing section hull spacing l2 = 1 mm. Moreover, an optimized convex hull expansion amount allocation scheme was obtained through an experimental study. The results of the FEM simulations and experimental study demonstrate that the optimized multi-convex hulls expansion tool (with an expansion rate of 1.92%) can induce the formation of a high CRS layer and a refined surface without causing significant microcracks in the hole walls. [ABSTRACT FROM AUTHOR]

Integrated induction heating and mechanical rolling forming (IH-MRF) is a new method for producing complex curvature hull plates. The plate undergoes deformation through sequential or simultaneous action of induction heating and mechanical rolling. Understanding the mechanism of this forming process is essential for developing intelligent forming systems. Finite element simulation is a leading research tool in this area. However, the rigorous requirements on the number of model nodes and incremental steps of the simulation for direct modeling of inductor and rollers result in inefficient modeling and calculation processes. To address this issue, an equivalent load model for IH-MRF simulation is proposed in this study. The inductor is simplified to an equivalent heat source model, and the roller is simplified to an equivalent mechanical load model. The equivalent load model for the simultaneous action of induction heating and mechanical rolling is a simple superposition of the equivalent heat source model and the equivalent mechanical load model. The experiment and simulation results are consistent in terms of temperature trends, temperature values, and deformation. The research in this paper lays the foundation for developing an intelligent IH-MRF forming system based on finite element simulation methods. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the mechanical behavior of corrugated board boxes, focusing attention on the strength that the boxes are able to offer in compression under stacking conditions. A preliminary design of the corrugated cardboard structures starting from the definition of each individual layer, namely the outer liners and the innermost flute, was carried out. For this purpose, three distinct types of corrugated board structures that include flutes with different characteristics, namely the high wave (C), the medium wave (B), and even the micro-wave (E), were comparatively evaluated. More specifically, the comparison is able to show the potential of the micro-wave which would eventually allow a significant saving of cellulose in the fabrication process of the boxes, thus reducing the manufacturing costs and causing a lower environmental footprint. First, experimental tests were carried out to determine the mechanical properties of the different layers of the corrugated board structures. Tensile tests were performed on samples extracted from the paper reels used as base material for the manufacturing of the liners and flutes. Instead, the edge crush test (ECT) and box compression test (BCT) were directly performed on the corrugated cardboard structures. Secondly, a parametric finite element (FE) model to allow, on a comparative basis, the study of the mechanical response of the three different types of corrugated cardboard structures was developed. Lastly, a comparison between the available experimental results and the outputs of the FE model was carried out, with the same model being also adapted to evaluate additional structures where the E micro-wave was usefully combined with the B or C wave in a double-wave configuration. [ABSTRACT FROM AUTHOR]

Cutting toolholders, with designed in-built compliant mechanisms, are frequently used for machining microfeatures. In this paper, compliant structures are designed using trusses as they exhibit a superior strength-to-weight ratio. Systematically stacked two-stage truss structures along with flexure hinges are designed to yield the desired precise cutting motion. The materially reduced efficient design amplifies the output force and greatly assists in overcoming cutting resistance during machining. The characteristics of the designed compliant tool holder are analysed by considering the output force and displacement for a given input. Both mathematical modelling to determine the force and finite element analysis to identify the critical stress regions when subjected to a prescribed input displacement are presented. As part of dynamic analysis, modal analysis and harmonic response studies were performed to determine how the trussed compliant structure deforms when subjected to dynamic loadings. The designed tool holder was additively manufactured using functionally rigid polyamide-12-glass-bead (PA12-GB) material. The performance of the developed cutting tool holder is then verified by machining radially graded surfaces following which, the machining results are presented in this paper. [ABSTRACT FROM AUTHOR]

The static stiffness of machine tools is one of the key parameters influencing the accuracy of dimensions, shape, and relative positioning of the surfaces of workpieces being machined. This paper presents an analysis of the effect of the stiffness of individual structural components on the resulting stiffness of a prototype vertical lathe with a steel-polymer concrete main frame. This analysis was carried out using a finite element model of the lathe, which was experimentally verified. It was shown that filling the body with polymer concrete significantly (by 30%) increases the static stiffness and damping of the lathe's steel support system. However, the sensitivity analysis carried out in the paper showed that the tool head bearing stiffness has a more significant effect on the static stiffness of the machine tool. [ABSTRACT FROM AUTHOR]

Single-point incremental forming (SPIF) is a technology that allows obtaining complex parts using a hemispherical end tool by applying a local deformation process in sheet metal. This dieless process presents the advantage of high formability limits and low cost. The increasing need for micro-components, namely, in the medical industry (implants and medical tools and accessories), has contributed to the development of the micro-single-point incremental forming (µ-SPIF) technique. However, this technique requires meeting certain challenges related to tool wear, resistance and precision of the manufactured parts, and increased formability. So, understanding the deformation and failure mechanisms in µ-SPIF is important to achieve improved formability. This paper is aimed at improving the predictions of the shear-modified GTN damage model by proposing an identification procedure for its numerous material parameters based on an inverse method coupling the numerical predictions with experimental results. The extended GTN model is first implemented into the finite element code Abaqus. The numerical approach is assessed through numerical simulations under shear and uniaxial tension loading. Then, a complete methodology is proposed to identify the set of material parameters using tensile and micro-single-point incremental forming (µ-SPIF) experimental results. The identification approach is based on the comparison of the numerical and experimental forces used to carry out the micro-incremental forming test with a pyramidal shape tool. To show the pertinence of the identification procedure, the numerical predictions of the modified GTN model with these material parameters are compared to the experimental results of µ-SPIF tests with different tool paths and geometrical forms. Finally, it is shown that the shear modification of the GTN model can predict the failure of sheets during metal forming. [ABSTRACT FROM AUTHOR]

