PSI - Issue 60

3

M Mohan Kumar et al. / Procedia Structural Integrity 60 (2024) 177–184 Mohan Kumar et.al / Structural Integrity Procedia 00 (2024) 000 – 000

179

Z-Stringer

Skin

Riveted stiffened panel

Integrally stiffened panel

Fig 1. Geometry of integrally stiffened panel and riveted stiffened panel

3. Finite Element Model Description 3.1 Finite element analysis model

Finite element models of unstiffened and both types of the stiffened panels are modelled and analyzed using finite element analysis tool namely MSC Patran /Nastran (shown in Fig. 2. 3 and 4 respectively) using the required load and boundary conditions. The components of the stiffened panel are predominantly meshed by four noded shell elements which is a 4-node element with sixdegrees of freedom at each node, with translations and rotations in all the three coordinate directions. Skin of the stiffened panel is meshed by QUAD 4 shell elements which is suitable for analyzing thin to moderately-thick shell structures. Stringers are meshed by 4 noded and 3 noded QUAD 4 AND TRIA3 elements generally used for linear, large rotation, and/or large strain nonlinear applications. The riveted stiffened panel rivets are modeled using 1D beam elements with multipoint constraint (MPC). MPC’s are used in general, to model thin sheet like parts that are connected with rivets, or fasteners. At the center of skin of both types of the stiffened panels a circumferential crack of initial crack length of 5 mm is considered with similar type of tensile loads being applied. Table I gives details of number of elements and element type used in the finite element model of the stiffened panel.