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.

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 Experimental Investigation of the Three-point Bending Fatigue Properties of Carbon Fiber Composite Laminates

2016 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
Meihong He ◽  
Tao Yang ◽  
Xuejuan Niu ◽  
Yu Du
Keyword(s):  
Fatigue Life ◽  
Carbon Fiber ◽  
Stress Level ◽  
Fiber Composite ◽  
Fatigue Loading ◽  
Fatigue Properties ◽  
Loading Frequency ◽  
Carbon Fiber Composite ◽  
Bending Fatigue ◽  
Three Point Bending

The three point bending fatigue properties of carbon fiber epoxy matrix composite laminates were compared for fatigue loading stress levels of 75, 80 and 85%, and fatigue loading frequencies of 10, 15 and 20Hz, respectively. The experimental results showed that: the bending fatigue life of the composites obviously decreased with the increase of the fatigue loading stress level or the loading frequency. The fatigue damage accumulation process could be divided into three distinct stages according to the accumulation rate: fast, slow and then fast. When the loading stress level was increased from 75 to 85%, the duration of the third stage decreased from 40 to 10% of the overall fatigue life. When the loading frequency was increased from 10 to 20Hz, the duration of the third stage increased from 20 to 40% of the overall fatigue life. Matrix cracking, fiber breaking, interface debonding and delamination were identified as the main three-point bending fatigue damage modes of the carbon fiber composite material, and the stress level and the loading frequency were found to significantly influence the fatigue failure properties of the composites.

A Study of Nozzles in Pressure Vessels under Pressure Fatigue Loading

1967 ◽  
Vol 182 (1) ◽  
pp. 657-684 ◽  
Author(s):  
J. Spence ◽  
W. B. Carlson
Keyword(s):  
Fatigue Life ◽  
Mild Steel ◽  
Pressure Vessel ◽  
Special Interest ◽  
Maximum Stress ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Full Size

Nozzles in cylindrical vessels have been of special interest to designers for some time and have offered a field of activity for many research workers. This paper presents some static and fatigue tests on five designs of full size pressure vessel nozzles manufactured in two materials. Supporting and other published work is reviewed showing that on the basis of the same maximum stress mild steel vessels give the same fatigue life as low alloy vessels. When compared on the basis of current codes it is shown that mild steel vessels may have five to ten times the fatigue life of low alloy vessels unless special precautions are taken.

Low Cycle Fatigue Properties of FGH720Li Superalloy

2021 ◽  
Vol 1035 ◽  
pp. 292-296
Author(s):  
Zi Chao Peng ◽  
Jun Ying Sheng ◽  
Xu Qing Wang ◽  
Yue Tang
Keyword(s):  
Fatigue Life ◽  
Powder Metallurgy ◽  
Applied Stress ◽  
Low Cycle Fatigue ◽  
Influencing Factor ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Nickel Base Superalloy ◽  
Loading Frequency ◽  
Cycle Fatigue

Low cycle fatigue (LCF) properties of a powder metallurgy(PM) nickel base superalloy FGH720Li were systematically studied in this work, including smooth LCF and notched LCF tested at various temperatures and different stress. The relationship between the fatigue life and applied stress was analyzed both for smooth fatigue and notch fatigue tests. The effects of loading frequency and stress ratio on LCF behavior were also studied. As an important influencing factor of the fatigue life in powder metallurgy superalloy, the effect of inclusions on LCF life was also investigated. The results showed that the fatigue properties of FGH720Li alloy was excellent, when tested at the temperature of 450°C and applied stress of 1230MPa, the fatigue life could exceed 5×104 cycles. When tested at 650°C and 1150MPa, the average fatigue life was still beyond 2×105 cycles.

scholarly journals The Influence of Laser Shock Peening on Fatigue Properties of AA2024-T3 Alloy with a Fastener Hole

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 495
Author(s):  
Ruslan Sikhamov ◽  
Fedor Fomin ◽  
Benjamin Klusemann ◽  
Nikolai Kashaev
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracks ◽  
Initial Crack ◽  
Fatigue Tests ◽  
Laser Shock Peening ◽  
Fatigue Properties ◽  
Hole Drilling ◽  
Laser Shock ◽  
Fastener Hole ◽  
Shock Peening

The objective of the present study was to estimate the influence of laser shock peening on the fatigue properties of AA2024-T3 specimens with a fastener hole and to investigate the possibility to heal the initial cracks in such specimens. Fatigue cracks of different lengths were introduced in the specimens with a fastener hole before applying laser shock peening. Deep compressive residual stresses, characterized by the hole drilling method, were generated into the specimens by applying laser shock peening on both sides. Subsequently, the specimens were subjected to fatigue tests. The results show that laser shock peening has a positive effect regarding the fatigue life improvement in the specimens with a fastener hole. In addition, laser shock peening leads to a healing effect on fatigue cracks. The efficiency of this effect depends on the initial crack length. The effect of laser shock peening on the fatigue life periods was determined by using resonant frequency graphs.

Effects of Water Jet Peening and Hardening Treatment on Fatigue Properties of SCr420

2009 ◽  
Author(s):  
Akira Shimamoto ◽  
Ryo Kubota ◽  
Sung-mo Yang ◽  
Dae-kue Choi ◽  
Weiping Jia
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Water Jet ◽  
Fatigue Properties ◽  
In Situ Observation ◽  
Axial Tensile ◽  
High Pressure Water Jet

An experimental study of high pressure water jet peening treatment on chromium steal SCr420 H3V2L2 is conducted to study the effects of cavitation impacts of high-speed water on fatigue crack initiation and propagation of notched specimens. There are six different kinds of specimens. First three kinds are treated with; only annealing, only water quenching, and only oil quenching. Other three kinds are treated with above heat treatment and water jet peening, respectively. An axial tensile fatigue tests’ condition is 260MPa maximum stress amplitude, 0 stress ratio and 10Hz frequency, while in-situ observation by SEM is employed. Although fatigue life of the specimens with annealing and water jet peening is shorter than that of only annealing, fatigue life of water and oil quenching with water jet peening specimens is obviously longer than those without water jet peening treatment. Water jet peening has increased residual stress inside the specimens on the latter case and raised their fatigue strength. In-situ observation on the crack tips approves above analysis.

