scholarly journals Corrosion-Induced Mass Loss Measurement under Strain Conditions through Gr/AgNW-Based, Fe-C Coated LPFG Sensors

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1598 ◽  
Author(s):  
Chuanrui Guo ◽  
Liang Fan ◽  
Genda Chen
Keyword(s):  
Mass Loss ◽  
Correlation Equation ◽  
Resonant Wavelength ◽  
Electrical Impedance Spectroscopy ◽  
Nacl Solution ◽  
Transverse Cracks ◽  
Loss Measurement ◽  
Laminate Layer ◽  
Layer Structures ◽  
Longitudinal Cracks

In this study, graphene/silver nanowire (Gr/AgNW)-based, Fe-C coated long period fiber gratings (LPFG) sensors were tested up to 72 hours in 3.5 w.t% NaCl solution for corrosion-induced mass loss measurement under four strain levels: 0, 500, 1000 and 1500 µε. The crack and interfacial bonding behaviors of laminate Fe-C and Gr/AgNW layer structures were characterized using Scanning Electron Microscopy (SEM) and electrical resistance measurement. Both optical transmission spectra and electrical impedance spectroscopy (EIS) data were simultaneously measured from each sensor. Under increasing strains, transverse cracks appeared first and were followed by longitudinal cracks on the laminate layer structures. The spacing of transverse cracks and the length of longitudinal cracks were determined by the bond strength at the weak Fe-C and Gr/AgNW interface. During corrosion tests, the shift in resonant wavelength of the Fe-C coated LPFG sensors resulted from the effects of the Fe-C layer thinning and the NaCl solution penetration through cracks on the evanescent field surrounding the LPFG sensors. Compared with the zero-strained sensor, the strain-induced cracks on the laminate layer structures initially increased and then decreased the shift in resonant wavelength in two main stages of the Fe-C corrosion process. In each corrosion stage, the Fe-C mass loss was linearly related to the shift in resonant wavelength under zero strain and with the applied strain taken into account in general cases. The general correlation equation was validated at 700 and 1200 µε to a maximum error of 2.5% in comparison with 46.5% from the zero-strain correlation equation.

A Study on Laser Welding of Titanium and Stainless Steel

2018 ◽  
Author(s):  
Angshuman Chattopadhyay ◽  
Gopinath Muvvala ◽  
Vikranth Racherla ◽  
Ashish Kumar Nath
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Weld Joint ◽  
Welding Speed ◽  
Fusion Process ◽  
Longitudinal Stress ◽  
Transverse Cracks ◽  
Cooling Rates ◽  
Melt Pool ◽  
Longitudinal Cracks

Joining of dissimilar metals and alloys has been envisioned since a long time with specific high end applications in various fields. One such combination is austenitic stainless steel grade SS304 and commercial grade titanium, which is very difficult to join under conventional fusion process due to extensive cracking and failure caused by mismatch in structural and thermal properties as well as formation of the extremely brittle and hard intermetallic compounds. One of the methods proposed in literature to control the formation of intermetallics is by fast cooling fusion process like laser beam welding. The present study has been done on laser welding of titanium and stainless steel AISI 304 to understand the interaction of these materials during laser welding at different laser power and welding speed which could yield different cooling rates. Two types of cracks were observed in the weld joint, namely longitudinal cracks and transverse cracks with respect to the weld direction. Longitudinal cracks could be completely eliminated at faster welding speeds, but transverse cracks were found little influenced by the welding speed. The thermal history, i.e. melt pool lifetime and cooling rate of the molten pool during laser welding was monitored and a relation between thermo-cycle with occurrence of cracks was established. It is inferred that the longitudinal cracks are mainly due to the formation of various brittle intermetallic phases of Fe and Ti, which could be minimized by providing relatively less melt pool lifetime at high welding speeds. The reason of the transverse cracks could be the generation of longitudinal stress in weld joint due to the large difference in the thermal expansion coefficient of steel and titanium. In order to mitigate the longitudinal stress laser welding was carried out with a novel experimental arrangement which ensured different cooling rates of these two metals during laser welding. With this the tendency of transverse cracks also could be minimized significantly.

