scholarly journals P-S-N Curve Description of Laser Metal Deposition Ti-6.5Al-2Zr-1Mo-1V Titanium Alloy after Duplex Annealing

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 418
Author(s):  
Tianshuai Wang ◽  
Xiaofan He ◽  
Xiaobo Wang ◽  
Yuhai Li
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Estimation Method ◽  
Likelihood Estimation ◽  
Fatigue Tests ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Life Distribution ◽  
Likelihood Functions ◽  
Distribution Parameters

Fatigue tests were conducted on standard smooth laser metal deposition (LMD) Ti-6.5Al-2Zr-1Mo-1V titanium alloy specimens under three constant-amplitude stresses. The mixed failure behaviors and the influence of internal pores on the fatigue life were discussed in detail. The double-peak characteristics of the fatigue life distribution have been observed, and a bimodal lognormal distribution (BLG) with five variables can be used to describe the fatigue life variation. A parameter estimation method based on the maximum likelihood estimation (MLE) method was proposed to estimate the BLG distribution parameters, and the Newton–Raphson algorithm was used to solve the nonlinear equations derived from the likelihood functions. A P-S-N curve description of LMD titanium alloy was established based on the BLG and verified by fatigue life data obtained from a fatigue test.

A Simulation Method of Establishing Fatigue Life Distribution

1976 ◽  
Vol 98 (1) ◽  
pp. 183-188 ◽  
Author(s):  
H. A. Elmaraghy ◽  
J. N. Siddall
Keyword(s):  
Fatigue Life ◽  
Material Properties ◽  
Digital Simulation ◽  
Simulation Method ◽  
Fatigue Tests ◽  
Design Tool ◽  
Statistical Characteristics ◽  
Life Distribution ◽  
Parametric Studies ◽  
Life Distributions

This paper presents a Monte Carlo simulation method for fatigue failure, by which the randomness of two material properties as well as that of the applied load can be incorporated into a stochastic model using an appropriate failure criterion to predict the statistical characteristics of fatigue life under constant and random amplitude cyclic loading conditions. In this technique, both the endurance limit Se and the fatigue strength coefficient Sf′ are treated as stochastic variables. The combined effect of the randomness of Se, Sf′, and the applied stress on the statistical characteristics of fatigue lives is predicted analytically using digital simulation of fatique tests. The life distributions and their statistical characteristics are found to be in good agreement with those obtained from analyzing the experimental results, indicating that the proposed technique and the underlying assumptions and hypotheses are adequate. The suggested method is believed to be an effective, fast, and easy-to-use design tool which is suitable for use on electronic computers. It is ideal for parametric studies compared with the costly and time-consuming laboratory fatigue tests. Minimum experimental data are needed as a basis for the analysis. New results are presented which show the effect of the randomness of the loads and material properties on the randomness of fatigue life distribution.

scholarly journals comparison of methods for the estimation of Weibull distribution parameters

2014 ◽  
Vol 11 (1) ◽  
Author(s):  
Felix Nwobi ◽  
Chukwudi Ugomma
Keyword(s):  
Weibull Distribution ◽  
Stock Prices ◽  
Goodness Of Fit ◽  
Estimation Method ◽  
Likelihood Estimation ◽  
Goodness Of Fit Tests ◽  
Distribution Parameters ◽  
Kolmogorov Smirnov ◽  
The Mean ◽  
Maximum Likelihood Estimation Method

In this paper we study the different methods for estimation of the parameters of the Weibull distribution. These methods are compared in terms of their fits using the mean square error (MSE) and the Kolmogorov-Smirnov (KS) criteria to select the best method. Goodness-of-fit tests show that the Weibull distribution is a good fit to the squared returns series of weekly stock prices of Cornerstone Insurance PLC. Results show that the mean rank (MR) is the best method among the methods in the graphical and analytical procedures. Numerical simulation studies carried out show that the maximum likelihood estimation method (MLE) significantly outperformed other methods.

