13th International Conference on the Technology of Plasticity (ICTP 2021): Xue Yu Ruan Honorary Symposium
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 A
Location: Virtual

Session Chair: Jun Chen, Shanghai Jiaotong University


Professor Ruan and the International Cold Forging Group (ICFG): Erman Tekkaya1; 1TU Dortmund
    This presentation is dedicated to Professor Ruan’s (Shanghai) contributions to the international cold forging community. As a member and chair of the International Cold Forging Group (ICFG), I could follow the immense work Professor Ruan performed under complicated political boundary conditions in the field of metal forming research with focus on cold forging. Professor Ruan hosted several times the ICFG in Shanghai and established strong links between the Chinese experts and the international community both in academia and industry. Many important research projects have been conducted jointly with European industrial companies and universities and the Shanghai Jia Tong University. With his reliable and trustful personality, Professor Ruan left a whole community of successful young Chinese researchers and several manufacturing plants in China of international enterprises in the field of cold forging.

Possibility of Shear Forging as the Third Basic Process of Cold Forging: Zhigang Wang1; Tomoyuki Hakoyama1; 1Gifu University
    Cold forging has been used widely to produce small parts with high precision. Upsetting and extrusion are the two basic methods of cold forging and parts with complicated shape are forged by combinations of upsetting and extrusion. The most important technical issue in cold forging is the extremely high tool pressure and thus materials with high strength are still difficult to be forged at room temperature due to the strength limitation of the tool materials. This paper proposes a new forging method called shear forging to reduce the forging load drastically. The possibility of shear forging as the third basic method of cold forging is discussed. Shear forging can provide a forging method of impossible shapes, materials with high strength and large size parts by cold forging at a low cost.

Machine Learning Based Prediction and Compensation of Springback for Tube Bending: Jun Ma1; Heng Li2; Guang-yao Chen2; Torgeir Welo1; Guang-jun Li3; 1Norwegian University of Science and Technology; 2Northwestern Polytechnical University; 3Chengdu Aircraft Industry (Group) Co., Ltd.
    Bent tubes are extensively used in the manufacturing industry to meet demands on lightweight and high performance. As one of the most significant phenomena affecting the dimensional accuracy in tube bending, springback causes problems in tube assembly and service, making the manufacturing process complex, time-consuming and difficult to control. This paper attempts to present an accurate, efficient and flexible strategy to control springback based on Machine Learning (ML) modeling. An enhanced PSO-BP network-based ML model is firstly established, providing a strong ability to account for the influences of material, geometry and process parameters on springback. For the supervised learning, training sample data can be collected from the historical production process or, alternatively, finite element simulation and laboratory type experiments. Using cold bending of aluminum tubes as the application case, the ML model is evaluated with high reliability and efficiency in springback prediction and compensation strategy of springback.

Understanding the Microscale Plastic Behavior and Deformation Mechanism of Magnesium Alloy via Ex-situ Experiments and Full-field Crystal Plasticity Modeling: Haiming Zhang1; Shuai Xu1; Xiaoqing Shang1; Zhenshan Cui1; 1Shanghai Jiao Tong University
    Magnesium alloys have been of growing interest for their low density and high specific strength, but their applications are impeded by their poor formability at room temperature. This work employs the state-of-art experimental and modeling techniques to understand the jointly effect of thickness and grain size on the plastic behavior and deformation mechanism of wrought Mg alloy. Equal channel angle pressing were applied to AZ31 Mg alloy to fabricate billets with various grain sizes but the same basal texture. Interrupted micro-tensile tests combined with ex-situ EBSD characterizations were carried on the fine-polished specimens with different grain size and thickness. It shows that mechanical twinning is significantly affected by both grain size and thickness. In particular, the volume fraction of extension twins decreases with the number of grains in the thickness. Full-field crystal plasticity simulations demonstrate that both the contributions of basal slip and twinning are rather sensitive to grain size.

Applicability of ALE Based FEM Methods in the Numerical Modeling of 3D Fine Blanking Processes: Pavel Hora1; 1ETHZ - Inst. of Virt. Manufacturing
     FEM simulations of 3D-fineblanking processes are challenging in respects to a) the handling of a strong FE mesh distortion b) constitutive models with strain, strain rate and temperature dependency and c) adequate failure criterion for the prediction of cracks. In the presentation those three mentioned aspects will be discussed. For solution to the FEM modeling problem, a new ALE-based method will be presented. The material properties will be specifically validated for large strain values based on tension-torsion tests. As a failure criterion the modified Mohr-Coulomb and the GISSMO damage accumulation method will be used. For the validation of the numerical results a special testing equipment was developed, which allows the experimental check of the micro-geometry of the cutting edge on the cutting and especially crack behavior. The numerical results are compared with those experimental tests.

