Papers by Author: Lei Jiang Yao

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Authors: Sheng Li Lv, Lei Jiang Yao, Xiao Yan Tong, Zheng Li
Abstract: Continuous carbon fiber reinforced silicon carbide composite material (C/SiC) is one of the most effective candidate materials for hot structures in aeronautic and aerospace applications. Its performances in the complicated service environments are widely concerned. A database, aiming at optimized design of C/SiC, was developed. The database collected original data on the fabrication, microstructure of C/SiC, as well as abundant data on performance experiments including tension, compression, shear, fatigue, creep, oxidation, high-temperature fatigue, and so on. The logic structure of the database, modeled by unified modeling language, provides a data link that connecting the processing, microstructure and performance of C/SiC, so that users can conveniently create a test result set to build the mathematical model of material design. Efficient software was developed to realize management, browsing and extension of the database.
Authors: Xiang Zheng, Xiao Yan Tong, Hao Chen, Lei Jiang Yao
Abstract: An experimental study of low-velocity impact characteristics and strength after impact was carried out on both woven fiber-reinforced resin matrix composites and woven fiber-reinforced ceramic matrix composites. The test specimens were impacted using a dropped-weight impact test apparatus with an instrumented spherical tip. Ultrasonic C-scan was used in nondestructive testing to characterize and quantify the impact damage. Much more damage of ceramic matrix composites than that of resin matrix composites occur and process in loading stage. The peak load of resin matrix composites is higher than that of ceramic matrix composites. According to the results of observing optical photographs and C-scan images, the damage area of ceramic matrix composites is greater than that of resin matrix composites and the difference increases as the energy increases. Damage resistance of ceramic matrix composites is lower than that of resin matrix composites, but damage tolerance of ceramic matrix composites is higher than that of resin matrix composites.
Authors: Hao Chen, Xiao Yan Tong, Xiang Zheng, Lei Jiang Yao
Abstract: One of the problems preventing the industrial application of composites is the lack of an efficient method to detect and discriminate among types of damage occurring during service. To solve this problem, low velocity impact experiments are carried out on T300/QY8911 composite laminates. And synchronously, the acoustic emission (AE) technique and impact monitoring systems were used to record the AE signals and the impact force. The damage evolution, damage modes and acoustic emission (AE) activity were easily detected and evaluated by the analysis of both AE waveform and impact load. In this way, the damage development process containing matrix cracking, delamination and fibers breakage is investigated. The energy release of damage are theoretically approximated and correlated with the AE energy. By the theory, the “high energy damage zone” is defined in the scatter diagrams of amplitude-frequency. It is easily to prove that the primary damage mode of “high energy damage zone” is delamination.
Authors: Jing Shen Wang, Lei Jiang Yao, Li Zhang, Bin Li, Liu Ding Chen, Xiao Yan Tong
Abstract: An experimental study of low velocity impact (LVI) was carried out on 2D carbon fabric reinforced silicon carbide (C/SiC) ceramic matrix composites. The C/SiC composite specimens were impacted by using a free-drop impact machine at different energy levels ranging from 1J to 9J and acoustic emission (AE) technique was used to detect the damage process. The results indicated that AE signals could evaluate the LVI damage behaviors of C/SiC composites from the different aspects. By comparing impact load process with AE hits and AE amplitude, the damage process could be determined. In the loading stage, matrix cracking mainly occurred in the composites; when impact load reached peak load, delamination and fiber fracture started to produce; in the unloading stage, the damage modes were mainly delamination and matrix cracking. AE event count fractions could quantify the main damage modes at different impact energy levels. At lower impact energy, matrix cracking was the main damage mode; when impact energy were between 3J and 6J, delamination and matrix cracking became the main damage modes; at higher impact energy, fiber fracture was the main damage mode.
Authors: Zheng Li, Lei Jiang Yao, Xiao Yan Tong
Abstract: Corrosion of ocean engineering structures leads huge economic loses each year. Corrosion protection technology has already become a very important method for design and manufacture of ocean engineering structures. To decrease corrosive loses and guarantee the safety of engineering structures, extensive studies are invested to understand corrosion mechanisms and rules of engineering materials, and to develop technologies on corrosion control and protection. These research projects have produced and are producing a great amount of test data, reports, products, experiences, and so on. If all these data resources can be collected and organized in a unified platform, it will take great advantages for products design or manufacture on corrosion protection. A database, named Database on Corrosion of Ocean Engineering Materials and Structures (CDOSDB), was planned. For a designer or manufacturer, it should be considered in serving environment, corrosion property of material, methods on corrosion protection, and experiences on protection of real engineering structures. So, the CDOSDB is mainly include ocean environmental information, test data in real sea, simulating test data in lab, methods and products on corrosion protection, survey on corrosion status and protection of real engineering structures, corrosion knowledge and corrosion models. Because the related data and information were collecting from different research institutes and publications, in order to make full use of them, a uniform specification are arranged and standardized. A website is designed and the web addresses is It makes the database sharable.
