scholarly journals Study of the fatigue behaviour of synthetic nodular cast irons at low and high frequency cyclic loading

2018 ◽  
Vol 157 ◽  
pp. 07014 ◽  
Author(s):  
Alan Vaško ◽  
Juraj Belan ◽  
Eva Tillová
Keyword(s):  
Cyclic Loading ◽  
High Frequency ◽  
Fatigue Testing ◽  
Low Frequency ◽  
Nodular Cast Iron ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cast Irons ◽  
Ultrasonic Fatigue ◽  
The Relationship

The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100. High frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both of them were carried out at sinusoidal cyclic push-pull loading (stress ratio R = -1) at ambient temperature (T ≈ 20 °C). The relationship σa = f (N) and fatigue strengths were determined experimentally; mechanical properties, microstructures and fracture surfaces were investigated.

scholarly journals Fatigue Properties of Nodular Cast Iron at Low Frequency Cyclic Loading

2017 ◽  
Vol 62 (4) ◽  
pp. 2205-2210 ◽  
Author(s):  
A. Vaško
Keyword(s):  
Cast Iron ◽  
Cyclic Loading ◽  
High Frequency ◽  
Stress Ratio ◽  
Low Frequency ◽  
Nodular Cast Iron ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Charge Composition ◽  
Cast Irons

Abstract Three melts of ferrite-pearlitic nodular cast iron with different charge composition were used for fatigue tests. Wöhler fatigue curves and fatigue strength were obtained, and microstructure and fracture surfaces were investigated. The aim of the paper is to determine the influence of charge composition on microstructure, mechanical and fatigue properties of synthetic nodular cast irons and their micromechanisms of failure. Fatigue tests were realised at low frequency sinusoidal cyclic push-pull loading (stress ratio R = −1) at ambient temperature (T = 20 ±5°C). They were carried out with using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100 at frequency f ≈ 120 Hz. The results of fatigue tests at low frequency cyclic loading are compared with fatigue properties at high frequency cyclic loading.

Influence of Frequency and Testing Technique on the Fatigue Behaviour of Quenched and Tempered Steel in the VHCF-Regime

2014 ◽  
Vol 891-892 ◽  
pp. 1430-1435 ◽  
Author(s):  
Norbert Schneider ◽  
Brita Pyttel ◽  
Christina Berger ◽  
Matthias Oechsner
Keyword(s):  
High Frequency ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Frequency Effect ◽  
Low Frequencies ◽  
Ultrasonic Fatigue ◽  
Quenched And Tempered Steel ◽  
Tempered Steel

Today in many cases ultrasonic testing machines with a frequency of f ≈ 20 kHz are used for investigations of the fatigue behaviour up to the very high cycle regime (VHCF-regime). A question that arises is if the results of these high frequency fatigue tests are comparable to conventional fatigue tests. This paper compares the fatigue behaviour of a quenched and tempered steel 50CrMo4 in two different tempered conditions investigated at low frequencies (f ≤ 400 Hz) on a servohydraulic testing machine and at a high frequency (f ≈ 20 kHz) on an ultrasonic fatigue testing machine. Effects which can occur because of the different testing techniques and testing frequencies are investigated. A concept is derived to describe the frequency effect caused by the strain rate. The estimations are compared with results of the fatigue tests.

scholarly journals Fatigue Properties Of Nodular Cast Irons Alloyed By Si, Mo And Cu

2019 ◽  
Vol 1 (1) ◽  
pp. 738-744
Author(s):  
Alan Vaško ◽  
Marek Krynke
Keyword(s):  
Cast Iron ◽  
Low Frequency ◽  
Hardness Test ◽  
Nodular Cast Iron ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Bending Test ◽  
Fatigue Properties ◽  
Cast Irons ◽  
Number Of Cycles

AbstractIn recent years, the research of nodular cast iron has been focused on increasing fatigue resistence. In the paper, two types of alloyed nodular cast irons have been investigated – SiMo-nodular cast iron alloyed by 4% of silicon and 1% of molybdenum and SiCu-nodular cast iron alloyed by 4% of silicon and 1.5% of copper. SiMo-nodular cast iron is suitable for high-temperature applications, for example the exhaust manifolds of the combustion engines. SiCu-nodular cast iron is used in various components of tribotechnical units. These components are often loaded by fatigue. The mechanical and fatigue behaviour of both nodular cast iron types has been studied by means of tensile test, impact bending test, hardness test and fatigue tests. Fatigue tests were realised at low frequency cyclic push-pull loading up to 10 million cycles. The relationship between the amplitude of stress and number of cycles to failure was investigated and the fatigue strength was determined. Mechanical and fatigue properties of both nodular cast iron types are correlated with the microstructure of specimens.