This paper presents an in situ monitoring method for numerical controlled manufacturing of large conceptual prototype based on multi-view stitching fusion (MSF). With the extensive application of numerical controlled manufacturing, like additive and subtractive manufacturing (ASM), the forming size tends to increase. Nevertheless, limited by optical lens and affiliated machine vision parameters, it is difficult to avoid the existence of blind areas when detecting defects including scratch, crack, pore, and thermal deformation by machine vision. To overcome the obstacles, multi-view information, including visible and depth sequences, were captured during the manufacturing progresses to expand monitoring scope. The overlapped regions of various frames were confirmed by stitching fusion of multi-views with homography matrix. The flaws were detected by superposing anomalous regions of multi-views which were extracted via multi-dimension synthetical anomalous degree map. The finite element analysis (FEA) was conducted to extract susceptible regions and locally adjust threshold. Inspired from digital twin visualization of Boundary representation (B-Rep), the numerical controlled manufacturing process of large textureless conceptual prototype can be quantized and visualized synchronously. The numerical outcomes were evaluated and verified that the MSF was effective in distinguishing wide-range defect regions of in situ large parts, thereby generating feedbacks. The physical experiment was implemented on W12 engine upper block and thin-walled shell of engineering machinery with laser stereo lithography appearance (SLA). The physical experiment prove that it is of great significance for fabricating large-scale high reflective objects with low defect and high efficiency, further for prototype verification of conceptual design. [ABSTRACT FROM AUTHOR]

Two-phase, brittle-hard materials are widely used not only in the tool industry but also increasingly in the aerospace industry. Due to the two-phase nature, the materials have unique material properties adapted to the respective application. But the material properties also lead to challenging machinability. Therefore, two-phase, brittle-hard materials are mostly ground. The analogy process of single-grain scratching is used to analyse the material removal behaviour and design the grinding process. Since single-grain scratching is time-consuming and costly, it is desirable to substitute the analogy process with numerical simulation. This paper discusses the suitability of the Smooth Particle Hydrodynamic (SPH) simulation method in combination with the Finite Element Method (FEM) for single-grain scratching of two-phase, brittle-hard materials. The approach is validated using the examples of tungsten carbide-cobalt (WC-Co) cemented carbides and Silicon carbide fibre-reinforced silicon carbide (SiC/SiC) ceramics. For both applications, the material removal behaviour was optically analysed and in good agreement with the experimental results and theoretical assumptions. For SiC/SiC ceramics, several surface phenomena could be identified in the simulation as well as in the experimental results. The scratching forces were compared qualitatively and were in good agreement with the experimental results for both applications. [ABSTRACT FROM AUTHOR]

To optimize the wall thickness quality of three-roll skew rolling (TRSR) hollow axle, this paper explores the wall thickness quality from the perspective of forming mechanism and test design analysis. First, the finite element model of TRSR hollow axle was established based on SIMUFACT software. Second, the evolution characteristics of workpiece wall thickness under various initial wall thickness conditions were found by single factor test. Third, based on the metal flow velocity, the formation mechanism of wall thickness at different positions of the workpiece is discussed, and the causes of various wall thickness defects are found. Fourth, the wall thickness quality evaluation index was proposed and the orthogonal test was carried out. The relationship between process parameters and wall thickness quality was obtained. Fifth, a method of using irregular billets was proposed to improve wall thickness quality. The results indicate that the diversity of initial wall thickness of the workpiece can lead to two phenomena: wall thinning and wall thickening. A larger wall thickness will result in thinning of the wall thickness, while a smaller wall thickness will result in thickening of the wall thickness. The method of adjusting process parameters has limited impact on improving wall thickness quality. The method of using irregular billets can greatly improve the wall thickness quality of the hollow shaft. [ABSTRACT FROM AUTHOR]

Process parameters have a great impact on product quality in stamping. In the paper, in order to improve the formability of 7A09 aluminum alloy in stamping, the influence of different heat treatment schemes on the properties of 7A09 aluminum alloy is analyzed, and a pretreatment process suitable for 7A09 aluminum alloy stamping is formulated. At the same time, to optimize pretreated 7A09 aluminum alloy stamping parameters, an improved BP neural network and multi-objective particle swarm algorithm are proposed. Relevant tensile and bulging experiments of different shapes are carried out for the pretreated 7A09 aluminum alloy material. The Hockett-Sherby constitutive equation is established. Take a double-C part as an example, the stamping process is simulated by a finite element model, and the stamping process of the double-C part is optimized by means of the improved BP neural network and multi-objective particle swarm algorithm. The results show that the proposed methods can effectively improve the quality of the formed part. [ABSTRACT FROM AUTHOR]

Alloy 2060, a new generation of aluminum–lithium (Al-Li) alloy, is widely used for aviation structural parts due to its high-specific strength and high-specific stiffness. However, poor formability of Al-Li alloy is commonly exhibited at room temperature. In this paper, the formability of Al-Li alloy 2060 was studied under the conditions of elevated temperatures. The Marciniak–Kuczynski (M–K) model was developed to effectively predict the forming limit curves (FLCs) under hot stamping conditions. Firstly, the hot tensile test was conducted to investigate the high-temperature deformation behaviors, and the Fields–Backofen equation was calibrated to represent the flow stress of the alloy. Then, the isothermal hemispherical punch tests were proposed to obtain the FLCs of Al-Li alloy 2060. Finally, the FLC predicted by the M–K model was input into the deep drawing finite element simulation model to verify the accuracy of the prediction results and predict the possible fracture of the hot stamping parts. The cup-shaped deep drawing test and the thin-walled shell part hot stamping test were carried out to verify the accuracy of the FLCs and the formability of the Al-Li alloy 2060. The results show that the true stress increases with the strain rate increasing and decreases with the temperature increasing. The established M–K model can accurately predict the FLCs of alloy 2060. It is also found that the initial thickness imperfection factor f0 is an important parameter that determines the change of FLC. Comparing the experimental and simulation results, it is concluded that the established M–K model would be adaptable in the FE simulation to estimate if the fracture of parts occurs. The simulation model considered the FLC can predict the fracture, thinning, and wrinkle of the parts. The stamping depth increases with the deformation temperature increasing and the blank holder force decreasing. [ABSTRACT FROM AUTHOR]

