Effect of Stress Concentration on Fatigue-Crack Initiation in HY-130 Steel

2009 ◽  
pp. 183-183-22 ◽  
Author(s):  
JM Barsom ◽  
RC McNicol
Keyword(s):  
Fatigue Crack ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Fatigue Crack Initiation

scholarly journals Experimental and numerical study on fretting wear and fatigue of full-scale railway axles

2020 ◽  
Vol 28 (4) ◽  
pp. 365-381
Author(s):  
Lang Zou ◽  
Dongfang Zeng ◽  
Yabo Li ◽  
Kai Yang ◽  
Liantao Lu ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Numerical Study ◽  
Equivalent Stress ◽  
Fatigue Crack Initiation ◽  
Fretting Fatigue ◽  
Full Scale ◽  
Fretting Wear ◽  
Stress Intensity Factor Range

AbstractThis study investigated the fretting wear and fatigue of full-scale railway axles. Fatigue tests were conducted on full-scale railway axles, and the fretting wear and fretting fatigue in the fretted zone of the railway axles were analysed. Three-dimensional finite element models were established based on the experimental results. Then, multi-axial fatigue parameters and a linear elastic fracture mechanics-based approach were used to investigate the fretting fatigue crack initiation and propagation, respectively, in which the role of the fretting wear was taken into account. The experimental and simulated results showed that the fretted zone could be divided into zones I–III according to the surface damage morphologies. Fretting wear alleviated the stress concentration near the wheel seat edge and resulted in a new stress concentration near the worn/unworn boundary in zone II, which greatly promoted the fretting crack initiation at the inner side of the fretted zone. Meanwhile, the stress concentration also increased the equivalent stress intensity factor range ΔKeq below the mating surface, and thus promoted the propagation of fretting fatigue crack. Based on these findings, the effect of the stress redistribution resulting from fretting wear is suggested to be taken into account when evaluating the fretting fatigue in railway axles.

Development of Structural Steel With High Resistance to Fatigue Crack Initiation and Growth: Part 3

2005 ◽  
Author(s):  
Hiroshi Katsumoto ◽  
Noboru Konda ◽  
Kazushige Arimochi ◽  
Kazuhiro Hirota ◽  
Atsushi Isoda ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Fatigue Fracture ◽  
High Resistance ◽  
Fatigue Crack Initiation ◽  
Conventional Steel ◽  
Welded Structure ◽  
Safety And Reliability

In recent years, higher safety and reliability of steel welded structures have been required as it shows growing concern about environmental problems. To prevent fatigue fracture is one of the most important challenges to improve the safety and reliability. A lot of studies how reduce stress concentration at critical areas have been carried out from the viewpoint of structural design as prevention measures while nothing has been studied from the viewpoint of material because fatigue strength of welded joints converges in limited range regardless of material strength. On the other hand, it was found that an appropriate dual phase microstructure could reduce the fatigue crack growth rate remarkably. The newly developed steel plate with high resistance to fatigue crack growth could extend the fatigue life of structures. The developed steels have already been applied to some ships and vessels, and a new bulk carrier applied the developed steels acquired the notation and descriptive note as the valuable ship with resistance to fatigue fracture by Nippon Kaiji Kyokai for the first time in the world. From further studies, it was found the developed steels had also high resistance to fatigue crack initiation as well as the growth even in welded structure. In this study, it was clarified that the fatigue strength of HAZ, where fatigue crack generally initiates, in the developed steel was higher than that in conventional steel and the stress concentration at toe of weld in the developed steel was smaller than in the conventional steel. It was considered the mechanism of suppression of fatigue crack initiation with FEM analysis and fatigue test. The newly developed steel can effectively extend fatigue fracture life of welded structure from the viewpoint of material.

Assessment Technology of Fatigue Crack Initiation Life of Weld Structures

2017 ◽  
Vol 86 (1) ◽  
pp. 56-58
Author(s):  
Seiichiro TSUTSUMI ◽  
Fincato RICCARDO ◽  
Mitsuru OHATA ◽  
Tomokazu SANO
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Assessment Technology ◽  
Crack Initiation Life

scholarly journals Crack Propagation in the Tibia Bone within Total Knee Replacement Using the eXtended Finite Element Method

2021 ◽  
Vol 11 (10) ◽  
pp. 4435
Author(s):  
Ho-Quang NGUYEN ◽  
Trieu-Nhat-Thanh NGUYEN ◽  
Thinh-Quy-Duc PHAM ◽  
Van-Dung NGUYEN ◽  
Xuan Van TRAN ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Fatigue Crack Initiation ◽  
Fracture Prevention ◽  
Patient Specific ◽  
Extended Finite Element ◽  
Tibia Bone ◽  
Age Related ◽  
Final Failure

Understanding of fracture mechanics of the human knee structures within total knee replacement (TKR) allows a better decision support for bone fracture prevention. Numerous studies addressed these complex injuries involving the femur bones but the full macro-crack propagation from crack initiation to final failure and age-related effects on the tibia bone were not extensively studied. The present study aimed to develop a patient-specific model of the human tibia bone and the associated TKR implant, to study fatigue and fracture behaviors under physiological and pathological (i.e., age-related effect) conditions. Computed tomography (CT) data were used to develop a patient-specific computational model of the human tibia bone (cortical and cancellous) and associated implants. First, segmentation and 3D-reconstruction of the geometrical models of the tibia and implant were performed. Then, meshes were generated. The locations of crack initiation were identified using the clinical observation and the fatigue crack initiation model. Then, the propagation of the crack in the bone until final failure was investigated using the eXtended finite element method (X-FEM). Finally, the obtained outcomes were analyzed and evaluated to investigate the age-effects on the crack propagation behaviors of the bone. For fatigue crack initiation analysis, the stress amplitude–life S–N curve witnessed a decrease with increasing age. The maximal stress concentration caused by cyclic loading resulted in the weakening of the tibia bone under TKR. For fatigue crack propagation analysis, regarding simulation with the implant, the stress intensity factorand the energy release rate tended to decrease, as compared to the tibia model without the implant, from 0.152.5 to 0.111.9 (MPa) and from 10240 to 5133 (J), respectively. This led to the drop in crack propagation speed. This study provided, for the first time, a detailed view on the full crack path from crack initiation to final failure of the tibia bone within the TKR implant. The obtained outcomes also suggested that age (i.e., bone strength) also plays an important role in tibia crack and bone fracture. In perspective, patient-specific bone properties and dynamic loadings (e.g., during walking or running) are incorporated to provide objective and quantitative indicators for crack and fracture prevention, during daily activities.

Sign in / Sign up

Export Citation Format

Share Document