scholarly journals Effect of Fatigue Loading Mode on 718 Alloy Fatigue Properties

2018 ◽  
Vol 47 (4) ◽  
pp. 335-341
Author(s):  
Juraj Belan ◽  
Lenka Kuchariková ◽  
Eva Tillová ◽  
Denisa Závodská ◽  
Mária Chalupová
Keyword(s):  
Structural Damage ◽  
Materials Science ◽  
Low Frequency ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Fatigue Lifetime ◽  
Loading Mode ◽  
Bending Load ◽  
Loading Modes

In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. If the loads are above a certain threshold, microscopic cracks will begin to form at the stress concentrators such as the surface, persistent slip bands (PSBs), interfaces of constituents in the case of composites, and grain interfaces in the case of metals. Eventually a crack will reach a critical size, the crack will propagate suddenly, and the structure will fracture. The first works about fatigue phenomenon were published since 1837 and intensively was investigated by Wöhler in 1860. With needs of using the progressive materials such titanium and Ni-base superalloys become more significant to put under the various fatigue loading these sorts of alloys. Presented article deals with how the various condition of loading influenced an IN718 alloy fatigue lifetime especially. The fatigue tests provided on this kind of material was done via low frequency loading and push-pull or rotation-bending stress up to this time. Fatigue tests of experimental material was carried out at two different frequencies, 20 kHz with stress ration R = - 1 (push – pull, σm = 0 MPa) as well as the three-point bending load R ˂ 1 (σom = 526.8 MPa) at low frequency 150 Hz at room temperature. The microstructure characterization and Scanning Electron Microscopy (SEM) fractography analysis of fatigue process were done as well. The main goal of study was analyze obtained data after fatigue test and consider, if the various loading modes have influence on fatigue lifetime (initiation sites, crack propagation character, etc.).

scholarly journals Effect of UV Ageing on the fatigue life of bulk polyethylene

2018 ◽  
Vol 165 ◽  
pp. 08002 ◽  
Author(s):  
Hamza Lamnii ◽  
Moussa Nait-Abdelaziz ◽  
Georges Ayoub ◽  
Jean-Michel Gloaguen ◽  
Ulrich Maschke ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Uv Irradiation ◽  
Chemical Structure ◽  
Fatigue Behavior ◽  
Crystalline Polymer ◽  
Fatigue Loading ◽  
Chain Scission ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Irradiation Effect

Polymers operating in various weathering conditions must be assessed for lifetime performance. Particularly, ultraviolet (UV) radiations alters the chemical structure and therefore affect the mechanical and fatigue properties. The UV irradiation alters the polymer chemical structure, which results into a degradation of the mechanical and fatigue behavior of the polymer. The polymer properties degradation due to UV irradiation is the result of a competitive process of chain scission versus post-crosslinking. Although few studied investigated the effect of UV irradiation on the mechanical behaviour of thermoplastics, fewer examined the UV irradiation effect on the fatigue life of polymers. This study focuses on investigating the effect of UV irradiation on the fatigue properties of bulk semi-crystalline polymer; the low density Polyethylene (LDPE). Tensile specimens were exposed to different dose values of UV irradiation then subjected to fatigue loading. The fatigue tests were achieved under constant stress amplitude at a frequency of 1Hz. The results show an important decrease of the fatigue limit with increasing absorbed UV irradiation dose.

scholarly journals Study on Fatigue Characteristics of Carbonation Erosion Prestressed Hollow Slabs in Whole Life Cycle

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Yuanxun Zheng ◽  
Kuan Li ◽  
Mengen Ji ◽  
Ehsan Moshtagh
Keyword(s):  
Life Cycle ◽  
Fatigue Life ◽  
Carbon Fiber ◽  
Steel Plate ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Hollow Beam ◽  
Whole Life Cycle ◽  
Life Cycle Failure