As a mature shape-controlling technology, the segmented cooling of the work roll can directly change the thermal expansion of the work roll, and that affects the thickness and elongation distribution along the width direction of the strip. However, it cannot improve shape defects at the two edges of a strip. In this paper, edge thermal spraying is applied to solve the shape defects at the two edges of a strip because it can change the temperature field and thermal expansion locally at the two edges of the work roll, which is contrary to cooling. Through establishing and solving the thermodynamic coupling finite element model of the work roll, it was found that edge thermal spraying can raise the temperature and thermal expansion at the edges of the work roll and hardly influence the temperature inside the work roll. The relationship between the local increment of thermal expansion and the temperature difference between cooling water and heating water was fitted to a linear model. Then, this model was applied in a real rolling process, and it was found that the effect of edge thermal spraying on flatness defects at the edges of the work roll was significant. [ABSTRACT FROM AUTHOR]

Machine hammer peening (MHP) is a novel surface modification process that can strengthen and smoothen the treated parts in one process, significantly improving their fatigue performance. The strengthening effect is mainly due to the induced highly controllable residual compressive stress on the subsurface. However, the residual compressive stress induced by MHP is usually anisotropic, with the component perpendicular to the feed direction more significant than parallel. The anisotropic residual stress will have an adverse effect if the treated parts are subjected to multiaxial loads, which puts forward high demands to precisely tune such anisotropy. For this purpose, a finite element model with a velocity-based driving mode is first established in this paper, which can simulate the residual stress induced by MHP. The origin of the anisotropy is then revealed by analyzing the evolution of the simulated residual stress. Based on this, methods to precisely tune the residual stress anisotropy are proposed. The residual stress anisotropy can be precisely tuned by optimizing MHP parameters, including the overlap ratio, impact velocity, and MHP path. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the impact of various cutting parameters on the micro-cutting mechanism of high-entropy alloy FeCoCrNiAl0.6. It examines the cutting force, cutting temperature, and residual stress of FeCoCrNiAl0.6 high-entropy alloy micro-cutting using the finite element simulation method. The research findings reveal the following: as the cutting depth increases, the three-dimensional cutting force gradually rises, exhibiting a significant growth trend, and there is a positive correlation between them. Increasing the cutting speed results in small fluctuations in cutting force, which remains relatively stable. Moreover, the cutting force gradually increases with higher feed rates, demonstrating a positive correlation. The maximum temperatures of the tool surface and chip surface increase with higher cutting depth, and they are positively correlated. There is a positive correlation between cutting temperature and cutting speed. With increased cutting speed, the maximum temperature of the cutting surface steadily rises. Simultaneously, during cutting, the chip temperature increases at a faster rate compared to the tool temperature with increasing cutting speed. As the feed rate continuously increases, the maximum temperatures of the chip surface and tool surface show a steady growth trend, and there is a positive correlation between them. During the cutting process, the workpiece surface is predominantly characterized by residual compressive stress. Under different cutting depths, the absolute value of the maximum residual compressive stress on the workpiece surface decreases. Under the influence of cutting speed, when the cutting speed is below 110 mm/s, the residual compressive stress on the workpiece surface demonstrates an increasing trend. For cutting speeds between 110 and 170 mm/s, the workpiece surface initially exhibits a decreasing trend followed by an increasing trend. Increasing the feed rate leads to an increase in the absolute value of the maximum residual compressive stress on the workpiece surface. [ABSTRACT FROM AUTHOR]

Machining-induced residual stress is an important measure of surface integrity. The residual stress affects the quality and performance of the workpiece. In the process of cutting, it often encounters the situation of multi-pass cutting. The formation of residual stress in the process of single- or multi-pass cutting has been widely studied, but few researchers consider the same total radial cut depth, divided into single-pass cutting and multi-pass cutting, and the last cutting in the process of multi-pass cutting is less studied. The difference between single-pass cutting and multi-pass cutting is that the former machining of cutting is used as the initial state of the latter machining. The stress/strain and temperature generated on the surface of the former machining can affect the subsequent cutting force, temperature, plastic deformation, and the final residual stress. This paper studies the distribution of cutting force and residual stress generated by single- and multi-pass cutting of Al-7075-T6, and focuses on the analysis of the multi-pass cutting strategy. The three-dimensional finite element method is used to simulate, and the experimental results are in good agreement with the simulation results. The results show that compared with single-pass cutting, multi-pass cutting can reduce the surface tensile stress and the magnitude and depth of underground residual compressive stress, and the effect of decreasing method is more obvious when multi-pass cutting. The last machining is affected by the previous cutting. When the next radial cutting depth is greater than the plastic deformation depth produced by the previous cutting, the next radial cutting depth is the same, and the trend of residual stress is approximately the same. The results can guide the optimization of residual stress in the multi-pass cutting strategy. [ABSTRACT FROM AUTHOR]

