© 2011, University of Delaware, all rights reserved

INTRODUCTION BASELINE SANDWICH CONSTRUCTION RESEARCH OVERVIEW

RESPONSE OF COMPOSITE SANDWICH HULL STRUCTURES UNDER SLAMMING IMPACT

Y. Tsuchida (PhDCE), and J.W. Gillespie, Jr.

University of Delaware . Center for Composite Materials . Department of Civil and Environmental Engineering

t Advanced composite sandwich structure has been becoming widespread as the primary hull structure of high-speed and high-performance marine vessels.

t One of the designer’s concerns is the response of composite sandwich hull structures under slamming.

t Objectives 1)  Characterize the composite sandwich hull

material with an improved impact tolerant core 2)  Validate numerical modeling for slamming loads

and response of composite sandwich structure 3)  Investigate durability of composite sandwich hull

material and local structure due to slamming loads

4)  Consider contributions and improvements in design practice for composite sandwich hulls

BASIC TEST MATRIX WATER IMPACT ONGOING & FUTURE WORK CORE SHEAR TEST

ACKNOWLEDGEMENTS This work is supported by the Office of Naval Research through the Advanced Materials Intelligent Processing Center.

Thanks go as well to Jordan Wagner, ARL.

t Characterization of Composite Sandwich Hull Material ²  Basic Properties under Static Loading ²  Rate-dependent Properties of Foam Core Material

t Validation of Numerical Modeling ²  Estimate Rate Effects from Water Impact Scenario ²  Modeling of Slamming Loads by CFD ²  Fluid-Structure Interaction (FSI)

t Durability under Slamming Impact ² Practical Testing under Dynamic / Cyclic Loading to

Simulate Slamming on Subcomponents of Composite Sandwich Hull Structure

t Contributions in Design Practice ² Effectiveness Assessment on the Durability Study

in the Ship Design

t Face Sheets 4x4 Twill Carbon / Epoxy Quasi-isotropic 8 Layers 0.1” [2.5 mm] Thick t Core Styrene Acrylonitrile (SAN) Polymer Foam 1.5” [38 mm] Thick t No Adhesive Interface t Processing ²  Out of Autoclave (OOA): Prepreg Vacuum Bagging / Oven Cure ²  Probability of High void content (>2 %) was observed

to be less than 10 %.

The basic mechanical tests will be performed to assess the baseline sandwich performance.

t Wagner’s Water Impact Model ²  Rigid Wedge Entering Calm Water ²  Approximation for β > 4°

t Analytical Solutions Pressure Distribution Pressure Limitation

( )( )

( )( ) 22

2

22

tan2 xtb

tbVdtdb

xtb

tbVp

w

ww

−=

−=

βπρ

ρ

22

2

max

cot22

2

⎟⎠

⎞⎜⎝

⎛=

⎟⎠

⎞⎜⎝

⎛=

βπρ

ρ

Vdtdbp

w

w

t Investigate Rate-dependent Properties of Foam Core

t Modify Test Method for Static Core Properties of Sandwich with Ductile Foam Material

t Develop Testing to Simulate Slamming Impact t FE Analysis for Sandwich Beams with Foam

Core t CFD Modeling for Water Impact Problem

Investigate core shear strength and modulus, and sandwich flexural stiffness Midspan (3 point) Loading, L= 6”, 4”, 3”

P

L

Specimen

Load Cell

DIC System

LVDT

Shear Strain Distribution Measured by Digital Image Correlation (DIC)