Smooth particle hydrodynamics study of surface defect machining for diamond turning of silicon

Acknowledgments The authors would like to thank EPSRC (EP/K018345/1) and Royal Society-NSFC International Exchange Scheme for providing financial support to this research.Peer reviewedPublisher PD

A Comparative Study on the Optimal Modeling of Laminated Glass

This study addresses the challenging task of modeling laminated glass responses to extreme loading scenarios for the design and analysis of protective structures. The primary objective is to seek an optimal modeling approach that balances accuracy and computational efficiency. To achieve this, the failure modeling of laminated glass layups comprising thin and thick panels with three and eleven layers is investigated under blast loading conditions. Various simulation techniques are employed, including the finite element method (FEM) with element erosion/deletion, smoothed particle hydrodynamics (SPH), and a hybrid approach involving the conversion of elements into particles. The feasibility and limitations of each technique are examined, considering both accuracy and computational cost. Experimental results from arena and shock tube testing scenarios assess the deployed modeling techniques and the presented comparisons. Emphasis is placed on mesh sensitivity and the significance of adaptive meshing in capturing fracture patterns. The present paper suggests that utilizing hybrid techniques results in optimal modeling outcomes. Furthermore, the stability of the modeling results under diverse blast conditions is confirmed. This article contributes to the field by offering insights into modeling laminated glass responses to extreme loading, emphasizing the use of hybrid techniques to strike a balance between accuracy and computational efficiency. This research enhances the understanding of protective structure design and analysis, highlighting the critical importance of computational methods in this context. Doi: 10.28991/CEJ-2023-09-11-018 Full Text: PD

A general comparetive study in long rod penetration using corrective smoothed particle method

Corrective smoothed particle method (CSPM) has been used to study the dynamic behavior of targets with different materials; AL, ALN and AL-ALN FGM in long rod penetration of an AL projectile. A mixed strength model with sigmoid formulation has been used to describe both yielding and fracture phenomena in the FGM. The strength model includes the JC dynamic yield relation and JHB fracture model with a continuum damage description approach. An efficient renormalization in continuity density approach is used to improve the SPH approximation of boundary physical variables. This study shows that the CSPM method in combination with the proper strength model describing the FGM dynamic behavior, can predict the mixed plastic and brittle response of different materials in long rod penetration problems

Smooth particle hydrodynamics study of surface defect machining for diamond turning of silicon

This paper presents the feasibility study of potential application of recently developed surface defect machining (SDM) method in the fabrication of silicon and similar hard and brittle materials by using Smooth Particle Hydrodynamics (SPH) simulation approach. Inverse parametric analysis simulation study was carried out to determine the Drucker-Prager (DP) constitutive model parameters of silicon by analysing the deformed material response behaviour using various DP model parameters. Indentation test simulations were carried out to perform inverse parametric study. SPH approach was exploited to machine silicon using conventional and surface defect machining methods. To this end we delve into opportunities of exploiting SDM through optimized machining quality, reduced machining time and lowering cost. The results of conventional simulation were compared with the results of experimental diamond turning of silicon. In the SPH simulations, various types of surface defects were introduced on the work-piece prior to machining. Surface defects were equally distributed on the front face of the workpiece. The simulation study encompasses the investigation of chip formation, resultant machining forces, stresses and hydrostatic pressure with and without SDM. The study reveals the SDM process is an effective technique to manufacture hard and brittle materials as well as facilitate increased tool life. The study also divulges the importance of SPH evading the mesh distortion problem and offer natural chip formation during machining of hard and brittle materials

