scholarly journals Fibre break failure processes in unidirectional composites: evaluation of critical damage states

2016 ◽  
Vol 374 (2071) ◽  
pp. 20150270 ◽  
Author(s):  
A. Thionnet ◽  
A. R. Bunsell
Keyword(s):  
Structural Integrity ◽  
Critical Density ◽  
Tensile Loading ◽  
Unidirectional Composites ◽  
Fibre Breakage ◽  
Fibre Break ◽  
Sustained Loading ◽  
Damage States ◽  
Large Clusters ◽  
Kinetics Of

Earlier work which successfully modelled the kinetics of fibre breakage in unidirectional composites under monotonic tensile loading has been extended to quantify the kinetics of fibre failure during both monotonic and sustained tensile loading. In both cases, failure was seen to occur when a critical density of large clusters (more than 16 fibres are broken within the representative volume element) of fibre breaks developed. However, in monotonic loading failure occurred very quickly after the first development of these large clusters, whereas under sustained loading the composite could accommodate greater levels of large clusters because of the lower applied load. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

scholarly journals Strain Capacity of Girth Welded Joints in HSAW Pipes

2017 ◽  
Author(s):  
Koen Van Minnebruggen ◽  
Stijn Hertelé ◽  
Wim De Waele
Keyword(s):  
Welded Joints ◽  
Structural Integrity ◽  
Tensile Load ◽  
Tensile Loading ◽  
Experimental Result ◽  
Large Strains ◽  
Automatic Welding ◽  
Strain Capacity ◽  
Axial Tensile ◽  
Welding Processes

The general aim of a recently finalized European project, i.e. EU RFCS SBD-Spipe, is to generate specific know-how concerning the development and possible use of spirally welded pipes for demanding applications. The demanding applications relate especially to structural integrity issues, both onshore and offshore, requiring good performance under application of large strains resulting in buckling, collapse and/or tensile loading. The outcome of this project can also be used as technical basis for improving standards and guidelines, that address design and safety of spirally welded pipelines. The contribution of Ghent University to this project focusses on the aspects of tearing resistance, defect tolerance and strain capacity of girth welded joints subjected to remote axial tensile load. A numerical and experimental approach is used for the assessment of flaw tolerability and strain development upon tensile loading. Spiral pipes of steel grade API-5L X70 with 36” and 48” diameters have been girth welded using both a manual and semi-automatic welding processes. Curved wide plate specimens have been extracted from the pipes and artificial weld defects have been introduced. The specimens have been loaded in tension up to failure at a temperature of −10°C. This paper reports on the experimental result of a series of curved wide plate tests.

Effect of the proximity to the 0°/90° interface on Energy Release Rate of fiber/matrix interface crack growth in the 90°-ply of a cross-ply laminate under tensile loading

2020 ◽  
Vol 54 (21) ◽  
pp. 3021-3034
Author(s):  
Luca Di Stasio ◽  
Janis Varna ◽  
Zoubir Ayadi
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Tensile Loading ◽  
Thickness Effect ◽  
Matrix Interface ◽  
Closure Technique ◽  
Geometric Configurations ◽  
Damage States ◽  
Fiber Matrix Interface

Models of Representative Volume Elements of cross-ply laminates with different geometric configurations and damage states are studied. Debond growth is characterized by the estimation of the Mode I and Mode II Energy Release Rate using the Virtual Crack Closure Technique. It is found that the presence of the [Formula: see text] interface and the thickness of the [Formula: see text] layer has no effect, apart from laminates with ultra-thin [Formula: see text] plies where it is however modest. The present analysis supports the claim that debond growth is not affected by the ply-thickness effect.

AE Methodology for the Evaluation of Structural Integrity

2006 ◽  
Vol 13-14 ◽  
pp. 17-22 ◽  
Author(s):  
Kanji Ono
Keyword(s):  
Structural Integrity ◽  
Moment Tensor ◽  
Signal Amplitude ◽  
Primary Sources ◽  
Signal Frequency ◽  
Source Characterization ◽  
Secondary Sources ◽  
Past Half Century ◽  
Damage States ◽  
Moment Tensor Analysis

This paper reviews various approach used in acoustic emission (AE) testing of structures so that further improvements can be realized in this important application of AE technology. In the past half century, many successful AE tests of structures have been completed, but quite often details remained private. Here, we attempt to organize the AE methodology in four steps. 1. Primary sources of brittle fracture, micro or macro cracks in contrast to secondary sources of friction or fretting, rust, etc. 2. Kaiser effects, arising from the irreversibility of AE, allow the detection of prior loading level and of damage states. 3. Source Location: This approach identifies the area of integrity loss. 4. Source Characterization: Combined AE parameters give good insight to the flaw types, but many other methods, including attenuation-corrected signal amplitude, signal frequency, waveform and wave propagation analysis and moment tensor analysis, may be useful. Avenues for better AE technology are suggested.

