scholarly journals Novel Methodology for Characterizing Regional Variations in the Material Properties of Murine Aortas

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Matthew R. Bersi ◽  
Chiara Bellini ◽  
Paolo Di Achille ◽  
Jay D. Humphrey ◽  
Katia Genovese ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Aortic Aneurysms ◽  
Image Correlation ◽  
Thick Wall ◽  
Biaxial Testing ◽  
Full Field ◽  
Composition And Structure ◽  
Panoramic Digital Image Correlation ◽  
Insight Into

Many vascular disorders, including aortic aneurysms and dissections, are characterized by localized changes in wall composition and structure. Notwithstanding the importance of histopathologic changes that occur at the microstructural level, macroscopic manifestations ultimately dictate the mechanical functionality and structural integrity of the aortic wall. Understanding structure–function relationships locally is thus critical for gaining increased insight into conditions that render a vessel susceptible to disease or failure. Given the scarcity of human data, mouse models are increasingly useful in this regard. In this paper, we present a novel inverse characterization of regional, nonlinear, anisotropic properties of the murine aorta. Full-field biaxial data are collected using a panoramic-digital image correlation (p-DIC) system. An inverse method, based on the principle of virtual power (PVP), is used to estimate values of material parameters regionally for a microstructurally motivated constitutive relation. We validate our experimental–computational approach by comparing results to those from standard biaxial testing. The results for the nondiseased suprarenal abdominal aorta from apolipoprotein-E null mice reveal material heterogeneities, with significant differences between dorsal and ventral as well as between proximal and distal locations, which may arise in part due to differential perivascular support and localized branches. Overall results were validated for both a membrane and a thick-wall model that delineated medial and adventitial properties. Whereas full-field characterization can be useful in the study of normal arteries, we submit that it will be particularly useful for studying complex lesions such as aneurysms, which can now be pursued with confidence given the present validation.

scholarly journals Non-Destructive Evaluation of Damage Mechanisms in Composite Sandwich Structure

2008 ◽  
Vol 13-14 ◽  
pp. 105-114
Author(s):  
Amit Puri ◽  
Alexander D. Fergusson ◽  
I. Palmer ◽  
Andrew Morris ◽  
F. Jensen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Structural Integrity ◽  
Wind Turbine Blade ◽  
Image Correlation ◽  
Box Girder ◽  
Full Field ◽  
Composite Sandwich ◽  
Non Destructive ◽  
Dic Technique

This paper presents the experimental results obtained of flexurally loaded wind turbine blade cross section material. All material was extracted from a wind turbine blade box girder and testing was conducted in four point configuration. The aim was to gain an understanding of the structural integrity of this lightweight material as it deforms in flexure. To allow for thorough analysis, digital image correlation (DIC) was used to produce full field strain maps of the deforming specimens. Results highlight the capability of the DIC technique to identify regions of failure, as well as the aspects responsible for them. Overall, the results present a foundation for tests on larger substructure, and eventually integration into manufacturing and maintenance aspects of the industry.

scholarly journals Strain Analysis on Electrochemical Failures of Nanoscale Silicon Electrode Based on Three-Dimensional In Situ Measurement

2020 ◽  
Vol 10 (2) ◽  
pp. 468 ◽  
Author(s):  
Zhifeng Qi ◽  
Zhongqiang Shan ◽  
Weihao Ma ◽  
Linan Li ◽  
Shibin Wang ◽  
...  
Keyword(s):  
Silicon Film ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Image Correlation ◽  
Mechanical Parameters ◽  
Stress Strain ◽  
Full Field ◽  
Battery Capacity

Nanoscale silicon film electrodes in Li-ion battery undergo great deformations leading to electrochemical and mechanical failures during repeated charging-discharging cycles. In-situ experimental characterization of the stress/strain in those electrodes still faces big challenges due to remarkable complexity of stress/strain evolution while it is still hard to predict the association between the electrode cycle life and the measurable mechanical parameters. To quantificationally investigate the evolution of the mechanical parameters, we develop a new full field 3D measurement method combining digital image correlation with laser confocal profilometry and propose a strain criterion of the failure based on semi-quantitative analysis via mean strain gradient (MSG). The experimental protocol and results illustrate that the revolution of MSG correlates positively with battery capacity decay, which may inspire future studies in the field of film electrodes.

