CHAOTIC DETECTION METHOD OF GEAR EARLY-STAGE FATIGUE CRACK

2005 ◽  
Vol 41 (08) ◽  
pp. 195 ◽  
Author(s):  
Chongsheng Li
Keyword(s):  
Fatigue Crack ◽  
Detection Method ◽  
Early Stage

Plastic Slip and Early Stage of Fatigue Damage in Polycrystals: Comparison between Experiments and Crystal Plasticity Finite Elements Simulations

2014 ◽  
Vol 891-892 ◽  
pp. 1711-1716 ◽  
Author(s):  
Loic Signor ◽  
Emmanuel Lacoste ◽  
Patrick Villechaise ◽  
Thomas Ghidossi ◽  
Stephan Courtin
Keyword(s):  
Fatigue Crack ◽  
Finite Elements ◽  
Crack Initiation ◽  
Fatigue Damage ◽  
Crystal Plasticity ◽  
Early Stage ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Plastic Slip

For conventional materials with solid solution, fatigue damage is often related to microplasticity and is largely sensitive to microstructure at different scales concerning dislocations, grains and textures. The present study focuses on slip bands activity and fatigue crack initiation with special attention on the influence of the size, the morphology and the crystal orientation of grains and their neighbours. The local configurations which favour - or prevent - crack initiation are not completely identified. In this work, the identification and the analysis of several crack initiation sites are performed using Scanning Electron Microscopy and Electron Back-Scattered Diffraction. Crystal plasticity finite elements simulation is employed to evaluate local microplasticity at the scale of the grains. One of the originality of this work is the creation of 3D meshes of polycrystalline aggregates corresponding to zones where fatigue cracks have been observed. 3D data obtained by serial-sectioning are used to reconstruct actual microstructure. The role of the plastic slip activity as a driving force for fatigue crack initiation is discussed according to the comparison between experimental observations and simulations. The approach is applied to 316L type austenitic stainless steels under low-cycle fatigue loading.

scholarly journals The early stage wheel fatigue crack detection using eddy current pulsed thermography

2017 ◽  
Author(s):  
Jianping Peng ◽  
Kang Zhang ◽  
Kai Yang ◽  
Zhu He ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Eddy Current ◽  
Crack Detection ◽  
Early Stage ◽  
Pulsed Thermography ◽  
Fatigue Crack Detection

scholarly journals A Miniaturized Pump Out Method for Characterizing Molecule Interaction with ABC Transporters

2019 ◽  
Vol 20 (22) ◽  
pp. 5529 ◽  
Author(s):  
Emmanuel Sevin ◽  
Lucie Dehouck ◽  
Romain Versele ◽  
Maxime Culot ◽  
Fabien Gosselet
Keyword(s):  
Abc Transporters ◽  
Detection Method ◽  
Cell Model ◽  
Early Stage ◽  
Cell Monolayer ◽  
Efflux Pumps ◽  
Apparent Permeability ◽  
Traditional Use ◽  
Molecule Design ◽  
Molecule Interaction

Characterizing interaction of newly synthetized molecules with efflux pumps remains essential to improve their efficacy and safety. Caco-2 cell line cultivated on inserts is widely used for measuring apparent permeability of drugs across biological barriers, and for estimating their interaction with efflux pumps such as P-gp, BCRP and MRPs. However, this method remains time consuming and expensive. In addition, detection method is required for measuring molecule passage across cell monolayer and false results can be generated if drugs concentrations used are too high as demonstrated with quinidine. For this reason, we developed a new protocol based on the use of Caco-2 cell directly seeded on 96- or 384-well plates and the use of fluorescent substrates for efflux pumps. We clearly observed that the new method reduces costs for molecule screening and leads to higher throughput compared to traditional use of Caco-2 cell model. This accelerated model could provide quick feedback regarding the molecule design during the early stage of drug discovery and therefore reduce the number of compounds to be further evaluated using the traditional Caco-2 insert method.

