56 results about "Helicopter dynamics" patented technology

The invention belongs to the technical field of helicopter dynamic tests, and discloses a helicopter flight control system transmission characteristic test method. The method comprises the steps of respectively performing sweep frequency excitation on a rotor time domain total distance and a periodic variable pitch through a control system, operating an excitation signal through a hydraulic actuator cylinder, and measuring the rotor time domain total distance and the periodic variable pitch under excitation; and performing FFT on the time domain total distance and the periodic variable pitch of the hydraulic actuator cylinder and a paddle to obtain a control system total distance and periodic variable pitch frequency domain transfer function. The method can be used for providing data for establishing a helicopter flight control system mathematical model based on tests, and providing basic technical support for establishing a helicopter rotor and body coupling stability model considering a flight control system and stability comprehensive analysis. The method has a certain engineering reference value for design and analysis of ground resonance and air resonance of advanced helicopters in China, and has far-reaching significance for guaranteeing safe flight and stability improvement of modern advanced helicopters.

The invention discloses a helicopter rotor and fuselage coupling stability modeling method, and belongs to the helicopter dynamics modeling and analysis technology. The method includes: adopting a modal synthesis technology to perform comprehensive modeling on a rotor and fuselage dynamics coupling system, describing the motion of a fuselage and rotors in different coordinates, establishing structural dynamics finite element method models of isolated rotor blades and an airframe structure respectively, adopting an aerodynamic model to model aerodynamic force, and deducing a rotor / airframe coupling system kinetic equation by applying the Hamilton principle; establishing an automatic flight control system control model, and deriving an aerodynamic load matrix related to the pitch variable, thereby establishing a rotor wing and aircraft body coupling aeroelastic stability analysis model considering the flight control system; and finally, solving a characteristic value through a characteristic value method, and judging the stability of the coupling system through a characteristic value solution. The model can be used for calculating and analyzing the'ground resonance 'and'air resonance' stability of all advanced helicopters, and key technical support is provided for model design and development.

The invention discloses a four-degree-of-freedom helicopter dynamic flight simulator. Simultaneous simulation of three modes of space yaw, rolling and pitching can be achieved under the centrifugal field, and overload simulation is achieved; mounting components on a rotating arm are arranged in a centralized manner, a balancing design method is adopted, a counterweight unit is designed according to the trimming principle and mounted on the rotating arm, the mass center of the dynamic flight simulator is placed on the revolution axis, and vibration of the simulator caused by imbalance is reduced. The asymmetric rotating arm structure is adopted to reduce the rotational inertia of the dynamic flight simulator, and energy consumption of the dynamic flight simulator is reduced; a transmissionunit is adopted to prevent vibration of a main reduction motor from being directly transmitted to the rotating arm to make the entire dynamic flight simulator vibrate excessively, the unbalanced forceof the rotating arm and the rotating arm mounting components is transmitted to the civil part through the transmission unit, and running stability of the main reduction motor is enhanced.

A helicopter dynamics simulation method based on Unignine comprises the steps that firstly, each component of a helicopter body is abstracted into a mass point, and the mass centers of all the mass points are calculated and serve as the mass center of a helicopter; and then a helicopter body motion equation, a rotor mathematical model and a tail rotor mathematical model are respectively constructed so as to obtain a dynamic model of the whole helicopter. According to the inherent attribute, the external environment and the current state of the helicopter to stimulate .stress of the helicopter,so that the helicopter can feed back the air environment in time. The attitude characteristics of the helicopter in flowing air are accurately reproduced, and the phenomena of load increase, load decrease, load movement and the like of the helicopter are accurately simulated by adopting a centroid dynamic calculation mode. Helicopter power under different speeds, different models and different environments can be simulated, and the helicopter attitude can be simulated more accurately.

The invention belongs to a tool designing technology, particularly relating to a main propeller hub and propeller shell assembly dismounting tool and method. The repairing technological level of helicopter dynamic components directly affects the quality of heavy repairing of helicopters in factories, and meanwhile, along with continuous improvement of the capacity of a company, repairing and maintaining operations of main propeller hub products are increasingly complicated and overloaded. A dismounting method and tool for disassembling a main propeller hub and propeller shell assembly of a helicopter and preventing parts from being damaged are required to be researched urgently so as to provide a convenient and effective working means for disassembling the main propeller hub and propeller shell assembly of the helicopter. At present, ready-made methods and tools do not exist, problems of deformation of upper and lower star plates, pulling damage of bearings, scratching damage of inner holes of the star plates and cross axles and the like are always caused in a disassembling process, parts are quite easily discarded as useless, and repairing quality and progress of products are affected. The invention provides the brand-new main propeller hub and propeller shell assembly dismounting tool and method. The tool is simple in structure and convenient to operate, and can meet requirements of dismounting of a main propeller hub, in a disassembling process, the bearings, the inner holes of the star plates and the cross axles cannot be damaged, the upper and lower star plates do not deform, and improvement of dismounting quality and dismounting efficiency of the propeller shell assembly during disassembling is facilitated.

The invention belongs to the technical field of helicopter vibration absorption, and relates to a helicopter dynamic vibration absorber. The vibration absorber comprises an upper supporting plate (1)and a lower supporting plate (2). One end of the upper supporting plate (1) and one end of the lower supporting plate (2) are fixed. The other end of the upper supporting plate (1) is fixed to the helicopter cockpit floor. A mass block is fixed to the other end of the lower supporting plate (2) and is suspended. The dynamic vibration absorber is small in structural size, simple and easy to install, can generate large antiresonance load, and has a good vibration absorbing effect. The service life of the vibration absorption structure is unlimited, and safety and reliability are achieved. When the dynamic vibration absorber is installed under the floor, a pilot is not disturbed, other control and system structures are not interfered, and the dynamic vibration absorber can well adapt to a helicopter.

The invention discloses a method for calculating the dynamic threshold value of a helicopter dynamic component based on Bayesian inference. The method comprises the following steps of 1) carrying outthe data preprocessing to filter noise in the data; 2) carrying out the feature extraction of respectively extracting features of normal data and fault data; 3) calculating the dynamic threshold, andusing Bayesian reasoning method to calculate the dynamic threshold of normal data and fault data. The invention has the advantages that in the feature extraction method, four methods of extracting inner loop feature frequency energy, extracting outer loop feature frequency energy, extracting ball feature frequency energy and extracting M6A are respectively adopted to carry out feature extraction on normal data and different types of fault data, so that the vibration characteristics of normal and fault data can be effectively reflected. In the calculation of dynamic threshold, the Bayesian reasoning method is used to consider not only the probability density of normal data, but also the probability density of different types of fault data, which improves the calculation accuracy of dynamicthreshold.