Cost-Effectiveness of Crack Sealing Materials and Techniques for Asphalt Pavements

2000 ◽  
Vol 1697 (1) ◽  
pp. 31-40 ◽  
Author(s):  
David R. Johnson ◽  
Reed B. Freeman ◽  
James R. Stevenson
Keyword(s):  
Pavement Management ◽  
Asphalt Pavements ◽  
First Year ◽  
Transverse Cracks ◽  
Pavement Management System ◽  
Crack Sealing ◽  
Surface Distress ◽  
Accepted Practice ◽  
Project History ◽  
Longitudinal Cracks

Sealing or filling cracked asphalt pavements to prevent the intrusion of water into the pavement structure has long been an accepted practice of the Montana Department of Transportation. Attempts were made to establish the most economical and effective method of sealing pavement cracks for Montana and to better determine crack sealing’s role within Montana’s pavement management system (PvMS). Four experimental test sites were constructed within crack-sealing projects. The test sites included combinations of nine sealant materials and six sealing techniques. Monitoring of the test sites includes visual inspections (for all of the sites) and nondestructive structural readings and surface distress identification under Montana’s PvMS (for one test location). One expectation of the inspections is an estimation of crack sealing’s useful life. Information on project history and project methodology, including the methods used for evaluating the performance of sealed cracks, is presented. Interim conclusions are presented, most of which have been obtained from the two test sites that have been in service for 3 years. Similar performance has been observed for all materials with ASTM D5329 cone penetrations in excess of 90. In general, routing of transverse cracks improved the performance of the sealants. Routing did not appear necessary for centerline longitudinal cracks. Observations from the first year of service for the most recent installation are noted. Notably, router operators appear to prefer the shallow reservoir configuration over square reservoirs. The highest failure rates occur during the coldest period of the year, and much of this distress “heals” after exposure to the summer heat.

Thermal Shock Cracks Initiation and Propagation of WCp / Steel Substrate Surface Composite at 500°C

2011 ◽  
Vol 109 ◽  
pp. 253-260 ◽  
Author(s):  
Ru Qing Huang ◽  
Zu Lai Li ◽  
Ye Hua Jiang ◽  
Rong Zhou ◽  
Fan Gao
Keyword(s):  
Thermal Stress ◽  
Thermal Shock ◽  
Steel Substrate ◽  
Substrate Surface ◽  
Test Method ◽  
Thermal Shock Test ◽  
Transverse Cracks ◽  
Surface Composites ◽  
Initiation And Propagation ◽  
Longitudinal Cracks

In order to provide a theoretical basis for the study of thermal fatigue properties on surface composites, thermal shock cracks initiation and propagation of WCP reinforced high chromium steel substrate surface composites were studied by thermal shock test method at 500 °C. The results show that cracks initiation and propagation begin within a few thermal shock cycles, and after 15 thermal shock cycles, the composites remain intact, indicating a good thermal shock resistance. The thermal shock cracks consist mainly of longitudinal and transverse cracks. Within a few thermal shock cycles, the initiation and propagation of longitudinal cracks play a dominant role; however, with the increase in the number of thermal shock, the transverse cracks may play a key role as the length and number of both types of cracks increases. However, the increase is slow. The longitudinal cracks are mainly caused by the first class thermal stress and the transverse cracks result from the culminant effects of the first and second thermal stress, interacting with each other.

scholarly journals An emissions-based fuel mass loss measurement for wood-fired hydronic heaters

2020 ◽  
Vol 142 ◽  
pp. 105731
Author(s):  
Joshua M. Weisberger ◽  
Joseph P. Richter ◽  
Joseph C. Mollendorf ◽  
Paul E. DesJardin
Keyword(s):  
Mass Loss ◽  
Loss Measurement ◽  
Fuel Mass

Measurement of Outgassing in a Vacuum Environment

2005 ◽  
Vol 277-279 ◽  
pp. 831-837
Author(s):  
Yong Hyeon Shin ◽  
Seung Soo Hong ◽  
In Tae Lim ◽  
J.H. Kim ◽  
Dae Jin Seong ◽  
...  
Keyword(s):  
Mass Loss ◽  
Production Process ◽  
Measurement Method ◽  
Suitable Method ◽  
Nano Technology ◽  
Loss Measurement ◽  
Measurement Systems ◽  
And Function