Ultrasonic Quantification Of Corroded Surfaces

1997 ◽  
Vol 503 ◽  
Author(s):  
W. M. Mullins ◽  
S. S. Shamachary
Keyword(s):  
Structural Integrity ◽  
Measurement Techniques ◽  
Surface Damage ◽  
Ultrasonic Measurement ◽  
General Corrosion ◽  
Corrosion Attack ◽  
Model Predictions ◽  
Ultrasonic Measurements ◽  
Kinetics Of

ABSTRACTThe surface damage introduced by general corrosion attack of surfaces is considered deleterious to long term structural integrity. As a result, the quantification of this damage represents an interest in the NDE community. In this document, the chemical kinetics of general attack are used to model the morphology of the surface as a function of time of exposure. Timeof- flight ultrasonic data for corroded surfaces are presented which appear to agree with the model predictions. The experimental results are critically reviewed with respect to the practical limitations of the ultrasonic experiments. The effect of exposure on surface morphology and surface stress concentration are shown and related to the classic ultrasonic measurement techniques. The relationships are used to suggest potentially important ultrasonic measurement techniques and to underline the inherent limitations of many classical ultrasonic measurements.

Risk Based Structural Integrity Management Using Bayesian Probabilistic Nets

2006 ◽  
Author(s):  
Roberto Montes-Iturrizaga ◽  
Ernesto Heredia-Zavoni ◽  
Enrique Marcial-Marti´nez ◽  
Michael Havbro Faber ◽  
Daniel Straub ◽  
...  
Keyword(s):  
General Framework ◽  
Structural Reliability ◽  
Structural Integrity ◽  
Suggested Approach ◽  
Annual Probability ◽  
Damage States ◽  
Jacket Structures ◽  
Integrity Management ◽  
Joint Consideration ◽  
Damage Processes

The present paper presents a general framework for integrity management of offshore steel jacket structures allowing for the risk based planning of inspections and maintenance activities with a joint consideration of all relevant deterioration and damage processes. The basic idea behind the suggested approach is to relate the relevant deterioration and damage processes, i.e. the exposure events, to damage states which in turn may be related to the overall integrity of the jacket structural system as measured through the Reserve Strength Ratio (RSR). This facilitates that any state of degradation, irrespective of the cause, can be assessed in terms of their impact on the annual probability of failure for the structure. Taking basis in data as well as subjective information regarding the annual occurrence probabilities of the relevant deterioration and damage processes, together with a probabilistic modeling of the quality of condition control, it is possible to assess the effect of condition control of each type of deterioration and damage phenomena. This then facilitates the development of a general framework for risk based integrity management. In the present work such a framework is formulated using Bayesian Probabilistic Nets (BPN) for evaluating the time varying global structural reliability of jackets subject to progressive deterioration of its members due to the combined effect of different sources of damage.

scholarly journals A Method for Accelerated Natural Weathering of Wood Subsurface and Its Multilevel Characterization

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 126
Author(s):  
Anna Sandak ◽  
Jakub Sandak ◽  
Marion Noël ◽  
Athanasios Dimitriou
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Degradation Process ◽  
Natural Weathering ◽  
Bordered Pits ◽  
Ft Ir ◽  
Short Time ◽  
Wood Surfaces ◽  
Kinetics Of

The function of altering weathering factors and degradation mechanisms are essential for understanding the weathering process of materials. The goal of this work was to develop a method for the acceleration of natural weathering and to investigate the molecular, microstructure and macrostructure degradation of wood caused by the process. Tests were performed in the whole month of July, which, according to previous research, is considered as the most severe for weathering of wood micro-sections. Sample appearance was evaluated by colour measurement. Scanning electron microscopy was used for evaluation of the structural integrity and changes in the microstructure of wood morphological components. Changes on the molecular level were assessed by means of FT-IR spectroscopy. Observation of the effects of weathering allowed a better understanding of the degradation process. Typical structural damage, such as cracks on bordered pits and cross-field pits, and, as a consequence, their erosion, revealed the sequence of the degradation process. It was confirmed that earlywood was more susceptible to damage than latewood. Even if the weathering test was conducted for a relatively short time (28 days) the ultra-thin wood samples changed noticeably. The progress of alteration was similar as usually noticed for wood surfaces, but occurred at shorter exposure times. The estimated acceleration factor was ×3, compare to the natural weathering kinetics of wood. The research methodology presented can be used for the determination of the weather dose-response models essential to estimate the future service life performance of timber elements.

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