In this paper, the whole life cycle (failure-reinforcement-failure) durability and related fatigue properties of prestressed hollow beam under carbonation erosion environment were studied. According to a 20 m hollow slab beam, the model of prestressed hollow beam was designed and made, and the durability and fatigue tests for the whole life cycle of prestressed hollow beam were carried out. The results showed that the compressive strength and elastic modulus of the specimens increased by about 20% under the action of carbonization erosion. With the increase of fatigue loading cycles, the crack occurrence and development speed of carbonized erosion components were greater than those of healthy components, and the fatigue life decreased sharply from 3 million cycles to 50,000 cycles. Pasting carbon fiber and steel plate had better reinforcement effect on the damaged prestressed plate beam and could help improving the fatigue life of the reinforced component. Comparing the reinforcement of different strengthening methods, it is found that the steel-plate-reinforced components have better mechanical properties and antifatigue attenuation characteristics than the carbon-fiber-reinforced ones. The research results have important theoretical value for improving the durability of structure and prolonging its service life.

Fatigue Damage and Life Prediction under Sequential Biaxial Loading

2006 ◽  
Vol 324-325 ◽  
pp. 255-258
Author(s):  
Dan Jin ◽  
Jian Hua Wu ◽  
Xu Chen
Keyword(s):  
Stainless Steel ◽  
Biaxial Loading ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
304 Stainless Steel ◽  
Loading Mode ◽  
Work Model ◽  
Loading Modes ◽  
Damage Rule ◽  
Additional Hardening

Fatigue tests are conducted on 304 stainless steel and 45C steel under fully reversed strain control conditions with two different loading modes. 45C steel exhibits cyclic softening under each phase loading. While for 304 stainless steel, much additional hardening is observed in out-of-phase loading. The damage values for failure of 45C steel is similar to the previous research, however, 304 stainless steel is not. Fatigue life is predicted based on the linear damage rule, the double linear damage rule, and the plastic work model of Morrow. The damage value is different in the same loading mode for the two materials according to linear damage rule.

Determination of Local Tensile and Fatigue Properties With the Use of Sub-Sized Specimens

2015 ◽  
Author(s):  
Jan Džugan ◽  
Pavel Konopik ◽  
Martin Rund ◽  
Radek Prochazka
Keyword(s):  
Residual Life ◽  
Tensile Tests ◽  
Test Methods ◽  
Standard Test ◽  
Fatigue Tests ◽  
Supercooled Austenite ◽  
Fatigue Properties ◽  
Standard Size ◽  
Loading Mode

Determination of mechanical properties with the use of sub-sized specimens is very important topic nowadays. The use of sub-sized samples can be quite wide in all cases when limited amount of the experimental material is available such as evaluation of residual life of in-service components, properties determination of developed nano-structured materials, assessment of dilatometric samples used for thermal and thermo-mechanical treatment development, local properties of weld joints and so on. Concerning this large application field it would be very useful to prepare standard for small size samples especially for most demanded material properties: tensile properties, notch impact transition temperature, fatigue properties, fracture toughness and creep. One of the widely used methods of miniature sample testing is Small Punch Test (SPT) that is used for determination of all above mentioned properties. However the main drawback of this method is need of known correlation relation between considered property and SPT for the material of interest. The correlation is needed due to different loading mode in comparison between SPT and standard test methods. Unfortunately, transferability of these correlation parameters between labs is very limited and thus each lab has to determine its own that limits the use of this method. More interest is recently paid to development of small size samples procedures using miniaturized standardized samples maintaining big advantage — the same loading mode between small sized and full sized samples. The same loading mode significantly reduces or completely removes complexity of the results transfer from small to standard size samples. The current paper is dealing with overview of various applications of small sized tensile tests and fatigue tests. Concerning tensile tests quasi static tensile test at room temperature as well as at elevated temperature are show together with results of dynamic tests and special tests of metastable supercooled austenite. The developed procedures performance is demonstrated by comparison of standard size and sub-size specimens results comparison for all tests, except supercooled austenite tests, where no standard size specimen exists.

