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The use of computational contact mechanics approaches to assess the performance of parts bearing stress concentrators

Lyashenko B. A., Stotsko Z. A., Kuzin O. A., Kuzin M. O.

Journal of Achievements in Materials and Manufacturing Engineering

2020

Vol. 103, nr 1

25--32

Purpose: The purpose of this work is to build new computational schemes for assessing the strength parameters of parts with inhomogeneous properties of surface layers in the presence of stress concentrators. Design/methodology/approach: Using the developed approaches of mathematical modeling and open software for calculating the structures of the FEM - FEniCS, the required thickness of the hardened zones of parts has been established, which ensures their minimum softening during operation, depending on the characteristics of the stress concentrator. Findings: It is shown that for each size of the surface stress concentrator there is a critical value of the hardening thickness, the excess of which does not affect the operational strength of the parts, but increases the cost of technological operations. Research limitations/implications: In this article proposes a method for calculating the influence of the dimensional characteristics of hardening zones on the contact strength of parts with stress concentrators under conditions of prevailing power loads. Practical implications: The results obtained in this work were used to determine the technological modes of plasma hardening, which ensure an increase in the contact strength of parts with stress concentrators, depending on their dimensional characteristics. Originality/value: Using the approaches of computational mechanics and mathematical and computer modeling, methods for controlling the contact strength of parts with inhomogeneous non-local properties in the presence of a surface stress concentrator are proposed for the first time.

Charakterystyki energetyczne obciążeń dynamicznych ciała człowieka

Kaźmierczak H.

Diagnostyka

2007

nr 2(42)

63-67

Oddziaływanie drgań na człowieka powoduje ich selektywne przenoszenie przez strukturę jego ciała. Wyznaczono analityczny model strukturalny dynamiki ciała człowieka. Synteza własności dynamicznych modelu systemu metodą podatności dynamicznych umożliwiła wyznaczenie charakterystyk dynamicznych struktury stojącego człowieka. Do wyznaczenia charakterystyk dynamicznych modelu ciała człowieka przyjęto parametry struktury modelu wg Potiemkina-Frołowa. Wyznaczono moce wejściowe reakcji człowieka na wymuszenia występujące na korpusie ciągnika. Ciągnik poddawany był wymuszeniom symulującym przejazd przez przeszkody (na stanowisku badań przyspieszonych). Częstotliwości podstawowe wymuszeń: 1Hz, 1,26Hz, 2,5Hz.

Vibration influence on man causes its selective transfer through the structure of human body. There was determined analytical structural model of human body dynamic. Synthesis of dynamical features of the model's system by dynamical receptivity method enabled determining of dynamical characteristics of structure of a standing man. For determine dynamical characteristics of human body there were suggested parameters of structure according to Potiemkin-Frolow model. There were determined exit powers of human reactions on forces occuring on a tractor's frame. The tractor was forced by simulation of going through the blocks (on a stand of accelerating tests). Basic frequencies of forces: 1Hz, 1,26Hz, 2,5Hz.