Research into Fatigue Crack Life Characteristics of Bellows Operated under High-Frequency Load

2014 ◽  
Vol 1025-1026 ◽  
pp. 162-166
Author(s):  
Konstantin Nikolaevich Figura ◽  
Igor Mikhailovich Yefremov ◽  
Dmitry Viktorovich Lobanov
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Safety Factor ◽  
High Frequency ◽  
Software Package ◽  
Reliability Evaluation ◽  
Ansys Software

The article considers the analysis of the bellows fatigue strength carried out using the Ansys software package. The results of the research into the fatigue crack life and fatigue safety factor of a bellow valve are given.The reliability evaluation of the bellow valve working under the high-frequency load has been given by the authors.

Peculiarities of Fatigue Fracture of Steel Hardened by Various Surface Treatments

2012 ◽  
Vol 527 ◽  
pp. 107-112
Author(s):  
Antanas Ciuplys ◽  
Valdas Kvedaras
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Carbon Steel ◽  
Fatigue Fracture ◽  
High Frequency ◽  
Surface Hardening ◽  
Fatigue Crack Initiation ◽  
Sample Surface ◽  
Metal Fatigue ◽  
The Impact

Fatigue strength is one of the most important mechanical properties. Durability and reliability of car parts is often defined by their fatigue strength, since most of them are loaded with dynamic, repeating or variable loads and the main type of failure is metal fatigue. Fatigue crack usually starts on the metal surface. The interrelationship of the surface layer together with the characteristics of internal metal volume determine the value of fatigue limit and the coefficient level of stresses’ intensity, which is required for the start of fatigue crack. Various hardening methods of surface have a huge impact on fatigue strength of structural materials. The choice of surface processing method is determined by properties and microstructure of a material, as well as the purpose and working conditions of part’s material. Very often the optimum processing is a combination of several methods, which enables to obtain the required properties (high fatigue strength, wear, etc.). Hardening with high-frequency electric current (HfEC) is widely used process for the surface hardening of steel. The components are heated by means of an alternating magnetic field to a temperature within or above the transformation range followed by immediate quenching. The core of the component remains unaffected by the treatment and its physical properties are those of the bar from which it was machined. Investigation of specific fatigue fracture properties enables to determine the kinetic of processes, related with fatigue crack initiation and propagation. Analysing fractures of machine parts and comparing them with the most specific “mode” fractures it is possible to determine the nature of affecting loads and the reason of part failure. The impact of several combined surfaces processing on the fatigue strength and fractures of carbon steel samples is investigated in the work. The surface was hardened using different processing combinations: by hardening with high frequency electricity currents, rolling by rollers, heating and cooling under different temperatures. Experimentally it was proved that thermal treatment of plastically deformed carbon steel significantly increases fatigue strength. After surface hardening with the given regimes, the microstructure and residual stresses are formed in such way that fatigue crack begins to grow under the hardened sample surface. Samples, in which the fatigue crack initiates inside the sample, have higher fatigue strength than the samples, the fatigue crack of which initiates on the surface.

scholarly journals Topological Optimization of a Complex Shape Forming Stamp

2021 ◽  
Vol 2096 (1) ◽  
pp. 012115
Author(s):  
I K Andrianov
Keyword(s):  
Mathematical Modeling ◽  
Fatigue Strength ◽  
Stress State ◽  
Software Package ◽  
Complex Shape ◽  
Scientific Research ◽  
Topological Optimization ◽  
Optimal Topology ◽  
Ansys Software ◽  
Cold Stamping

Abstract The scientific research is devoted to the mathematical modeling of the optimal topology of stamps with a complex forming surface. Topological optimization is based on the SIMP method by creating a field of pseudo-densities and minimizing the pliability of the structure under the influence of load. When setting the problem, it is proposed to take into account the fatigue strength of polymers, taking into account the restrictions on the stress state. According to the results of the calculation in the ANSYS software package, an optimal redistribution of the stamp material and a reduction in volume due to the removal of elements that have little effect on the rigidity of the structure is obtained. The results of the study can be further applied in the field of hot and cold stamping by creating stamping tools of minimal volume.

scholarly journals Crack-Length Estimation for Structural Health Monitoring Using the High-Frequency Resonances Excited by the Energy Release during Fatigue-Crack Growth

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4221
Author(s):  
Roshan Joseph ◽  
Hanfei Mei ◽  
Asaad Migot ◽  
Victor Giurgiutiu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Health Monitoring ◽  
Acoustic Waves ◽  
High Frequency ◽  
Fem Analysis ◽  
Signal Frequency ◽  
Propagation Pattern

Acoustic waves are widely used in structural health monitoring (SHM) for detecting fatigue cracking. The strain energy released when a fatigue crack advances has the effect of exciting acoustic waves, which travel through the structures and are picked up by the sensors. Piezoelectric wafer active sensors (PWAS) can effectively sense acoustic waves due to fatigue-crack growth. Conventional acoustic-wave passive SHM, which relies on counting the number of acoustic events, cannot precisely estimate the crack length. In the present research, a novel method for estimating the crack length was proposed based on the high-frequency resonances excited in the crack by the energy released when a crack advances. In this method, a PWAS sensor was used to sense the acoustic wave signal and predict the length of the crack that generated the acoustic event. First, FEM analysis was undertaken of acoustic waves generated due to a fatigue-crack growth event on an aluminum-2024 plate. The FEM analysis was used to predict the wave propagation pattern and the acoustic signal received by the PWAS mounted at a distance of 25 mm from the crack. The analysis was carried out for crack lengths of 4 and 8 mm. The presence of the crack produced scattering of the waves generated at the crack tip; this phenomenon was observable in the wave propagation pattern and in the acoustic signals recorded at the PWAS. A study of the signal frequency spectrum revealed peaks and valleys in the spectrum that changed in frequency and amplitude as the crack length was changed from 4 to 8 mm. The number of peaks and valleys was observed to increase as the crack length increased. We suggest this peak–valley pattern in the signal frequency spectrum can be used to determine the crack length from the acoustic signal alone. An experimental investigation was performed to record the acoustic signals in crack lengths of 4 and 8 mm, and the results were found to match well with the FEM predictions.

