On-chip fracture testing of freestanding nanoscale materials

2015 ◽  
Vol 150 ◽  
pp. 222-238 ◽  
Author(s):  
Renaud Vayrette ◽  
Jean-Pierre Raskin ◽  
Thomas Pardoen
2009 ◽  
Vol 626-627 ◽  
pp. 65-70
Author(s):  
Hui Ping Zhang ◽  
X.P. Ji ◽  
Jue Wang ◽  
Er Liang Liu

This paper deals with the effect of cutting speed on chip fracture strain in high speed cutting. Firstly, a chip-fracture-strain-measuring device is designed and made according to chip breaking principle. Secondly, experiments are performed by the chip-fracture-strain-measuring device. The experiment results show that chip fracture strain increases first and then diminishes as cutting speed increasing in high speed cutting while feedrate and depth of cut are constant values. Lastly, the effect of cutting speed on chip fracture strain is theoretically analysed from three main factors which affect chip fracture strain. The study above lays a theory and basis for future investigation of chip fracture strain of the other metals and for future investigation the mechanism and chip breaking forecast system of 3-D groove insert in high speed cutting.


Author(s):  
Sahar Jaddi ◽  
Jean-Pierre Raskin ◽  
Thomas Pardoen

Abstract An on-chip fracture mechanics method is extended to characterize subcritical crack growth in submicron freestanding films. The method relies on a self-actuated concept based on MEMS fabrication principles. The configuration consists of a notched specimen attached to actuator beams involving high internal stress. Upon release, a crack initiates at the notch, propagates, and arrests. Several improvements are worked out to limit the mode III component and to avoid crack kinking. The method is applied to subcritical crack growth in 140-nm-thick SiO2 films under different humidity conditions. The data reduction scheme relates crack growth rate to stress intensity factor. The static fracture toughness value is ~ 0.73 MPa $$\sqrt{\mathrm{m}}$$ m , with standard error of 0.01 MPa $$\sqrt{\mathrm{m}}$$ m and standard deviation of 0.17 MPa $$\sqrt{\mathrm{m}}.$$ m . Subcritical crack growth rates are much smaller than in bulk specimens. A major advantage is that many test samples can be simultaneously monitored while avoiding any external equipment. Graphic Abstract


2009 ◽  
Vol 29 (4) ◽  
pp. 423-424
Author(s):  
Yu. A. Khaikevich

2020 ◽  
Vol 477 (14) ◽  
pp. 2679-2696
Author(s):  
Riddhi Trivedi ◽  
Kalyani Barve

The intestinal microbial flora has risen to be one of the important etiological factors in the development of diseases like colorectal cancer, obesity, diabetes, inflammatory bowel disease, anxiety and Parkinson's. The emergence of the association between bacterial flora and lungs led to the discovery of the gut–lung axis. Dysbiosis of several species of colonic bacteria such as Firmicutes and Bacteroidetes and transfer of these bacteria from gut to lungs via lymphatic and systemic circulation are associated with several respiratory diseases such as lung cancer, asthma, tuberculosis, cystic fibrosis, etc. Current therapies for dysbiosis include use of probiotics, prebiotics and synbiotics to restore the balance between various species of beneficial bacteria. Various approaches like nanotechnology and microencapsulation have been explored to increase the permeability and viability of probiotics in the body. The need of the day is comprehensive study of mechanisms behind dysbiosis, translocation of microbiota from gut to lung through various channels and new technology for evaluating treatment to correct this dysbiosis which in turn can be used to manage various respiratory diseases. Microfluidics and organ on chip model are emerging technologies that can satisfy these needs. This review gives an overview of colonic commensals in lung pathology and novel systems that help in alleviating symptoms of lung diseases. We have also hypothesized new models to help in understanding bacterial pathways involved in the gut–lung axis as well as act as a futuristic approach in finding treatment of respiratory diseases caused by dysbiosis.


2016 ◽  
Vol 136 (6) ◽  
pp. 244-249
Author(s):  
Takahiro Watanabe ◽  
Fumihiro Sassa ◽  
Yoshitaka Yoshizumi ◽  
Hiroaki Suzuki

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