Based on the Theory of the Miner Fatigue Damage of Fuzziness Analysis and Mathematical Modeling

2013 ◽  
Vol 437 ◽  
pp. 124-128 ◽  
Author(s):  
Xiao Fen Liu ◽  
Zhuo Wu ◽  
Ming Song ◽  
Min Zheng
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Membership Function ◽  
Test Results ◽  
Fuzzy Analysis ◽  
Loading Sequence ◽  
The Membership Function

In this paper, based on Miner rule, fuzzy analysis was carried out on predicting the fatigue damage, and mathematical model was established by considering loading sequence and interaction between loads and introducing the membership function. The analysis results show that the predicting fatigue life via the "Blurredregion" extension methods is closer to the test results.

A Multi-Level Low Cycle Fatigue Damage Model for Forging Die Material

2006 ◽  
Vol 514-516 ◽  
pp. 804-809
Author(s):  
S. Gao ◽  
Ewald Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Die Material ◽  
Multi Level ◽  
Loading Sequence ◽  
Forging Die

The forging die material, a high strength steel designated W513 is considered in this paper. A fatigue damage model, based on thermodynamics and continuum damage mechanics, is constructed in which both the previous damage and the loading sequence are considered. The unknown material parameters in the model are identified from low cycle fatigue tests. Damage evolution under multi-level fatigue loading is investigated. The results show that the fatigue life is closely related to the loading sequence. The fatigue life of the materials with low fatigue loading first followed by high fatigue loading is longer than that for the reversed loading sequence.

Fatigue Life Prediction for Variable Strain at a Mixing Tee by Use of Effective Strain Amplitude

2020 ◽  
Author(s):  
Koji Miyoshi ◽  
Masayuki Kamaya
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Hot Spot ◽  
Effective Strain ◽  
Single Overload ◽  
Loading Sequence

Abstract Mixing flow causes fluid temperature fluctuations near the pipe walls and may result in fatigue crack initiation. The authors have previously reported the loading sequence effect on thermal fatigue in a mixing tee. The fatigue damage around the hot spot, which was heated by the hot jet flow from the branch pipe, obtained by Miner’s rule was less than 1.0. Since the strain around the hot spot had waveforms with periodic overload, the loading sequence with periodic overload caused reduction of the fatigue life around the hot spot. In this study, the effect of a single overload on the fatigue crack growth rate was investigated in order to clarify the reduction of the fatigue life at the mixing tee due to strain with periodic overload. In addition, the prediction method of the fatigue life for the variable thermal strain at the mixing tee was discussed. It was shown the crack growth rate increased after an overload for both cases of tensile and compressive overloads. The effective strain amplitude increased after the application of a single overload. The fatigue life curve was modified by considering the increment of the effective strain range. The fatigue damage recalculated using the modified fatigue life curve was larger than 1.0 except in a few cases. The fatigue life could be assessed conservatively for variable strain at the mixing tee using the developed fatigue curve and Miner’s rule.

Nonlinear Cumulative Fatigue Damage Model

2011 ◽  
Vol 328-330 ◽  
pp. 1440-1444
Author(s):  
Hua Zou ◽  
Qiang Li ◽  
Shou Guang Sun
Keyword(s):  
Mathematical Model ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Welded Joint ◽  
Damage Model ◽  
Reasonable Explanation ◽  
Curve Method ◽  
Cumulative Fatigue Damage ◽  
Damage Rule

Cumulative fatigue damage is an important consideration in determining the fatigue life of structures. A cumulative linear damage rule cannot provide a reasonable explanation for cumulative fatigue damage, but a damage curve method based on nonlinear cumulative fatigue damage model can give a reasonable explanation. In this paper, a specific mathematical model is put forward, which is based on the damage curve method. In the model, miner formula is modified properly and an exponent formula is give out to fit the damage accumulate. According to a two-step fatigue test of aluminum–alloy welded joint, the comparison between the calculated results and the testing results is less than 5%. It shows that the model is reasonable and accuracy.

Fatigue Life Assessment for Variable Strain in a Mixing Tee by Use of Effective Strain Range

2021 ◽  
Author(s):  
Koji Miyoshi ◽  
Masayuki Kamaya
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Hot Spot ◽  
Effective Strain ◽  
Strain Range ◽  
Life Assessment ◽  
Miner’S Rule ◽  
Loading Sequence ◽  
Miner's Rule

Abstract Mixing flow causes fluctuations in fluid temperature near a pipe wall and may result in fatigue crack initiation. Movement of the hot spot, at which the pipe inner surface was heated by hot flow from the branch pipe, causes thermal stress fluctuations. In this study, the effect of the loading sequence on thermal fatigue in a mixing tee was investigated. In addition, the prediction method of the fatigue life for the variable thermal strain in the mixing tee was discussed. The time histories of the strain around the hot spot were estimated by finite element analysis for which the temperature condition was determined by wall temperature measured in a mock-up test. The accumulated fatigue damage around the hot spot obtained by Miner's rule was less than 1.0. Since the strain around the hot spot had waveforms with periodic overload, the loading sequence with periodic overload caused reduction of the fatigue life around the hot spot. Crack growth tests showed that a single overload decreased crack opening strain and increased the effective strain range. The increment of the effective strain range accelerated the crack growth rate after the overload. The accumulated fatigue damage for the strain in the mixing tee was calculated using Miner's rule and the strain ranges which added the maximum increment of the effective strain range. The accumulated fatigue damage was larger than 1.0 under most conditions. The proposed procedure is suitable to predict the conservative fatigue life in a mixing tee.

