scholarly journals The lifetime forecasting of machine elements by fatigue strength criterion

Diagnostyka ◽  
2021 ◽  
pp. 39-49
Author(s):  
Yuriy Khomyak ◽  
Oleksandr Kibakov ◽  
Stanislav Medvedev ◽  
Ilya Nikolenko ◽  
Victoria Zheglovа
Keyword(s):  
Fatigue Strength ◽  
Strength Criterion ◽  
Machine Elements

scholarly journals ДО РОЗРАХУНКІВ ДЕТАЛЕЙ НА МІЦНІСТЬ В ЙМОВІРНІСНОМУ АСПЕКТІ

2018 ◽  
Vol 124 (4) ◽  
pp. 17-25
Author(s):  
Л. М. Березін ◽  
М. М. Рубанка
Keyword(s):  
Fatigue Strength ◽  
Strength Criterion ◽  
Subject Area ◽  
Statistical Characteristics ◽  
Limited Data ◽  
Statistics And Probability ◽  
Reliability Characteristics ◽  
Wide Range ◽  
Further Development

Generalization of regulations, empirical and analytical information concerning the determination of the statistical characteristics of the strength of metals and details for used in strength calculations in the probabilistic aspect. Are used modern methods of searching, describing and analyzing information to audit a variety of possible solutions in the subject area of research, developments with the strength of materials, mathematical statistics and probability theory. Is presented the possibility of using at the design stages for calculations of determine the statistical characteristics of the fatigue resistance of details at limited data on the mechanical characteristics of the strength of the material. The research results make it possible to take reasonable proposals to improve the fatigue strength of details. The further development of the theory and methodology of mathematical solutions for designing machine parts with specified reliability characteristics by the fatigue strength criterion while minimizing their weight and size. Is presented information that improves the quality and efficiency of design solutions for ensure the specified reliability of details. The calculation is performed on the example of cylindrical coil springs with a wide range of changes in their geometric, elastic and force parameters.

Research on Dynamic Fatigue Strength Criterion of BTA Deep Hole Boring Bar for Consideration Vortex Surrounded by Internal and External Cutting Fluid

2011 ◽  
Vol 189-193 ◽  
pp. 2264-2268
Author(s):  
Wu Zhao ◽  
De Jie Chen
Keyword(s):  
Fatigue Strength ◽  
Fatigue Failure ◽  
Working Conditions ◽  
Failure Modes ◽  
Processing System ◽  
Strength Criterion ◽  
Cutting Fluid ◽  
Hole Drilling ◽  
Deep Hole ◽  
Boring Bar

Fatigue failure is the most common failure mode of boring bar in the deep-hole boring processing system. For solving the problem of fatigue failure on boring bar, the new fatigue strength criterion of boring bar is proposed considering the working state including internal and external cutting fluid vortex, linear crack of the across-section, and the maximum bending - torsion coupled stress of boring bar. Firstly, approximate calculation formula of the maximum bending stress was derived considering internal and external cutting fluid coupled effect induced vortex motion. Secondly, near the region of crack tip, the maximum shearing stress was studied when the failure modes of boring bar was considered to linear crack on its cross-section. Finally, the new fatigue strength criterion was established based on bending-torsion combination alternating stress fatigue strength theory. An example calculation in practice showed that if fatigue strength of boring bar is satisfied to the new fatigue strength criterion, its static strength must be satisfied. The new fatigue strength criterion can be used in analyzing the boring bar’s fatigue strength on both complicated working conditions and also single working conditions. The mechanism of failure and destruction of boring bar on BTA deep hole drilling in generally actual working conditions were studied in this paper which are helpful to promote the service life cycle of boring bar in practice. Some rules are also derived to assess the dynamic performance of working boring bar, which structure parameters will be selected reasonably according to it.

The Analysis of Practical Usage Experience of the Ship Structures Fatigue Strength Criterion

2003 ◽  
Author(s):  
Gennadiy V. Egorov ◽  
Vitaliy V. Kozlyakov ◽  
Nickolay N. Sivoborodchenko
Keyword(s):  
Fatigue Strength ◽  
Fatigue Resistance ◽  
Strength Criterion ◽  
Trial And Error ◽  
Ship Structures ◽  
Analytical Formulation ◽  
Section Modulus

It is shown in the report, that the trial-and-error requirements of the Rules of classification societies to the minimum section modulus of transport ships, including the FPSO-type ships, are based, mainly, on the maintenance of their strength, the lack of which in riveted ships exhibits in the form of weakening of rivet joints, and in welded ships in the form of cracks. The analysis of proposals for analytical formulation of the fatigue strength criterion (F.S.C.) during 150 years of development of steel shipbuilding confirms this thesis. It is shown, that modern recommendations of IACS (1999) do not provide stable reserves of fatigue resistance for ships of different standard-sizes, especially those constructed from high-tensile steels. In the report the ways of perfecting of the requirements to fatigue strength are offered.

