Effects of cyclic loading on occurrence of brittle fracture in notched specimens

2015 ◽  
pp. 599-604 ◽  
Author(s):  
T Iwashita ◽  
K Azuma
Keyword(s):  
Cyclic Loading ◽  
Brittle Fracture ◽  
Notched Specimens

scholarly journals Verification of Brittle Fracture Criteria for Bimaterial Structures

2014 ◽  
Vol 8 (1) ◽  
pp. 44-48
Author(s):  
Grzegorz Mieczkowski ◽  
Krzysztof Molski
Keyword(s):  
Experimental Data ◽  
Composite Materials ◽  
Cyclic Loading ◽  
Brittle Fracture ◽  
Axial Loading ◽  
Loading Conditions ◽  
Fracture Criteria ◽  
Interfacial Cracks ◽  
Theoretical Results ◽  
Brittle Fracture Criteria

Abstract The increasing application of composite materials in the construction of machines causes strong need for modelling and evaluating their strength. There are many well known hypotheses used for homogeneous materials subjected to monotone and cyclic loading conditions, which have been verified experimentally by various authors. These hypotheses should be verified also for composite materials. This paper provides experimental and theoretical results of such verifications for bimaterial structures with interfacial cracks. Three well known fracture hypotheses of: Griffith, McClintock and Novozhilov were chosen. The theoretical critical load values arising from each hypotheses were compared with the experimental data including uni and multi-axial loading conditions. All tests were carried out with using specially prepared specimens of steel and PMMA.

scholarly journals Low Cycle Fatigue Life Evaluation of Notched Specimens Considering Strain Gradient

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1001
Author(s):  
Shenghuan Qin ◽  
Zaiyin Xiong ◽  
Yingsong Ma ◽  
Keshi Zhang
Keyword(s):  
Cyclic Loading ◽  
Constitutive Model ◽  
Strain Gradient ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Plastic Behavior ◽  
Cycle Fatigue ◽  
New Model ◽  
Hysteresis Behavior ◽  
Notched Specimens

An improved model based on the Chaboche constitutive model is proposed for cyclic plastic behavior of metal and low cycle fatigue of notched specimens under cyclic loading, considering the effect of strain gradient on nonlinear kinematic hardening and hysteresis behavior. The new model is imported into the user material subroutine (UMAT) of the finite element computing software ABAQUS, and the strain gradient parameters required for model calculation are obtained by calling the user element subroutine (UEL). The effectiveness of the new model is tested by the torsion test of thin copper wire. Furthermore, the calibration method of strain gradient influence parameters of constitutive model is discussed by taking the notch specimen of Q235 steel as an example. The hysteresis behavior, strain distribution and fatigue failure of notched specimens under cyclic loading were simulated and analyzed with the new model. The results prove the rationality of the new model.

Research on the Mechanism of Fatigue Crack Initiation of X60 Pipeline Steel after Per-Tension Deformation

2012 ◽  
Vol 197 ◽  
pp. 798-801
Author(s):  
Yu Rong Jiang ◽  
Mei Bao Chen
Keyword(s):  
Fatigue Crack ◽  
Cyclic Loading ◽  
Brittle Fracture ◽  
Crack Initiation ◽  
Pipeline Steel ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Fracture Characteristics ◽  
Metallic Inclusions ◽  
The Matrix

It is impossible to keep pipelines free from defects in the manufacturing, installation and servicing processes. In this paper, pre-tension deformation of X60 pipeline steel was employed to experimentally simulate the influence of dents and the mechanism of fatigue crack initiation of X60 pipeline steel after per-tension deformation under cyclic loading were investigated. The results indicate that the mechanism of fatigue crack initiation is the typical cleavage fracture characteristics and the cracks mainly initiates from the non-metallic inclusions which was the local brittle fracture materials such as MnS inclusion. With the pre-tension deformation increase, the yield strength of the matrix was increased and the toughness decreased due to the work-hardening effect. With the effects of the non-metallic inclusions larger, the fatigue cracks initiated from the non-metallic inclusions easier.

scholarly journals Influence of strain rate on ductile versus brittle fracture for ductile cast iron EN-GJS-500-14 in V-notch three-point bending tests

2018 ◽  
Vol 188 ◽  
pp. 02019
Author(s):  
Maqsood Ahmad ◽  
Joachim Lindkvist ◽  
Magnus Andersson
Keyword(s):  
Solid Solution ◽  
Brittle Fracture ◽  
Strain Rate ◽  
Ductile Cast Iron ◽  
Strain Rates ◽  
Bending Tests ◽  
Three Point Bending ◽  
Brittle Behavior ◽  
Notched Specimens ◽  
Scanning Electron

Three point bending tests on V-notched specimens machined from a component cast in EN-GJS 500-14 nodular iron solid solution strengthened by silicon have been carried out. The 3P bending tests were performed at different stroke speeds (10-3 ~ 102 mm/s). The resulting strain rates at the V notch varied in the range of 1·10-4 ~ 5,8 s-1. The fracture surface of 3P bending tests was quantified in terms of ductile and brittle fracture using Scanning Electron Microscope (SEM). EN-GJS 500-14 has an increased brittle behavior with increasing strain rate. Predominately ductile fracture was observed for the strain rates 1·10-4~4·10-2S-1. . At the strain rate of about 1 s-1 more significant change in ductile to brittle fracture is seen. The 3P bending tests at -15°C showed predominately brittle fracture for the strain rates investigated 3,6·10-2 ~ 2,3 s-1.

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