The Laboratory "Dynamics and Extreme Characteristics of Promising Nanostructured Materials" was established at Saint Petersburg State University on June 30, 2022, under the leadership of Professor Li Baoqiang with the support of the Government of the Russian Federation (Resolution 220) within the framework of Agreement No. 075-15-2022-1114 on the provision of federal budget grants in the form of subsidies in accordance with Clause 4 of Article 78.1 of the Budget Code of the Russian Federation.
The laboratory is engaged in the development of various areas of nanomaterials mechanics; the development of scientific principles for obtaining new metallic bulk nanomaterials, including those with ultra-high mechanical properties, as well as their innovative application in structural engineering, electrical engineering, and medicine; and the study of various new materials and their application in modern fields of industry and science. Special attention in the Laboratory's research is paid to interdisciplinarity, investigating current problems at the intersection of different scientific fields, including research on nanomaterials mechanics, physics and materials science of nanostructures, nanoengineering, bioengineering, and chemistry.
The laboratory is engaged in the development of various areas of nanomaterials mechanics; the development of scientific principles for obtaining new metallic bulk nanomaterials, including those with ultra-high mechanical properties, as well as their innovative application in structural engineering, electrical engineering, and medicine; and the study of various new materials and their application in modern fields of industry and science. Special attention in the Laboratory's research is paid to interdisciplinarity, investigating current problems at the intersection of different scientific fields, including research on nanomaterials mechanics, physics and materials science of nanostructures, nanoengineering, bioengineering, and chemistry.
Project objectives
- Identifying fundamental patterns of fracture processes and structural transformations in new advanced nanostructured materials, particularly materials obtained through a combination of severe plastic deformation and heat treatment methods, as well as hydrogels and coatings, based on classical principles of continuum mechanics and fundamentally new approaches to dynamic fracture and structural transformations that account for the scale and structural-temporal characteristics of material behavior.
- Setting up new experiments and developing existing experimental methods to study the behavior of engineering and medical materials, including nanostructured materials, nanocomposites, and nanocoatings under dynamic non-stationary thermomechanical influences.
- Developing recommendations for the advancement of existing and the creation of new regulations and standards to assess the load-bearing capacity of new advanced materials introduced into industry under extreme operating conditions.
- Developing fundamental principles for optimizing technological processes and determining optimal methods for the targeted acquisition of physical and mechanical properties of advanced nanostructured materials.
- Improving the quality and attractiveness of educational and research activities in the field of creation and mechanics of new advanced materials at Saint Petersburg State University.
- Attracting young scientists and students to cutting-edge research and new educational programs in materials science, mechanics of materials, and extreme states of continuous media.
- Enhancing the international reputation of Saint Petersburg State University as a primary center of Russian education and science through collaboration with leading scientists in the field, foreign research centers, and the publication of project results in prestigious international and central academic journals.
- Creation of a new innovative laboratory focused on the dynamics and extreme characteristics of advanced nanostructured materials, capable of continuing tasks 1)-7) at a world-class level after the completion of the 2022-2024 stage.
Scientific Results
- A fundamental analogy has been discovered between the rupture of a linear oscillator and the dynamic fracture of solids, enabling a simple engineering interpretation of complex continuum behavior in extreme states under intense thermomechanical loads. Key effects of dynamic rupture in media were identified, specifically fracture delay and the increase in ultimate stresses of the system under high-speed impact. Accounting for the inertial properties of the system helps capture these effects and thus clearly demonstrates and explains the inapplicability of standard strength models when considering extreme loads. It is shown that the linear oscillator is an easy-to-use yet functional tool for interpreting complex fast-fracture effects, allowing for "specialized" application to various cases. The mathematical model is calibrated using known experimental results on dynamic crack initiation in plates and spallation. It is demonstrated that the model performs well despite its simplicity and the strength of the assumptions made.
- Based on the incubation time approach, a new model of thermal softening associated with stress relaxation—i.e., a decrease in internal resistance to deformation with increasing bulk temperature—has been constructed. Plastic deformation under extreme high-speed impacts is often accompanied by a clear adiabatic temperature rise. A model of thermal softening of metals subjected to high-speed loading has been developed. The new approach accounts for strain rate sensitivity as a manifestation of the temporal sensitivity of materials. A comprehensive analysis of the developed relaxation plasticity model (RP-model) was conducted, showing that this model can be derived from a time-dependent yield surface equation using the incubation time concept. Based on experimental data for HSLA-65 steel, a 93W-4.9Ni-2.1Fe tungsten-based composite, and Ti-6Al-4V titanium alloy, the descriptive capabilities of the developed RP-model are compared with other constitutive models (phenomenological and micromechanism-based), as well as an artificial neural network (ANN) model.
Education and Personnel Retraining:
4 PhD dissertations and 1 Doctoral dissertation (D.Sc.) were defended.Collaboration:
NanoMet LLC (Russia)Website: https://nanomaterials.spbu.ru/ru/
Contact person: Li Baoqiang, Professor, Head of Laboratory
Address: Stary Peterhof, Universitetsky pr., 28, Faculty of Mathematics and Mechanics, rooms 3240, 3224.
E-mail: st008007@spbu.ru
Contact person: Li Baoqiang, Professor, Head of Laboratory
Address: Stary Peterhof, Universitetsky pr., 28, Faculty of Mathematics and Mechanics, rooms 3240, 3224.
E-mail: st008007@spbu.ru
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