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.

scholarly journals Fatigue Characteristics of Materials Used in Transport Industry Applications

2019 ◽  
Vol 1 (1) ◽  
pp. 810-818
Author(s):  
Juraj Belan ◽  
Lenka Kuchariková ◽  
Magdalena Mazur ◽  
Eva Tillová ◽  
Mária Chalupová
Keyword(s):  
Cast Alloy ◽  
Human Life ◽  
Low Frequency ◽  
Fatigue Tests ◽  
Point Of View ◽  
Fatigue Properties ◽  
Major Interest ◽  
Transport Industry ◽  
Industry Applications ◽  
Materials Used

AbstractDesigners have a major interest about fatigue properties of materials used in transport industry. Each component in transport works under alternating stress. From this point of view the fatigue properties are important for single parts lifetime resulting into safety of whole components as cars and airplanes what leads to safety on the roads or air and have influence on human life as well. Therefore this paper deals with fatigue properties of wrought Inconel alloy IN 718 and aluminum cast alloy AlSi9Cu3. Both materials were put on fatigue push – pull test, but Ni – based IN 718 alloy at frequency of loading around 20 000 kHz (High Frequency High Cycles Fatigue) and aluminum alloy AlSi9Cu3 at frequency of loading around 80 Hz (Low Frequency High Cycles Fatigue). These parameters were chosen with respect of usage such materials for production of components used in transport industry applications. Results after fatigue tests are presented as Wohler curve. For prediction of source of fracture the SEM fractography analysis of fatigue fracture surfaces was made.

scholarly journals Improvement of rubber recipe for massive tires by addition of non-traditional fillers

2020 ◽  
Vol 81 (4) ◽  
pp. 196-204
Author(s):  
I. A. Litvinova ◽  
I. V. Veselov ◽  
Y. A. Gamlitskiy
Keyword(s):  
Fatigue Loading ◽  
Critical Value ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Fatigue Properties ◽  
Actual Operating ◽  
Strength Tests ◽  
Industrial Rubber ◽  
Fatigue Characteristics ◽  
Alternating Bending

We investigated the effect of new fillers on the properties of rubbers for solid tires. Modified by fullerenes and unmodified iron oxide fillers were used as new fillers. Fatigue characteristics were determined by two methods: multiple tension on the UR-500 device in accordance with GOST 261-79; alternating bending with rotation on the device SZPI in accordance with GOST 10952-75. The main tasks of constructing fatigue curves were to assess the compliance of the results of strength tests (tension at a constant speed to break) with fatigue in terms of fatigue life, fatigue strength, and fatigue energy density of fracture. In addition, the task was to verify the possibility of plotting on one Weller curve points obtained on different devices - UR 500 and ZPI. The ranking of rubbers in static does not coincide with each other. Since the fatigue loading conditions are closer to the actual operating conditions than the static ones, in order to predict the behavior of rubber goods in operation, one should focus on the results of fatigue tests. Combining the results of fatigue tests with repeated tension and with alternating bending with rotation showed that this procedure is valid, but only in cases where the temperature of self-heating on the ZPI device does not exceed a certain critical value when thermal decomposition begins. The results of fatigue tests showed that the use of the studied fillers with small degrees of filling (up to 30 mass parts) can be justified. An example is Ferrocolor fraction 0–20 ?m with a mass fraction of 5 m.h. In this case, the fatigue properties practically do not deteriorate in comparison with industrial rubber for solid tires, in which new fillers are not added.

Fatigue Properties of Electro-Active Papers for Biomimetic Actuators

Materials ◽  
2005 ◽  
Author(s):  
John Shelton ◽  
William J. Craft ◽  
Jaehwan Kim ◽  
Jamil Grant ◽  
Jag Sankar ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Low Voltage ◽  
Mechanical Strain ◽  
Low Frequency ◽  
Fatigue Loading ◽  
Load Level ◽  
Polymer Materials ◽  
Creep Model ◽  
Fatigue Properties ◽  
Strain Diagram

