Crack morphology models for fracture toughness and fatigue strength analysis

2019 ◽  
Vol 42 (9) ◽  
pp. 1965-1979 ◽  
Author(s):  
Andrea Carpinteri ◽  
Andrea Spagnoli ◽  
Michele Terzano
Alloy Digest ◽  
2017 ◽  
Vol 66 (12) ◽  

Abstract NITRODUR 8524 (8CrMo16, 1.8524) is one of the Nitrodur family of nitriding steels that are used where high surface hardness and good fatigue strength are required and the material is also subjected to high temperatures. Nitrided surfaces maintain their hardness and strength at operating temperatures of up to approximately 500–550 deg C (932–1022 deg F). This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness. It also includes information on surface qualities as well as casting and forming. Filing Code: SA-807. Producer or source: Schmolz + Bickenbach Group.


2020 ◽  
Vol 10 (1) ◽  
pp. 394-400 ◽  
Author(s):  
I. M. W. Ekaputra ◽  
Rando Tungga Dewa ◽  
Gunawan Dwi Haryadi ◽  
Seon Jin Kim

AbstractThis paper presents the reliability estimation of fatigue strength of the material used for crank throw components. The material used for crank throw components is forged S34MnV steel and subsequently heat-treated by normalising and tempering. High cycle fatigue testing under fully reversed cycling (R = −1) was performed to determine the fatigue limit of the material. The staircase test method is used to obtain accurate values of the mean fatigue limit stress until a number of cycles up to 1E7 cycles. Subsequently, the fatigue test results depend strongly on the stress step and are evaluated by the Dixon-Mood formula. The values of mean fatigue strength and standard deviation predicted by the staircase method are 282 MPa and 10.6MPa, respectively. Finally, the reliability of the design fatigue strength in some selected probability of failure is calculated. Results indicate that the fatigue strength determined from accelerated staircase test is consistent with conventional fatigue testing. Furthermore, the proposed method can be applied for the determination of fatigue strength and standard deviation for design optimisation of S34MnV steel.


2018 ◽  
Vol 68 (15) ◽  
pp. 924-930 ◽  
Author(s):  
J. A. Solís-Ruiz ◽  
G. M. Alonzo-Medina ◽  
A. May-Pat ◽  
L. Dominguez-Cherit ◽  
N. Acuña-Gonzalez ◽  
...  

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 847 ◽  
Author(s):  
Ryoichi Saito ◽  
Nao-Aki Noda ◽  
Yoshikazu Sano ◽  
Jian Song ◽  
Takeru Minami ◽  
...  

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.


2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987801 ◽  
Author(s):  
Qi An ◽  
Hua Zhao ◽  
Peihai Li ◽  
Maohai Fu

In this study, a method for analyzing the fatigue strength of a bogie frame under a random load was proposed. Based on the geometric features, a welded joint coordinate system was established to compute the stress components of each node in this coordinate system. With the influence of small amplitude cycles included, based on the corrected S–N curve and a method for calculating the equivalent constant amplitude stress, the node and comprehensive degree of utilization were calculated based on the anti-fatigue design grade of welded joints to evaluate the fatigue strength of a structure under a given lifespan. The FKM and International Institute of Welding methods were used to evaluate the fatigue strength of typical welded joints of a bogie frame. The characteristics of the node degree of utilization under different analytical methods were compared, and the results showed that when the time histories of the three stress components of the nodes had significant non-proportional features, the FKM method obtained conservative results. When the time histories of the three stress components of the nodes were synchronized, the criterion value specified by the International Institute of Welding method was the main factor affecting the distribution characteristics of the node degree of utilization. The analysis based on the International Institute of Welding method can effectively balance the lightweight design and reliability of the structure.


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