Design and Test of a Sandwich T-Joint for Naval Ships

Within the EUCLID project, ‘Survivability, Durability and Performance of Naval Composite Structures’, one task is to develop improved fiber composite joints for naval ship super structures. One type of joint in such a super structure is a T-joint between sandwich panels. An existing design consists of panels joined by filler and over-laminates of the same thickness as the skin laminates. In a superstructure a T joint may be loaded in tension if an internal blast occurs in two adjacent compartments or by an underwater explosion if two adjacent rooms have no support underneath the separating wall. Improved T-joints have been designed and investigated with focus on improved strength (survivability) and limiting delamination progress in over-laminates. This paper describes the design and test of a sandwich T-joint with reduced weight but with the same or higher strength than the existing design. The lightweight T-joint is designed for sandwich panels with 38 mm thick balsa foam core and 4 mm thick glass fiber/vinylester skin laminates. The panels are joined by filler forming a smooth transition (radius 35 mm) from the T-panel to the base panel, and over-laminated with laminates of 6mm thickness. Tensile (pull-out) tests are performed to load the structures in tension and the strength and failure mode are compared with results from tests on the existing T-joint base design. For the geometries in the present study, an increase of the over-laminate plies resulted in a 13% increase in the failure load

[1]  U. V. R. S. Turaga,et al.  Failure Modes and Load Transfer in Sandwich T-Joints , 2000 .

[2]  G. C. Sih,et al.  Failure mechanics of composites , 1985 .

[3]  R. Shenoi,et al.  Fatigue behaviour of single skin FRP tee joints , 1999 .

[4]  Aage Lystrup,et al.  Design and test of lightweight sandwich T-joint for naval ships , 2005 .

[5]  R. A. Shenoi,et al.  Influence of material and geometry variations on the behaviour of bonded tee connections in FRP ships , 1992 .

[6]  R. A. Shenoi,et al.  Design of joints and attachments in FRP ships' structures , 1994 .

[7]  Damage tolerance of laminated tee joints in FRP structures , 1998 .

[8]  E. Theotokoglou.  Study of the Numerical Fracture Mechanics Analysis of Composite T-Joints , 1999 .

[9]  S. John,et al.  Fracture behaviour of composite maritime T-joints , 2006 .

[10]  R. A. Shenoi,et al.  A Study of Structural Composite Tee Joints in Small Boats , 1990 .

[11]  Torgeir Moan,et al.  Experimental and Numerical Study of Composite T-Joints , 1996 .

[12]  J. E. van Aanhold,et al.  Dynamic and static performance of composite T-joints , 2002 .

[13]  R. Thomson,et al.  Geometry and damage effects in a composite marine T-joint , 2004 .

[14]  B. D. Agarwal,et al.  Analysis and Performance of Fiber Composites , 1980 .

[15]  P. Sinha,et al.  Finite Element Analysis of Composite Wing T-Joints , 2002 .

[16]  G. Steven,et al.  Failure Analysis of Composite T-Joints Including Inserts , 1997 .

[17]  E. Theotokoglou.  Strength of Composite T-Joints under Pull-Out Loads , 1997 .