Design And Development Of Aeronautical Unlocking Device Based On NiTi Shape Memory Alloy

With the development of aerospace technology,the use of aircraft scenarios are also increasing,such as satellite separation,satellite space deployment,aviation emergency rescue and material delivery,etc.,the successful completion of the above flight tasks rely on unlocking devices.The payload that needs to be unlocked has different sensitivity to the unlocking shock environment and different requirements for unlocking devices.Pyrotechnic unlocking method is one of the earliest and most commonly used connection/separation technologies,but it will inevitably produce impact and polluting chemical gases during startup,which will cause damage to some sensitive devices and optical instruments.Therefore,it is of great significance to study new non-pyrotechnic unlocking technology.At present,non-pyrotechnic unlocking technology is mainly focused on the field of new intelligent materials and structural equipment,among which shape memory alloy has gained more attention for its high quality material function characteristics.In this paper,a non-pyrotechnic unlocking device based on shape memory alloy is designed in combination with theoretical calculation and simulation analysis to meet the requirements of large load,fast response and low energy consumption for aircraft cargo delivery,and relevant technical indicators are verified.Firstly,the mathematical model of SMA spring-biased spring actuator was established,the stress-strain mathematical model of SMA actuator was derived based on Brinson constitutive model,and the thermal response process of SMA actuator was modeled and derived according to Joule effect equation,which was used as the theoretical basis for the design of SMA unlocking device.Secondly,the design of SMA spring with different structural parameters,using different heat treatment process parameters for processing,and then its phase change temperature,elastic modulus,thermodynamic response characteristics and fatigue characteristics were tested,the phase change recovery force,fatigue attenuation characteristics and other mechanical properties were tested and evaluated.Thirdly,a lever type SMA two-stage unlocking device is proposed,which releases the lever two-stage unlocking device through SMA spring to realize unlocking function.Solidworks software is used to carry out 3D modeling,and theoretical analysis and calculation are carried out on the force in the unlocking process.The finite element software ANSYS and kinematics analysis software ADAMS are used to simulate the structural strength,stiffness and unlocking dynamic process,so as to verify the rationality of the unlocking device design.Finally,A prototype of SMA unlocking device was manufactured,and A resistance thermal drive experiment was designed to test it.Under the excitation of 3.5A DC power supply,the unlocking time was 0.5s,and the repeated use times could reach more than 100 times.The results show that the SMA unlocking device designed in this paper has the characteristics of small volume,large load,low energy consumption and fast response,which provides engineering reference for non-pyrotechnical separation method in aerospace field.