The Design Of The Leaf Spring Landing Gear System For Certain UAV

The leaf spring landing gear has the advantages of simple configuration,low cost and convenient maintenance.It is widely used in small and medium sized UAVs.However,compared with the traditional landing gear using oil-gas buffer,leaf spring landing gear is commonly observed bouncing off the ground,and has a low rate of convergence after landing.Therefore,it is hard to grantee the cushion performance,not to mention using the unreasonable structure or material.The cushion performance of landing gear is a key index to measure whether it could grantee the safety of the aircraft during taking off and landing.To improve the effect of the buffer,as well as the advantages of the leaf spring landing gear on the UAV take-off and landing system,several key factors were taken into consideration to study the influence of the cushion performance in this thesis.Based on the overall parameters of the certain UAV,a preliminary design was conducted in this thesis,including the landing gear layout,main structure,steering mechanism and braking mechanism.After that,a physical prototype for drop test was manufactured based on the engineering drawings.According to the requirements,the test platform,including basket system and date collection system,was designed to carry out the drop test and obtain the test results(displacement,acceleration and support force of the dropping procedure).Considering the test results and document literature,we can find that the dropping process of composite leaf spring has a large deformation.So a well-known nonlinear dynamics software LS-DYNA was introduced to establish the dynamic model.The results show that the simulation datum agree well with the experimental datum,which verified the accuracy of the dynamic model.Based on the proper dynamic procedure,the effects of tire pressure,section shape and thickness of leaf spring on acceleration and amplitude attenuation speed were analyzed.The results show that reducing the tire pressure and the thickness of the leaf spring can effectively improve the cushioning performance of the leaf spring landing gear.The analysis results can guide the improving design of the leaf spring landing gear.The research results in this thesis could be helpful to expand the application of the leaf spring landing gear on the UAV,and lead the study and optimization of the cushioning performance of leaf spring landing gear.