Papers by Keyword: Self-Repairing

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Authors: Qing Bo Wu, Fu Yang Chen, Chang Yun Wen
Abstract: In this paper, a self-repairing control scheme for attitude control of a quadrotor helicopter via active disturbance rejection control is proposed. Firstly, a model of the quadrotor helicopter is gained by its dynamic equations with pitch, roll and yaw axis. Then the active disturbance rejection controller is introduced, which is used to design the control system. The control system consists of PID controller in inner-loop and ADRC controller in outer-loop. Disturbances and uncertainties can be compensated by the ADRC to achieve smaller tracking error. Finally, the simulation results of the four-rotor helicopter validate the efficiency and self-repairing capability of the proposed control algorithm, compared with that of the PID control and the separate ADRC control.
Authors: Tian Zhen Meng, Jin Yan Cai, Ya Feng Meng, Sai Zhu
Abstract: Embryonic bionic hardware has made great progress since its appearance, while self-healing strategies have some disadvantages. Based on the repair methods scholars proposed, a new strategy on the self-repairing of electronic arrays was presented. The key idea is when cells in the array fail, using spare cells replace them, with no change of the normal cells. This self-repairing strategy contains three parts, that is, an array of working cells, a layer of spare cells and a control layer. The theoretical analysis and simulation results show the new single-cell replacement strategy has the following advantages: easier implementation and largest self-healing capacity.
Authors: Sándor Kling, Tibor Czigány
Abstract: The geometry and mechanical properties of solid and hollow carbon fibres were investigated by light-and scanning electron microscopy, and by single fibre tensile tests. The hollowness factor of fibres was determined by their external and internal diameter. The tensile strength was determined by single fibre tensile break tests. It was shown that the bigger the diameter of the fibres the lower the mechanical properties is. It was found that the hollow carbon fibres are suitable for preparation of a self-repairing composite with the advantage over other solutions because of their geometrical and mechanical properties.
Authors: Wen Gang Chen, Yu Zhou Gao, Hui Chen Zhang, Ze Fei Tan
Abstract: The characteristics of the 1045 steel pairs using serpentine particles as grease lubricant additive were investigated by an AMSLER friction and wear tester. The surface topographies and composition of the worn surface of 1045 steel rings were identified by SEM and XPS. The results show that the additives can form a self-repairing film on the worn metal surface. It can reduce the abrasion of the friction pairs significantly. The main elemental compositions of the film are Fe, O, Si, C and Mg, which indicates that the additives directly take part in the formation of the self-repairing film.
Authors: Qing Yu Cao, Ting Yu Hao, Bo Su
Abstract: An experimental program was carried out to investigate whether EVA (ethylene vinyl acetate) heat-melt adhesive can potentially act as a self-healing agent in cement-based material. The effects of incorporation of EVA and heating on the properties of mortar were studied. Experimental results show that the interface between EVA and cement matrix was well improved after heating, which allows a significant improvement in flexural strength and toughness of specimen; Pre-damaged specimens in various degrees (30%, 50% and 70%) were effectively repaired by EVA and the repair efficiency all exceeded 100%. Keywords:crack; heat-melt adhesive; self-repairing
Authors: Yi Xin, Wei Zhang, Shu Zhang, Bin Shi Xu
Abstract: The surface configuration, the size and the shell thickness of the microcapsule were investigated. The average size and shell thickness were 100-200μm and 10nm separately. The mechanism performance of the microcapsule was tested by Nano Indentation Test. The results showed that the shell material—UF behaved as a non-linear viscoelastic material that different from the macroscopical performance. Analyzed and computed the un-load curves by non-linear simulation, the results showed that Educed Modulus of the microcapsule was 8.201GPa, which was a little lower than that of the epoxy resin 9.26GPa. And it also proved that the self-repair microcapsule in the epoxy resin dope would break as the microcrack expanded in the matrix, and let out the repair agent to fill the crack and to recover the matrix.
Authors: Filip Ilie, Constantin Tita
Abstract: Molybdenum disulphides (MoS2), which belong to the family of transition metal dichalcogenides, are well known for their solid lubricating behaviour. Thin films of MoS2 exhibit extremely low coefficient of friction in dry environments, and are typically applied by mixed in oil, grease or impregnated into porous matrix of powdered materials, sputter deposition, pulsed laser ablation, evaporation or chemical vapour deposition and, which are essentially either line-of-sight or high temperature processes. Solid lubricant coatings are attractive because they can reduce friction-generated heat. MoS2 is a common solid lubricant. However, the use of MoS2 can limited by excessive wear, as well as a friction coefficient. Several studies on solid lubricant coatings demonstrated success in lubricating dry sliding contacts over very long periods in tribometer tests or reciprocating sliding experiments.Several pellet-on-disk and pad-on-disk tribometer tests were conducted to study the lubrication characteristics of third-body particles of MoS2 powder. The tests consisted of simultaneous pellet-on-disk and pad-on-disk sliding contacts. Results from the tests show the self-repairing, self-replenishing, oil-free lubrication mechanism of MoS2. A theoretical control volume fractional coverage (CVFC) model was developed to predict: - (1) the friction coefficient at the pad-on-disk interface and - (2) the wear coefficient for the lubricated pellet-on-disk sliding contact. The fractional coverage varies with time and quantifies the amount of third-body film covering the disk asperities. Results from the model capture the tribological behaviour of the experimental sliding contacts reasonably well. The aim of this paper is modeling and experimentation of solid lubrification with MoS2 particles through self-repairing and self-replenishing and through the comparision between theoretical and experimental results obtained in the process of friction and wear by tribological tests.
Authors: Willy C.K. Tan, J.C. Kiew, K.Y. Siow, Z.R. Sim, H.S. Poh, M.D. Taufiq
Abstract: When one cut himself, it's amazing to watch how quickly the body acts to mend the wound. Immediately, the body works to pull the skin around the cut back together. The concept of repair by bleeding of enclosed functional agents serves as the biomimetric inspiration of synthetic self repair systems. Such synthetic self repair systems are based on advancement in polymeric materials; the process of human thrombosis is the inspiration for the application of self healing fibres within the composite materials. Preliminary results based on flexural 3 point bend test on prepared samples have shown the healed hollow fibre laminate has a healed strength increase of 47.6% compared to the damaged baseline laminate. These results gave us confidence that there is a great potential to adopt such self healing mechanism on actual composite parts like in aircraft’s composite structures.
Authors: Biao Wang, Chao Wu, Tong Ge
Abstract: A novel remotely operated underwater vehicle-a hybrid remotely operated underwater vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes. For broad-area survey, the vehicle can operate as an autonomous underwater vehicle (AUV) capable of mapping the sea floor with sonars and cameras. For close up imaging and sampling, the vehicle can operate as a remotely operated underwater vehicle (ROV) employing a optic fiber tether for real-time telemetry of data and video to its operators on a surface ship. In order for the vehicle to achieve a certain survivability and reliability level, a self-repairing control system (SRCS) has been designed. This paper presents the two basic technologies in SRCS: fault diagnosis and isolation (FDI) and reconfigurable control. For FDI, a model-based hierarchical fault diagnosis system is designed for the HROV. Then, control strategies which reconfigure the control system at intervals according to information from the FDI system are presented. Combining the two technologies, we obtained the fundamental frame of SRCS for the HROV.
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