SIMPLE ESTIMATING METHOD FOR JOINT RIGIDITY/DEFORMATION OF STRUCTURAL MEMBER

PROBLEM TO BE SOLVED: To evaluate the application possibility of a beam model by estimating local rigidity of the joint part by regarding the total of rigidity of a panel as the local rigidity by finding flexural rigidity of a main pipe flange surface-substituted virtual rectangular panel by a beam theory and a band plate theory. SOLUTION: A branch pipe having a rectangular cross section estimates local rigidity and deformation of the joint part of a structural member installed on the flange surface of a larger hollow main pipe. For example, a branch pipe having a cross section of (2a×2b) is vertically installed on the flange surface of the main pipe having a width 2W as a T-joint of mutual rectangular cross-sectional members. Since out-of- plane bending, in-plane bending and axial tension act on this branch pipe, when the out-of-plane bending acts, it is supposed that the branch pipe is put in a supporting state by a virtual rectangular panel. A boundary condition of the virtual rectangular panel is supposed. Next, rigidity of the flange surface at out-of-plane bending acting time is found by a simple estimating expression. Therefore, the whole can be analyzed by a beam model by addition of a spring corresponding to local deformation by evaluating the application possibility of the beam model to estimate rigidity of the whole frame structure such as an automobile.