Gigacycle Fatigue of Welded Joints of Structural Materials (A Review)

2016 ◽  
Vol 17 ◽  
pp. 14-30 ◽  
Author(s):  
Okechukwu P. Nwachukwu ◽  
Alexander V. Gridasov ◽  
Ekaterina A. Gridasova
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Structural Materials ◽  
Fatigue Tests ◽  
Material Defects ◽  
Graphite Cast Iron ◽  
Ultrasonic Fatigue ◽  
Materials Used ◽  
Fatigue Failures

This review looks into the state of gigacycle fatigue behavior of some structural materials used in engineering works. Particular attention is given to the use of ultrasonic fatigue testing machine (USF-2000) due to its important role in conducting gigacycle fatigue tests. Gigacycle fatigue behavior of most materials used for very long life engineering applications is reviewed.Gigacycle fatigue behavior of magnesium alloys, aluminum alloys, titanium alloys, spheroid graphite cast iron, steels and nickel alloys are reviewed together with the examination of the most common material defects that initiate gigacycle fatigue failures in these materials. In addition, the stage-by-stage fatigue crack developments in the gigacycle regime are reviewed. This review is concluded by suggesting the directions for future works in gigacycle fatigue.

Role of Dominance Status in Shock-Stimulated Agonistic Behavior

1971 ◽  
Vol 29 (3) ◽  
pp. 768-770 ◽  
Author(s):  
G. McA. Kimbrell ◽  
D. Chesler
Keyword(s):  
High Frequency ◽  
Agonistic Behavior ◽  
Defensive Behavior ◽  
Low Frequency ◽  
Behavior Patterns ◽  
Dominance Status ◽  
Very Low Frequency ◽  
The Relationship ◽  
Shock Situation

To clarify the relationship between dominance status and frequency of specific sub-classes of agonistic behavior in response to foot shock, 30 mice were selected on the basis of high- or low-dominance status and paired in a foot-shock situation. Dominant pairs exhibit a high frequency of defensive behavior patterns whereas submissive pairs exhibit a very low frequency of defensive patterns.

scholarly journals Ultrasonic fatigue testing under multiaxial loading conditions on a railway wheel

2019 ◽  
Vol 300 ◽  
pp. 18003 ◽  
Author(s):  
Pedro R. da Costa ◽  
Henrique Soares ◽  
Luís Reis ◽  
Manuel Freitas
Keyword(s):  
Stress Ratio ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Cycle Frequency ◽  
Railway Wheel ◽  
Material Specimen ◽  
Hydraulic Machines ◽  
Wide Range ◽  
Ultrasonic Fatigue ◽  
Very High

Ultrasonic fatigue testing is a relative recent fatigue methodology that uses resonant principles for the induction of stress cycles in a specific designed material specimen. This experimental method can apply very high cycle frequency, the most common frequency being 20 kHz, and was created with the main purpose of studying material fatigue life in the Very High Cycle Fatigue regime between 107 and 109 cycles with a higher performance of time and energy wise in comparison to conventional servo-hydraulic machines. In this study an improvement of an already built multiaxial ultrasonic fatigue machine in the Instituto Superior Técnico laboratories was carried out to specific designed specimens and afterwards a fatigue study was made for a material of a worn-out railway wheel. The particular design of the specimen was achieved by numerical and experimental analysis based on previous experiments and components. Thermographic imaging and the application of rosette strain gauges to the main throat of the specimens were conducted in order to validate the improved specimen design and to understand the real induced stresses on the specimen. Afterwards fatigue tests were conducted for several specimens for a wide range of stresses with a stress ratio R=-1 and an axial vs shear stress ratio of around 0.58. Results were analysed and fracture analysis was also carried out.

Dynamic relation between global Islamic and conventional sectoral stock and bonds indexes

2020 ◽  
Vol 07 (02) ◽  
pp. 2050006
Author(s):  
Sukriye Tuysuz
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Stock Index ◽  
High Frequency Part ◽  
Dynamic Relation ◽  
The Relationship

This paper examines the relationship between 10 Global sectoral conventional and Islamic assets. For each sector, a conventional, an Islamic stock index and a bond are retained. The analyzed relations are done by taking into account diverse investment horizons by using MODWT and GARCH-DCC-type models. Our results indicate that adding bond indexes into a portfolio composed with conventional stock or Islamic stock is efficient. As for the correlations between conventional and Islamic sectoral indexes, they depend on the sector. Relations between returns of securities are quite similar to the relations between high-frequency part of these series and are very volatile at low frequency.

Development of a New Fatigue Testing Machine for High Frequency Fatigue Damage Assessment

2013 ◽  
Author(s):  
Naoki Osawa ◽  
Tetsuya Nakamura ◽  
Norio Yamamoto ◽  
Junji Sawamura
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Fatigue Testing ◽  
Low Cost ◽  
Plate Thickness ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Frequency Effect ◽  
Wave Load ◽  
Out Of Plane

A new simple fatigue testing machine, which can carry out fast and low-cost fatigue tests of welded joints subject to wave with high frequency vibration, has been developed. This machine is designed for plate bending type fatigue tests, and wave load is applied by using motors with eccentric mass. Springing vibration is superimposed by attaching an additional vibrator to the test specimen, and whipping vibration is superimposed by an intermittent hammering. Fatigue tests which simulate springing and whipping by a conventional servo-type fatigue testing machines are very expensive and use a large amount of electricity. If one uses these conventional machines, it is difficult to simulate superimposed stress wave forms at high speed, and it takes long hours of testing to examine the high frequency effect. In contrast, it is found that fatigue tests can be carried out in fast, i.e. waves with 10Hz or higher frequency for out-of-plane gusset welded joint specimens with 12mm plate thickness by using the developed machine. The electricity to be used for fatigue tests could be minimal, for example one thousandth of that needed for conventional machines. These results demonstrate the superiority of the developed machine.

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