Composite laminates are widely used in various engineering applications due to their excellent mechanical properties and lightweight nature. However, predicting their behaviour and damage evolution remains a challenge due to the complexity of the inter/intralaminar failure modes. In this paper, we propose a new progressive damage model that takes into account both inter and intralaminar failure modes to accurately predict the flexural behaviour and damage evolution of composite laminates under three-point bending. The proposed model incorporates a progressive failure algorithm and gradual stiffness degradation rules through a user defined subroutine UMAT to predict further damage evolution following damage initiation, estimated by the combination of the three-dimensional Puck failure criteria and the cohesive zone model. One of the objectives of this research is to develop a finite element model (FEM) capable of simulating the behaviour of different composite laminates under three-point bending, to reduce effectively processing time and testing costs. As part of the investigations carried out in this study of two types of composite laminates IMS194/CYCOM977-2 and AS4/PEEK, we considered the prediction of ultimate load and stiffness. The results showed significant agreement with the experiments, as well as degradation trends in the load vs. deflection curves. In addition, the interaction between matrix cracking and delamination has been addressed, alongside the impact of cohesive zone elements on the strength of the material. Corrodingly, we found that the interface strength should be considered, to fully exploit the laminate features, and to reduce the effect of delamination which causes intra-laminar longitudinal cracks to appear under the effect of higher inter-laminar stresses. Furthermore, a mesh dependency of the model used has been conducted, to determine the optimal mesh size and shape required to accurately capture the behaviour of the composite laminates. The significance of our study lies in the development of a more accurate and reliable progressive damage model that can improve the design and engineering of composite laminate. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) is widely used in the aerospace field due to its excellent physical and mechanical properties such as high specific strength, high specific modulus, and good corrosion resistance. However, it is prone to bring burrs, tears, matrix, and fiber debonding during the cutting process due to its non-homogeneity and anisotropy, which seriously affects the service life of the material. To explore the damage failure mechanism of the CFRP cutting process, 2D and 3D finite element simulation models were established based on Abaqus in this paper. Furthermore, the influence law of fiber direction on cutting damage failure and chip forming was analyzed from micro and macro levels. Finally, the effectiveness of the simulation model was verified by experiments. The results show that the cutting surface of CFRP with a 45° fiber angle is serrated, and the local failure is not obvious; the main defect of CFRP with 90° fiber angle cutting is a matrix and fiber debonding, and some fibers will be crushed and off. Serious degumming phenomenon occurred in the cutting process of CFRP with 135° fiber angle, and the bending and fracture of fiber also occur below the cutting depth. It is noteworthy that the stress distribution diverges along the fiber direction. [ABSTRACT FROM AUTHOR]

Fused silica glass and other hard and brittle materials are widely used in optical components, microfluidic chips and other fields, which have the characteristics of high hardness, low ductility, and difficult processing. Using traditional milling method not only causes tool wear, but also causes the surface and sub-surface damage of components, which seriously affects the quality of components. In order to improve the surface quality and processing efficiency, laser-assisted micro-milling process is proposed in this paper. Using laser as a material softening tool, the ductility domain of the material can be enlarged, and the surface roughness of the fused silica workpiece can be effectively improved. In this paper, through the method of finite element simulation and experiments, the relationship between laser parameters and processing temperature of fused silica elements is calculated, and several groups of laser parameters are selected as experimental parameters. The experimental results shows that the surface roughness of fused silica workpiece can be effectively reduced to 51 nm, and the tool wear width can be reduced to 3.8 μm after laser assisted. [ABSTRACT FROM AUTHOR]

In this paper, the injection molding technique is selected, and different internal and external defects have been evaluated, including warpage, short shot, and shrinkage. Different geometric and injection machine inputs such as gate type, filling time, part cooling time, holding pressure time, and melt temperature have been chosen, respectively. The Taguchi method is applied to find the best level of each parameter. In recent years, researchers have been focused on using machine learning techniques with a combination of meta-heuristic methods to calculate the optimal process parameters in injection molding to increase the quality of the final product. However, the computational load of the machine learning methods and meta-heuristic algorithms is far behind in handling real-time applications. The main motivation of this study is to reach an accurate model with a low computational load to handle the real-time computational load even in the presence of lower CPU power controller mechanisms. Then, the genetic programming method is employed to extract the optimal mathematical model of the injection-molding process, which relates the processing parameters, including part cooling time, filling time, melt temperature, and holding pressure time, to output which is the combination of shrinkage rate, short shot, and warpage. The extracted optimal mathematical formulation of the genetic programming method is employed inside the interior point nonlinear programming solver via the fmincon function of MATLAB software to calculate the optimal parameters of the process as fast as possible. The genetic programming results are compared with previous methods such as decision tree, support vector regression, and multilayer perceptron to prove the acceptable accuracy of the first part of the paper with the lower computational load. Then, the means square error between the finite element method and the extracted result using the hybrid genetic programming and interior point nonlinear programming solver is 47.06%, 93.75%, and 83.63% lower than previous methods, including decision tree, support vector regression, and multilayer perceptron, respectively. [ABSTRACT FROM AUTHOR]

Forming large thin-walled hemispherical parts by hydroforming, serious thinning of wall thickness, instability of suspension area, and fracture are often accompanied. In order to solve the above problems, this paper takes AA6061-T6 aluminum alloy thin-walled hemispherical parts as the research object, and uses the method of finite element numerical simulation analysis and experimental verification to carry out the formability analysis of double-layer sheet hydroforming. In order to improve the accuracy of numerical simulation, uniaxial tensile tests are carried out on AA6061-T6 tensile specimens. Based on the BP neural network prediction model, a constitutive model that can truly reflect the plastic deformation characteristics of materials is established, which can provide more accurate material properties for numerical simulation. In this paper, the wall thickness and fittability of the parts are taken as the evaluation indexes, and the simulation analysis of the double-layer sheet hydroforming is carried out combined with the pre-bulging process, and the process flow of the single-sheet and the double-layer sheet hydroforming is compared and analyzed. The forming law of formed sheet under different friction coefficient between sheets and different upper sheet thickness is discussed. In addition, the influence of different temperature on the forming quality of parts is also discussed. It is found that the sheet metal will soften at the appropriate temperature, and the wall thickness distribution of the parts suspending area will be further improved. Finally, the forming experiments are carried out using the optimized process conditions, and the results are basically consistent with the simulation results. The results show that the research can effectively provide scientific guidance for the forming of large thin-walled hemispherical parts. [ABSTRACT FROM AUTHOR]

