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Monitoring Failure Behaviour of Pultruded CFRP Composites by Electrical Resistance Measurement
Yaqin Mao,Yunhua Yu,Dezhen Wu,Xiaoping Yang 한국탄소학회 2004 Carbon Letters Vol.5 No.1
The failure behaviours of unidirectional pultruded carbon fiber reinforced polymer (CFRP) composites were monitored by the electrical resistance measurement during tensile loading, three-point-bending, interlaminar shear loading. The tensile failure behaviour of carbon fiber tows was also investigated by the electrical resistance measurement. Infrared thermography non-destructive evaluation was performed in real time during tensile test of CFRP composites to validate the change of microdamage in the materials. Experiment results demonstrated that the CFRP composites and carbon fiber tows were damaged by different damage mechinsms during tensile loading, for the CFRP composites, mainly being in the forms of matrix damage and the debonding between matrix and fibers, while for the carbon fiber tows, mainly being in the forms of fiber fracture. The correlation between the infrared thermographs and the change in the electrical resistance could be regarded as an evidence of the damage mechanisms of the CFRP composites. During three-point-bending loading, the main damage forms were the simultaneity fracture of matrix and fibers firstly, then matrix cracking and the debonding between matrix and fiber were carried out. This results can be shown in Fig. 9(a) and (b). During interlaminar shear loading, the change in the electrical resistance was related to the damage degree of interlaminar structure. Electrical resistance measurement was more sensitive to the damage behaviour of the CFRP composites than the stress/time curve.
Early Childhood Kindergarten Programs in China: Issues of Access and Funding
Zeng Yaqin,Berenice Nyland,Zeng Xiaodong 환태평양유아교육연구학회 2011 Asia-Pacific journal of research in early childhoo Vol.5 No.1
China has a complex system of multiple types of preschool provision, different funding models, a rural-urban divide and a diverse population in relation to place of origin, language dialects and socio economic status. In this paper we explore the complex situation of preschool provision and implications for policy makers in China. As the provision of preschool education is increasingly privatized there is a concern that children from low income families may not have access to quality early care and education services. Affordability and access to education in the early years has become a major concern of governments concerned about equity and the development of human capital. Case studies have been carried out in Beijing, as a developed urban centre and in Yinchuan, as a rural centre in the west of China. The data presented examines the relationship between types of service, fees charged and the income of families who access these services.
Monitoring Failure Behaviour of Pultruded CFRP Composites by Electrical Resistance Measurement
Mao, Yaqin,Yu, Yunhua,Wu, Dezhen,Yang, Xiaoping Korean Carbon Society 2004 Carbon Letters Vol.5 No.1
The failure behaviours of unidirectional pultruded carbon fiber reinforced polymer (CFRP) composites were monitored by the electrical resistance measurement during tensile loading, three-point-bending, interlaminar shear loading. The tensile failure behaviour of carbon fiber tows was also investigated by the electrical resistance measurement. Infrared thermography non-destructive evaluation was performed in real time during tensile test of CFRP composites to validate the change of microdamage in the materials. Experiment results demonstrated that the CFRP composites and carbon fiber tows were damaged by different damage mechinsms during tensile loading, for the CFRP composites, mainly being in the forms of matrix damage and the debonding between matrix and fibers, while for the carbon fiber tows, mainly being in the forms of fiber fracture. The correlation between the infrared thermographs and the change in the electrical resistance could be regarded as an evidence of the damage mechanisms of the CFRP composites. During three-point-bending loading, the main damage forms were the simultaneity fracture of matrix and fibers firstly, then matrix cracking and the debonding between matrix and fiber were carried out. This results can be shown in Fig. 9(a) and (b). During interlaminar shear loading, the change in the electrical resistance was related to the damage degree of interlaminar structure. Electrical resistance measurement was more sensitive to the damage behaviour of the CFRP composites than the stress/time curve.
Test Analysis and Study on Cutting Destruction Properties of Solid Ice-snow Road
Li Yaqin,WuWenfu,Wang Junfa,Qiu Xinwei 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.5
Build cutting resistance measurement system based on single-chip microcomputer and high speed camera in order to analysis cutting destruction of solid ice-snow. The experimental model has been built according to the rotating orthogonal experiment methods when tests, take the cutting resistance as objective function, A significant factor in the depth of cutting, rake angle as well as tool installation angle as influencing factors, and analysis found that the relationship between the primary and secondary factors were setting angle>density>cutting depth. By comparing theoretical models and experimental models found both the maximum error is about 8.7%, the minimum error is about 12.8%, the median error of about 12%, which verified the availability of theoretical model. Affecting the snow removal efficiency of parameters were carried out the optimal tests study, and found that the best setting angle of cutting tool is from 46°to 52°on the condition that the temperature is lower than -15°C, the thickness of snow and ice is less than 35mm, and rake angle -10°~ -9°.Optimal combination of parameters meet not only the job requirements but also provide a valuable reference for the optimum design of snow removal tool structure and process parameters, and the overall design of a prototype in the future.