Simulations for Design and Manufacturing

Glass fiber reinforced plastics (GFRP) is an important class of materials due to its high strength-to-weight ratio. Delamination during drilling of GFRP composites reduces the strength of the components considerably, and the components may fail to meet the requirements. Very less work is reported on finite element (FE) studies on delamination while drilling of FRP composites. The nonhomogeneous and anisotropic nature of the work material complex oblique cutting process are the major difficulties for the FEM study. In this work, FE model using ABAQUS 6.10 is developed for drilling of GFRP composites using conventional twist drill. A “VUSDFLD” subroutine for ABAQUS 6.10/Explicit is written and incorporated with the material model during the simulation. Thrust force and torque obtained from simulation are compared with the experimental values reported in the literature. Good agreement between the simulation and experimental results was observed.

The application of emulsion for combined heat extraction and lubrication requires continuous monitoring of quality of the emulsion to sustain the desired machining environment. To sustain a controlled machining environment, it is necessary to adopt an effectively lubricated tool–work interface. As a result, the study of the machining process using a limited amount of lubricant/coolant (Minimum Quantity Lubrication) is highly appropriate. The aim of this research is to develop a Computational Fluid Dynamics (CFD) model to duplicate the atomization (mist formation) in MQL milling. Air pressure and mass flow rate were considered as the process parameters. Discrete Phase Model (DPM) was used to simulate the atomization because the mass flow rate of the oil is very low and also it acts as a discrete medium in air. The diameter of the droplet and velocity of the jet were acquired at various input conditions for achieving the optimal values of oil mass flow rate and air pressure respectively. It is seen that medium size (around 10.2 µm) of droplet plays a significant role in improved performance by the way of reduction in cutting force and surface roughness in MQL milling of SS304.

Self-Reacting Friction Stir Welding is a variant of Friction Stir Welding (FSW) in which through a modification in the tool design, welding can be carried out in the absence of a backing plate. In this variant, the tool has two shoulders connected by the pin. Due to this small modification in tool design, the process is significantly influenced. In the present work, the effect of tool traverse speed using a fixed gap bobbin tool on the weld quality has been studied using a Finite Element Method (FEM) model and experimental study. The present work has been carried out on 4-mm-thick aluminium alloy AA6061-T6 plates, which have been welded in butt configuration. Uniaxial tensile tests of the welded samples have been carried out to correlate the traverse speed with yield strength and ultimate tensile strength. Three-point bend tests have been carried out to expose any flaws present in the joints and compare mechanical properties on the two sides of the joints. In addition to this, the joint macrostructure has been studied and has been compared with the stir zone developed in the FEM model. The microstructure in the various zones of the welded joints for different traverse speeds has been studied and compared with the grain structure of the base material to reveal its effect. A relationship has been established between the process parameters and the resulting average grain size in the joint.

Friction stir welding (FSW) is a solid-state joining process. Modeling of FSW process provides insight into the mechanism of the process in terms of heat generation, material flow, etc. In the present chapter, modeling of FSW process in DEFORM-3D using Lagrangian method is discussed. Various governing equations involved in the finite element modeling of FSW are explained. Three different solvers, viz., conjugate gradient, sparse, and combination of the two, are compared based on computation time and accuracy of the solution. The developed method is validated with the experimental force and torque. The model is further used to study the temperature distribution and material flow. The latter is studied using particle tracking method.

The investigation presented streamlines its framework towards understanding the implications of spring back effect of Ti-6Al-4V alloy (Grade 5) sheet metals through experimental and numerical procedures. Base metal and automated TIG welded samples each of 2 mm thickness are subjected to three-point bend test on a Universal Testing Machine. Research reports are immense and provide an analytical insight into forecasting of the spring back effect in sheet metal. Yet, it raises several complexities while also excluding few critical contributories that have prominent repercussion posing disparity among literatures. These contradicting reports raise pointers thereby creating ambiguity and lack of understanding. Such shortcomings are addressed through this work undertaken with an aim to develop a finite element model on ABQUAS/CAE platform to estimate the spring back effect on base and welded samples, respectively. The results accomplished through the numerical model show good agreement with the experimentally recorded values. The outcome of the study demonstrates that punch stroke and thickness of the sheet metal are the key components dictating the degree of spring back effect in forming process. Sheet metal thickness shows disproportional variation with spring back effect, whereas contradictory observation is recorded for punch stroke variations.

This paper presents the numerical prediction of fracture depth in the part formed with the incremental sheet forming (ISF) process. The plastic deformation behaviour during forming is modelled through Johnson–Cook plasticity model and fracture is simulated through the constant equivalent plastic strain criteria. Finite element analysis has been used for the numerical investigation of the effectiveness of the present material model. The results from simulations are validated through physical experiments on a three-axis machining centre. Two truncated cones of different wall angles with 0.91-mm-thick sheets of Al1050 H14 material were formed by ISF process. The results delineate a new perspective on present material model with respect to ISF and offer an accurate FEA model for carrying simulations of ISF process.

