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Abstract

Titanium alloys are difficult-to-machine materials due to their complex mechanical and thermophysical properties. An essential factor in ensuring the quality of the machined surface is the analysis and recommendation of vibration processes accompanying cutting. The analytical description of these processes for machining titanium alloys is very complicated due to the complex adiabatic shear phenomena and the specific thermodynamic state of the chip-forming zone. Simulation modeling chip formation rheology in Computer-Aided Forming systems is a practical method for studying these phenomena. However, dynamic research of the cutting process using such techniques is limited because the initial state of the workpiece and tool is a priori assumed to be "rigid", and the damping properties of the fixture and machine elements are not taken into account at all. Therefore, combining the results of analytical modeling of the cutting process dynamics with the results of simulation modeling was the basis for the proposed research methodology. Such symbiosis of different techniques will consider both mechanical and thermodynamic aspects of machining (specific dynamics of cutting forces) and actual conditions of stiffness and damping properties of the “Machine-Fixture-Tool-Workpiece” system.
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Authors and Affiliations

Vadym Stupnytskyy
1
ORCID: ORCID
She Xianning
1
ORCID: ORCID
Yurii Novitskyi
1
ORCID: ORCID
Yaroslav Novitskyi
1
ORCID: ORCID

  1. Lviv Polytechnic National University, Lviv, Ukraine
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Abstract

In the academic community within Poland, there is an ongoing debate about the optimal strategies for a redesign of PhD programs; however, the views of PhD students in relation to contemporary doctoral study programs are not widely known. Therefore, in this article, we aim to answer the following questions: (1) what are the demands and the resources for doctoral studies at the Jagiellonian University (JU) as experienced by PhD students? (2) how are these demands and resources related to study burnout and engagement? To gain answers to these questions, we conducted an on-line opinion-based survey of doctoral students. As a result, 326 JU PhD students completed a questionnaire measuring 26 demands and 23 resources along with measures of study burnout and levels of engagement. The results revealed that the demands of doctoral studies at the JU (as declared by at least half of the respondents) are: the requirement to participate in classes that are perceived as an unproductive use of time, the lack of remuneration for tutoring courses with students, a lack of information about possible career paths subsequent to graduation, the use of PhD students as low-paid workers at the university, a lack of opportunities for financing their own research projects, and an inability to take up employment while studying for a doctoral degree. In terms of resources, at least half of the doctoral students pointed to: discounts on public transport and the provision of free-of-charge access to scientific journals. Analyzing both the frequency and strength of the relationships between resources/demands and burnout/engagement, we have identified four key problem areas: a lack of support from their supervisor, role ambiguity within University structures for PhD students, the conflict between paid work and doctoral studies, and the mandatory participation in classes as a student.

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Authors and Affiliations

Konrad Kulikowski
Rafał Damaziak
Anna Kańtoch

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