Investigation of cutting mechanics in single point diamond turning of silicon

As a kind of brittle material, silicon will undergo brittle fracture at atmospheric pressure in conventional scale machining. Studies in the last two decades on hard and brittle materials including silicon, germanium, silicon nitride and silicon carbide have demonstrated ductile regime machining using single point diamond turning (SPDT) process. The mirror-like surface finish can be achieved in SPDT provided appropriate tool geometry and cutting parameters including feed rate, depth of cut and cutting speed are adopted.The research work in this thesis is based on combined experimental and numerical smoothed particle hydrodynamics (SPH) studies to provide an inclusive understanding of SPDT of silicon. A global perspective of tool and workpiece condition using experimental studies along with localized chip formation and stress distribution analysis using distinctive SPH approach offer a comprehensive insight of cutting mechanics of silicon and diamond tool wear. In SPH modelling of SPDT of silicon, the distribution of von Mises and hydrostatic stress at incipient and steady-state was found to provide the conditions pertinent to material failure, phase transformation, and ductile mode machining. The pressure-sensitive Drucker Prager (DP) material constitutive model was adopted to predict the machining response behaviour of silicon during SPDT. Inverse parametric analysis based on indentation test was carried out to determine the unknown DP parameters of silicon by analysing the loading-unloading curve for different DP parameters. A very first experimental study was conducted to determine Johnson-Cook (J-C) model constants for silicon. High strain rate compression tests using split Hopkinson pressure bar (SHPB) test as well as quasi-static tests using Instron fatigue testing machine were conducted to determine J-C model constants.The capability of diamond tools to maintain expedient conditions for high-pressure phase transformation (HPPT) as a function of rake angle and tool wear were investigated experimentally as well as using SPH approach. The proportional relationship of cutting forces magnitude and tool wear was found to differ owing to wear contour with different rake angles that influence the distribution of stresses and uniform hydrostatic pressure under the tool cutting edge. A new quantitative evaluation parameter for the tool wear resistance performance based on the cutting distance was also proposed. It was also found that the machinability of silicon could be improved by adopting novel surface defect machining (SDM) method.The ductile to brittle transition (DBT) with the progressive tool wear was found to initiate with the formation of lateral cracks at low tool wear volume which transform into brittle pitting damage at higher tool edge degradation. A significant variation in resistance to shear deformation as well as position shift of the maximum stress values was observed with the progressive tool wear. The magnitude and distribution of hydrostatic stress were also found to change significantly along the cutting edge of the new and worn diamond tools.As a kind of brittle material, silicon will undergo brittle fracture at atmospheric pressure in conventional scale machining. Studies in the last two decades on hard and brittle materials including silicon, germanium, silicon nitride and silicon carbide have demonstrated ductile regime machining using single point diamond turning (SPDT) process. The mirror-like surface finish can be achieved in SPDT provided appropriate tool geometry and cutting parameters including feed rate, depth of cut and cutting speed are adopted.The research work in this thesis is based on combined experimental and numerical smoothed particle hydrodynamics (SPH) studies to provide an inclusive understanding of SPDT of silicon. A global perspective of tool and workpiece condition using experimental studies along with localized chip formation and stress distribution analysis using distinctive SPH approach offer a comprehensive insight of cutting mechanics of silicon and diamond tool wear. In SPH modelling of SPDT of silicon, the distribution of von Mises and hydrostatic stress at incipient and steady-state was found to provide the conditions pertinent to material failure, phase transformation, and ductile mode machining. The pressure-sensitive Drucker Prager (DP) material constitutive model was adopted to predict the machining response behaviour of silicon during SPDT. Inverse parametric analysis based on indentation test was carried out to determine the unknown DP parameters of silicon by analysing the loading-unloading curve for different DP parameters. A very first experimental study was conducted to determine Johnson-Cook (J-C) model constants for silicon. High strain rate compression tests using split Hopkinson pressure bar (SHPB) test as well as quasi-static tests using Instron fatigue testing machine were conducted to determine J-C model constants.The capability of diamond tools to maintain expedient conditions for high-pressure phase transformation (HPPT) as a function of rake angle and tool wear were investigated experimentally as well as using SPH approach. The proportional relationship of cutting forces magnitude and tool wear was found to differ owing to wear contour with different rake angles that influence the distribution of stresses and uniform hydrostatic pressure under the tool cutting edge. A new quantitative evaluation parameter for the tool wear resistance performance based on the cutting distance was also proposed. It was also found that the machinability of silicon could be improved by adopting novel surface defect machining (SDM) method.The ductile to brittle transition (DBT) with the progressive tool wear was found to initiate with the formation of lateral cracks at low tool wear volume which transform into brittle pitting damage at higher tool edge degradation. A significant variation in resistance to shear deformation as well as position shift of the maximum stress values was observed with the progressive tool wear. The magnitude and distribution of hydrostatic stress were also found to change significantly along the cutting edge of the new and worn diamond tools

Multiphysics Modeling and Numerical Simulation in Computer-Aided Manufacturing Processes

The concept of Industry 4.0 is defined as a common term for technology and the concept of new digital tools to optimize the manufacturing process. Within this framework of modular smart factories, cyber-physical systems monitor physical processes creating a virtual copy of the physical world and making decentralized decisions. This article presents a review of the literature on virtual methods of computer-aided manufacturing processes. Numerical modeling is used to predict stress and temperature distribution, springback, material flow, and prediction of phase transformations, as well as for determining forming forces and the locations of potential wrinkling and cracking. The scope of the review has been limited to the last ten years, with an emphasis on the current state of knowledge. Intelligent production driven by the concept of Industry 4.0 and the demand for high-quality equipment in the aerospace and automotive industries forces the development of manufacturing techniques to progress towards intelligent manufacturing and ecological production. Multi-scale approaches that tend to move from macro- to micro- parameters become very important in numerical optimization programs. The software requirements for optimizing a fully coupled thermo-mechanical microstructure then increase rapidly. The highly advanced simulation programs based on our knowledge of physical and mechanical phenomena occurring in non-homogeneous materials allow a significant acceleration of the introduction of new products and the optimization of existing processes.publishedVersio

Numerical study of fluid-structure interaction with macro-scale particle methods

The problems of fluid-structure interaction (FSI) are often encountered in different industries as well as the nature. The macro-scale particle methods are advantageous in the FSI simulations, which include smoothed particle hydrodynamics (SPH), macro-scale pseudo- particle modelling (MaPPM), and so forth. Compared with the grid-based numerical techniques, particle methods could provide the flow and/or deformation details without complex tracking of interfaces. The progress of FSI simulation of multiphase flows with rigid particles is presented, and some major findings about heterogeneous structures are stressed. Meanwhile, weakly compressible outflow from elastic tube is investigated, and some preliminary results of flow details are presented. The possible development of macro-scale particle methods in the FSI simulation is prospected finally