Materials processed by severe plastic deformation (SPD) achieve ultrafine grain (UFG), thus making them suitable for advanced engineering applications. Equal channel angular pressing (ECAP) is one of the most popular techniques of SPD process which imposed ultra-large plastic strain on bulk material to produce a UFG metal. These techniques extrude the materials through a specially designed die channel without significantly changing in die geometry. In an ECAP process, with increase in the number of pass, more grain refinement is possible, but it is rarely used due to practical difficulties in implementation. In order to overcome such difficulties, the ECAP channel with more number of turns is used to enhance the grain refinement of long billet in a single pass. Two-turn ECAP die is one of them to double the amount of plastic strain in a single pass with following route C rotation while process repetition is still open for more grain refinement. This paper describes new incremental ECAP channel (three-turn) of SPD process and followed by route A rotation. In order to find the processes parameter as well as die geometry of V-shape ECAP channel, an FEA simulation of S-shape ECAP channel with validation has been carried out, and process kinematics are established.

Incremental sheet metal forming (ISF) process is an emerging technology used in various sectors of industries to reduce the cost of dies and for flexible manufacturing. Robotic assistance in ISF, like in other manufacturing processes, has been attempted by several researchers to make the processes more flexible and efficient. Hence, in addition to the conventional ISF process description, a detailed account of robotic assistance in ISF is also explained here. When a serial robot is used as a machining platform, most of the original tooling and machinery can be preserved. On the other hand, when such machining process is adopted to be used for ISF, due to varying forming forces and as stiffness of the robot may not be high, forming tool may deflect causing error in tool path, which in turn results in errors in geometry of the part. In order to compensate for this deflection, knowledge about the level of stiffness of robot in all its configurations and prediction of forces with sufficient accuracy are required. Hence, developing a procedure to predict forming forces is explained here. This will include dynamic analysis of a two-degree-of-freedom serial manipulator which is to be used in the forming operation. Dynamic analysis will give variation of forces with respect to the movement of links and joints used. Using the results of dynamic analysis, dimensional synthesis can be done which will also include determining link lengths. Inverse dynamic model is used to obtain the joint torques and forces for desired acceleration of platform using the state variables of the robot, i.e. the position and velocities. After finding out dimensions of link and joints, workspace volume is to be found out. To investigate the reliability of the proposed design for dynamic performance, multi-body dynamic (MBD) analysis and simulation of the manipulator is done using COMSOL Multiphysics. In the present work, task of the robot is to carry and manipulate sheet metal on which incremental forming operation is performed. Robotic manipulator manipulates the sheet with respect to 3-axis CNC tool to get a final shape. We mainly focus on dynamic analysis of a serial two-degree of freedom (2-DOF) robot used for incremental sheet metal forming.

The electrochemical discharge machining is a hybrid machining process. This process includes the electrochemical and electro-discharge machining which is employed to machining of conducting as well as nonconducting materials. In this chapter, the explicit dynamics ANSYS was used for the analysis of strain, stress, and deformation of different materials in electrochemical discharge machine model. The solid model of the electrochemical discharge machine is developed in ANSYS Workbench. By using ANSYS, the force and displacement were applied to the cathode tool on the different workpiece materials, and the equivalent elastic strain, equivalent (von Mises) stress, and total deformation were evaluated under certain conditions. The obtained results were compared with one another to understand the characteristics of different materials.

Selective laser sintering of submicron size powder known as micro-sintering is emerging as advanced solution for producing micro-mesoscale products with minimum porosity and the features smaller than 500 µm. In the present chapter, molecular dynamics (MD) based simulation study is proposed to understand laser–metal interaction during selective laser sintering of nanoparticles. In this chapter, neck formation mechanism during selective laser sintering (SLS) of two spherical ultrafine copper powder of 1.82 nm (nm) diameter has been studied. Further, sintering mechanism has been modelled as deformation of nanoparticles which are elastic as well as plastic in nature which is mainly caused due to interatomic or intermolecular potentials. MD simulation-based virtual experiments have been conducted using three pairs of identical spherical copper nanoparticles of diameter 1, 2 and 3 nm to establish relations between laser power, irradiation time with the size of neck growth. In this chapter, thermo-mechanical mechanism of laser sintering of copper nanoparticles has been studied employing MD Simulations. MD simulations are conducted using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) (LAMMPS MD Simulator. http://​lammps.​sandia.​gov/​index.​html in [1]).