scholarly journals Design of Jack-Up Platform for 6 MW Wind Turbine: Parametric Analysis Based Dimensioning of Platform Legs

2019 ◽  
Vol 26 (2) ◽  
pp. 183-197
Author(s):  
Paweł Dymarski
Keyword(s):  
Fatigue Strength ◽  
Wind Turbine ◽  
Parametric Analysis ◽  
Strength Criterion ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Strength Analysis ◽  
Main Task ◽  
Jack Up ◽  
The Impact

Abstract The article presents the results of the research conducted within the framework of the project entitled WIND-TU-PLA (ERA-NET, MARTEC II), the general aim of which was to design and analyse supporting structures for wind turbines intended for operation on the South Baltic area. The research part described in the article aimed at developing a preliminary design for a jack-up platform which can operate on water areas with depth of 40 m. The main task was to determine optimal dimensions of platform legs and the radius of their spacing. Two jack-up platform concepts differing by spacing radius and hull dimensions were designed with the intention to be used as a supporting structure for a 6-MW offshore wind turbine. For each concept, the parametric analysis was performed to determine optimal dimensions of platform legs (diameter Dleg and plating thickness tleg). Relevant calculations were performed to assess the movements of the platform with parameters given in Table 1 in conditions simulating the action of the most violent storm in recent 50 years. The obtained results, having the form of amplitudes of selected physical quantities, are shown in comprehensive charts in Fig. 6 and 7. Based on the critical stress values (corresponding to the yield stress), the area was defined in which the impact strength conditions are satisfied (Fig. 14). Then, the fatigue strength analysis was performed for two selected critical leg nodes (Fig. 12). Its results were used for defining the acceptable area with respect to structure’s fatigue (Fig. 14). Geometric parameters were determined which meet the adopted criteria, Table 6. The decisive criterion turned out to be the fatigue strength criterion, while the yield point criterion appeared to be an inactive constraint.

scholarly journals Method of the shortcut estimation of rails' reliability by the fatigue strength criterion

2009 ◽  
Vol 41 (1) ◽  
pp. 68-73
Author(s):  
L. A. Sosnovskii ◽  
N. A. Makhutov ◽  
V. I. Matviatsov ◽  
A. A. Kebikov
Keyword(s):  
Fatigue Strength ◽  
Strength Criterion

Analysis of machine elements in shape of helicoidal shell on cylindrical shell

2007 ◽  
Vol 221 (6) ◽  
pp. 627-638 ◽  
Author(s):  
S Savicevic ◽  
S Zekovic
Keyword(s):  
Differential Equation ◽  
Cylindrical Shell ◽  
Cross Section ◽  
Shell Thickness ◽  
Strength Criterion ◽  
Uniform Pressure ◽  
Machine Elements ◽  
The Finite Difference Method ◽  
Automated Determination

A procedure for the automated determination of the geometric parameters of a helicoidal shell on a cylindrical one that is applied to machines for special purposes is presented in this paper. A differential equation for the bending of a helicoidal shell subjected to a uniform pressure and a differential equation for the cylindrical shell loaded by a uniformly distributed moment along the helix are used to define the boundary conditions along the cross-section of these shells. The finite difference method is used to solve the differential equation for the bending of a helicoidal shell in MATLAB software. The values of the shell thickness are determined for different parameters using a strength criterion. Different models of the helicoidal shell are analysed.

scholarly journals Fatigue fracture criterion of composite materials

2019 ◽  
Vol 488 (5) ◽  
pp. 488-492
Author(s):  
A. R. Arutyunyan
Keyword(s):  
Composite Materials ◽  
Fatigue Strength ◽  
Fatigue Fracture ◽  
Damage Accumulation ◽  
Strength Criterion ◽  
Experimental Results ◽  
Reinforced Plastics ◽  
Damage And Fracture ◽  
Scattered Damage ◽  
The Moment

The first investigations on the fatigue strength of composite materials were carried out on cyclic tension of plastics reinforced by fiberglass. Since that time, intensive studies of fatigue strength of composite materials were begin. The experimental data obtained for different types of composite materials shown, that the fatigue fracture processes are governed by the accumulation of defects of different nature. The main mechanisms that determine the durability of composites is the kinetics of the damaged state development until the final fracture. At the same time, according to the experimental results, the damage accumulation curve of the total damage is defined by increased function of the time (number of loading cycles) until to the moment of macro fracture. In this paper, based on these studies and the conception of scattered damage and fracture, fatigue strength criterion is formulated. Fatigue criterion coefficients are concretized and damage accumulation curves are plotted, which depends on the number cycles and stress level. The comparison with experimental results on fatigue of glass-reinforced plastics and carbon fiber reinforced plastics is given.

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