The Effect of Stepped Field Shaper on Magnetic Pressure and Radial Displacement in Electromagnetic Inside Bead Forming: Experimental and Simulation Analyses Using maxwell and abaqus Software

Electromagnetic forming (EMF) is a high strain rate forming technology which can effectively deform and shape high electrically conductive materials at room temperature. A field shaper is frequently used for concentrating the magnetic pressure in the desired forming area. The geometric parameters of a field shaper, as an intermediate device, affect the magnetic pressure and radial displacement in electromagnetic inside bead forming. EMF consists of electromagnetic and mechanical parts simulated using maxwell and abaqus software, respectively. The effects of geometric parameters of the stepped field shaper on magnetic pressure and radial displacement were investigated, and the best parameters were determined. Experimental tests were performed at various discharge voltages and the results were compared with simulation. The results indicated that using the stepped field shaper, the magnetic pressure concentration ratio increased from about 23–85% in comparison with using a direct coil. The maximum magnetic pressure increased by approximately 21% due to the effective concentration of magnetic pressure. Consequently, regardless of the electromagnetic energy losses because of using a field shaper, the radial displacement increased by 8% in simulation and 6% in experiment. The result of this study would be also helpful in designing field shapers in similar applications which is highly crucial and strongly recommended.

Arbitrary Lagrangian Eulerian FEA Method to Predict Wavy Pattern and Weldability Window During Magnetic Pulsed Welding

Finite element simulations of high strain rate forming processes have received significant attention over the last decade. For instance, in Magnetic Pulsed Welding (MPW), extremely high plastic strain regions develop. Thus, a traditional pure Lagrangian analysis is not able to accurately model the process due to excessive element distortion near the contact zone. In this study, the Arbitrary Lagrangian Eulerian (ALE) method is used to simulate a MPW process while retaining a high-quality mesh. Also the ALE method was able to numerically predict the necessary process parameters to achieve a wavy pattern region for two Al6061-T6 plates impacted during the MPW process. The captured wavy pattern region in this study can be used as a first estimation of parameters necessary to achieve a successful MPW component and thus reduce trial and error experimental investigations.

Metallurgical Investigations on Hyperplasticity in Dual Phase Steel Sheets

Several researchers have reported that dual phase steel sheets exhibit hyperplasticity, that is, a significant formability improvement under certain high strain rate forming conditions. Hyperplastic behavior of dual phase steels formed using an electrohydraulic forming (EHF) process was previously investigated by the authors at both macro- (Golovashchenko et al., 2013, “Formability of Dual Phase Steels in Electrohydraulic Forming,” J. Mater. Process. Technol., 213, pp. 1191–1212) and microscales (Samei et al., 2013, “Quantitative Microstructural Analysis of Formability Enhancement in Dual Phase Steels Subject to Electrohydraulic Forming,” J. Mater. Eng. Perform., 22(7), pp. 2080–2088). A relative deformation improvement of approximately 20% in ferrite grains and 100% in martensite islands was reported in the EHF specimens compared to specimens formed under quasi-static conditions. In this paper, the remarkable deformation improvements of the constituents are discussed in terms of metallurgical mechanisms of deformation. The nucleation and multiplication of dislocations in ferrite and deformation twinning in martensite were found to be the principal mechanisms responsible for the significant improvements of deformation in EHF. In addition, these mechanisms enhance the plastic compatibility between the two phases which reduces the risk of decohesion and delays the onset of fracture in EHF specimens.

High Strain, High Strain Rate Forming of Difficult to Deform Tubular Parts

High demand for formed tubular components and the necessity to increase their strength to weight ratio have established a need for new, effective, and low cost forming technologies. This work investigates the application of a propellant-driven water stream to the formation of high tensile strength alloys such as stainless steel 321, Inconel 625, and Ti–3Al–2.5V. The proposed forming technology is based on the utilization of high pressure developed in liquid flowing through a tubular work piece. This pressure results from superposition of compression waves generated in the course of the impact of the liquid by products of propellant combustion. An experimental setup, used for the study of the technology in question, consisted of a tubular component, inserted into a split die assembly, and a combustion chamber, which generated gas, driving water through a work piece. This setup was successfully used for high strain, high strain rate forming of tubular components. In particular, the formation of various shapes in the course of an expansion of seamless tubing was examined. Despite large strains, exceeding in some cases the static test elongation limit, the generated samples were characterized by a uniform wall thinning and structural integrity. For example, a 55% expansion of Ti–3Al–2.5V tube was attained using a simple setup. The acquired experimental data show that the technology can be applied to form alloys characterized by high tensile strength, low static elongation limits, and low modulus of elasticity. Simplicity and low capital cost of the process determine its competitiveness in comparison to conventional quasistatic hydroexpansion, hot forming, and high-energy rate explosive forming processes.