As a kind of interference rivet with compensation at the head, the reduced countersunk head half-crown rivet can achieve long life sealing riveting for airplane types or engine rooms with special requirements for sealing and fatigue performance. In the present study, a quartered three-dimensional finite element model was created to simulate the riveting process. The FE model was validated from the perspective of driven head dimensions and interferences based on the experiment results. The effects of feed displacement of rivet dies, feed speed ratio of rivet dies, pre-feed displacement of upper rivet die and countersunk depth on the forming quality of riveted lap joints were systematically studied. The results showed that the average interference increased with the increase of the feed displacement of rivet dies, while it decreased with the increase of the feed speed ratio of rivet dies and pre-feed displacement of upper rivet die. The countersunk depth of 1.05 mm is the transition depth for the rivet studied in this paper. In addition, the results of combined effect of feed speed ratio of rivet dies and pre-feed displacement of upper rivet die on the forming quality proved that the influence laws of single parameter were no longer suited for the scenario of combined effect of multiple riveting parameters. This paper can provide scientific and normative guidance for the applications of reduced countersunk head half-crown rivet in engineering structure. [ABSTRACT FROM AUTHOR]

The corner filling of hexagonal convex ring is an important basic problem in the variable section forming technology of tube. It is easy to crack the tube in the forming area of the corner and difficult to obtain qualified products. This paper presents a new method of forming hexagonal convex ring with ultrasonic-assisted granular medium forming (UGMF) technology. Based on the finite element method (FEM) and discrete element method (DEM) coupling model, the wall thickness of tube, the shrinkage length of tube end, forming force, and the radius of corner are investigated. The experimental results show that vibration can reduce the radius of corner forming, improve the wall thickness distribution of corner area, and reduce the forming force. All these results indicate that UGMF is a new forming technology for convex ring tubes with hexagonal. [ABSTRACT FROM AUTHOR]

Through-mask electrochemical micromachining (TMEMM) has been widely used in the machining of micro-structures because of its high processing efficiency, no electrode loss, and no residual stress. In order to solve the problem of poor structure uniformity in the process of TMEMM, this paper proposed a moving cathode TMEMM technology on the basis of conventional TMEMM and made a microgroove array based on the moving cathode TMEMM technology. Firstly, the numerical analysis of moving cathode TMEMM was carried out by COMSOL finite element analysis software. The influence of different machining parameters on the anodic micro-groove etching profile was studied and the nonuniformity of the etching depth was calculated. The simulation results show that moving cathode TMEMM can improve the etching depth uniformity of microgroove array structure. Secondly, on the basis of numerical simulation, TMEMM experiments were carried out. The experimental results indicate that the moving cathode TMEMM method can effectively improve the size uniformity of microgroove array. It can be observed by microscope that the microgroove array obtained by TMEMM with a moving cathode has good structural morphology and higher uniformity. Compared with conventional TMEMM, the uniformity of TMEMM with moving cathode improved by 68.3% and the simulation results are basically consistent with the experimental results. The moving cathode TMEMM method can greatly improve the uniformity of microgroove array. [ABSTRACT FROM AUTHOR]

This paper addresses the problems of easy deformation, difficult dimensional control and difficult accuracy assurance during the production of thin-walled gears for helicopter spoke cutting. It uses finite element simulation technology, metal cutting principles, process optimization and other design and manufacturing technologies to reveal the causes of cutting deformation, effectively predict the deformation of parts during cutting, and develop reasonable deformation control strategies. This study explores the effects of cutting force, residual stress and clamping method on gear machining deformation. The deformation of the spoke plate is analysed by finite element simulation. Abaqus software is adopted to establish a finite element model for 2D turning simulation to predict the machining residual stresses and cutting forces during gear turning machining with different cutting parameters. The simulated cutting forces are compared with the residual stresses and experimentally measured values to verify the accuracy of the finite element model and provide a theoretical basis for model construction in the next simulation study. With Abaqus software, the effect of different cutting forces on the deformation of the spoke plate is simulated, and the effect of the superposition of cutting and clamping forces on the deformation of the spoke plate is simulated using life and death cell technology to simulate the machining of the workpiece. Then, a corresponding fixture is designed to realise the corresponding clamping position for machining experiments, and the deformation of the spoke plate is measured by CMM (coordinate measuring machine) to verify the realism of the simulation. This research provides scientific theoretical guidance and process support for aerospace thin-walled gear spoke plate turning. [ABSTRACT FROM AUTHOR]

This paper explores the possibility of applying reverse engineering to flexible coupling spare parts through additive manufacturing. Although couplings' simplicity makes them go unnoticed, they connect elements that transmit power between two shafts, thus being an essential component for most of the machinery currently used in the industry. In this study, flexible couplings with different infill density (60% and 80%) were 3D printed by the fused filament fabrication technique. The original and the additive manufactured couplings were modelled to compare their compressive response and energy-absorbing characteristics, and experimental tests were performed to validate finite element analysis. To derive an optimal material distribution within coupling structure, a generative design approach was conducted through nTopology software. With this novel simulation-driven design, it is possible to reduce the weight of the redesigned part up to 15.8% by defining the wall thickness of the internal structure based on the results of finite element simulation, while maintaining its functionality. Moreover, an economic-environmental study was carried out. Results ensure that the 3D printed prototypes are suitable for replacing the original one under its current operating conditions. Additionally, the economic study shows that the redesigned couplings allow companies to save more than €2700 per coupling in relation to CO2 emission payments. [ABSTRACT FROM AUTHOR]

Cast steel nodes are widely used as important components of offshore platform, owing to their better performance than welded nodes. In this paper, the mold filling and solidification process of cast steel nodes were numerically simulated and verified by the finite element analysis commercial software package—ProCAST, and the occurrence of shrinkage porosity was quantitatively predicted based on the simulation results. The numerical simulation results of the preliminary design showed that the overall filling was stable with bottom gated system, agreeing well with the design requirements. However, the shrinkage porosities in the intersection of lower tubes and main tube were evident due to the insufficient feeding. Optimization of the casting design was carried out through repeated computer simulation. By incorporating chills in the cores, the optimized design showed that the shrinkage porosities in the intersection of lower tubes and main tube were effectively eliminated. In view of these aforementioned optimizations, the casting steel can meet the technical requirements in an actual production. [ABSTRACT FROM AUTHOR]

