IHS ESDU Strength of stringers in panel in compression. STRUCT 02.01.16

ESDU Struct 02.01.16 provides values of the ratio of the edge stress in the panel at failure to the failure stress of the stiffener alone flexing in a direction normal to the sheet. The values may be read from curves plotting that ratio against the ratio of stringer to plate cross-sectional areas (the latter normal to the compressive load), factored by the slope of the curve of edge stress plotted against average stress in the panel (which may be obtained from ESDU Struct 02.01.03 or 02.01.23). The curves apply to various values of the ratio of the second moments of area of the stringer section about an axis through its centroid and about an axis in the midplane of the sheet. To obtain the panel edge stress at failure requires a value for the stringer stress at failure and that is found from ESDU Struct 01.01.01. The data in ESDU 76016 may be used to correct the results for the effect of yielding. The method takes into account the effect of buckling of the sheet on its contribution to the flexural stiffness of the stringer, but the effects of different buckling forms for the stringer and panel and of inter-rivet buckling are ignored; this is permissible for panels in which the sheet thickness is less than that of the stringer. A fully worked example illustrates the use of the curves and the other ESDU documents.