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New Characteristics in the Assessment of Reliability of Machines and Devices

Kopania Gabriela, Kuczmaszewska Anna

Management and Production Engineering Review

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2021

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Vol. 14, No. 4

45--52

EN

The aim of this work is to present new reliability characteristics expressed as functions of some variable expressing the measure of effective operation of a machine or a device. These characteristics can be used for both renewable and non-renewable objects. Their mathematical idea reflects the essence of already known characteristics, i.e. it expresses the probability of failure but expressed as a function of a variable, not necessarily identified with time.

2

Fatigue strength determination of ship structural joints. Part I. Analytical methods for determining fatigue strength of ship structures

Kozak J., Górski Z.

Polish Maritime Research

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2011

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nr 2

28-36

EN

Spectacular accidents at sea which have happened for a few last years show that hull structures of contemporary sea-going ships are not perfect and must be systematically improved. Fatigue strength is one of the groups of strength problems which affect design of contemporary ship’s structures and greatly contribute in their improvement process. In this paper several approaches to estimation of fatigue life of hull structural elements are presented. In practice the some approaches based on nominal stresses, „hot spot” stresses or notch stresses which constitute the basis for fatigue life determination by using ó-N design curves are applied. In this paper the existing proposals have been critically analyzed and their drawbacks (often hidden) presented.

3

Safety enhancement and fatigue life protection of the lorry frames carrying elements by using of its real working conditions simulation

Leitner B., Kelemen M.

Diagnostyka

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2010

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nr 2(54)

11-16

EN

The goal of this paper will be to present FEM application in the TATRA 815 lorry frame structure fatigue life estimation. Structure critical nodes from the fatigue damage point of view have been found and analyzed. Analysis of the particular traffic states influence on the fatigue damage cumulation is going to be presented too.

4

Evaluation of a fatigue cumulative damage in service life prediction

Čačko J.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2001

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Vol. 269, z. 67

27-46

EN

Damage accumulation is evaluated according to a cumulative damage hypothesis, and the residual life is predicted with respect to a fatigue failure criterion. The estimation of cumulative damage under service loading is significantly influenced by a time loading history. The problem of the history effect can be converted to the problem of investigation of equivalent loading with non-zero stress/strain mean value. The conversion method is based in specification of an equivalent amplitude of the harmonic cycle with zero stress and strain mean values. At the same time, a relative damage that is accumulated in the course of equivalent cycle must be the same as the relative damage of actual cycle which has been identified by the rainflow method. The submitted approach enables to utilize the knowledge of cumulative damage process and fatigue behaviour prediction under harmonic loading and to use it for any complex operating loading spectrum. The base of the method and obtained results are presented in the paper.