Title page for ETD etd-06102011-122723


Type of Document Dissertation
Author McQuigg, Thomas Dale
Author's Email Address tmcquigg@vt.edu
URN etd-06102011-122723
Title Compression After Impact Experiments and Analysis on Honeycomb Core Sandwich Panels with Thin Facesheets
Degree PhD
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Kapania, Rabesh K. Committee Chair
Patil, Mayuresh J. Committee Member
Scotti, Stephen J. Committee Member
Seidel, Gary D. Committee Member
Walker, Sandra P. Committee Member
Keywords
  • Honeycomb Core Sandwich Panels
  • Compression After Impact
  • Damage Tolerance
  • Finite Element Analysis
  • Multicontinuum Failure Theory
Date of Defense 2011-05-27
Availability unrestricted
Abstract
A better understanding of the e ffect of impact damage on composite structures is necessary

to give the engineer an ability to design safe, efficient structures. Current composite

structures suff er severe strength reduction under compressive loading conditions, due to even

light damage, such as from low velocity impact. A review is undertaken to access the current

state-of-development in the areas of experimental testing, and analysis methods. A set of

experiments on Nomex honeycomb core sandwich panels, with thin woven fi berglass cloth

facesheets, is described, which includes detailed instrumentation and unique observation

techniques. These techniques include high speed video photography of compression after

impact (CAI) failure, as well as, digital image correlation (DIC) for full- field deformation

measurements. The eff ect of nominal core density on the observed failure mode is described.

A finite element model (FEM) is developed to simulate the experiments performed in the

current study. The purpose of this simulation is to predict the experimental test results, and

to con rm the experimental test conclusions. A newly-developed, commercial implementation

of the Multicontinuum Failure Theory (MCT) for progressive failure analysis (PFA) in

composite laminates, Helius:MCT, is included in this model. The inclusion of PFA in the

present model gives it the new, unique ability to account for multiple failure modes. In addition,

signi ficant impact damage detail is included in the model as a result of a large amount

of easily available experimental test data. A sensitivity study is used to assess the eff ect of

each damage detail on overall analysis results. Mesh convergence of the new FEM is also

discussed. Analysis results are compared to the experimental results for each of the 32 CAI

sandwich panel specimens tested to failure. The failure of each specimen is accurately predicted

in a high-fi delity, physics-based simulation and the results highlight key improvements

in the understanding of honeycomb core sandwich panel CAI failure. Finally, a parametric

study highlights the strength benefi ts compared to mass penalty for various core densities.

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