Cellulose-based Electro-Active Papers (EAPap) have been studied as potential actuators as a result of their low voltage operation, light weight, and low power consumption. In addition, they are bio-degradable and potentially inexpensive.1 The construction of many EAPap electromechanical actuators has been based on cellulose paper film coated with thin electrode layers. This EAPap actuator has shown a reversible and reproducible bending movement as well as longitudinal displacement under low voltage alternating current. However, the EAPap is a complex anisotropic material, which has not been extensively characterized and additional basic and design testing is required before developing EAPap application and devices. It is important to know the extended fatigue and elastic properties of EAPap materials, and this requires testing and evaluation. It has been known that the cellulose based EAPap has two distinct elastic constants connected by a bifurcation point along the stress strain diagram.2 The initial Young’s modulus of EAPap is in the range of 5-8GPa, - quite high compared to other polymer materials.3 Since these materials are anisotropic, elastic properties also differ as a function of orientation. These materials are sensitive to humidity and temperature. Fatigue tests conducted and described in this paper identify critical properties of this under-analyzed class of materials to provide a measure of its fatigue capabilities. Mechanical strain of EAPap materials has been evaluated, and it appears to follow closely a linear creep model as confirmed by low frequency cyclic (fatigue) loading. The creep parameter has also been determined to be a function of temperature and load level for all the EAPap materials tested.

scholarly journals Fast screening of the fatigue properties of thermoplastics reinforced with short carbon fibers based on a heat build-up protocol

2018 ◽  
Vol 165 ◽  
pp. 08001 ◽  
Author(s):  
Louis Leveuf ◽  
Yann Marco ◽  
Vincent Le Saux ◽  
Libor Navratil ◽  
Sylvain Leclercq ◽  
...  
Keyword(s):  
Carbon Fibers ◽  
Fatigue Tests ◽  
Thermoplastic Composite ◽  
Fatigue Properties ◽  
Fatigue Lifetime ◽  
Fast Screening ◽  
Experimental Protocols ◽  
Heat Build Up ◽  
Short Carbon

This study deals with the characterization of the fatigue lifetime of a short carbon fiber reinforced PEEK matrix thermoplastic composite using a heat build-up protocol. Several commercial grades and fillers ratios are considered in order to challenge the ability of the technique to capture the influence of these variations. First, the materials investigated and the experimental protocols are described. The way to build the heat build-up curves is outlined. Then the results obtained from the heat build-up and the fatigue experiments are presented. Finally these results are used to discuss two main points. The first one is the validity of the hypotheses needed to apply the approach, ranging from the evaluation of the dissipation to the response during the fatigue tests. The second one is the capability to predict the fatigue curves accurately throughout an energetic criterion and to catch the influence of the variation of material on the fatigue properties. The results presented here are published with more details in [47].

Fatigue Lifetime and Crack Growth Behavior of WC-Co Cemented Carbide

2014 ◽  
Vol 891-892 ◽  
pp. 955-960 ◽  
Author(s):  
Hiroko Mikado ◽  
Sotomi Ishihara ◽  
Noriyasu Oguma ◽  
Kenichi Masuda ◽  
Shingo Kawamura
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Tests ◽  
Growth Behavior ◽  
Cemented Carbide ◽  
Fatigue Properties ◽  
Crack Growth Behavior ◽  
Fatigue Lifetime

It is well known that WC-Co cemented carbides have excellent wear resistance. However, information about their fatigue crack growth behavior and fatigue properties is limited. In the present study, rotating bending fatigue tests were carried out on a fine grained WC-Co cemented carbide to evaluate its fatigue lifetime and crack growth behavior. From observations of the micro-notched specimen surface during the fatigue process, it was revealed that most of the fatigue lifetime of the tested WC-Co cemented carbide is comprised of crack growth cycles. Using the basic equation of fracture mechanics, the relation between the rate of fatigue crack growth da/dN and the maximum stress intensity factor Kmax of the WC-Co cemented carbide was derived. From this relation, both the threshold intensity factor Kth and the fatigue fracture toughness Kfc of the material were determined. Fatigue lifetime of the WC-Co cemented carbide was estimated based on the fatigue crack growth law.

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