Extrusion Technology of High-performance Aluminum Alloy Profiles with Large Complex Section: Guoqun Zhao1; Cunsheng Zhang1; 1Shandong University
    Focused on the extrusion technology of high-performance aluminum alloy profiles with large complex sections, a series of work has been carried out. The hot deformation behavior of aluminum alloy was studied, the constitutive equations and processing maps were derived for several kinds of alloys. The effects of process parameters and die structures on deformation of extruded profiles were researched. The optimization methods for designing large and complex extrusion die structures were put forward. The welding behavior and microstructure evolution on welding interface in porthole die extrusion process were revealed, and a new no-dimensional prediction model for solid-state welding was proposed, in which the stress triaxiality, equivalent strain rate, temperature and contact time were coupled. Moreover, the isothermal extrusion, on-line quenching and stretching straightening technique were studied. A series of extrusion dies and profile products were developed and applied in the high-speed train, light weight vehicles and large-scale engineering structures.

Bulk Microforming From Sheet Metal - A Promising Approach for the Mass Production of Cold Formed Metallic Micro Parts: Martin Kraus1; Marion Merklein1; 1Institute of Manufacturing Technology (LFT)
    Within this paper, multi-stage bulk microforming from sheet metal is investigated for the fabrication of metallic micro parts in laboratory scale with the material Cu-OFE. In a first step, the process-influencing variable of the blank holder pressure is analysed in the first forming stage in order to derive measures for the highest possible material utilization. The two-stage forming of the pin with cup is compared with a single-stage process to assess the part quality and material utilization depending on the process strategy. Using the correct geometric scaling, size effects are identified and their effects on the forming process are evaluated. The experimental results reveal that it is possible to fabricate micro parts with a diameter of 470 µm and a minimum wall thickness of 36 µm reproducible by using the presented cold bulk microforming process strategy.

Prof. Xue-Yu Ruan and His Academic Life: Zhen Zhao1; Zhen-Shan Cui1; Jun Chen1; 1Shanghai Jiao Tong University
    This presentation is a brief introduction of Prof. Xue-Yu Ruan and his academic life. As the pioneer of cold forging technology development in China, the research of Prof. Ruan and his team on cold forging is systematic which covers the process, the material, the lubrication, the tooling and the press. The outputs have been widely used in Chinese cold forging or cold extrusion industry. He is enthusiastic in the innovation of new technology, such as digital manufacturing technology, artificial intelligence and knowledge engineering, etc. Within these areas, great contributions from him and his team are acknowledged. During his whole life, Prof. Ruan established lots of international collaborations and he was fully enjoying the international communications with his good friends.

Manufacturing Processes of Non-metallic Materials: Jian Cao1; 1Northwestern University
    In honor of Prof. Ruan’s broad program portfolio, I am presenting a summary of our non-metallic manufacturing processes work conducted at our Advanced Manufacturing Processes Laboratory of Northwestern University. The topics mainly include forming of woven composites prepreg materials and electrospinning.

On the Convexity Bound of the Generalized Drucker's Yield Function CB2001 for Orthotropic Sheets: Wei Tong1; Seung-Yong Yang2; 1Southern Methodist University; 2Korea University of Technology and Education
     Drucker's sixth-order polynomial yield function for isotropic materials was generalized in the literature for modeling orthotropic sheet metals via a generalization of the two invariants of the deviatoric stress using the theory of representation. The constant c in the original Drucker's isotropic yield function is found to be bound between -27/8 and 9/4 per the convexity requirement. In many subsequent modeling applications of orthotropic sheets, the same bound is also tactically assumed for the constant c in the generalized Drucker's yield function. In this study, the validity on assuming such a convexity bound on the adjustable constant c for orthotropic sheets is examined closely. It isfound that a single convexity bound between -27/8 and 9/4 on the constant c does not hold at all for any of those yield functions formulated from the theory of representation approach.

Professor Ruan-An Extaodinary Pioneer within the Global Scientific Network Metal Forming: Reiner Kopp1; 1RWTH Aachen University
    Within the speech the outstanding scientific activities, the particularly successful cooperation with industrial companies all over the world and the deep relations to numerous colleagues in many countries are recognized.