2
RUDN University Engineers Propose a New Approach for Accounting Plastic Anisotropy in the Theoretical Description of Metal Forming Processes

RUDN University Engineers Propose a New Approach for Accounting Plastic Anisotropy in the Theoretical Description of Metal Forming Processes

RUDN University engineers have shown that theoretical calculations traditionally used to describe the compression of metal work pieces, do not consider an important property of materials. Scientists have proposed a new approach that considered the missing property and showed that the result in this case changes by 15-20%.

The metal details are obtained by forming processes, that include for example rolling, extrusion, forging, as well as upsetting a cylindrical work piece (when it is increased in diameter with reduction in length). The practical application of upsetting goes together with theoretical models, but they are based on an initially incorrect assumption. It is usually assumed that the properties of the material are isotropic, that is, the same in all directions. In reality, this is not the case and the properties are anisotropic. RUDN University engineers proposed a new approach to theoretical calculations and showed that considering anisotropy significantly affects the cylinder draft.

“The analysis of cylinder’s upsetting is usually based on isotropic models. In addition, these solutions ignore the the regime of sticking on the friction surface, which always occurs in exact solutions near the axis of symmetry. In turn, the sticking regime leads to the appearance of a rigid region moving together with the plate. Neglecting the anisotropy of the material and the noted properties of exact solutions makes the practical value of these solutions questionable. Our overall motivation was to demonstrate, using a simple example, that plastic anisotropy, which is a very common property of metallic materials, should not be ignored in upper bound solutions for metal forming processes”, said Sergei Alexandrov, professor at RUDN University’s Department of Civil Engineering.

The researchers studied a problem in which an entire metal cylinder is pressed by two parallel plates. The speed of the plates is set, the dimensions of the cylinder are known. It is assumed that the physical properties of the cylinder are orthotropic, that is, they differ in three perpendicular directions. RUDN University engineers took the upper bound theorem as the basis of theoretical analysis. The Hill’s quadratic yield criterion was also used for calculations, which connects stresses along different axes in a certain combination.

RUDN University engineers tested the theoretical calculations on numerical examples — four materials with different anisotropies. The results showed that anisotropy affects the force that must be applied to upset a cylinder. The difference in strength was 15-20%. This is explained by the fact that due to anisotropy there are regions inside the cylinder that interact with each other in different ways, there is friction and sticking.

“A distinguishing feature of the solution is that plastic anisotropy and the existence of a rigid region are considered. The existence of the rigid region automatically means that there is a region of sticking friction. It can be concluded that Plastic anisotropy affects the limit load required to deform the specimen. It may increase or decrease the limit load as compared to the isotropic case”, said Sergei Alexandrov, professor at RUDN University’s Department of Civil Engineering.

The study is published in Materials. 

Visiting Professors View all
12 Dec 2024
In 2024, RUDN started accepting applications for the new annual Prize for Scientific Achievement in Chemistry. The award was established to honour contributions to fundamental and applied research, as well as merit in achieving the UN Sustainable Development Goals.
187
International scientific cooperation View all
12 Dec 2024
From 19 to 23 November 2024, RUDN hosted the III International Scientific Conference ‘For the Sustainable Development of Civilisation: Cooperation, Science, Education, Technology’. The event gathered more than 2000 participants from 72 countries.
172
Similar newsletter View all
20 Apr
A volunteer of the Red Army and head of the veterinary medicine course — Matilda Mityaeva's combat and scientific path

Matilda Pavlovna Mityaeva was born in 1925. In November 1942, she volunteered for frontline duty. She participated in the Great Patriotic War from November 1942 to June 1945 as part of the 53rd Infantry Division of the 475th Infantry Regiment. She was wounded twice.

24
20 Apr
RUDN University Team – the 1st place in the all-russian competitive selection of scientific projects “Technologies for human health”

The team led by Sergey Zyryanov, Head of the Department of General and Clinical Pharmacology, became the winner of the All-Russian competition of scientific projects "Technologies for Human Health".

32
20 Apr
RUDN University Scientific Agenda to 2030: New Programme for R&D and Innovation Activities Development

RUDN University constantly adapts to the changes of the modern world and responds to challenges flexibly. This allows us to keep the standard of a world-class research university. The sphere of science is no exception. Peter Dokukin, Head of the Research Division, presented the updated R&D Programme at the meeting of the RUDN University Academic Council.

23
Similar newsletter View all