High Resolution Characterization of Materials Used in Packages Through Digital Image Correlation

2005 ◽  
Author(s):  
V. Srinivasan ◽  
S. Radhakrishnan ◽  
X. Zhang ◽  
G. Subbarayan ◽  
T. Baughn ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Full Field ◽  
Dependent Behavior ◽  
Very High Spatial Resolution ◽  
Speckle Patterns ◽  
Materials Used ◽  
Characterization Of Materials

In this study, we demonstrate a simple, full field displacement characterization technique based on digital image correlation (DIC). We develop a robust correlation measure implemented in a code and use it to characterize materials at high spatial and displacement resolution. We describe the methods implemented in the DIC code and compare against those available in the literature. We show how sample preparation may be entirely eliminated by using the natural speckle inherent in specular (rough) surfaces. We demonstrate further that the use of natural speckle enables very high spatial resolution (100 microns or less) since creating artificial speckle patterns in miscroscale spatial regions is a significant challenge. The software is also designed to be robust to varying contrasts between the deformed and the undeformed images. Its accuracy is enhanced by using NURBS (Non-Uniform Rational B-Spline) as the interpolating function in the code. We demonstrate the developed software and the underlying procedure on several packaging problems of interest. We measure the CTE of Alumina (Al2O3) using its natural speckle, we calculate the strain and therefore the modulus during mechanical testing of composite materials and we characterize the time dependent behavior of a micro-fiber reinforced composite (RT/Duroid) at high temperature.

scholarly journals Filament wound composite fatigue mechanisms investigated with full field DIC strain monitoring

2021 ◽  
Vol 11 (1) ◽  
pp. 401-413
Author(s):  
Eivind Hugaas ◽  
Andreas T. Echtermeyer
Keyword(s):  
Strain Field ◽  
Structural Integrity ◽  
Pressure Vessels ◽  
Image Correlation ◽  
Catastrophic Failure ◽  
Fiber Failure ◽  
Full Field ◽  
Matrix Cracks ◽  
Filament Wound ◽  
Over Time

Abstract Fatigue of filament wound materials was investigated using Digital Image Correlation DIC monitoring every 50th cycle of a high cycle fatigue test of a split disk ring sample. The ring was cut from a filament wound glass fiber reinforced polymer pressure vessel and had a hole. The strain field redistributed over time, lowering and moving strain concentrations. The redistributive behavior was most extensive in areas that later developed local fiber failure, which soon led to catastrophic failure. Microscopy was carried out on partially fatigued material. Damage evolved as matrix cracks and matrix splitting of groups of fibers and complete debonding of single fibers. This occurred at borders of voids and matrix cracks, easing progressive fiber failure. It was concluded that fatigue in filament wound composites has an extensive matrix damage phase before final failure. Fibers could locally withstand strains close to and above the static failure strain for considerable number of cycles if little local strain field redistribution was observed. The used method was able to detect changes in the strain fields that preceded catastrophic failure. It was concluded that DIC combined with the post processing methods presented may serve as a valuable tool for structural integrity monitoring of composite pressure vessels over time.

A strain-based approach to study interaction between non-coplanar through-thickness edge notches

2018 ◽  
Vol 53 (8) ◽  
pp. 687-698 ◽  
Author(s):  
Kaveh Samadian ◽  
Stijn Hertelé ◽  
Wim De Waele
Keyword(s):  
Brittle Fracture ◽  
Failure Modes ◽  
Structural Integrity ◽  
Equivalent Strain ◽  
Image Correlation ◽  
Combination Rules ◽  
Full Field ◽  
Integrity Assessment ◽  
Double Edge ◽  
Fundamental Insight

Structural integrity assessment procedures to assess the effect of interaction between multiple adjacent flaws normally consist of two stages. First, alignment rules categorize non-coplanar flaws as aligned or non-aligned. Second, combination rules classify aligned flaws as interacting or non-interacting. Although these criteria are applied to different failure modes like brittle fracture, elastic–plastic fracture and plastic collapse, most of them were developed based on linear elastic fracture mechanics for the sake of simplicity. However, there are very limited references available for the technical background of these criteria. This lack of justifying backgrounds becomes more critical when applying these procedures to any other failure modes other than brittle fracture. This article studies the interaction between non-coplanar edge notches in scenarios of large deformation. Hereto, strain patterns are studied through full-field deformation measurements utilizing both experimental and numerical tools. Digital image correlation is used to measure strain during experiments and to verify the finite element analyses. The results show that in addition to the crack driving force, which represents a local response of notches, the global strain distribution within the specimen in terms of strain patterns can be used to probe the interaction between non-coplanar flaws. The authors suggest a novel criterion based on the trajectory of maximum equivalent strain to distinguish between aligned and non-aligned flaws. This study is based on double-edge notched tension specimens and gives a fundamental insight into flaw interaction in failure modes other than brittle fracture.

