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.

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.

Assessment of contact-induced damage mechanisms in thick-walled composite cylinders

2020 ◽  
Vol 39 (17-18) ◽  
pp. 679-699
Author(s):  
Ruben AJ Weerts ◽  
Olivier Cousigné ◽  
Klaas Kunze ◽  
Marc GD Geers ◽  
Joris JC Remmers
Keyword(s):  
Damage Tolerance ◽  
Numerical Study ◽  
Failure Mechanisms ◽  
Pressure Vessels ◽  
Thick Wall ◽  
Thin Wall ◽  
Fiber Failure ◽  
Damage Mechanisms ◽  
Filament Wound ◽  
Composite Cylinders

In order to unravel the damage mechanisms occurring in composite-overwrapped pressure vessels (COPVs) subjected to crash conditions, a combined experimental-numerical study has been performed. For the purpose of generality and simplicity, quasi-static contacts on filament-wound cylinders are considered in this paper, as a precursor for geometrically complex impacts on COPVs. Rings with different wall thicknesses are tested to assess how failure mechanisms change when transitioning from thin-wall to thick-wall cylinders. The experimental results are used to identify, which mechanisms occur, and the numerical model is subsequently exploited to analyze the corresponding mechanisms. Based on the understanding of the mechanisms, a method to improve the damage tolerance of thick cylinders is presented. The rings are locally pre-delaminated during manufacturing to promote the growth of these pre-delaminations instead of the initiation of fiber failure.

scholarly journals Progressive Fatigue Failure Analysis of a Filament Wound Ring Specimen with a Hole

2021 ◽  
Vol 5 (9) ◽  
pp. 251
Author(s):  
Eivind Hugaas ◽  
Nils Petter Vedvik ◽  
Andreas T. Echtermeyer
Keyword(s):  
Failure Analysis ◽  
Fatigue Testing ◽  
Progressive Failure ◽  
Matrix Material ◽  
Image Correlation ◽  
Parameter Study ◽  
Fiber Failure ◽  
Progressive Failure Analysis ◽  
Filament Wound ◽  
The Matrix

A progressive FEA mechanical fatigue degradation model for composites was developed and implemented using a UMAT user material subroutine in Abaqus. Numerical results were compared to experimental strain field data from high frequency digital image correlation (DIC) of split disk fatigue testing of pressure vessel cut outs with holes. The model correctly predicted the onset and evolution of damage in the matrix as well as the onset of fiber failure. The model uses progressive failure analysis based on the maximum strain failure criterion, the cycle jump method, and Miner’s sum damage accumulation rule. A parameter study on matrix properties was needed to capture the scatter in strain fields observed experimentally by DIC. S-N curve for the matrix material had to be lowered by 0% to 60% to capture the experimental scatter. The onset of local fiber failure had to be described by local S-N curves measured by DIC having 2.5 times greater strain than that of S-N curves found from standard coupon testing.

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.

Experimental Investigation on Underwater Buckling of Thin-Walled Composite and Metallic Structures

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Michael Pinto ◽  
Helio Matos ◽  
Sachin Gupta ◽  
Arun Shukla
Keyword(s):  
Pressure Pulse ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Image Correlation ◽  
Local Pressure ◽  
Metallic Structures ◽  
Full Field ◽  
Pressure Transducers ◽  
Flow Energy ◽  
Filament Wound

An experimental study on the underwater buckling of composite and metallic tubes is conducted to evaluate and compare their collapse mechanics. Experiments are performed in a pressure vessel designed to provide constant hydrostatic pressure through the collapse. Filament-wound carbon-fiber/epoxy, glass/polyester (PE) tubes, and aluminum tubes are studied to explore the effect of material type on the structural failure. Three-dimensional digital image correlation (DIC) technique is used to capture the full-field deformation and velocities during the implosion event. Local pressure fields generated by the implosion event are measured using dynamic pressure transducers to evaluate the strength of the emitted pressure pulse. The results show that glass/PE tubes release the weakest pressure pulse and carbon/epoxy tubes release the strongest upon collapse. In each case, the dominating mechanisms of failure control the amount of flow energy released.

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.

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.

Delamination Identification in Stiffened Composite Panels Using Surface Strain Data

2017 ◽  
Vol 754 ◽  
pp. 379-382
Author(s):  
George Lampeas ◽  
Christos Katsikeros ◽  
Konstantinos Fotopoulos
Keyword(s):  
Strain Field ◽  
Structural Integrity ◽  
Decomposition Methods ◽  
Surface Strain ◽  
Composite Panel ◽  
Data Decomposition ◽  
Full Field ◽  
Stiffened Composite Panels ◽  
Strain Data ◽  
Efficient Processing

The structural integrity of a composite structure can be greatly compromised by damage inside the component. Invisible damage, e.g. caused by low-speed impact, can significantly reduces composite components capability to efficiently carry loads. In the present study, an innovative approach of strain-based delamination identification and localization is investigated, based on the efficient processing of full-field surface strain measurements. Surface strain data, potentially derived by full-field optical methodologies are used in the assessment of the delamination pattern, through strain field perturbations caused due to damage evolution. Relations between delamination damage and surface strain field disturbances are established by exploiting data decomposition methods using Zernike polynomial moments. The methodology is successfully demonstrated in the case of a stiffened composite panel.

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