CAD Application Development On Tubular Joints Of Space Tube-truss Structures

Steel tube-truss structures are widely used in the space structure projects recently. Tube-truss strctures adopt planar or special truss form, and adopt the special tubular joints, which are weld nodes using pipes connected together.Steel tube-truss structures does not have a long time to receive a good development, and so many problems are in the designing and processing, because its code is not perfect for this kind of important joints. At the same time, the analysis softwares do not suit the actual problems totally. So this article analyses some critical problems existing in the designing and processing of the tubular truss, and programming for the designing on the software platform of MSTCAD, perfects the combination between designing and processing, so that ensures the precision and the efficiency.After introducing the background knowledge of the tubular truss, the programs for the joint strength checking calculation are developed, and on the basis of space analytic geometry theory, the different styles of the joints can be judged, and calculate the strength of the basic node styles. At the other hand, the programs contain the judgement of the other joints which have been in the researching phase, according to the recent study conclusion and method. The programs also consider the relevant motheds to deal with many special problems on the joints existing in the actual projects. At the same time, in order to reduce the safety hidden tuoubles caused by the structure itself or the constructors, a program is given to calculate the minimum cylinder distance between the every two bars. This part can give a result to the places where are likely to overlap between the weld and some members put up and the result can be used to as the safety evaluate paramater of the structure.On the precondition of satisfying the precision request of the manufaction, the programs use the discrete mothed to simulate the exact form of the special crossing line. This mothed can solve the problems which the analytic geometry is hard to get the equation of the crossing line or the equation is not fit for the autual manufaction. In the program, the place between the members can be calculated automatically, and the connecting order can be judged according to the section of the models. The action and the reletionship of the other members on the same joints can also be automatical judged and the results are displayed. After considering many special problems probably appearing on the actural joints, the programs can calculate the partical dihedral angle and the points' special place on the cylinder on each discrete line, and draw the calculational curves through developing the drawing programs on the computer, at last, output the final rusults by the CAD software.Finally, on the basis of the calculation to the crossing line, the strength judging calculation programs to the weld on the tubular joints are developed, and all of the results and the total datas are given as the direction of the structural construction.