Alterations in Finite Element Results Given Constitutive Models From Tubular and Planar Biaxial Testing of the Same Porcine Coronary Arteries

2012 ◽  
Author(s):  
Joseph T. Keyes ◽  
Danielle R. Lockwood ◽  
Jonathan P. Vande Geest
Keyword(s):  
Constitutive Models ◽  
Design Parameters ◽  
Stress Distributions ◽  
Fiber Architecture ◽  
Biaxial Testing ◽  
Form Versus ◽  
Planar Form ◽  
Progression Of Disease ◽  
Insight Into

The biomechanical characterization of tissue offers insight into items such as progression of disease and design parameters for implants1,2. To biomechanically evaluate the properties of blood vessels, biaxial testing is frequently performed because biological samples often exhibit anisotropy, and are most frequently under tension from the applied pressures and stretches3,4. Deciding whether to splay a tubular sample open to test in planar form versus performing pressure-inflation testing is a decision often determined by what testing equipment is available. The purpose of this abstract is to compare pressure-inflation behavior, stress distributions, and fiber architecture in planar versus tubular biaxial testing of the same arteries.

scholarly journals Operational Deflection Shape Extraction from Broadband Events of an Aircraft Component Using 3D-DIC in Magnified Images

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Ángel J. Molina-Viedma ◽  
Elías López-Alba ◽  
Luis Felipe-Sesé ◽  
Francisco A. Díaz
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Structural Integrity ◽  
Spatial Information ◽  
Random Excitation ◽  
Plane Motion ◽  
Image Correlation ◽  
Full Field ◽  
3D Information ◽  
Window Area

Recently, many works have shown the capabilities of noninterferometric optical techniques, such as digital image correlation, to characterise modal behaviour. They provide a global insight into the structure or component behaviour which implies massive spatial information, unaffordable by traditional sensor instrumentation. Moreover, phase-based motion magnification (PMM) is a methodology which, based on a sequence of images, magnifies a periodic motion encoded in phase time-domain signals of the complex steerable pyramid filters employed to decompose the images. It provides a powerful tool to interpret deformation. However, the interpretation is just qualitative and should be avoided if out-plane motion is recorded as only one camera is employed. To overcome this issue, 3D digital image correlation (3D-DIC) has been linked with PMM to provide measurements from stereoscopic sets of images, providing full-field displacement maps to magnified images. In this work, the combination of PMM and 3D-DIC has been employed to evaluate the modal behaviour of an aircraft cabin under random excitation. The study was focused on the passenger window area due to its significance to the structural integrity as a discontinuity of the peel. Operational deflection shapes at different resonances were characterised by magnifying a single resonance in the spectrum and then measuring with 3D-DIC. These measurements were validated with those obtained in forced normal mode tests. Motion and displacement videos improved the understanding of the identified resonance deformation. Actually, a relevant behaviour was noticed in the window’s frame, a quite narrow area where using traditional sensors would not provide such a detailed 3D information.

Characterization of Different Adhesives for Bonding Thermal Protection System (TPS) on a Space Crew Capsule

2015 ◽  
Vol 830-831 ◽  
pp. 407-410
Author(s):  
Digendranath Swain ◽  
S. Karthigai Selvan ◽  
G. Rajesh Kumar ◽  
J.O. Abhilas ◽  
Binu P. Thomas ◽  
...  
Keyword(s):  
Real Time ◽  
Structural Integrity ◽  
Thermal Protection ◽  
Ground Level ◽  
Structural Performance ◽  
Full Field ◽  
Strain Behavior ◽  
Test Objective ◽  
Base Structure

This paper demonstrates a unique application of DIC wherein the structural performance and structural integrity have been evaluated together almost in real-time. The results obtained from the ground level tests, simulating the bonding between the TPS to the base structure of a space crew module, are reported to find the adequacy of two different adhesives prior to actual bonding. The test objective was to characterize the adhesives based on the structural performance (deflection and strain behavior) of the TPS and conduct health monitoring in real-time (i.e. abort the test whenever the TPS fails). The dual objective could be met using DIC in a full-field and non-contact manner, which was essential due to the limitations of the contacting type measurements.

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