The coupling of the electromagnetic field and the mechanical structure field is one of the main problems in the theoretical study of Electromagnetic Forming (EMF). In this study, two possible approaches for the simulation of the electromagnetic tube compression forming process were implemented and compared: A loose-coupled and a sequential-coupled algorithm. In the loose-coupled the electromagnetic field and mechanical structure field were solved separately, but in the sequential-coupled algorithm, the electromagnetic simulation and the mechanical structure simulation were iteratively performed by using Maxwell equations and Finite Difference Method (FDM) as subroutine VDLOAD in ABAQUS software. A deformation of the tube and consequently a change in inductance of tube during the process in the sequential-coupled algorithm was considered. The depth of bead in loose-coupled algorithm compared to experimental result had a 35% error, but in a sequential-coupled algorithm this error has been reduced to 5%. To predict tearing in this process Johnson-Cook damage criterion used. Increasing of discharge voltage and tube thickness respectively, had maximum effect on Johnson-Cook damage. Amount of damage less than 0.8 is conservatively suitable for the safe area without fracture.

Electromagnetic forming is a high energy rate forming process applied for manufacturing and assembly of many parts that are used in automobile and aerospace industries. In this process, the electromagnetic body forces (Lorentz forces) are used to produce metallic parts. Joining high electrical conductivity parts by using electromagnetic forming process is an innovative method. Therefore, it is very important to use a proper technique to ensure the quality of the Strength of Electromagnetic Joints. In this article, this process was simulated in ABAQUS. Then geometric, physical and mechanical specifications of the tube and coil are entered to subroutine and the magnetic pressure is obtained; by applying them on tube in ABAQUS software, agent analysis of the process and deformation of the work-piece is obtained. The effective process parameters such as discharge voltage, clearance between the tube and die, wall thickness and length of the tube on depth of bead were experimentally investigated by design of experiment technique based on Taguchi Method and signal to noise. Finally, very good agreement was found between simulation and experimental results. The depth of bead in sequential coupled algorithm compared to experimental result had about 4% error.

Tube forming is a common forming process in industry. There are several methods in tube forming, whereas industries are looking for best methods with low cost and high speed. For this reason, industries need new modern forming methods. Electromagnetic forming and tube hydroforming are two modern processes which are used in manufacturing of hollow complex parts. These two processes are considered as high speed forming methods in automotive industries. In this paper, the processes of electromagnetic forming of tubes and high speed hydroforming of tubes have been investigated by numerical simulations and empirical method. Firstly, the results of numerical solutions by ABAQUS software are compared with empirical tests. At last these two forming methods have been compared in terms of displacement, stress distribution and thickness distribution. The results of deformation and thickness of the tip of the bulged tubes in empirical tests are in good agreement with the results of numerical simulations of this research. The results show that formability and bulge height in electromagnetic forming process are higher than high speed hydroforming. However, high speed hydroforming may be used in applications such as shirring fitting of parts and rings on tubes instead of electromagnetic forming.

Electromagnetic forming is a high energy rate forming process which is applied for manufacturing and assembly of many parts that are used in automobile and aerospace industries. In this process, the electromagnetic body forces (Lorentz forces) are used to produce metallic parts. In this article, the influence of important process parameters such as discharge voltage, friction coefficient, clearance between the tube and die, wall thickness and length of tube, on the radial displacement and workpiece thinning were investigated. The output of governing equations in the form of pressure applied on the part by using a subroutine in a Fortran Program. A dynamic analysis using two dimensional axisymmetric models were performed and Johnson-Cook theory was applied to represent the effect of strain rate sensitivity and show the plastic behavior in the deformation process. Finally, the numerical results were compared with the results reported by other researchers and found a good agreement between them.

