13th International Conference on the Technology of Plasticity (ICTP 2021): Joining by Forming and Deformation I
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

Monday 10:20 AM
July 26, 2021
Room: Virtual: Room E
Location: Virtual

Session Chair: Peter Groche, Institute for Production Engineering and Forming Machines


Development of Criteria for Strain Induced Oxide Layer Fracture during Cold Rolling of Aluminum: Mahsa Navidirad1; John Plumeri1; Wojciech Stepniowski1; Tyler Christ1; Masashi Watanabe1; Wojciech Misiolek1; 1Lehigh University
    A combination of physical experimentation as well as numerical simulation of bond rolling of aluminum sheets has been investigated in this study. The surfaces of the sheets were anodized in sulfuric acid with addition of indigo carmine in order to provide the oxide layer coloration as well as two specified oxide thicknesses. A progressive reduction per pass has been implemented in consecutive experiments at constant rolling speeds to develop different degree of oxide surface expansion leading to its fracture. A numerical model of the rolling process has been constructed utilizing DEFORM-3D software, wherein strain, strain rate, and stress fields were calculated. The calculated localized strain distribution reinforces with experimental data to determine the critical localized deformation criteria leading to different stages of the oxide layer fracturing. Classical metallography as well as electron microscopy techniques were used to evaluate the evolution of the oxide fracture as a function of deformation.

Fretting Damage and Fatigue Property Analysis of Self-piercing Riveted Joints of AA5052 Aluminium Alloy: Zhichao Huang1; Yongchao Zhang1; Jiamei Lai2; 1East China Jiaotong University; 2Nanchang University
    The fatigue tests of self-piercing riveted joints of AA5052 aluminium alloy were carried out by axial tension-tension loading mode. The micro fracture characteristics of specimen with different parameters was analyzed by scanning electron microscopy and X-ray spectrometer, and the fatigue property as well as fretting damage failure mechanism of SPR joint were studied. The results show that the fatigue cracks occur in the fretting damage area where stress concentration exist. The form and the distribution of the fretting crumbs are important factors which affect the fatigue property of joint. Within the value range, the fatigue life prolongs with the increase of stress ratio, however decrease with the increase of loading level adopted. The fatigue property differs between different riveting direction, and better strength property could be obtained when the rivet direction reverse.

Fatigue Characteristics and Failure Mechanism of Self-piercing Riveting DP590 and AA6061 Plates: Zhichao Huang1; Yinglian Jia1; Jiamei Lai2; 1East China Jiaotong University; 2Nanchang University
    Duplex steel, aluminium alloy, carbon fiber reinforced composites and other materials have become the preferred lightweight materials for automobiles. The self-piercing riveted joints of dual phase steel DP590 and aluminium alloy AA6061 were selected for fatigue tests, and the fatigue properties of the joints were analyzed. The typical fatigue failure fractures were observed by scanning electron microscopy(SEM), and the micro failure mechanism of the joints was analyzed. The results show that the fatigue properties of self-piercing riveted joints are different with different upper substrates. The failure modes of the joints are all fracture of the lower substrates. When the upper substrate is DP590 plate under high fatigue load, the cracks are easy to initiate in the rivet area. The cracks of the other self-piercing riveted joints originate on the side of the lower plate and extend along the rivet area to the width of the substrate.

From Bridge to Bumper – Utilization of Pre-stressing during Manufacturing of Hybrid Sheet Metal Structures: Henning Husmann1; Peter Groche1; 1Institute for Production Engineering and Forming Machines
    Pre-stressing is often used in civil engineering to increase the load bearing capacity of bridges and buildings. In order to exploit this potential in sheet metal structures as well, efficient processes for joining and pre-stressing of tendons are required. Therefore, an approach to join and pre-stress fiber reinforced plastic (FRP) straps and sheet metals during a forming process is proposed. The FRP strap is placed around two collars drawn into the sheet. A punch plastically expands the collar, while the FRP strap is elastically elongated, resulting in beneficial pre-stresses after unloading due to the different spring-back. In this paper, the predominant mechanism is verified and parameters influencing the pre-stress are identified by experimental and numerical investigations. The hypothesis is investigated, that a customized pre-stress and thus a higher strength during the structure’s usage can be controlled by varying the collar’s expansion. Possible applications include bumpers and side impact beams.

Computer Aided Modeling of the Hot Forming Staking Process Based on Experimental Data: Sebastian Härtel1; Eric Brückner1; Birgit Awiszus1; Michael Gehde1; 1Chemnitz University of Technology
    As a non-detachable and point-acting joint, thermoplastic staking is primary used for the production of electronic and sensor elements as well as for the joining of components in the automotive interior and exterior. Commonly, the advantages of staking processes are its cost-efficient and seemingly simple process control. Regarding the industrial application, staking is principally a well-established forming process. However, despite of the high number of applications, the joint design and the process settings are mainly based on extensive empirical tests. At present, the FE-simulation of these thermoplastic staking processes are not state-of-the-art. Due to these facts, within the frame of the paper, these gaps are to be closed by the computer aided modeling of the hot forming staking to map the heating and forming behavior of this process close to reality. This procedure demands the associated experimental validation of the simulation. In summary, the numerical model shows a high conformity to the experimental data and allows a simulative mapping of the morphological characteristics of the riveted joint as well as indicative statements to the process parameters, which means in particular the minimal heating time for forming and the optimized post-heating time for a morphological homogenization.