Evaluation and optimization of effective parameters in electrohydraulic forming process

Abstract

Electrohydraulic forming (EHF) method is used extensively in industrial applications for its high capacity in improving the formability of various sheet metals. EHF is a high-velocity sheet metal forming process in which two electrodes are positioned in a water-filled chamber and a high-voltage discharge between the electrodes generates a high pressure to form the sheet metal. The EHF method contains innate complexity and depends on different parameters. Then, it is essential to investigate the process thoroughly and present the experiment procedure in such a way that an optimum condition can be met. In the present study, the effective parameters of the EHF (with and without using bridge wire) on free forming of circular Brass 260 sheets are analyzed by employing the design of experiment technique. Numerous experimental tests are performed, and the process parameters are optimized implementing response surface methodology and Minitab software. The most affective parameters were determined by analysis of variance method. Based on the results for EHF without using wire, it can be stated that maximum dome height is obtained when discharge energy is maximum and other two factors (stand-off distance and electrode diameter) are minimum. There also exists an optimum amount of electrode gap determined according to the process conditions. In case of EHF using wire, it was found that the aluminum wire was more efficient than copper and tungsten. Also, there are optimum values for the length and diameter of bridge wire that depended on the experimental conditions.

Multivariate Quadratic Nonlinear Regression Model of the Ultimate Pull-Out Load of Electrohydraulic Expansion Joints Based on Response Surface Methodology

“…There was only less than 0.01% possibility that an F-value this large could occur due to noise. Considering the 95% reliability, the model with a probability value (the smallest significance level that may make the null hypothesis H 0 negative) lower than 0.05 was considered significant [21]. In the analysis of variance, the linear terms A, B, and C had a significant influence on the response.…”

“…Different discharge energy will affect the pull-out load and the failure mode of the joints. In the electrohydraulic forming process, in addition to the discharge energy, the diameter and length of the wire can also affect the forming result [21]. Therefore, the discharge energy and the wire characteristics (diameter and length) have a great influence on the electrohydraulic expansion joining.…”

Energy dissipation and efficiency of exploding stainless steel wires of various lengths and diameters

“…[20,21]), the production of nano-particles (see e.g. [22,23]) and in particular sheet metal forming [24][25][26]. Here, a shock wave is produced by the wire explosion in a water basin in contact with a metal sheet, which is driven into a given die.…”

“…Here, a shock wave is produced by the wire explosion in a water basin in contact with a metal sheet, which is driven into a given die. Such a process has been considered for steel as well as aluminium sheets [24][25][26] as an alternative to electrohydraulic forming using copper or aluminium wires with dimensions in a similar range as our steel wires. A systematic study of the optimal electric circuit parameters, however, was missing in these papers.…”