Research On The Overall Stability Design Method Of The Single-layer Combined Latticed Shell Based On Aluminum Honeycomb Panels

The single-layer combined latticed shell based on aluminum honeycomb panels,where the aluminum alloy honeycomb plate participates in the joint work of the aluminum alloy bar,has the characteristics of high strength lightweight structure.As a relatively soft spatial structure,the single-layer combined latticed shell based on aluminum honeycomb panels is very sensitive to stability problem.But the existing literatures do not have the design method of stability of this new type of composite reticulated shell.In this paper,the overall stability of the single-layer combined latticed shell based on aluminum honeycomb panels was studied theoretically and experimentally.The main conclusions were obtained as following:(1)In order to carry out large-scale parametric analysis on a large number of models of the composite reticulated shell,a reasonable equivalent method of this kind of structure must be proposed.In this paper,the basic theory and practical method of equivalent honeycomb plate,aluminum alloy bar,joint and plate-bar working together were discussed,and the effectiveness of the improved equivalent plate theory was verified.(2)It was found by numerical calculation of the lattice shell example that the overall stability of the shell is very sensitive to geometric nonlinearity,material elastoplastic and initial defects.Therefore,this paper adopted the uniform defect modal method considering double nonlinearity as the stability analysis method.The results showed that the instability modes of composite reticulated shells were changed due to the effective contribution of honeycomb plates to the structural stiffness.And the overall stability bearing capacity of the composite reticulated shells was significantly increased compared with that of the non-plate reticulated shells,with an increase of 252.33%.(3)A designed full-scale model of the single-layer combined latticed shell based on aluminum honeycomb panels with a diameter of 3 meters was manufactured by using CNC machine tools and other finishing equipment.After comparing with the finite element results,it was found that the theoretical value of the stability capacity was in good agreement with the measured value of the test,with an average error of only 5.58%.And the instability modes of the two were basically the same,which were both local collapse near the loading point.It verified that the stability analysis method adopted in this paper is reasonable.(4)In order to analyze the influencing factors of the stability of the single-layer combined latticed shell based on aluminum honeycomb panels comprehensively,a large number of numerical models were established based on the initial defects,support conditions,joint stiffness,ratio of vector to span,ring number of bars and section size of components.And the overall stability of the models was deeply analyzed.The results show that the influence mechanism and degree of these factors were very different.The out-of-plane stiffness of the shell will be significantly enhanced by increasing the stiffness of the joints,the number of rings and the size of the rod section.While the in-plane stiffness of the shell will be enhanced by increasing the section size of honeycomb plates and the rise-span ratio.The initial defect will greatly reduce the initial stiffness of the structure,and its influence on the stability of the reticulated shell tends to be stable when it exceeds S/300.While the support condition has little effect on the stability of the composite reticulated shell.(5)Based on the results of parameter analysis,the whole-process load-displacement curves of 270 cases of shells with different conditions were analyzed,and a practical formula for the overall stability was obtained by using regression analysis.Through statistical verification,the design formula proposed can be used to calculate the overall stable bearing capacity of the combined latticed shell with high accuracy and appropriate safety,which provides a certain theoretical basis for the engineering design regulations of this new type of spatial structure in the future.