Research On In-orbit Continuous Construction Scheme Of Triangular Truss Structure

Space truss structure is widely used in space solar power stations,communication satellites,long baseline space observers and other fields.The light-weight,large-size,and small-volume space truss structure is of great significance for improving the powergenerating capacity of space solar power stations and the sensitivity of space observers.Currently,the space truss used in the orbit is mostly deployable structures.However,there is still much unused space inside the deployable structures,and their packing size is limited by the rocket carrying capacity.In contrast,space truss constructed in orbit has a advantage in smaller launch volume and longer truss length.This thesis aims at developing the winding forming systems for the triangular truss and the effects of truss structural parameters on its bending fundamental frequency.The structure and winding path of the triangular truss that can be wounding-formed are analyzed.Sort out and select the planar truss webs that can be constructed continuously.Modify the shape of the web to obtain make the trianglular truss can be formed by winding.Express the node coordinates,element number with the truss configuration parameters for the subsequent finite element analysis.In response to the demand for estimating the fundamental frequency of the space truss,an analogous single-rod bending vibration formula is substituted for the section moment of inertia and the linear density of the truss to obtain an approximate formula for the bending fundamental frequency of the truss.Finite element simulations were used to verify the prediction of the formula on the effects of the truss section length,bay length,truss rod diameter,material specific modulus on the truss fundamental frequency,and the results support the rationality of the formula.According to this formula,a scaling rule based on the constant bending-fundamental frequency of the truss is proposed.This scaling rule can provide a theoretical reference for the verification of the scaling model of large trusses;In addition,measures to increase the fundamental frequency of the truss are obtained.Designed a triangular truss winding forming system,and analyzed the matching relationship between machine motion parameters and truss structure parameters;6material types can be used for truss-winding formation based on the selection of proper material types,rod forming methods,node connection methods and material storage methods.And the combination schemes were evaluated.The scheme of winding truss as thermoplastic carbon fiber rod are being formed by pultrusion was selected as the preferred scheme.The prototype of the key module of the forming system was developed to make truss sample,And bending stiffness test and bending vibration test were done to evaluate the performance of the truss.Analyzed the reasons that thermoplastic carbon fiber rod is blocked in pultrusion molding,and solved the problem;To sovle the problem that the ordinary traction device is not powerful enough to provide the driving force required for pultrusion,a caterpillar traction device and an rotary traction device were developed to increase the traction force,realized the preparation of truss chords and diagonal rods by pultrusion process;tested the static stiffness and vibration characteristics of the truss samples,the static stiffness is 30.8% smaller than the theoretical value,and the bending vibration frequency is 17.8%-21.6% smaller than the theoretical value,the reasons for the error were analyzed;Comparing the bending stiffness of the truss and the rod with the same material and the same linear density,the theoretical value and test value of the bending stiffness of the truss are 6.62 times and 4.59 times of the theoretical bending stiffness of the rod respectively.