Article
Mathematics
Yannis Angelopoulos, Stefanos Aretakis, Dejan Gajic
Summary: We rigorously derive the asymptotic behavior of solutions to the scalar wave equation on subextremal Kerr backgrounds, including the behavior for projections to angular frequencies greater than 1 and greater than 2. The asymptotics in Kerr spacetimes differ significantly from the non-rotating Schwarzschild case, with slower decay rates for higher angular frequencies and oscillations along the null generators of the event horizon. We introduce a physical space-based method that resolves the difficulties of coupling angular modes and loss of ellipticity in the ergoregion, providing a framework for determining the correct numerology of Kerr late-time asymptotics.
ADVANCES IN MATHEMATICS
(2023)
Article
Materials Science, Multidisciplinary
Ahmad Amini, Ali Alavi Nia
Summary: Despite variations in forming processes at different speeds, the effect of forming speed on the formability of tailor welded blanks (TWB) and its constituent sheets was examined. Tensile tests and formability experiments were conducted at different strain rates to construct forming limit curves (FLC). The results showed that strain-hardening indicators decreased with increasing strain rate and the flow stress of base metals could be predicted by a constitutive model. At medium-speed forming, the strain concentration in TWB occurred in the thin sheet near the dome center, and the formability decreased due to strain-hardening lowering, friction reduction, and inertial effects.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Amit Kumar, Ravi Kumar Digavalli, Vijay Gautam, Hariharan Krishnaswamy
Summary: This study investigates the influence of different processing techniques on the residual stress distribution in tailor welded blanks. The results show that hydroforming leads to lower and more uniformly distributed residual stresses, which can be beneficial for automotive applications.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2022)
Article
Engineering, Manufacturing
Himanshu Lalvani, Paranjayee Mandal
Summary: This study demonstrates the applicability of electron beam welding and laser beam welding techniques in manufacturing tailored welded blanks from different aluminum sheets. With an optimal post-weld heat treatment, improvements in elongation and hardness distribution of the welds were achieved, allowing for cold forming at ambient temperature.
JOURNAL OF MANUFACTURING PROCESSES
(2021)
Article
Engineering, Civil
N. Klinke, A. Schumacher
Summary: This paper introduces a new scheme for the automatic optimization of tailor rolled blanks, which is important for lightweighting vehicle bodies designed for mass production under cost restrictions. The optimization scheme includes CAE processes such as manufacturing simulation, structural behavior simulation, and production cost estimation. The optimization is based on high-quality metamodels to evaluate different optima.
THIN-WALLED STRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
Valentin Oleksik, Dan Dobrota, Sever-Gabriel Racz, Gabriela Petruta Rusu, Mihai Octavian Popp, Eugen Avrigean
Summary: This paper studied the behavior of Metal Active Gas tailor welded blanks during the single point incremental forming process experimentally. Fractures were found to occur in one side welded blanks even at moderate wall angles during SPIF, while double side welded blanks showed decreased formability but could still produce parts at moderate angles.
Article
Chemistry, Physical
Gabriela-Petruta Rusu, Radu-Eugen Breaz, Mihai-Octavian Popp, Valentin Oleksik, Sever-Gabriel Racz
Summary: This study investigates the behavior of tailor welded blanks subjected to a single point incremental forming (SPIF) process. The results show that one-sided welded blanks cannot be successfully formed, while two-sided welded blanks can achieve the desired depth.
Article
Materials Science, Multidisciplinary
Dario Basile, Raffaella Sesana, Manuela De Maddis, Luca Borella, Pasquale Russo Spena
Summary: The automotive industry is seeking innovative techniques to produce lighter, more efficient, and less polluting vehicles. One of the latest technologies is the fabrication of body-in-white and car parts using aluminum tailor welded blanks. However, their lower formability and the potential for weld defects in the laser welding process limit their use. This study investigates the effects of laser welding parameters on the mechanical properties and formability of aluminum tailor welded blanks.
Article
Automation & Control Systems
Vito Busto, Donato Coviello, Andrea Lombardi, Mariarosaria De Vito, Donato Sorgente
Summary: In the past few decades, various numerical models have been developed to simulate the keyhole laser welding process, including sophisticated multiphase models and less computationally expensive thermo-mechanical models. This study used a double-conical volumetric heat source to evaluate the laser joining process of sheets with different thicknesses, and the experiments showed that the model could satisfactorily estimate the shape and dimensions of the fused zone.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2022)
Article
Engineering, Civil
Luxin Yu, Xianguang Gu, Lijun Qian, Ping Jiang, Wei Wang, Ming Yu
Summary: The use of TRB structures can enhance the crashworthiness of vehicles. Optimizing the geometric distribution of TRB structures can reduce weight, increase energy absorption, and significantly improve the vehicle's crashworthiness.
THIN-WALLED STRUCTURES
(2021)
Article
Engineering, Civil
Bhupesh Singh Katiyar, Sushanta Kumar Panda, Partha Saha
Summary: In this study, laser welded blanks of different thicknesses were fabricated and subjected to stretch forming and crushing tests. It was found that the collapse mode was affected by the thickness ratio, while the presence of weld zone and the selection of thickness combination can enhance energy absorption capacity. The numerical modeling incorporating strain rate, material anisotropy, forming histories and WZ properties improved the prediction of collapse modes and load-displacement response.
THIN-WALLED STRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
Jie Wu, Yuri Hovanski, Michael Miles
Summary: A finite element model was used to study the influence of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. It was found that increasing thickness differential decreases the normalized equivalent plastic strain and normalized LDH values, providing an evaluation of blank formability.
Article
Engineering, Civil
Yi-quan Shu, Nan Xiang, Hao-ran Wang, Meng-han Yang, Peng-yi Wang, Tao Huang, Jun-qing Guo, Fu-xiao Chen
Summary: The study focuses on controlling the deformation of tailor-welded blanks (TWBs) using a non-uniform pressure field established by heterogeneous elastomers. The forming processes were simulated using heterogeneous elastomers with different ratios of Shore hardness as flexible dies. The results showed that reducing the hardness can greatly improve the deformation uniformity of TWBs and alleviate stress localization in the weld seam and its heat-affected zones.
THIN-WALLED STRUCTURES
(2023)
Article
Engineering, Manufacturing
Tanveer Majeed, Nooruddin Ansari, Yashwant Mehta, Arshad Noor Siddiquee
Summary: The size of the tool shoulder significantly affects the quality of joints in friction stir welding of tailor-welded blanks. Increasing the shoulder size leads to larger grain size, elimination of void defects, and the highest strength observed in joints fabricated with an 18 mm shoulder size.
JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME
(2022)
Article
Automation & Control Systems
Hui Wang, Lizi Liu, Haibao Wang, Jie Zhou
Summary: With the development of lightweight vehicles, tailor-welded blanks (TWBs) are being increasingly used in the automotive industry. This paper introduces a new method to control the forming defects of TWBs, characterised by metallography and tensile tests, and optimises forming parameters by introducing edge and notch cutting. The effectiveness of the proposed method is verified through experiments, showing consistent results with numerical simulations.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2022)
