Direct Measurement and Modeling of Glass Under Shock Loading
Abstract
Abstract Statement of Work We will use intense, shaped laser beams to generate shock waves that propagate within silica and other glass samples. We will record optical images to characterize the propagating shocks, to determine the shock pressures and the compressional and shear strain amplitudes, and to monitor macroscopic structural responses including transient and long-lived density changes and fracture. We will record vibrational spectra to monitor microscopic responses that indicate changes in bond angles and coordination and in the degree of local order that may suggest similarity to highpressure crystalline structures. We will conduct x-ray diffraction to further elaborate shockinduced microscopic structure. We will formulate, implement and test a computational framework for numerical modeling and simulation of the shock response of silica and other glasses to extreme shock loading taking into account the influence of shear and phase transformation and compare the results to those of the experimental measurements. Objectives We aim to monitor and characterize experimentally and model numerically the extreme structural changes that glasses can undergo when subjected to shock loading. We will study silica and other glasses including soda lime with the objectives of elucidating the macroscopic and microscopic shock-induced structural changes. We will investigate the effects of both compression or shear through experimental measurements and numerical simulations. We will advance our capabilities for measurements of materials under shock loading by designing shock and sample geometries that result in high shock pressures and in high compressional and shear strain amplitudes. We will also design measurement strategies for independent determination of both compressional and shear strain. We will further advance our measurement capabilities by developing and applying time-resolved vibrational spectroscopy and x-ray diffraction methods that can be conducted on a single-shot basis so that permanent damage to the shocked samples does not prevent detailed measurement of their dynamical changes in microscopic as well as macroscopic structure. We will advance the state of the art in modeling of glass response to extreme shock loading by developing a computational modeling framework with the ability to simulate unique responses of glass under extreme loads Approach We will build on recent development of a method that permits direct visualization of focusing shock waves as they pass through sample materials. Intense pulses of laser light initiate a shock wave that propagates in the plane of a microns-thick sample. The propagating shock wave and the material response to it are directly accessible to probe light of nearly any wavelength including terahertz through optical through x-ray spectral ranges. Shock waves and sample geometries will be designed to reach high pressures through shock focusing or amplification and in some cases to convert compression to shear so that the effects of both compressional and shear strains on the samples can be measured. Vibrational spectra will be measured through coherent Raman scattering or terahertz absorption. The measurements will be conducted by recording
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 22, 2016
- Source ID
- N000141512694
Entities
People
- Keith A. Nelson
Organizations
- Massachusetts Institute of Technology
- Office of Naval Research
- United States Navy