Variable Loading Sequence Effect for Thermal Fatigue at a Mixing Tee

2019 ◽  
Author(s):  
Koji Miyoshi ◽  
Masayuki Kamaya
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Pipe Wall ◽  
Hot Spot ◽  
Fatigue Tests ◽  
Stress Fluctuation ◽  
Fluctuation Range ◽  
Miner’S Rule ◽  
Loading Sequence ◽  
Miner's Rule

Abstract Mixing flow causes fluctuations in fluid temperature near the pipe wall and may result in fatigue crack initiation. In a previous study, the authors reported the characteristics of the thermal stress to cause thermal fatigue at a mixing tee. A large stress fluctuation was caused by movement of the hot spot, at which the pipe wall was heated by hot flow from the branch pipe. According to a general procedure, fatigue damage is calculated by the linear damage accumulation rule. However, it has been reported that Miner’s rule does not always predict the fatigue life conservatively for variable stress amplitude. In this study, we investigated the change in fatigue life due to variable strain around the hot spot. The time histories of the strain around the hot spot were estimated by finite element analysis (FEA) for which the temperature condition was determined by wall temperature measured in a mock-up test. Strain-controlled fatigue tests were conducted using smooth cylindrical specimens made of stainless steel. The fatigue damage at failure of the specimen was calculated using Miner’s rule. The calculated fatigue damage around the hot spot became less than unity and the minimum value was 0.18. Therefore, Miner’s rule predicted non-conservative fatigue life. In addition, the calculated fatigue damage inside the hot spot was larger than those outside the hot spot and at the position of maximum stress fluctuation. Fatigue tests using strain with periodic overload were also conducted in order to investigate the effect of the loading history on fatigue life. It was shown that the strain with periodic overload reduced the fatigue life. The calculated fatigue damage for the strain at the maximum position of stress fluctuation range seemed to be smaller than those at other positions. This implies that the fatigue life can be estimated conservatively from the viewpoint of the loading sequence effect by calculating the fatigue damage using Miner’s rule for the strain at the maximum position of stress fluctuation range.

scholarly journals Optimization of Fuzzy Tsukamoto Membership Function using Genetic Algorithm to Determine the River Water

2017 ◽  
Vol 7 (5) ◽  
pp. 2838 ◽  
Author(s):  
Qoirul Kotimah ◽  
Wayan Firdaus Mahmudy ◽  
Vivi Nur Wijayaningrum
Keyword(s):  
Genetic Algorithm ◽  
Water Quality ◽  
River Water ◽  
Membership Function ◽  
Aquatic Ecosystems ◽  
River Water Quality ◽  
Fuzzy Membership ◽  
Fuzzy Membership Function ◽  
Test Results ◽  
The Membership Function

Some aquatic ecosystems in rivers depend on the river water, so it needs to be maintained by measuring and analyzing the river water quality. STORET is one of the methods used to measure the river water quality, but it takes a quite high of time and costs. Fuzzy Tsukamoto is an alternative method that works by grouping the river water data, but it is difficult to determine the membership function value. The solution offered in this study is the use of genetic algorithm to determine the membership function value of each criterion. Based on the test results, the optimization of fuzzy membership function using genetic algorithm provides higher accuracy value that is 95%, while the accuracy value without optimization process is 90%. The parameters used in genetic algorithm are as follows: population size is 80, generation number is 175, crossover rate (<em>cr</em>) is 0.6, and mutation rate (<em>mr</em>) is 0.4.

Effects of Regular and Nano Sized Hydrated Lime Fillers on Fatigue and Bond Strength Behavior of Asphalt Mastic

2018 ◽  
Vol 2672 (28) ◽  
pp. 31-41 ◽  
Author(s):  
Aditya Kumar Das ◽  
Dharamveer Singh
Keyword(s):  
Fatigue Life ◽  
Bond Strength ◽  
Fatigue Damage ◽  
Asphalt Binder ◽  
Hydrated Lime ◽  
Moisture Damage ◽  
Test Results ◽  
Asphalt Mastic ◽  
Asphalt Mastics ◽  
Number Of Cycles

