Frank and Ora Lee Marble Professor of Aeronautics and Mechanical Engineering

Modeling and Simulation of Ballistic Impact of Polyurea Rods on Glass Plates (ONR)

The general aim of this study is to develop an understanding of complex dynamics and potential for wave attenuation in protective systems that combine hard and soft materials. We seek to make progress towards the formulation and implementation of simple yet predictive failure criteria for brittle materials, such as glass, and soft materials, such as polyurea. The brittle fracture and fragmentation capability will be validated against experimental data such as Bless and Brar's impact experiments on glad rods.

We will verify that the simulations accurately capture the speed of the ensuing failure wave. We also seek to obtain explicit multiscale 'optimal scaling laws' that permit consideration of void nucleation, growth and coalescence in polymers, ultimately resulting in tearing, in a computational efficient manner. This capability will be validated against PU Taylor impact experiments. In a parallel and coordinated effort, Prof. Kerstin Weinberg will conduct quasistatic uniaxial experiments of polyurea up to failure. The experiments will provide data for the validation and calibration of the ductile failure criterion, as well as microscopy observations for further validation of the multiscale failure criterion. We will apply the modeling and computational capability to assess the dynamic performance of various systems, including: i) A monolithic glass rod; ii) Two abutting glass rods with normal interface; iii) Two abutting glass rods with inclined interface; iv) Two glass rods separated by a normal polyurea layer; v) Two glass rods separated by an inclined polyurea layer; and vi) An assembly of several glass rods separated by normal polyurea layers.