Error estimation between simple, closed-form analytical formulae and full-scale FEM for interlaminar stress prediction in curved laminates

Curved, laminated composite structures are frequently subject to delamination failure caused by interlaminar stresses. While solid-element FEM is able to accurately capture stresses in the through-thickness direction, computational costs are often excessive. Thus, the interest in alternative methods is high. Although simple analytical formulations were already presented in open literature, they are often bound to certain assumptions. Of great interest is the error behavior of the interlaminar stress values if certain assumptions are disregarded, e.g. for the sake of investigating more realistic structures. With the help of solid-element FEM, detailed information about interlaminar stresses in different structures were gained and compared to the ones yielded by the simplified formulae. The results were found to be good for singly curved and acceptable for doubly curved structures. However, for laminated composites featuring very complex and irregular geometries, a calculational efficient approach utilizing stacked, multilayered shell elements seems to be more promising.