This paper presents a novel hybrid cutting model for the prediction of workpiece temperature distribution during the dry milling process of compacted graphite iron (CGI). The hybrid model consists of an analytical force model based on a mechanistic approach and finite element analysis (FEA) based on the thermal model. The heat generated during the milling process transferred to the workpiece is computed via the advection heat partition model. The workpiece temperature distribution obtained through the heat loads, using as boundary conditions in the FEA, was calculated by means of cutting forces. The developed force and thermal models have been experimentally validated, and good agreement between the measured and calculated results has been observed. The energy and active work calculations show that by doubling the feed during CGI milling, an energy saving of about 10% is achieved despite almost doubling the cutting forces. [ABSTRACT FROM AUTHOR]

Gear rolling is a cold-forming process by using a cylindrical blank to produce gear teeth with high strength, good surface finish, and high material utilization rate. Gear tooth profile deviation is one of the most important factors in evaluating the gear accuracy. In order to understand the forming process of gear tooth, this paper is dedicated to studying the rolling process from geometry relation based on gear mesh theory. Then, the way of material flow to form the gear tooth in the rolling process is investigated by finite element method. The comparison results show that tooth profile rolled by standard rigid body tool still has a certain tooth profile deviation and tooth thickness deviation during the process of one-way rolling. The left side of the rolled gears has a longer effective length and a worse profile deviation than the right side. The increase in material plasticity and a slower increase in reduction are conducive to improving the accuracy of the precision of the formed workpiece the height of the effective tooth profile. This research will be helpful for process parameter selection and subsequent research for defect compensation. [ABSTRACT FROM AUTHOR]

Nickel-based high-temperature alloys (Inconel 718) are considered to be difficult-to-machine materials with high yield strength and high-temperature strength properties and are widely used in the aerospace industry. Due to the low thermal conductivity of Inconel 718 material, it leads to severe machining hardening and easy to cause tool wear. In this paper, three step drills with different second point angles are proposed, the thrust force and torque models of twist and step drill bits are established, and then the critical burr generating states of the drills are analyzed. The experimental and finite element simulation analyses of the four drills showed that the thrust force, torque, burr, effective stress, and chip flow rate generated by the step drill under conventional drilling conditions were less than those of the twist drill. The torque and thrust force decrease as the angle of the second point angle of the step drill decreases. The smaller the second point angle of step drill, the higher the chip flow rate, the lower the maximum effective stress and the better the machining quality. In addition, the step drill is then compared with conventional drilling (CD) and ultrasonic-assisted drilling (UAD) to analyze the differences in temperature and chip morphology, and the results show that the machining temperature is lower and chip breaking performance is better under ultrasonic-assisted drilling. [ABSTRACT FROM AUTHOR]

The severe wear of cemented carbide tool can lead to problems such as short tool life and poor part surface integrity. Fortunately, it has been found that the tool wear may be reduced by modifying the cutting edge microgeometry. However, there are a few studies that offer specific instructions for this modification. In addition, it is costly to realize this for machining tools through merely experiments. Therefore, in this paper, an improved approach is proposed by combining the finite-element (FE) simulation method with a user-defined wear rate model. To achieve this, a new wear rate model was proposed at first, regarding the wear mechanisms of the carbide tool during machining of Inconel 718 alloy. Then, four sets of carefully designed cutting tests and FE simulations were carried out to calibrate and verify the new model. At last, extensive FE simulations were conducted to investigate the influence of tool edge microgeometry on tool life. The simulated results indicate that the tool life increases with the increase of the form factor K within a given range. This finding on optimized tool edge was further verified by performing a group of cylindrical turning experiments. The experimental measurements reveal that the tool life has increased by 24% and 50% maximum when increasing K from 0.9 to 2.8 under the two given cutting conditions. [ABSTRACT FROM AUTHOR]

The traditional assembly of aircraft panels mainly adopts special welding fixtures, which cannot meet the needs of timely production and delivery of diversified products. To address this problem, this paper designs a low-cost reconfigurable flexible fixture for preassembling the aircraft panel (short for RFFP), which can achieve the low-cost and flexible preassembly of multiple panels. Besides aiming at the layout optimization problem of the RFFP to ensure the aerodynamic accuracy of the panel, an intelligent layout optimization method of the fixture is proposed, which is combined the convolutional neural network (CNN) with the genetic algorithm (GA) to solve the optimal layout of contour boards as locators for the skin. In this method, the mathematical model of fixture layout optimization is firstly established with the objective of minimizing skin all strain energy. On this basis, the finite element model of the panel-fixture system is built considering the riveting, the self-weight of the panel, and the tension of the elastic bandage. Then, a fixture layout optimization agent model based on CNN is created, and GA is applied to obtain the optimal solution of the agent model, i.e., the optimal fixture layout. Finally, an aircraft fuselage panel is taken as an experimental case for validating the proposed method. The results show that the skin all strain energy can be effectively reduced. The preassembly quality and efficiency of the aircraft panel can be improved, demonstrating the effectiveness and feasibility of this proposed method. [ABSTRACT FROM AUTHOR]

Due to the hidden joint structure, good joining strength, and simple die structure, double-sided self-pierce riveting (DSSPR) has been seen as a potential alternative to self-pierce riveting or resistance spot welding. The chamfered angle position, a new design parameter of tubular rivets, has been proved to influence the joining strength significantly. However, the corresponding mechanism is still unclear. In this paper, the DSSPR experiments of Al 5052 aluminum alloy sheets using tubular rivets with five chamfered angle positions were carried out. The finite element analysis was adopted to clarify the influence mechanism of the chamfered angle position on the joining strength. Mechanical properties and energy absorption were investigated through single-lap shear tests and cross-tension joint pull-out tests. The deformation behavior of sheets and rivet during the DSSPR process were investigated systematically using finite element simulation. The results showed that chamfered angle position has a significant effect on the section structure and mechanical performance of the joint. The shear strength of l = 0.25 and the pull-out strength of l = 0 were about 125% and 221% higher than that of l = 0.5, respectively. In addition, the counter force F1 influences the rivet expansion direction, and the forces F2 and F3 mainly affect the rivet bending degree. The finite element simulation can effectively predict the material flow, stress, and strain distribution of the rivet and sheets during the DSSPR process. When l = 0 or 0.25, the sheet material flows to the outside of the rivet, and a vortex-like phenomenon is formed at the chamfered position. The influence mechanism of the chamfered angle position on the DSSPR process is discussed and explained. The results can provide a deep understanding of the DSSPR process and help to accelerate its engineering application. [ABSTRACT FROM AUTHOR]

