Machining of Aircraft Titanium With Abrasive-Waterjets for Fatigue Critical Applications

2010 ◽  
Author(s):  
H.-T. Liu ◽  
Y. Hovanski ◽  
M. E. Dahl
Keyword(s):  
Stainless Steel ◽  
Laboratory Tests ◽  
Fatigue Performance ◽  
Test Results ◽  
Cnc Milling ◽  
Visual Appearance ◽  
Grit Blasting ◽  
Dog Bone ◽  
Abrasive Waterjets ◽  
Awj Cutting

Laboratory tests were conducted to determine the fatigue performance of AWJ-machined aircraft titanium. Dog-bone specimens machined with AWJs were prepared and tested with and without sanding and dry-grit blasting with Al2O3 as secondary processes. The secondary processes were applied to remove the visual appearance of AWJ-generated striations and to clean up the garnet embedment. The fatigue performance of AWJ-machined specimens was compared with baseline specimens machined with CNC milling. Fatigue test results of the titanium specimens not only confirmed our previous findings in aluminum dog-bone specimens but in comparison also further enhanced the fatigue performance of the titanium. In addition, titanium is known to be difficult to cut, particularly for thick parts, however AWJs cut the material 34% faster than stainless steel. AWJ cutting and dry-grit blasting are shown to be a preferred combination for processing aircraft titanium that is fatigue critical.

Machining of Aircraft Titanium With Abrasive-Waterjets for Fatigue Critical Applications

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
H.-T. Liu ◽  
Y. Hovanski ◽  
M. E. Dahl
Keyword(s):  
Numerical Control ◽  
Fatigue Performance ◽  
Abrasive Waterjet ◽  
Test Results ◽  
Cnc Milling ◽  
Visual Appearance ◽  
Grit Blasting ◽  
Dog Bone ◽  
Abrasive Waterjets ◽  
Awj Cutting

Laboratory tests were conducted to determine the fatigue performance of abrasive-waterjet- (AWJ-) machined aircraft titanium. Dog-bone specimens machined with AWJs were prepared and tested with and without sanding and dry-grit blasting with Al2O3 as the secondary processes. The secondary processes were applied to remove the visual appearance of AWJ-generated striations and to clean up the garnet embedment. The fatigue performance of AWJ-machined specimens was compared with baseline specimens machined with Computer Numerical Control (CNC) milling. Fatigue test results of the titanium specimens not only confirmed our previous findings in aluminum dog-bone specimens but also further enhanced the fatigue performance of the titanium. In addition, titanium is known to be difficult to cut, particularly for thick parts, however, AWJs cut the material 34% faster than stainless steel. AWJ cutting and dry-grit blasting are shown to be a preferred combination for processing aircraft titanium that is fatigue critical.

Achievements in High Specific-Speed Water Turbines

1934 ◽  
Vol 128 (1) ◽  
pp. 361-407
Author(s):  
A. A. Fulton
Keyword(s):  
Stainless Steel ◽  
Laboratory Tests ◽  
Steady Increase ◽  
Test Results ◽  
Suction Tube ◽  
Generating Sets ◽  
Laboratory Test Results ◽  
Water Turbine ◽  
Specific Speed ◽  
Water Turbines

The steady increase in the capacity of generating sets created a demand for the high specific-speed turbine which was met by several experimenters. “Specific speed” is the speed at which a turbine will run under unit head when developing unit power, and nowadays a “high specific-speed” water turbine denotes one having a runner of the propeller type and a specific speed between 100 and 230 r.p.m. Difficulties were encountered in the development of propeller turbines, especially in connexion with cavitation. Laboratory tests and the use of visual study methods have played an important part in the solution of these difficulties. The method of fixing suction head in conjunction with laboratory test results is explained, and a comparison is made between the various forms of suction tube in use. Much work has been done to overcome the effects of localized cavitation, and stainless steel has been found to be very effective, especially when runners are cast entirely of that material. A method of operation has been developed to dispense with the use of inlet sluice gates in large machines. Several methods in use for operating the movable runner blades are described. The introduction of the high specific-speed turbine has led to a large increase in the number of automatic stations. The great size attained by these turbines has entailed the construction of equally large generators, the development of which has had its own problems.

scholarly journals Application of Strainrange Partitioning to the Prediction of Creep-Fatigue Lives of AISI Types 304 and 316 Stainless Steel

