Nonlinear Mechanical Properties Of Lenticular Space Deployable Mast With Biaxiality Bending Furl Deformation

The Lenticular Space Deployable Mast(LSDM)has the characteristics of ultra-light,ultra-thin,ultra-long,high specific stiffness and high receiving rate.It can be used as the supporting component of the spatial structure such as large film antenna and solar sail,and is one of the most promising spatial deployable structures.Due to the launch vehicle envelope constraints,the LSDM needs to be accommodated in the spacecraft with the deployable structure before launching.Biaxiality bending large furl deformation occurs in the LSDM,and it involves many complex nonlinear mechanical behaviors such as local buckling,contact and friction,which can easily lead to structural damage.It is urgent to systematically study the mechanical properties of biaxiality bending furl LSDM.The main work of this paper is as follows :(1)Theoretical modeling and parameter influence analysis of final closing state of the LSDM.The furl deformation is divided into two parts: transverse flattening(from circular arc to straight line)and longitudinal winding(from straight line to circular arc).Considering the laminated characteristics of carbon fiber reinforced composites,the expressions of structural response and total strain energy of each layer of composites are derived.On this basis,the influence of the cross-sectional geometry of the LSDM and the composite layer parameters on the structural stress state and strain energy are analyzed.The results show that the radius of the drum,the thickness of the arc section,the radius of the arc section and the ply angle have obvious effects on the peak stress.When the ratio of drum radius to arc radius is different,the variation of stress peak with the above parameters shows different characteristics.The relationship between the ply angle and the strain energy is non-monotonic,and there is a specific ply angle to minimize the strain energy.(2)Nonlinear finite element modeling and structural response analysis of the whole process of the LSDM from expansion to furl.Considering the nonlinear factors such as local buckling,global contact and sliding friction of the LSDM,the analysis model of the LSDM winding process is established by finite element method,and the correctness of the model is verified by comparing with the theoretical analysis results of the furl state.Based on the explicit dynamic analysis method,the structural stress and driving load of the end flattening,traction lap and winding of the LSDM are analyzed.The deformation and stress distribution of the LSDM during the folding process are obtained,and the flattening force or winding torque required by the folding mechanism are obtained.The results show that when the LSDM is locally flattened,the concave arc section will produce shape mutation,resulting in amplification of structural response.The peak stress is always located near the local flattening position,and the maximum value is 582 MPa.In this study,the mechanical properties and influencing factors of the LSDM in the winding process and winding state are obtained,which lays a theoretical foundation for the analysis of the mechanical properties of the LSDM with biaxiality bending furl and provides technical reference for the improvement design of the LSDM and its closure mechanism.