scholarly journals Fatigue life of propulsion shafts: direct calculation as per modern methods

2020 ◽  
Vol S-I (2) ◽  
pp. 68-71
Author(s):  
V. Platonov ◽  
◽  
A. Filatov ◽  
Keyword(s):  
Numerical Simulation ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Direct Calculation ◽  
Critical Plane ◽  
Proportional Loading ◽  
Plane Method ◽  
Critical Stresses ◽  
Modern Methods ◽  
Fatigue Model

This study is an alternative FEM-based fatigue strength calculation for propulsion shafts as per RS Rules. Direct numerical simulation yielded the fields of stresses and strains. Lifetime assessment was based on S-N fatigue model: critical stresses for this model were obtained as per critical-plane method taking into account non-proportional loading of propulsion shafts. It compares two shaft designs: in compliance with RS Rules and with deviation from them.

Multiaxial Fatigue Life Prediction of Metallic Materials Based on Critical Plane Method under Non-Proportional Loading

2017 ◽  
Vol 730 ◽  
pp. 516-520 ◽  
Author(s):  
Er Nian Zhao ◽  
Wei Lian Qu
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Metallic Materials ◽  
Loading Conditions ◽  
Critical Plane ◽  
Proportional Loading ◽  
Plane Method ◽  
Strain Paths

The critical plane method is widely discussed because of its effectiveness for predicting the multiaxial fatigue life prediction of metallic materials under the non-proportional loading conditions. The aim of the present paper is to give a comparison of the applicability of the critical plane methods on multiaxial fatigue life prediction. A total of 205 multiaxial fatigue test data of nine kinds of metallic materials under various strain paths are adopted for the experimental verification. Results shows that the von Mises effective strain parameter and KBM critical plane parameter can give well predicted fatigue lives for multiaxial proportional loading conditions, but give poor prediction lives evaluation for multiaxial non-proportional loading conditions. However, FS parameter shows better accuracy than the KBM parameter for multiaxial fatigue prediction for both proportional and non-proportional loading conditions.

Study of the Multiaxial Fatigue Life Influencing Factors Based on the Critical Plane Approach

2011 ◽  
Vol 295-297 ◽  
pp. 2314-2320
Author(s):  
Peng Min Lv ◽  
Chun Juan Shi
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Phase Difference ◽  
Amplitude Ratio ◽  
Uniaxial Stress ◽  
Multiaxial Fatigue ◽  
Normal Strain ◽  
Critical Plane ◽  
Proportional Loading ◽  
Maximum Shear Strain

The tension-torsion thin walled tube specimens were used as the researching object in this paper. The method of determination to the critical plane which has the maximum normal strain and maximum shear strain was expounded. The strain state on the critical plane under non-proportional loading was analyzed, and the unified prediction model was used to calculate the fatigue life. In order to research the influence of phase difference on fatigue life under the non-proportional loading, the relation of the equivalent strain and the phase difference in different positive strain amplitude and different strain amplitude ratio were analyzed. It’s found that the dangerous phase difference which has the shortest fatigue life is in direct relation with the strain amplitude ratio. The general formula of dangerous phase difference is presented. Through the material mechanics performance and fatigue parameters of uniaxial stress state, the coefficients in the formula can be obtained and the coefficients of 15 kinds of common materials are given for practical application.

Numerical Simulation and Experimental Research on Fatigue Strength of the Injector Guide Pillar under Complex Loads

2010 ◽  
Vol 118-120 ◽  
pp. 196-200
Author(s):  
Jin Guo Li ◽  
Xiao Gui Wang ◽  
Zeng Liang Gao
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Numerical Simulation ◽  
Experimental Study ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Numerical Analysis ◽  
Experimental Research ◽  
Contact Surface ◽  
Electronic Measurement

Under the complex loads, the injector guide pillar (IGP) used in injection machine was failure only after 1.5-year-service. In order to determine the cause of the fracture, the numerical simulation technology was applied to analyze the mechanical properties of the IGP. The contact between the mating surfaces of the clamping mechanism was modeled; nonlinear multi-region contact of surface-surface was applied to establish the contact model of FEA. The constraint of tie was used for modeling thread joint. The simulated results indicated that the smaller area of contact surface, the higher value of stress in the neck of IGP. Electronic measurement was also used to check the results of stress in IGP obtained by FEA. It was found that the experimental data agreed well with simulated results. Based on the numerical analysis and experimental study, the structure of IGP was improved by adopting a smoother double-round neck. The fatigue life of the improved structure was longer than that of the original machine.

scholarly journals Transition from complex strained state to simple one under non-proportional loading: comparison of various approaches

2021 ◽  
Vol 1 (395) ◽  
pp. 42-46
Author(s):  
A. Filatov ◽  
Keyword(s):  
Absolute Maximum ◽  
Strained State ◽  
Critical Plane ◽  
Principal Stresses ◽  
Proportional Loading ◽  
Plane Method ◽  
Time Histories ◽  
Von Mises ◽  
Von Mises Stresses

Object and purpose of research. This paper discusses ship structures. Its purpose is to compare the most common methods for transition from complex strained state to the simple one in calculations of fatigue strength under non-proportional loading. Materials and methods. This paper describes the method of absolute maximum principal stresses, the method of signed von Mises stresses, Sins method and critical-plane method. Main results. Analysis of time histories for design stresses obtained as per above-mentioned methods for the simplest examples of non-proportional loading. The comparison of these results was illustrated by a case study (loading of an icebreaker propulsion shaft). Conclusion. It is shown that, of all the methods discussed in this paper, only critical-plane method can fully take the loading process into account. None of the other methods can take into account the changes in orientation of principal stresses, so their results could be both somewhat too high and too low.