Authors: Zheng Li, Long Cheng, Lei Jiang Yao, Xiao Yan Tong
Abstract: Data is the main subject of enterprise resource planning. It is an important way to enhance economic efficiency and competitiveness, by taking advantage of information technology to implement the data/information management and ensure their objectivity, accuracy and efficiency. In product design and manufacture process, the life time of data resources are divided into production, collection, arrangement, inputting, transmission, using, etc. If data resources information management system and management platform is established, it can record, share and manage data timely and accurately. At the beginning of data management, the clear and reasonable planning is an important foundation to achieve data information management. So, the concrete problems of planning were discussed about management objective, content and mode. In the course of design and manufacture, the data types, data management user and management basic conditions were summarized, and then it was discussed about framework and process of data resource management. Finally, the concrete operation and management measures were discussed on each link of data life cycle. The paper’s idea has a great impact for reference to integration and compromise of product’s data resources, establishment data resources management platform and taking management measures.
Authors: Bin Li, Xiao Yan Tong, Zi Yang Feng, Lei Jiang Yao
Abstract: Plain plate specimens of 2D plain woven C/SiC composites were performed on Instron8801. Infrared (IR) thermography was recorded using an infrared camera. Acoustic emission (AE) signal was detected by two AE wide band sensors attached on specimen. They were measured synchronously and real-timely. Thermal dissipation Q was deduced based on the first law of thermodynamics. When the applied stress was lower than fatigue endurance limit, Q rose in the early cyclic loading stage and then the rate of Q accumulation gradually approached a steady value as the proceeding cycles, conversely, Q rose quickly until led to failure of the composites. AE accumulated energy was discussed based on the AE data. Higher applied stress would cause more damage within the composites, and more AE signals were detected. Compared with damage calculated from modulus, Q and AE accumulated energy had fairly well agreement with the damage. It can be concluded that it is possible to employ these non-destructive evaluation methods as in-situ damage evolution indicators for 2D C/SiC composites.
Authors: Lei Jiang Yao, Zi Yang Feng, Qi You Cheng
Abstract: Three non-destructive test (NDT) methods were used to detect the two dimensional C/SiC specimens after low velocity impact (LVI) of various energies. The damage areas characterized by these methods were very different. Both ultrasonic and thermographic images reveal the LVI damages, while X ray is non-sensitive to the interior damage. However, small delaminations were not found by thermography and accurate judgment depends on the experience and the resolution of the infrared camera. And the result acquired from the higher frequency transducer was very confused because of the inherent defects. It is suggested that using both ultrasonic C-scan and thermography to evaluate the LVI damage of C/SiC. It is also suggested using the transducer of low frequency to perform the ultrasonic C-scan.
Authors: Sheng Shan Li, Xiao Yan Tong, Lei Jiang Yao, Bin Li
Abstract: Utilized photomicrographs taken by scanning electron microscope (SEM), an accurate representative volume element (RVE) model for plain weave C/SiC composites is established. Based on the steady-analysis method, the in-plane and thickness direction thermal conductivity of the C/SiC composites are calculated as 25.6Wm-1K-1 and 12.1Wm-1K-1, respectively. The manufacturing flaws have different effect on thermal conductivity. Compared with RVE without flaws, the result shows that matrix cracks make thermal conductivity decrease by 7.2% in the in-plane direction and have little effect in the thickness direction; matrix porosities have a significant effect on thermal conductivity, which make the thermal conductivity decrease by 16.7% in the in-plane direction and decrease by 25.4% in the thickness direction. The variation law of thermal conductivity along with porosity volume is also observed: as matrix porosity volume fraction is increasing, the thermal conductivity of material shows significant decrease.
Authors: Sheng Li Lv, Qing Na Zeng, Lei Jiang Yao, Liu Ding Chen, Xiao Yan Tong
Abstract: The aim of this paper is to propose a microstructure modeling for prediction of thermal conductivity of plain weave C/SiC fibre bundles considering manufacturing flaws. Utilized photomicrographs taken by scanning electron microscope (SEM), an accurate representative volume element (RVE) model for carbon fiber bundles is established. Based on the steady-analysis method, the axial and transverse thermal conductivity of the carbon fibre bundles are calculated as 40.32Wm-1K-1 and 11.33 Wm-1K-1, respectively. The manufacturing flaws have different effects on thermal conductivity, the study shows that class A porosity has a significant effect on thermal conductivity, which leads to the thermal conductivity on the axial direction decrease by 13.31% and transverse direction decrease by 20.56% compared with no flaws RVE. While class B porosity has little influence on the k-value. The change law of axial and transverse thermal conductivity along with porosity volume is also observed: as porosity volume fraction is increasing, the thermal conductivity of fibre bundles shows significant linear decrease.
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