Papers by Keyword: Self-Repairing

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.

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

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.

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.

Abstract: The nanoMgO and active nanoSiO₂ were prepared by the special liquid-phase precipitation method. Subsequently, Chrysotile nanotube was prepared of by hydrothermal method using the nanoMgO and active nanoSiO₂ as precursors at 220°C under 23atm in basic solution. The surface topographies and composition of the Chrysotile nanotube were characterized by XRD and TEM. Then, the dispersive property of particles modified by oleic acid was analyzed by IR. The tribological properties) were explored by adding the modified nanomagnesium silicate hydroxide to 2^# lithic-grease after dispersing uniformly. Compared with the blank sample, it can significantly reduce the friction traces of the metal surface, improve extreme pressure performance. The friction coefficient is still stable when the temperature is raised during the friction. Nanotube power can be adhered and spread on the worn metal surface. Thus self-repairing coating forms on the worn surface.

Abstract: Intelligent material is a kind of multifunctional composite bionic design, can sense environmental conditions, through the sensor network, interest will be provided to the control system, to respond to take action. Self-diagnosis and through self-growth, in situ composite regeneration mechanism of system failure, repair some local damage or destroy; to the changing external environment and conditions, timely adjust its structure and function. Because of its relative to the performance of traditional materials with special excellent, with broad prospects for development.

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.

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.

Abstract: The aim of this study was to investigate the friction and wear behavior of GCr15/1045 steel under different nano-particle additive conditions using a reciprocating horizontal tribometer. The results indicate that the nano-particle additives could decrease friction coefficient of CGr15/1045 steel and reduce the wear of material compared with the dry condition. Nano-particles play an important role of polishing the micro-gibbosity of contact surfaces during the friction process. The nano-particles of Ca10(PO4)6, TiO2 and TiN can form the self-repairing film on the worn surface of 1045 steel. The analysis indicates that the self-repairing effect of nano-particle of TiN is best and the self-repairing effect of nano-particle of TiO2 is worst.

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.