The present study evaluates effects of regular sized hydrated lime (RHL) and nano sized hydrated lime (NHL) on fatigue and bond strength of asphalt mastic. The asphalt mastics were produced in the laboratory using AC-30 binder with different combinations of basalt–RHL, and basalt–NHL fillers. The dosages of RHL and NHL were selected as 0%, 5%, 10%, 15%, and 20% by weight of asphalt binder, and the percentage of basalt filler was adjusted accordingly. Filler to binder (F/B) ratio was selected as 0.8 (by mass ratio) for all mastic sample preparation. The fatigue damage behavior (number of cycles to fatigue damage/failure) of asphalt mastic was evaluated using a linear amplitude sweep (LAS) test. Further, the interfacial bond strengths of asphalt mastic and aggregate samples were evaluated using the bitumen bond strength (BBS) test. Overall test results indicate that mineralogy, surface area, and interaction properties of RHL and NHL fillers have a significant effect on fatigue, bond strength, and moisture damage performance of asphalt mastic. The results from the LAS test showed that NHL filler predominantly enhanced the fatigue life of asphalt mastic as compared with RHL filler. BBS test results imply that the contribution of NHL filler is significant over RHL filler in improving the bond strength and moisture damage resistance of asphalt mastic. Overall asphalt mastic with 20% NHL filler had better fatigue life, bond strength, and moisture damage performance over mastic with other percentages of RHL or NHL fillers.

Fatigue Life Prediction of Composite Laminates under Block Loading

2014 ◽  
Vol 697 ◽  
pp. 114-117
Author(s):  
Qing Hui Ji ◽  
Ping Zhu ◽  
Jia Hai Lu ◽  
Chao Zhu
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Fatigue Damage ◽  
Life Prediction ◽  
Testing Machine ◽  
Damage Index ◽  
Block Loading ◽  
Proposed Model ◽  
Loading Sequence ◽  
Stress Ratios

The loading sequence effect and life prediction of carbon fiber-reinforced polymer (CFRP) composite materials were experimentally investigated in this paper. All fatigue tests of block loading under four stress ratios R (including 0.1, 0.5, 10 and –1) were carried out on the servo-hydraulic Shimadzu testing machine. The fatigue damage index derived from the linear Palmgren–Miner rule was as reference to evaluate the damage degree. The life prediction model based on residual strength theory was proposed. The experimental results showed that the effect of loading sequence on the fatigue damage was obvious. The relation between the parameter of the proposed model and the stress ratio was studied depending to different failure mode. At last, the contrast of prediction and experimental data indicated that the proposed model had enough accuracy to predict fatigue life of block loading for composite materials.

MATHEMATICAL MODELING OF PROPELLER SERIES

2014 ◽  
Vol 156 (B2) ◽  
Author(s):  
M Bukarica
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Expert System ◽  
Propulsion System ◽  
Test Results ◽  
Reliability Of Results ◽  
Mathematical Functions ◽  
Ship Propulsion ◽  
Mathematical Expressions ◽  
Selection Of

Propeller series are used in the process of designing the ship propulsion system, propeller and engine. The emergence of computers has made it possible to create a program, an expert system, which greatly accelerates and improves this process. In order to create such a program, it is necessary to provide a mathematical model of the test results, i.e. describe them by some mathematical expressions. In addition to this mathematical model, such a program must also have a mathematical model of the ship resistance. Precision and reliability of results produced by the expert system for the selection of the ship propulsion system depends on precision of the mathematical models it uses. Usual modeling procedures use standard mathematical functions and statistical methods. The aim of this paper is to present a "natural method" of mathematical modeling using spline functions, to compare them with each other, and to point out their advantages and deficiencies.

Application of the method of mathematical modeling for forecasting channel deformations at the underwater crossing of the main pipeline

2020 ◽  
Vol 10 (6) ◽  
pp. 599-609
Author(s):  
Valery А. Gruzdev ◽  
◽  
Georgy V. Mosolov ◽  
Ekaterina A. Sabayda ◽  
◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Roughness Coefficient ◽  
Computational Domain ◽  
Channel Deformations ◽  
Geological Surveys ◽  
Kuban River ◽  
The Stability ◽  
Protective Structures

In order to determine the possibility of using the method of mathematical modeling for making long-term forecasts of channel deformations of trunk line underwater crossing (TLUC) through water obstacles, a methodology for performing and analyzing the results of mathematical modeling of channel deformations in the TLUC zone across the Kuban River is considered. Within the framework of the work, the following tasks were solved: 1) the format and composition of the initial data necessary for mathematical modeling were determined; 2) the procedure for assigning the boundaries of the computational domain of the model was considered, the computational domain was broken down into the computational grid, the zoning of the computational domain was performed by the value of the roughness coefficient; 3) the analysis of the results of modeling the water flow was carried out without taking the bottom deformations into account, as well as modeling the bottom deformations, the specifics of the verification and calibration calculations were determined to build a reliable mathematical model; 4) considered the possibility of using the method of mathematical modeling to check the stability of the bottom in the area of TLUC in the presence of man-made dumping or protective structure. It has been established that modeling the flow hydraulics and structure of currents, making short-term forecasts of local high-altitude reshaping of the bottom, determining the tendencies of erosion and accumulation of sediments upstream and downstream of protective structures are applicable for predicting channel deformations in the zone of the TLUC. In all these cases, it is mandatory to have materials from engineering-hydro-meteorological and engineering-geological surveys in an amount sufficient to compile a reliable mathematical model.

Sign in / Sign up

Export Citation Format

Share Document