Electromagnetic forming is a high energy rate forming process which is applied for manufacturing and assembly of many parts that are used in automobile and aerospace industries. In this process, the electromagnetic body forces (Lorentz forces) are used to produce metallic parts. In this article, the influence of important process parameters such as discharge voltage, friction coefficient, clearance between the tube and die, wall thickness and length of tube, on the radial displacement and workpiece thinning were investigated. The output of governing equations in the form of pressure applied on the part via a subroutine in a Fortran Program. A dynamic analysis using two dimensional axisymmetric models were performed and Johnson-Cook theory was applied to represent the effect of strain rate sensitivity and show the plastic behavior in the deformation process. Finally, the numerical results were compared with the results reported by other researchers and found a good agreement between them.

Indentation forming is an internal tube forming process in which a mandrel with a diameter slightly larger than that of the tube is pressed inside the tube and in so doing, creates the internal profile. Forming forces have a significant effect on the spring back, residual stress, quality of the inner surface, quality of tube dimensions, and tool wear. In this study, the forming process of CK45 steel tube by carbide tungsten tool in the presence of ultrasonic vibration has been simulated and the effect of ultrasonic on the forming mechanism has been investigated by introducing two regimes according to the forming conditions. The effects of tool feed-speed and amplitude of vibration on forming force reduction have been investigated. According to the simulation results, the main reason for the force reduction in the presence of longitudinal tube ultrasonic vibration is the intermittent phenomenon which is the continuous or impulsive regime. The critical amplitude which determines the borderline of continuous and impulsive regimes is obtained 38μ m by the simulation of the process. The maximum force reduction obtained in continuous regime is 64. 2% at the critical amplitude. The simulation results are consistent well with the previous experimental data.

Self-inductance coefficient is one of the most important parameters in electromagnetic forming process. Presence of work piece near coil, in electromagnetic forming process, affects the coil self-inductance coefficient seriously and therefore other process parameters such as electrical current amplitude, frequency and pressure applied on the work piece are affected too. In this paper, the coil work piece equivalent self-inductance coefficient, which has not been calculated in previous relevant works, is calculated numerically using a commercial FE code. To obtain the electrical current distribution profile in the coil cross sections, first a cylindrical coil is simulated without any work piece. Then its self-inductance coefficient is compared with analytical calculation results. By using simulation results, the variation of magnetic-flow versus electrical-current has been plotted. The curve slope (self-inductance coefficient) has been extracted by using least squares method. The calculated self-inductance coefficients of the coils with various dimensions show a good agreement with analytical results presented in other references. Next, this method is used to simulate and calculate the coil-work piece equivalent self-inductance coefficient in electromagnetic tube expansion process. At the end, as a parametric study, work pieces with various diameters are simulated and their equivalent self-inductance coefficients are calculated. The results agree with the experimental results due to the presence of an external conductive case around a cylindrical coil, which has already been presented in the literature.

Determining capacitance and coil parameter in electromagnetic forming (EMF) process is one of the common difficulties in industrial applications of the process. In the present paper, an algorithm has been presented in order to calculate EMF device electrical current pulse with various capacitances and coil parameters. At first, an initial guess is considered for angular frequency and capacitance. Then, the effective part of the current pulse is calculated by an iterative computational subroutine using FE method. In this paper, an electromagnetic tube expansion problem, previously analyzed experimentally in the literature, has been studied. The comparison shows an acceptable agreement between numerical and experimental results.

High speed and absence of a precise control over pressure distribution confine sheet Electromagnetic Forming into a die to simple shapes having shallow depth. It is possible to reach a higher depth by using a convex punch instead of a concave die. In this study, sheet Electromagnetic Forming on a punch and sheet Electromagnetic Forming into a die are investigated. The electromagnetic part of the study is investigated analytically and its mechanical part is studied numerically. In order to couple electromagnetic with mechanical parts, no-coupling method is used. The obtained results are verified by comparing the obtained results with previous experimental ones in literature. Rate-dependent and rate-independent hardenings are taken into consideration for the mechanical behavior for material of AAl1050. Using appropriate hardening model for material yields acceptable results. Moreover, a convex punch instead of a concave die is used to reach to a higher depth in sheet Electromagnetic Forming.