Impact and energy absorption of laminated and sandwich composites

Advanced fiber reinforced composites combine high specific strength and stiffness. Advanced composites are currently being introduced into modern U.S. Navy ships to achieve weight savings, maintenance reduction, and signature reduction. These advancements manifest themselves in Naval ships as increases in survivability, payload, range, speed, and weapon systems performance. In this thesis, vinyl ester resin matrix laminates and sandwich composites are emphasized since they are increasingly being used in naval applications. Impact damage of laminated and sandwich composites under low-velocity and high-velocity impact are investigated. Delamination damage is explored in detail since delamination is one of the major failure modes of many advanced composites structures. Delamination initiation loads for various laminates having different stacking sequences are compared. In many laminates containing various stacking sequences, placing the 900 laminae on the outside (as opposed to the inside) will reduce the delamination initiation load under impact. Moreover, an open literature survey of numerous laminated and sandwich composites having different stacking sequences and thicknesses and subjected to low-velocity impact is undertaken. The failure mode, failure load, and displacement at failure of these composites are summarized. Other topics investigated include (1) effects of a composite's constituents on damage susceptibility, (2) post-impact residual characterization and strength, and (3) nondestructive testing techniques. Prediction methods for residual strength are tabulated based on the impact damage type for laminated and sandwich composites. Further, NASA and Boeing compression-after-impact tests are summarized for laminated composites after low-energy impacts.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Kilic, Yavuz, S.M. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• James H. Williams, Jr.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/44883

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/44883