1977 ◽  
Vol 99 (2) ◽  
pp. 264-271 ◽  
Author(s):  
J. F. Saltsman ◽  
G. R. Halford
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Fatigue Test ◽  
Laboratory Tests ◽  
Heat Treatments ◽  
Test Results ◽  
316 Stainless Steel ◽  
Creep Fatigue ◽  
Testing Techniques

As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.

scholarly journals High Cycle Fatigue Performance of LPBF 304L Stainless Steel at Nominal and Optimized Parameters

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1591
Author(s):  
Mohammad Masud Parvez ◽  
Tan Pan ◽  
Yitao Chen ◽  
Sreekar Karnati ◽  
Joseph W. Newkirk ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Strength ◽  
Impact Toughness ◽  
Process Parameters ◽  
High Cycle Fatigue ◽  
Minimum Energy ◽  
Fatigue Performance ◽  
304L Stainless Steel ◽  
Test Results ◽  
Cycle Fatigue

In additive manufacturing, the variation of the fabrication process parameters influences the mechanical properties of a material such as tensile strength, impact toughness, hardness, fatigue strength, and so forth, but fatigue testing of metals fabricated with all different sets of process parameters is a very expensive and time-consuming process. Therefore, the nominal process parameters by means of minimum energy input were first identified for a dense part and then the optimized process parameters were determined based on the tensile and impact toughness test results obtained for 304L stainless steel deposited in laser powder bed fusion (LPBF) process. Later, the high cycle fatigue performance was investigated for the material built with these two sets of parameters at horizontal, vertical, and inclined orientation. In this paper, displacement controlled fully reversed (R = −1) bending type fatigue tests at different levels of displacement amplitude were performed on Krouse type miniature specimens. The test results were compared and analyzed by applying the control signal monitoring (CSM) method. The analysis shows that specimen built-in horizontal direction for optimized parameters demonstrates the highest fatigue strength while the vertical specimen built with nominal parameters exhibits the lowest strength.

Investigation on Material Selection in Missan Oilfields Similar Environment

2014 ◽  
Vol 641-642 ◽  
pp. 427-433
Author(s):  
Shuang Cheng ◽  
Feng Lin ◽  
Pei Long Yang ◽  
Pei Ke Zhu ◽  
Jin Gen Deng ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Carbon Steel ◽  
Nickel Alloy ◽  
Martensitic Stainless Steel ◽  
Material Selection ◽  
Pressure Ratio ◽  
Service Condition ◽  
Corrosion Mechanism ◽  
Test Results ◽  
Chrome Steel

This paper analyzed the corrosion environment of Missan oilfields and investigated the oilfield country tubular goods used in other similar oilfields. Summarized the effect of partial pressure ratio of H2S/CO2 and Cl-to the corrosion behavior of OCTG. This paper concluded the service condition, test results and anti-corrosion mechanism of carbon steel, low-chrome steel, modified martensitic stainless steel and nickel alloy. Finally arrived at conclusion that the nickel alloy can meet the requirement of Missan oilfields, some literature reported that the modified martensitic stainless steel can apply in H2S/CO2 environment. In the condition that be easy to replace the tubular, carbon steel and low-chrome steel tubular can meet the requirement with corrosion inhibitor.

Effects of Surface Finish and Loading Conditions on the Low Cycle Fatigue Behavior of Austenitic Stainless Steel in PWR Environment for Various Strain Amplitude Levels

2009 ◽  
Author(s):  
Jean Alain Le Duff ◽  
Andre´ Lefranc¸ois ◽  
Jean Philippe Vernot
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Amplitude ◽  
Surface Finish ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Complex Loading ◽  
Loading Conditions ◽  
Test Results ◽  
Cycle Fatigue