The Study on the Fatigue Test and Reliability for the Steel of Train Wheel

2012 ◽  
Vol 198-199 ◽  
pp. 146-149
Author(s):  
Wen Qin Han ◽  
Jin Yu Zhou
Keyword(s):  
Fatigue Life ◽  
Safety Evaluation ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Design Standards ◽  
Design Data ◽  
Fatigue Design ◽  
Grouping Method ◽  
Fluctuation Method ◽  
Curve Equation

To obtain fatigue design data of the train wheel steel , the fatigue tests were carried out for the steel of K type and B type train wheel separately, which fatigue limit was measured using the fluctuation method, the fatigue life of two kinds of wheel steels were tested using the grouping method at the three stress levels, two different materials and different structures have an influence on the fatigue properties of the wheels using reliability principle. The fatigue life distribution of the B type is scattered relatively . S-N curve equation and P-S-N curve equation of the two kinds of steel were calculated . The theoretical basis were put up for developing design standards and safety evaluation of the both wheel.

Fatigue Life Curves of NiTi Alloys – The Z Effect

2010 ◽  
Vol 643 ◽  
pp. 69-77 ◽  
Author(s):  
Ana Maria Gontijo Figueiredo ◽  
Berenice Mendonça Gonzalez ◽  
Vicente Tadeu Lopes Buono ◽  
Paulo José Modenesi
Keyword(s):  
Fatigue Life ◽  
High Strain ◽  
Rotation Speed ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Large Strains ◽  
Unusual Behavior ◽  
Niti Alloys ◽  
Stable Austenite ◽  
Unstable Austenite

Superelasticity is closely related to shape memory effect. It refers to the property presented by some materials submitted to large strains (usually up to about 8%) to restore their original shape immediately after unloading without the need of heating. This phenomenon results directly from a diffusionless transformation of the material from an austenitic to a martensitic phase (martensitic transformation). The recovering mechanism is the reverse transformation, from martensite to austenite. This paper compares fatigue live curves obtained in bending-rotation fatigue tests carried out on wires of NiTi alloys with three different microstructures, stable austenite, unstable austenite (superelastic), and stable martensite. These curves are also compared to data from the literature. The tests were strain controlled and the wires were submitted to strain amplitudes from 0.6% to 12.0%. To minimize changes in material properties, the wire temperature was monitored using a thermocouple and controlled by its rotation speed. For strain amplitudes up to 4%, the εa-Nf curve for superelastic wires was consistent with those reported in the literature, closely approaching the curve of the stable austenite wire. For higher strain amplitudes, fatigue life of superelastic wires increased with strain until it approached the fatigue life curve of stable martensitic wire. This unusual behavior results in a “Z-shaped” curve for high strain values. It is possibly linked to the changes in microstructure and fatigue properties that occur when the superelastic material is deformed.

The Finite Element Research of Fatigue Properties of Steel Q345 Butt Welded Joint

2014 ◽  
Vol 670-671 ◽  
pp. 1087-1090
Author(s):  
Wei Ping Ouyang ◽  
Liang Sheng Chen ◽  
Xiu Dong Xu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Welded Joint ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Structural Stress ◽  
Design Development ◽  
Stress Theory

The research of fatigue properties of the butt welded joint, though a large number of fatigue tests are need to be carried out, has significant influence to hoisting equipment’s design, development and using safety. This paper conducted a study on simulating the fatigue properties of widely used steel Q345 butt welded joint’s by finite element method based on the improved linear equivalent structural stress theory. The originally massive amount of fatigue tests and data processing could be saved. In order to ensure the accuracy of the fatigue modeling, a batch of Q345 butt welded joints were prepared for the fatigue tests which is used to contrast with the modeling result. The stress distribution under different load situation and the fatigue life of the joints, which have profound reference significance to hoisting machinery industry, can be acquired through modeling.

Fatigue Properties of a Ck45 Steel Coated with a Post-Heat Treated Ni-Cu-P Electroless Deposit

2006 ◽  
Vol 514-516 ◽  
pp. 574-578
Author(s):  
Sasan Yazdani ◽  
N. Parvini-Ahmadi ◽  
Tohid Saeid
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Crack Nucleation ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Interfacial Cracks ◽  
Heat Treated ◽  
Base Steel ◽  
Surface Notch

The Fatigue tests under rotating bending conditions have been conducted on samples of a quenched and tempered Ck45 steel in two different conditions: (a) uncoated, (b) coated with an electroless Ni-Cu-P deposit, followed by a post-heat treatment (PHT) at 673 K for 1 h. Such a deposit had a thickness of approximately 10µm, with Cu and P contents of 6wt.% and 13.7wt.% respectively. The results indicate that plating the base steel with this kind of deposit leads to a reduction of the fatigue life of the material. The reduction in fatigue life has been quantified in terms of the Basquin parameters of the materials tested under different conditions. The microscopic observation of the fracture surfaces of the samples indicates that the reduction in fatigue life is associated with the nucleation of fatigue cracks on the coating-substrate interface and the deposit remains well adhered to substrate during fatigue testing since interfacial cracks have been very rarely observed. It is therefore concluded that, in the present case, the interface acts as a surface crack source or surface notch, which decreases the fatigue life of the coated material by reducing the crack nucleation stage.

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