Enhancement of Surface Integrity of Titanium Alloy With Copper by Means of Laser Metal Deposition Process

2020 ◽  
pp. 245-270
Author(s):  
Mutiu F. Erinosho ◽  
Esther T. Akinlabi ◽  
Sisa Pityana
Keyword(s):  
Titanium Alloy ◽  
Surface Integrity ◽  
Adhesive Bonding ◽  
Sea Water ◽  
Laser System ◽  
Research Work ◽  
Deposition Process ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Aerospace Applications

The laser metal deposition process possesses the combination of metallic powder and laser beam respectively. However, these combinations create an adhesive bonding that permanently solidifies the laser-enhanced-deposited powders. Titanium alloys (Ti6Al4V) Grade 5 have been regarded as the most used alloys for the aerospace applications, due to their lightweight properties and marine application due to their excellent corrosion resistance. The improvements in the surface integrity of the alloy have been achieved successively with the addition of Cu through the use of Ytterbium laser system powered at maximum of 2000 Watts. The motivation for this research work can be attributed to the dilapidation of the surface of titanium alloy, when exposed to marine or sea water for a longer period of time. This chapter provides the surface modification of titanium alloy with the addition of percentage range of Cu within its lattices; and the results obtained from the characterizations conducted on the laser deposited Ti6Al4V/Cu alloys have been improved.

Laser Metal Deposition of Titanium Alloy: A Review

2020 ◽  
pp. 87-95
Author(s):  
Bonolo S. Boshoman ◽  
Esther T. Akinlabi ◽  
Mutiu F. Erinosho ◽  
Oluwagbenga T. Johnson
Keyword(s):  
Titanium Alloy ◽  
Metal Deposition ◽  
Laser Metal Deposition

Assessment of Failure Life Evaluation Methods for Structural Discontinuities with Fatigue and Creep-Fatigue Tests on Multi-Perforated Plate Made of Mod.9Cr-1Mo Steel

2021 ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Takano Masahito
Keyword(s):  
Fatigue Life ◽  
Perforated Plate ◽  
Estimation Method ◽  
Evaluation Methods ◽  
Fatigue Tests ◽  
Reduction Factor ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Number Of Cycles ◽  
Failure Life

Abstract This study compares and assesses the different fatgue and creep-fatigue life eveluation methods by performing tests of perforated plate made of Mod.9Cr-1Mo steel. Multi-perforated plate was subjected to mechanical cyclic loading at 550°C, and crack initiation and propagation on the surfaces of the holes were observed. A series of finite element analyses (FEA) were carried out to predict the number of cycles to failure by the several failure life evaluation methods, and these predictions were then compared with the test results. Several types of evaluation methods that use the elastic FEA were applied, namely the stress redistribution locus (SRL) method, simple elastic follow-up method. In addition to these, evaluation was also carried out using the results of inelastic FEA to compare these elastic FEA based estimation method. The comparisons indicate that, for all conditions tested, the SRL method provided a rational prediction of the fatigue and creep-fatigue life when ? = 1.6 was applied, where ? = 1.6 is the recommended reduction factor for this method in general use. A comparison of the SRL method and the results of the inelastic FEA indicated that the applicability of the value of factor ? in the SRL method depends on the elastic region remaining in the cross-section including the evaluated point and the spread in the plastically deformed region in the specimen.

Experimental Study on Electromagnetic Stirring Assisted Laser Metal Deposition Titanium Alloy

2014 ◽  
Vol 41 (3) ◽  
pp. 0303004 ◽  
Author(s):  
钦兰云 Qin Lanyun ◽  
杨光 Yang Guang ◽  
卞宏友 Bian Hongyou ◽  
王维 Wang Wei ◽  
任宇航 Ren Yuhang
Keyword(s):  
Experimental Study ◽  
Titanium Alloy ◽  
Metal Deposition ◽  
Electromagnetic Stirring ◽  
Laser Metal Deposition

Bayes Inference for Drilling Mud Pump Piston Life

2013 ◽  
Vol 295-298 ◽  
pp. 3142-3147 ◽  
Author(s):  
Zi Mei Su ◽  
Yong Quan Sun ◽  
Hui Juan Yuan ◽  
Jian Ying Guo
Keyword(s):  
Confidence Limit ◽  
Shape Parameter ◽  
Likelihood Estimation ◽  
Point Estimation ◽  
Oil Field ◽  
Drilling Mud ◽  
Life Distribution ◽  
Bayes Inference ◽  
Daqing Oil Field ◽  
Distribution Parameters

Bayes confidence limit for domestic drilling mud pump piston life was given. Maximum likelihood estimation of mud pump piston life was discussed under Weibull life distribution. For further, failure mechanism of the same batch mud pump piston was studied, the shape parameter of Weibull distribution was considered to be constant. Bayes point estimation and confidence limit of distribution parameters and mud pump piston life were given, according to field life data collected from Daqing oil field, under non-information priori and conjugate prior information for scale parameter. Example shows the effectiveness of the proposed method.

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