In February/March 2007, The NRC issued Regulatory Guide “RG1.207” and Argonne National Laboratory issued NUREG/CR-6909 that is now applicable in the US for evaluations of PWR environmental effects in fatigue analyses of new reactor components. In order to assess the conservativeness of the application of this NUREG report, Low Cycle Fatigue (LCF) tests were performed by AREVA NP on austenitic stainless steel specimens in a PWR environment. The selected material exhibits in air environment a fatigue behavior consistent with the ANL reference “air” mean curve, as published in NUREG/CR-6909. LCF tests in a PWR environment were performed at various strain amplitude levels (± 0.6% or ± 0.3%) for two loading conditions corresponding to a simple or to a complex strain rate history. The simple loading condition is a fully reverse triangle signal (for comparison purposes with tests performed by other laboratories with the same loading conditions) and the complex signal simulates the strain variation for an actual typical PWR thermal transient. In addition, two various surface finish conditions were tested: polished and ground. This paper presents the comparisons of penalty factors, as observed experimentally, with penalty factors evaluated using ANL formulations (considering the strain integral method for complex loading), and on the other, the comparison of the actual fatigue life of the specimen with the fatigue life predicted through the NUREG report application. For the two strain amplitudes of ± 0.6% and ± 0.3%, LCF tests results obtained on austenitic stainless steel specimens in PWR environment with triangle waveforms at constant low strain rates give “Fen” penalty factors close to those estimated using the ANL formulation (NUREG/6909). However, for the lower strain amplitude level and a triangle loading signal, the ANL formulation is pessimistic compared to the AREVA NP test results obtained for polished specimens. Finally, it was observed that constant amplitude LCF test results obtained on ground specimens under complex loading simulating an actual sequence of a cold and hot thermal shock exhibits lower combined environmental and surface finish effects when compared to the penalty factors estimated on the basis of the ANL formulations. It appears that the application of the NUREG/CR-6909 in conjunction with the Fen model proposed by ANL for austenitic stainless steel provides excessive margins, whereas the current ASME approach seems sufficient to cover significant environmental effects for representative loadings and surface finish conditions of reactor components.

Predicting abnormal laboratory blood test results in the intensive care unit using novel features based on information theory and historical conditional probability (Preprint)

2021 ◽  
Author(s):  
Camilo E. Valderrama ◽  
Daniel J. Niven ◽  
Henry T. Stelfox ◽  
Joon Lee
Keyword(s):  
Machine Learning ◽  
Intensive Care ◽  
Conditional Probability ◽  
Blood Test ◽  
Laboratory Tests ◽  
Conditional Entropy ◽  
Admission Diagnosis ◽  
Test Results ◽  
Abnormal Laboratory ◽  
Blood Tests

BACKGROUND Redundancy in laboratory blood tests is common in intensive care units (ICU), affecting patients' health and increasing healthcare expenses. Medical communities have made recommendations to order laboratory tests more judiciously. Wise selection can rely on modern data-driven approaches that have been shown to help identify redundant laboratory blood tests in ICUs. However, most of these works have been developed for highly selected clinical conditions such as gastrointestinal bleeding. Moreover, features based on conditional entropy and conditional probability distribution have not been used to inform the need for performing a new test. OBJECTIVE We aimed to address the limitations of previous works by adapting conditional entropy and conditional probability to extract features to predict abnormal laboratory blood test results. METHODS We used an ICU dataset collected across Alberta, Canada which included 55,689 ICU admissions from 48,672 patients with different diagnoses. We investigated conditional entropy and conditional probability-based features by comparing the performances of two machine learning approaches to predict normal and abnormal results for 18 blood laboratory tests. Approach 1 used patients' vitals, age, sex, admission diagnosis, and other laboratory blood test results as features. Approach 2 used the same features plus the new conditional entropy and conditional probability-based features. RESULTS Across the 18 blood laboratory tests, both Approach 1 and Approach 2 achieved a median F1-score, AUC, precision-recall AUC, and Gmean above 80%. We found that the inclusion of the new features statistically significantly improved the capacity to predict abnormal laboratory blood test results in between ten and fifteen laboratory blood tests depending on the machine learning model. CONCLUSIONS Our novel approach with promising prediction results can help reduce over-testing in ICUs, as well as risks for patients and healthcare systems. CLINICALTRIAL N/A

Study on Conventional Domed Bursting Disc Material and Burst Pressure Test

2013 ◽  
Vol 690-693 ◽  
pp. 2371-2378
Author(s):  
Wei Pu Xu ◽  
Yi Ting Liu
Keyword(s):  
Stainless Steel ◽  
Tensile Test ◽  
316L Stainless Steel ◽  
Performance Test ◽  
Test Method ◽  
Burst Pressure ◽  
Test Results ◽  
Manufacturing Method ◽  
Pressure Test ◽  
Disc Material

A brief overview is given in the conventional domed bursting disc structure and manufacturing method. 316L stainless steel as a template is selected. With the investigation on bursting disc material tensile test method, the test results are summarized,also the burst results of disc burst pressure in different sizes. With the help of bursting disc material performance test and bursting disc burst pressure test of 316L , the test results provide a reference for other types of bursting disc.

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