Behavior and Failure Modes of Sandwich T-Joint Using Cohesive Zone Material Model and Contact Elements

Abstract

One of the significant concerns of sandwich panels is their joints. T-joint is one the most common joint in sandwich structures. This paper deals with the numerical study of triangle T-joint under static loading. The results of numerical solution obtained by ANSYS modeling are verified with the results of experimental tests obtained in the literature. In general, the results obtained for anticipated failure load by numerical solution with the results of experimental test is in good agreement. Contact elements and cohesive zone material model are used to model the adhesive layer, hence debonding and fracture of adhesive is observed by the numerical modeling. Also, by using a written macro code in the ANSYS software, the ability of damage is explained for the core of sandwich panels; thus both the modes in fracture of T-joints (core shear failure in base panel and debonding of adhesive) are modeled. Core materials consist of Divinycell H100, H160, H250, and HCP70 are used for modeling sandwich panels, so that the function of joint is studied under different conditions of the sandwich core material. Nine different geometrical models are created by changing the base angle of the core triangle. The absorbed energy associated with different segments of the T-joint are used to investigate the effect of joint geometry and core material on the load transfer and failure mode of the T-joint.

Effect of Joint Geometry on the Behavior and Failure Modes of Sandwich T-Joints Under Transverse Static and Dynamic Loads

“…[15][16][17][18][19], if a weak foam (with low shear strength) is used in the manufacturing process of the sandwich panels, the core of the base panel (horizontal sandwich panel) may be damaged under a tensile load. In other words, the joint failure mode is the core shear fracture.…”

“…For this reason, in order to improve the safety factor and efficiency in different structures like vessels and speedboats, sandwich T-joints should be examined. Due to the importance of this subject, in the last decade many researchers have investigated T-joints of composites (laminated) [1][2][3][4][5][6][7][8][9][10][11] and sandwich panels [12][13][14][15][16][17][18][19][20][21][22]. In general, there are two types of T-joints in which their types depend on the shape of filler, fillet, and over laminate (OL) existing in the joint.…”

“…For this reason, the final strength of the joint itself was not measured. Khalili and Ghaznavi [16][17][18][19] have modeled the joint proposed by Tafttguard and Listryp [15] using a numerical method and reviewed the joint's final strength under tensile load by rising the shear strength in the core of the sandwich panels. In modeling the sandwich panels, they employed four foams of Divinycell 1 H grade (DIAB Co., DeSoto, Texas, USA), namely Divinycell HCP70, H250, HI60, and H100 and examined the efficiency of the joint under different conditions.…”

“…The results from their studies indicated that the application of the foam Divinycell HCP70 might improve the final 156 S. M. R. Khalili et al strength of the joint. It is worthy to note that in the studies [15][16][17][18][19], the given joint has been analyzed only under tensile load. In this paper, the behavior of a sandwich T-joint has been studied under transverse load and compared with the obtained results from the analysis on the joint under tensile load.…”

A numerical approach for the shape optimization of woven fabric composite structural elements

“…Also, increasing the fiber insertion depth reduces T-joint deflection and improves the damage initiation load and reducing the interface thickness reduces the T-joint deflection and improves the damage initiation load. Some more recent works on T joints include [46,47,48,49] Another similar type of joining element is the Pi-joint. Among the first studies to examine its mechanical performance are [50,51].…”