cutting-procedures-tensile-testing-ageing-flexible-unidirectional

Cutting Procedures, Tensile Testing, and Ageing of Flexible Unidirectional Composite Laminates

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, ...

National Institute of Standards and Technology

We present a new methodology to accurately measure strain magnitudes from 3D nanodevices using Electron Backscatter Diffraction (EBSD). Because the dimensions of features on these devices are smaller than the interaction volume for backscattered electrons, EBSD patterns from 3D nanodevices will frequently be the superposition of patterns from multiple material regions simultaneously. The effect of this superposition on EBSD strain measurement is demonstrated, along with an approach to separate EBSD patterns from these devices via subtraction. The subtraction procedure is applied to 33 nm wide SiGe lines, and it provides accurate strain magnitudes where the traditional EBSD strain analysis method undervalues the strain magnitude by an order of magnitude. The approach provides a strain measurement technique for nanoscale 3D structures that is high spatial resolution, nondestructive, and accurate.

Strain measurement of 3D structured nanodevices by EBSD.

Compared to more commonly used strain measurement techniques, electron backscatter diffraction (EBSD) offers improved spatial resolution and measurement sensitivity. Additionally, EBSD can provide the full deformation tensor, whereas other techniques, such as digital image correlation (DIC), are limited to only in-plane strains and rotations. In this work, EBSD was used to measure strains and rotations in-situ during testing of a single-crystal silicon micromechanical test specimen. The theta-like specimen geometry was chosen due to the complex and spatially-varying strain states that exist in the circular frame of the sample during testing, as well as the nominally uniform strains in the central web. Full-field strain maps were generated for each strain and rotation component and compared to those from finite element analyses (FEA), showing strong agreement in all cases. Additionally, potential sources of error and their impact on both measurement accuracy and uncertainty are discussed.

In-situ elastic strain mapping during micromechanical testing using EBSD.

Applying high-resolution electron backscatter diffraction (HR-EBSD) to materials without regions that are amenable to the acquisition of backgrounds for static flat fielding (background subtraction) can cause analysis problems. To address this difficulty, the efficacy of electron beam induced deposition (EBID) of material as a source for an amorphous background signal is assessed and found to be practical. Using EBID material for EBSD backgrounds allows single crystal and large-grained samples to be analyzed using HR-EBSD for strain and small angle rotation measurement.

Article	Year
Strain measurement of 3D structured nanodevices by EBSD. Ultramicroscopy\| PubMed ID: 28863279	2018
In-situ elastic strain mapping during micromechanical testing using EBSD. Ultramicroscopy\| PubMed ID: 29161620	2018
Selected Area Electron Beam Induced Deposition of Pt and W for EBSD Backgrounds. Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada\| PubMed ID: 30773153	2019

William Osborn

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