This paper proposes a new flexible and microscale roll gap control technology to obtain a stronger strip flatness control ability. According to the principle of microscale roll gap control technology, an electromagnetic control rolling mill with the function of roll profile control and large diameter ratio rolling is designed and built. To analyze the flatness control ability, a comprehensive finite element model (FEM) is established, and an indentation experiment and a rolling experiment are carried out. The simulation results show that under different rolling forces and tensions, the average quadratic crown control ability is more than 40 μm, and the average quartic crown control ability is more than − 3 μm. The control ability increment of the quadratic crown is greater than that of the quartic crown. In the indentation experiment, a stable roll profile can be achieved by PID control after reaching the target roll profile. Increasing the regulation amount can change the strip crown from positive to negative. Even under high rolling force conditions, microscale roll gap control technology can also realize a strip crown adjustment of 19.5 to 0.5 μm. Moreover, this technology can adjust the strip shape from edge waves to non-waves and middle waves in the rolling experiment. In this paper, the feasibility of using this technology to adjust the roll gap shape has been verified, and we demonstrate that the roll gap control goal of uniform transverse size distribution can be achieved. [ABSTRACT FROM AUTHOR]

A novel high-order discretization method for the prediction of milling stability is proposed in this paper to increase the accuracy and efficiency considering the differential of directional cutting coefficient and vibration velocities. Same to the existing full-discretization method (FDM) and semi-discretization method (SDM), the milling system is expressed as a linear time-periodic equation and the time period is discretized into discrete time intervals to approximate the solution. In this algorithm, the cutting force coefficient matrix of the whole integrand is reconstructed to lay the foundation for the fast and accurate approximation. Then, the monodromy matrix (or the Floquet matrix) is calculated by the method used in the temporal finite element analysis (TFEA) instead of the multiple recursive algorithms which can improve the computational time. Finally, the computational efficiency is defined in a new way which gives quantitative comparisons for different discretization methods. It is shown that the proposed method can reduce the computational cost by 91–95% when the same errors are required. [ABSTRACT FROM AUTHOR]

Modeling the forces during micro-milling processes is directly linked to the chip load and mechanistic model parameters that are generally dependent on the tool/work combination. Tool runout, deflection, and the material's elastic recovery mainly affect the chip load as a function of feed. Experimentally measured micro-milling forces can be employed to identify cutting force coefficients and runout parameters. However, decoupling the interplay among runout, deflection, and elastic recovery is difficult when only measured forces are considered. In this paper, machined surface topography has been considered as an additional process output to investigate the influence of runout and deflection separately. The machined surface topography was investigated using a scanning laser microscope to identify minimum chip thicknesss and runout parameters. A finite element model of tool deflection has been developed based on the end mill geometry used in the experiments. The finite element model was used to obtain a surrogate model of the tool deflection which was implemented into the mechanistic model. Nanoindentation tests were conducted on the coated WC tool to identify its material properties which are employed in the finite element model. An uncut chip thickness model is constructed by considering preceding trochoidal trajectories of the cutting edge, helix lag, tool runout, tool deflection, and the chip thickness accumulation phenomenon. The force model was validated experimentally by conducting both slot and side milling tests on commercially pure titanium (cp-Ti). The predicted cutting forces were shown to be in good agreement with the experimental cutting forces. [ABSTRACT FROM AUTHOR]

The strips with good flatness after finish rolling will have flatness defects such as edge wave after run-out table cooling. These defects are caused by the residual stress due to inhomogeneous thermal and microstructural behaviors during the cooling stage. The traditional residual stress control methods rely too much on experience, resulting in poor control effect and poor universality. Therefore, this study proposed two residual stress control methods based on model calculation: water flow central crown and center wave compensation control. The former is mainly based on controlling the uniformity of strip transverse temperature and microstructure. The latter is mainly controlled by mutual compensation of internal stresses. In this paper, the mathematical models of water flow central crown cooling and critical center wave compensation stress were established, respectively. Meanwhile, a post-buckling model of hot-rolled strip was established to calculate the aim flatness value at exit of finishing mill under critical compensation stress. Furthermore, a fully coupled finite element model based on temperature, phase transitions, and stress was developed and it was verified using experimental data. Finally, the above two residual stress control methods were realized in the finite element model. The results showed that the two methods can reduce the residual stress and improve the flatness, and the application of center wave compensation control is more effective. [ABSTRACT FROM AUTHOR]

Multi-roller flow forming has the characteristics of multi-directional loading, which can improve the quality and accuracy of spun products. Roller number and parameter arrangement in a roller set will affect the material flow and rib filling in multi-roller flow forming of cylinders with inner ribs. Therefore, in this paper, a finite element model of multi-roller flow forming was established to explore the effects of roller number and parameter arrangement on the material flow mechanism and the saturation degree of inner ribs of aluminum cylinders with oblique cross ribs. The results show that increasing the roller number can limit the diameter expansion and promote the radial flow of material, thus improving the filling efficiency of rollers and the saturation degree of inner ribs, and that, selecting a large profile radius of roller for the front roller and small profile radius for the subsequent roller is beneficial to rib filling, and the greater the thinning ratio of the first roller, the more material flow into the groove of inner ribs. In addition, an aluminum alloy cylinder with cross ribs had been formed successfully in this study, which had good dimensional accuracy and mechanical properties. The hardness test was used to verify plastic strain distribution in the simulation. These results can provide process guidance for manufacturing on flow forming of cylinders with oblique cross ribs. [ABSTRACT FROM AUTHOR]