Investigating Fatigue Strength of Vacuum Carburized 17CrNi6-6 Steel Using a Resonance High Frequency Method

2014 ◽  
Vol 225 ◽  
pp. 45-52 ◽  
Author(s):  
Piotr Kula ◽  
Konrad Dybowski ◽  
Sebastian Lipa ◽  
Robert Pietrasik ◽  
Radomir Atraszkiewicz ◽  
...  
Keyword(s):  
High Pressure ◽  
Fatigue Strength ◽  
High Frequency ◽  
Vacuum Carburizing ◽  
Frequency Method ◽  
Single Degree Of Freedom ◽  
Bending Fatigue ◽  
Single Degree ◽  
Bending Fatigue Strength ◽  
Frequency Changes

The bending fatigue strength of 17CrNi6-6 steel subjected to vacuum carburizing with high pressure gas hardening has been measured using a novel high-frequency technique. The test records the changes in resonance and consists of observing resonance frequency changes in a vibrating system with a single degree of freedom as a result of the forming of a fatigue crack. Moreover, a mechanism of fatigue nucleation and propagation in steel hardened by vacuum carburizing is presented.

Fatigue Strength Assessment of a Structure Considering Corrosion Wastage and Corrosion Fatigue

2018 ◽  
Author(s):  
Norio Yamamoto ◽  
Tomohiro Sugimoto ◽  
Kinya Ishibashi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Life Assessment ◽  
Actual State ◽  
Corrosive Environment ◽  
Corrosion Fatigue Crack ◽  
Long Life

It is known that the fatigue strength decreases in corrosive environment and many experiments were carried out to comprehend the decrease in fatigue strength in corrosive environment. In order to comprehend the actual state, a cycle speed of fatigue test loads should correspond to a wave frequency. Therefore, an experiment in the long life region is practically difficult, then the corrosion fatigue data available for the life assessment of the structure is quite limited. In this study, the fatigue strength of the welded joints in long life service was evaluated according to the calculations of corrosion fatigue crack propagation subjected to the random loadings which followed an exponential distribution. In the crack propagation calculations, the progress of corrosion wastage from the plate surface and the resultant stress increase were considered simultaneously. In the high stress and the short life region, the decrease in fatigue strength due to the accelerated crack propagation in corrosive environment was dominant because the progress of corrosion wastage was little. On the other hand, in the low stress and the long life region, the decrease in fatigue strength became dull as longer the fatigue life because the corrosion fatigue crack propagation was suppressed by the corrosion wastage, but after that the fatigue strength showed the precipitous decrease due to the increase in stress resulted by the progress of corrosion wastage.

Fatigue Crack Growth Behavior of High Carbon Steel (SM53C) by Using Induction Hardening

2008 ◽  
Author(s):  
Hyun Bae Jeon ◽  
Tae Hoon Song ◽  
Sung Ho Park ◽  
Sun Chul Huh ◽  
Won Jo Park
Keyword(s):  
Fatigue Crack ◽  
Carbon Steel ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
High Frequency ◽  
High Carbon Steel ◽  
Induction Treatment ◽  
Special Focus ◽  
High Carbon ◽  
High Frequency Induction

Recently, with the high performance and efficiency of machine, there have been required the multi-functions in various machine parts, such as the heat resistance, the abrasion resistance and the stress resistance as well as the strength. Fatigue crack growth tests were carried out to investigate the fatigue characteristics of high carbon steel (SM53C) experienced by high-frequency induction treatment. The influence of high-frequency induction treatment on fatigue limit was experimentally examined with the special focus on the variation of surface microstructure and the fatigue crack initiation and propagation through fractography. Also, the shape of hardening depth, hardened structure, hardness, and fatigue-fracture characteristics of SM53C composed by carbon steel are also investigated.

scholarly journals Fatigue Strength Analysis and Fatigue Damage Evaluation of Roller Chain

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 847 ◽  
Author(s):  
Ryoichi Saito ◽  
Nao-Aki Noda ◽  
Yoshikazu Sano ◽  
Jian Song ◽  
Takeru Minami ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Damage ◽  
Fatigue Crack Initiation ◽  
Strength Analysis ◽  
The Finite Element Method ◽  
Roller Chain ◽  
Press Fitting ◽  
The Press ◽  
Static Tensile

This paper deals with the roller chain commonly used for transmission of mechanical power on many kinds of industrial machinery, including conveyors, cars, motorcycles, bicycles, and so forth. It consists of a series of four components called a pin, a bush, a plate, and a roller, which are driven by a sprocket. To clarify the fatigue damage, in this paper, the finite element method (FEM) is applied to those components under three different types of states, that is, the press-fitting state, the static tensile state, and the sprocket-engaging state. By comparing those states, the stress amplitude and the average stress of each component are calculated and plotted on the fatigue limit diagram. The effect of the plastic zone on the fatigue strength is also discussed. The results show that the fatigue crack initiation may start around the middle inner surface of the bush. As am example, the FEM results show that the fatigue crack of the inner plate may start from a certain point at the hole edge. The results agree with the actual fractured position in roller chains used in industry.

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 429-432 ◽  
Author(s):  
Yukio Miyashita ◽  
Kyohei Kushihata ◽  
Toshifumi Kakiuchi ◽  
Mitsuhiro Kiyohara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Crack Growth Resistance ◽  
Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

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