13th International Conference on the Technology of Plasticity (ICTP 2021): High Speed and Impulse Forming II
Program Organizers: Glenn Daehn, Ohio State University; Libby Culley, The Ohio State University; Anupam Vivek, Ohio State University; Jian Cao, Northwestern University; Brad Kinsey, University of New Hampshire; Erman Tekkaya, TU Dortmund; Yoshinori Yoshida, Gifu University
Thursday 9:15 AM
July 29, 2021
Room: Virtual: Room E
Location: Virtual
Session Chair: Lander Galdos, Mondragon University
Local Microscopic and Integral Macroscopic Analysis of Magnetic Pulse Welds and Deformations for Dissimilar Metal Joints: Frank Huberth1; Balaji Ragupathi1; Christian Scheffler2; Verena Psyk2; Johannes Preußner1; 1Fraunhofer IWM; 2Fraunhofer IWU
Magnetic pulse welding (MPW) technique combines high speed forming, impact and results in a partial weld at the collision zone of the accelerated flyer and the impacted target. Flyer, target and the acting coil can be positioned in different configurations resulting in different deformations of target and flyer accelerated by the magnetic pulse in the coil and thus different welds. The local effects for dissimilar metal joints of aluminum EN-AW-1050 and copper Cu-DHP are investigated for different configurations and impact energies by local micro tensile tests in thickness direction of the welded two metal sheets leading to the local weld strength distribution. For micro sample preparation, thin cross-sectional stripes (0.5 mm) are extracted from the contact parts of the sheets. The micro experiments are accompanied by micro structural analysis. These local microscopic testing and analysis results are correlated to integral macroscopic lap shear tests on the welds supported by simulations.
Grain Size Effect on Formability in Electromagnetically-assisted Micro-bulging of Pure Titanium Sheet: Chengxi Zhu1; Jie Xu1; Haiping Yu1; Debin Shan1; Bin Guo1; 1Harbin Institute of Technology
It has been revealed that geometry and grain size effects have great effect on the formability of metal foils during quasi-static forming processes. However, there is little research on how these size effects influence formability of metal foils during high speed forming process e.g. electromagnetic forming. To characterize these size effects in electromagnetic bulging, miniaturized Nakazima test and numerical investigation were conducted. Pure titanium foils with different thickness and different grain sizes were utilized in the experiment. In addition, to clarify how forming speed influence the formability of metal foils, different forming voltages were adopted. Finite element method then was used to analyze the electromagnetic bulging process. To analyze how the size effects affect the ductile fracture in electromagnetic micro-forming, M-K failure criterion was modified to model the forming limit in micro-scaled deformation,and is found to be able to model the decrease of forming limit caused by size effects.
Influence of Ultrasonic-assistance on the Forming Limits of Steel: Manuel Jäckisch1; Marion Merklein1; 1Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Manufacturing Technology (LFT)
Since Blaha discovered the beneficial effect of superimposing high-frequency oscillations to the metal forming process, the occurring force and stress reduction are well-known phenomena. Leading to an immediate flow stress reduction, the so-called ultrasonic-assistance is a promising approach to enable forming with reduced process forces. While the feasible force reduction has been investigated intensively, only a few analyses have been conducted in the context of the impact of ultrasonic-superposition on the forming limits. Latest investigations state earlier material failure due to localized forming with high strain rates. Within this paper, the influence of superimposed vibrations on the forming limits of C35E is investigated with regard to distinct oscillation amplitudes. For this purpose, ultrasonic-assisted shear tests are carried out and compared to high-speed shear tests with similar strain rates. This way, effects only caused by the high strain rates and those resulting from the recurring cyclic loading are separated.
Recent Developments of Vaporizing Foil Actuator Technique for Manufacturing Applications: K. Sajun Prasad1; Jianxiong Li1; Blake Barnett1; Yu Mao1; Glenn Daehn1; Anupam Vivek1; 1The Ohio State University
Vaporizing Foil Actuator (VFA) is an impulse or high-speed manufacturing technology using electrically driven rapid vaporization of thin conductors to produce short-duration pressure pulses of high magnitude. This impulse technique has been implemented for varied applications such as high strain rate forming, shearing, collision welding, and springback calibration. VFA technology for manufacturing processes potentially offers improved accuracy, reliability, and environmental safety and creates opportunities to design new products by joining similar and dissimilar material combinations. The paper includes the results of industrially relevant “work-in-progress” research with the VFA tool. The process’s applications, mainly regarding advanced manufacturing such as metal-matrix composite (MMC) welding, axisymmetric welding, and impact-mediated additive manufacturing processes, are presented and discussed. The applications of the method characterize adequate responses to support the manufacturing process.
Augmentation of Plasma-based Impulse Generation with Rapid Chemical Reactions: Brian Thurston1; Yu Mao1; Troy Lewis1; Anupam Vivek1; Glenn Daehn1; 1The Ohio State University
The use of a chemical explosive mixture to augment the Vaporizing Foil Actuator (VFA) and Laser Impact Welding (LIW) processes is introduced in this study. A liquid explosive known as Picatinny Liquid Explosive (PLX) was used to augment the capabilities of both the VFA and LIW processes. 304 stainless steel flyers 3mm thick driven by PLX augmented VFA and unaugmented VFA are compared. Similarly, 0.442mm thick Al3003 flyers driven by laser impact and PLX augmented laser impact are compared. In all cases a Photon Doppler Velocimetry (PDV) system was used to collect the velocity time profiles of the flyers. All PLX augmented experiments showed increases in both flyer acceleration and peak velocity over the same time scales as the unaugmented experiments. This indicates that the PLX provided impulse occurs at the same time as the VFA/laser impulse. The augmented VFA experiments showed a 28% velocity increase over the unaugmented experiments at 10kJ input energy. The augmented laser impact process exhibited peak flyer velocities 236% higher than laser impact using only the laser. Here we demonstrate that chemical augmentation is capable of significantly increasing flyer velocities for both VFA and LIW at the same input energies and under similar conditions. This development should expand the repertoire of flyer materials and thicknesses that can be impact welded by VFA and LIW.