Outgassing, the evolution of gas from the material in a vacuum, is not only a source of micro contamination in a semiconductor or the flat display panel production process, but it also a limitation factor in the ultra clean process of nano-technology. The outgassing from the materials of satellites and spacecrafts must be controlled for increased safety and function because space is also a vacuum environment. Several methods are used in outgassing measurement in general, but there is no one method suitable for obtaining all outgassing data. The most suitable method for a particular application must be chosen by the experimenter or user. Three types of outgassing measurement systems were fabricated and characterized, ‘Throughput method,’ ‘Rate of Rise method’ and ‘Mass Loss Measurement method’. The outgassing rates of many kinds of materials were measured and characterized using these systems.

scholarly journals Blended species plywood (white cypress pine and hoop pine): Effect of veneer thickness on susceptibility to attack by the subterranean termite Coptotermes acinaciformis

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 4655-4671
Author(s):  
Christopher J. Fitzgerald ◽  
Robert L. McGavin
Keyword(s):  
Mass Loss ◽  
Field Trial ◽  
Subterranean Termite ◽  
Termite Resistance ◽  
Loss Measurement ◽  
Visual Damage ◽  
Hoop Pine ◽  
Minimal Damage ◽  
Cypress Pine

Blended species plywood blocks comprising of 24 different veneer configurations of naturally durable white cypress pine and non-durable hoop pine were exposed to the subterranean termite Coptotermes acinaciformis in a field trial in Australia. Three thicknesses of cypress (1.8, 2.8, and 3.0 mm) and hoop pine (1.0, 1.5, and 3.0 mm) veneer were included. Blocks were assessed for termite damage using a visual damage rating and mass loss measurement. Blocks using all hoop pine veneers received substantial damage; however, blocks that had cypress face and back veneers had improved termite resistance, particularly for the 1.0-mm hoop pine core veneers. When cypress longbands were blended with hoop pine crossbands that created alternating layers, minimal damage was sustained in the hoop pine veneers; however, the damage increased with increasing hoop pine veneer thickness. All cypress veneers received essentially no termite damage, and cypress veneer thickness did not influence the severity of hoop pine veneer damage. The trial indicated that the plywood made with hoop pine core veneers, cypress pine face, and back veneers offered some termite resistance if the hoop pine veneer thickness was kept thin. Alternating cypress and hoop pine further improved the termite resistance.

scholarly journals Pixel-Level Recognition of Pavement Distresses Based on U-Net

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Deru Li ◽  
Zhongdong Duan ◽  
Xiaoyang Hu ◽  
Dongchang Zhang
Keyword(s):  
Deep Neural Networks ◽  
Data Augmentation ◽  
Discriminative Learning ◽  
Road Maintenance ◽  
Transverse Cracks ◽  
Test Dataset ◽  
Learning Rates ◽  
Pavement Distresses ◽  
Validation Set ◽  
Longitudinal Cracks

This study develops and tests an automatic pixel-level image recognition model to reduce the amount of manual labor required to collect data for road maintenance. Firstly, images of six kinds of pavement distresses, namely, transverse cracks, longitudinal cracks, alligator cracks, block cracks, potholes, and patches, are collected from four asphalt highways in three provinces in China to build a labeled pixel-level dataset containing 10,097 images. Secondly, the U-net model, one of the most advanced deep neural networks for image segmentation, is combined with the ResNet neural network as the basic classification network to recognize distressed areas in the images. Data augmentation, batch normalization, momentum, transfer learning, and discriminative learning rates are used to train the model. Thirdly, the trained models are validated on the test dataset, and the results of experiments show the following: if the types of pavement distresses are not distinguished, the pixel accuracy (PA) values of the recognition models using ResNet-34 and ResNet-50 as basic classification networks are 97.336% and 95.772%, respectively, on the validation set. When the types of distresses are distinguished, the PA values of models using the two classification networks are 66.103% and 44.953%, respectively. For the model using ResNet-34, the category pixel accuracy (CPA) and intersection over union (IoU) of the identification of areas with no distress are 99.276% and 99.059%, respectively. For areas featuring distresses in the images, the CPA and IoU of the model are the highest for the identification of patches, at 82.774% and 73.778%, and are the lowest for alligator cracks, at 14.077% and 12.581%, respectively.

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