RAASCH CHALLENGE FOR SHELL ELEMENTS

The Raasch challenge problem of a curved strip with a tip in-plane she ar Load is examined in an attempt to better understand how certain she ll element features affect its solution. Various shell element formula tions are used in the assessment in an attempt to define any inherent pathological problems of the shell finite elements or the problem itse lf Six different hat shell elements and two solid brick elements are a ssessed by this problem, and the findings are very surprising. Selecte d aspects of shell finite-element development that are relevant to thi s problem are briefly described. These aspects are the inclusion of tr ansverse shear flexibility in the element formulation, the addition of drilling degrees of freedom, and the realignment of shell surface nor mals. Shell elements without transverse shear flexibility appear to co nverge to an appropriate value (i.e., 5% stiffer than the three-dimens ional solution). Shell elements with transverse shear flexibility do n ot appear to converge.