In order to better analyze and control the micro milling process of micro ball-end milling cutter, a method combining finite element method (FEM) and regression analysis is proposed to simulate and analyze the micro cutting process of cutting edge micro-element at different axial height positions to achieve micro milling force prediction. Combining cutting edge curve equations and actual measurements establish an accurate micro ball-end milling cutter model, and discrete along the axial direction of the cutter to obtain multiple sets of cutting edge micro-element of equal thickness. In this study, a workpiece micro-element model corresponding to the axial height position of the cutting edge micro-element is established based on the actual cycloidal motion trajectory during the micro milling of the cutting edge. Finite element simulation of single-edge bevel cutting of cutting micro-elements is implemented. Based on the micro cutting force data obtained from the micro cutting simulation, regression analysis is used to obtain the cutting edge micro-element unit cutting force related to axial height and cutter rotation angle for a certain amount of feed per tooth, and then the integral summation is used to achieve the micro milling force prediction. A comparative analysis of the full slot micro milling experiments shows that the predicted micro milling forces are in good agreement with the measured values, which directly verifies the correctness and reliability of the cutting edge micro-element cutting numerical simulation and micro milling force prediction method in the paper. [ABSTRACT FROM AUTHOR]

Double-wire arc additive manufacturing (DWAAM) has a broad application prospect in the fabrication of component because of its higher deposition efficiency than WAAM. However, in the fabrication process of large-size component, due to the large weld bead size, the complexity of structure, and serious heat accumulation, the overall deposition quality will be affected and macro defects will appear. In this paper, DWAAM deposition path strategy is studied in detail by finite element method and experiment. Compared with the change of temperature field and deformation, the heat accumulation of folding path is serious, but the deformation is small (< 3 mm). The folding path is selected as the final path based on the mechanical properties of the samples of 3 paths. The macroscopic defects (unmelted wire, droplet splashing, uneven weld bead, and melt pool collapse) of the deposited sample are analyzed, and the formation mechanism is studied. In addition, by reducing the arc length, improving the arc magnetic blow, and reducing the heat input, large-size special-shaped structural components are successfully manufactured. The defects in the macro morphology are improved. [ABSTRACT FROM AUTHOR]

To improve the rigidity of large composite fuselage panels and reduce the deformation caused by factors such as gravity during the assembly locating process, this paper presents a multi-objective optimisation method of the discrete fixturing layout based on the integration of a back-propagation neural network (BPNN) with the elitist nondominated sorting genetic algorithm (NSGA-II), which considers the characteristics of the composite fuselage panel, such as its complex structure and high tendency to undergo damage when subjected to force, in addition to the control the fixturing system cost. This method can simultaneously determine the optimal number and positions of tooling fixturing points. First, a binary integer variable is proposed to represent the fixturing layout, to realise the coupling representation of the number and positions of the fixturing points. To improve the optimisation efficiency, after comprehensively comparing the prediction accuracies of several commonly used surrogate models, a BPNN prediction model is constructed to describe the nonlinear mapping relationship between the fixturing layout and the maximum deformation (maximum Mises stress) of the composite fuselage panel based on the limited samples obtained by finite element analysis (FEA) and minimax Latin hypercube sampling (MLHS). Thereafter, the allowable deformation of the composite fuselage panel is considered the constraint; the number of fixturing points and the stress of the panel are used as the optimisation objectives. The Pareto solution set of the fixturing layout is determined using NSGA-II. Finally, a composite front fuselage panel case study of a wide-body airliner is considered to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Chatter is a major problem that restricts production efficiency and product quality in the cold rolling process at high speed. Although many research studies have focused on relating rolling parameters to mill stability, information about the roll-stack in the axial direction and the strip in the width direction have not yet been considered due to the limitations of modeling methods. This paper proposes a new finite element model for the Universal Crown Control mill (UCM mill) with an improved Timoshenko beam used to investigate the influence of flatness control actuators on the mill stability. A dynamic rolling force calculation formula coupled with a mixed lubrication model is obtained. Then, the structure–process coupling model is established to simulate the rolling process at both steady and unsteady states. The results show that the work roll bending (WRB) has the greatest impact on the critical speed, followed by the intermediate roll shifting (IRS) and the intermediate roll bending (IRB). During vibration, the distribution of the friction stress varies rapidly, and a negative forward slip appears, which exacerbates vibration. Furthermore, the analysis of the energy dissipation in the rolling interface illuminates the vibration mechanism. Therefore, this study contributes to mechanism improvement and chatter suppression in the cold rolling process. [ABSTRACT FROM AUTHOR]

Turning of the thin-walled cylindrical workpiece is technologically highly demanding process due to the high flexibility of the workpiece. In this paper, a mathematical treatment of integral-based model of the cutting force which takes into account feed, cutting speed, depth of cut and tool nose radius leading to a model of tool-workpiece interaction is presented. The force interaction together with the compliant workpiece dynamics leads to a machining stability formulation. The effect of the aforementioned parameters on characteristic exponents is calculated and validated by comparison with experimentally identified exponents. One of the outputs with immediate practical value is identification of the process damping, which is in the studied case shown to be significantly higher than structural damping of the workpiece itself. This means that without loss of reliability in stability prediction the experimental modal analysis of a given workpiece may be omitted and workpiece's dynamics may be described only by mass and stiffness matrices which can be easily and reliably obtained by a finite element analysis. [ABSTRACT FROM AUTHOR]

When the car suddenly collides, the webbing bunching phenomenon will occur at the upper guide ring (D-ring) of the height adjuster of the seat belt, causing serious damage to the human chest by local positive pressure. In this paper, finite element method is used to calculate lateral displacement of seat belt. The BP neural network training method was used to fit the relationship between the displacement response and the random parameters, and the reliability function was established. The reliability and reliability sensitivity of random parameters were calculated by first-order second-moment method, and the influence rule of belt guide ring and belt parameters on reliability was obtained, which provided a theoretical basis for the parameter reliability design of safety belt guide ring. [ABSTRACT FROM AUTHOR]