Experimental Study of Fatigue Crack Initiation and Strain Evolution around a Micro-Void by In Situ SEM and Digital Image Correlation

2017 ◽  
Vol 754 ◽  
pp. 75-78 ◽  
Author(s):  
De Qiang Wang ◽  
Ming Liang Zhu ◽  
Fu Zhen Xuan
Keyword(s):  
Fatigue Crack ◽  
Digital Image Correlation ◽  
Crack Initiation ◽  
Digital Image ◽  
Early Stage ◽  
Fatigue Crack Initiation ◽  
Image Correlation ◽  
Dominant Factor ◽  
Strain Evolution

Fatigue crack initiation stage occupies a large proportion of total fatigue life in modern engineering materials and structures which are often designed under lower service loading conditions. In this paper, the fatigue crack initiation behavior from a micro-void in a small-scale specimen was studied in-situ in SEM. Surface morphologies were monitored in-situ and images were taken during interrupted tests at selected number of cycles, and displacement and strain map around the void was calculated based on digital image correlation (DIC) technique. The results indicated that the strain evolution near the micro-void could be divided into stages, before crack initiation. The strain increasing rate was fast in the early stage and slower in the second stage. A critical cyclic strain value for fatigue crack initiation from the micro-void was obtained around 9%, and was believed to be the dominant factor for early stage of fatigue damage.

Detecting Loosening of Bolted Connections in a Pipeline Using Changes in Natural Frequencies

2011 ◽  
Author(s):  
K. He ◽  
W. D. Zhu
Keyword(s):  
Damage Detection ◽  
Natural Frequencies ◽  
Detection Method ◽  
Complex Geometry ◽  
Early Stage ◽  
Measurement Noise ◽  
Modeling Error ◽  
Bolted Connections ◽  
Bolted Connection ◽  
Stiffness Reduction

Loosening of bolted connections in a structure can significantly reduce the load-bearing capacities of the structure. Detecting loosening of bolted connections at an early stage can avoid failure of the structure. Due to the complex geometry of a bolted connection and the material discontinuity between the clamped components, it is difficult to detect loosening of a bolted connection using conventional non-destructive test methods. A vibration-based method that uses changes in natural frequencies of a structure to detect the locations and extent of damage can be used to detect loosening of bolted connections, since the method focuses on detecting a stiffness reduction, which can result from loosening of the bolted connections. Experimental and numerical damage detection using the vibration-based method was conducted to detect the loosening of the bolted connections in a fullsize steel pipeline with bolted flanges. With the recent development of a predictive modeling technique for bolted connections in thin-walled structures, an accurate physics-based finite element model of the pipeline that is required by the vibration-based damage detection method is developed. A trust-region search strategy is employed to improve the damage detection method so that convergence of the damage detection algorithm can be ensured for under-determined systems, and the robustness of the algorithm can be enhanced when relatively large modeling error and measurement noise are present. The location and extent of the loosened bolted connections were successfully detected in experimental damage detection using changes in the natural frequencies of the first several modes; the exact location and extent of the loosened bolted connections can be detected in the numerical simulation where there are no modeling error and measurement noise.

Early Visualization Detection of Gray Mold (Botrytis) on Eggplant Leaves Based on Multi-Spectral Image

2015 ◽  
Vol 741 ◽  
pp. 323-327
Author(s):  
Yan Yang
Keyword(s):  
Detection Method ◽  
Early Stage ◽  
Gray Mold ◽  
Usual Method ◽  
Excessive Amount ◽  
Disease Spread ◽  
Spectral Image ◽  
Fungal Strains ◽  
Entire Field ◽  
Fungus Disease

Gray mold (Botrytis) is a common fungus disease on eggplants,it can reduce the production by 20-30% at worse. Most disease infestations are not evenly distributed across the cultivation area but in patches [1]. The usual method of prevention is spraying fungicide on entire field, which would requires an excessive amount of fungicide and resulting, increases cost of production, pollutes the environment, and improves of resistance fungal strains [2]. In fact, the fungicide can be spray only the area infected which is rather small on the early stage and it is fully capable of controlling disease spread. Therefore, rapid disease detection is the key. The accurate and effective detection method would be helpful for reducing the dosage of fungicide and preventing disease spread.

Sign in / Sign up

Export Citation Format

Share Document