Investigation and modeling of penetration process for composite laminates impacted by a blunt-ended projectile
Abstract
The objectives of the present research are to investigate the penetration process and to develop a corresponding computational model for composite laminates subjected to the impact of a blunt-ended projectile. Three specimen configurations were arranged to study the effect in dimensions. A series of static punch tests were conducted to characterize the load-displacement relation. The progressive damage mechanisms were identified by terminating the tests at various check points along the static punch curve. X-ray radiography, optical microscopy, and acoustic microscopy were used to inspect the tested specimens. Delamination and plugging were found to be the two major damage modes in the penetration process. It was further observed that the delamination is initiated by some matrix cracks. However, the plugging appears to be a localized behavior, and the experimental data reveal that the load for plug formation is independent of the span of the specimen. High velocity impact experiments were also performed for dynamic penetration. In general, the major damage modes resemble those observed in the static punch tests. Besides the striking velocity, the residual velocity of the projectile was measured as well for specimens subjected to complete penetration. The ballistic limit of composite laminates can be calculated from the difference between the initial and the residual kinetic energy of the projectile. An axisymmetric finite element analysis was employed to model the penetration process of composite laminates. An apparent modulus scheme together with the fracture mechanics concept was adopted to simulate the major damage events during penetration. The static punch curve was incorporated into the present analysis as a penetration criterion so that the ballistic limit of composite laminates can be estimated. The validity of the proposed model is verified by the agreement between experimental data and computational results. It is concluded that the ballistic limit can be predicted by the present model without performing dynamic impact tests.
Degree
Ph.D.
Advisors
Sun, Purdue University.
Subject Area
Mechanics|Aerospace materials|Mechanical engineering
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