Low Cycle Fatigue Life Prediction of Ti-6Al-4V Titanium Alloy under Multi-Axial Non Proportional Cyclic Loading

2013 ◽  
Vol 668 ◽  
pp. 814-817
Author(s):  
Rui Feng Wang ◽  
You Tang Li ◽  
Hu Ping An
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Testing Machine ◽  
Equivalent Strain ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Plane Method ◽  
Torsional Strain ◽  
Method Model

A series multi-axial tension and torsion low cycle fatigue life experiments of Ti-6Al-4V alloy were conducted on the MTS tension and torsion joint testing machine, in which the torsional strain control and non proportional cyclic loading method under the loading paths of circular, rectangular, square, oval and diamond were successively used. The experimental results are compared and analyzed with the results that calculated by the equivalent strain model, the energy method model and the critical plane method model. The results show that the critical plane method is the accurate prediction model to predict the multi-axial low cycle fatigue life of Ti-6Al-4V alloy.

Multiaxial fatigue assessment for outer cylinder of landing gear by critical plane method

2021 ◽  
pp. 095441002110260
Author(s):  
Yingyu Wang ◽  
Xiaofan Zhang ◽  
Xingliang Dong ◽  
Weixing Yao
Keyword(s):  
Outer Cylinder ◽  
Fatigue Loading ◽  
Landing Gear ◽  
Multiaxial Fatigue ◽  
Critical Plane ◽  
Proportional Loading ◽  
Fatigue Lifetime ◽  
Plane Method ◽  
Multiaxial Stress State ◽  
Maximum Variance

The in-service loadings on the landing gear are usually complex and from different directions, which lead to the fatigue critical locations in the landing gear structure mostly in multiaxial stress state. A methodology based on the critical plane method was proposed for estimating the fatigue lifetime of outer cylinder of the main landing gear undergoing variable amplitude (VA) multiaxial proportional loading. The orientation of the critical plane was determined by the so-called maximum variance method. The Bannantine–Socie’s cycle counting method and Miner’s linear rule were applied with Zhang–Yao’s criterion in this research. The calculated results on the fatigue lifetime of the outer cylinder were compared with the experimental data. The results indicate that the methodology proposed in this article is a sound method for fatigue life prediction of engineering components bearing complex VA multiaxial fatigue loading.

scholarly journals Multiaxial Fatigue Life Prediction of GH4169 Alloy Based on the Critical Plane Method

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 255 ◽  
Author(s):  
Jianhui Liu ◽  
Zhen Zhang ◽  
Bin Li ◽  
Shanshan Lang
Keyword(s):  
Fatigue Life ◽  
Shear Strain ◽  
Yield Stress ◽  
Control Parameter ◽  
Multiaxial Fatigue ◽  
Critical Plane ◽  
Maximum Shear Strain ◽  
Plane Method ◽  
Gh4169 Alloy ◽  
Additional Hardening

The multiaxial fatigue life of GH4169 alloy was predicted based on the critical plane method. In this paper, a new critical plane-damage multiaxial fatigue parameter is proposed, in which the maximum shear strain is considered to be the main damage control parameter, and the correction parameter, including the normal stress and strain of the maximum shear strain plane, is defined as the second control parameter. The axis of principle strain rotates under non-proportional loading. Meanwhile, the mechanism of the variation of material microstructure and slip systems leads to an additional hardening phenomenon. The ratio of cyclic yield stress to static yield stress is used to represent cyclic strengthening capacity, and the influence of the phase difference and loading condition on the non-proportional reinforcement effect is considered. It is also proposed that different materials have different influences on the additional hardening phenomenon. Meanwhile, the model revision results in stress under asymmetrical loading. Experimental data of GH4169 alloy show that the proposed model can provide better prediction than the Smith–Watson–Topper (SWT) and Fatemi–Socie (FS) models.

Creep-Fatigue Strength of Sn-8Zn-3Bi Solder Under Multiaxial Loading

Materials ◽  
2005 ◽  
Author(s):  
Takaei Yamamoto ◽  
Takamoto Itoh ◽  
Masao Sakane ◽  
Hiroshi Sasaki ◽  
Kazuhiko Shuto ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Torsion Test ◽  
Multiaxial Loading ◽  
Strain Wave ◽  
Proportional Loading ◽  
Strain Waves ◽  
Creep Fatigue ◽  
Multiaxial Creep ◽  
Strain Hold

This paper describes the multiaxial creep-fatigue of Sn-8Zn-3Bi solder in proportional and non-proportional loadings. Push-pull and reversed torsion tests were carried in proportional test using fast-fast, slow-fast, fast-slow, slow-slow and strain-hold waves. Non-proportional tests were also carried out using box, step and circle strain waves. In proportional test, smallest creep-fatigue lives were observed in push-pull slow-fast test. Creep-fatigue lives in reversed torsion test were longer by a factor of 2 than those in push-pull test compared with the same strain wave. Non-proportional loading reduced the creep-fatigue life. Circle strain wave showed the smallest fatigue life in non-proportional loading. A non-proportional strain proposed by the authors correlated all the proportional and non-proportional fast-fast data within a factor of two scatter band.

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