Confidence of Detection of Fracture Signals Using Acoustic Emission

2007 ◽  
Vol 7-8 ◽  
pp. 147-152
Author(s):  
Rhys Pullin ◽  
Karen M. Holford ◽  
S.L. Evans
Keyword(s):  
Cluster Analysis ◽  
Acoustic Emission ◽  
Crack Length ◽  
Cluster Size ◽  
Specific Area ◽  
Fracture Length ◽  
Cluster Threshold ◽  
Point Bend ◽  
High Level ◽  
Practical Investigation

This paper reports on a practical investigation into methodology confidence of detection (COD) in acoustic emission (AE) testing. The developed technique relies on a commercially available software technique called “source cluster analysis” that examines the number of detected signals over a specific area. Two factors that control cluster analysis are cluster size (the area that signals are detected within) and cluster threshold (the number of detected events required to trigger a cluster). A confidence of detection matrix was developed based on altering cluster size and cluster threshold which was then applied to a practical investigation of a four-point bend test monitored using AE. Fracture length in the specimen was monitored using a foil crack gauge. The varying sizes and thresholds of the confidence matrix were used in a cluster analysis of the recorded AE data, as the initial cluster formed in the fracture region a crack length could be identified (based on the foil crack gauge). Results showed that it was possible to detect a crack length of 0.55 mm with a very high level of confidence.

Evaluation of locations for testing dry bean cultivars in western Canada using statistical procedures, biological interpretation and multiple traits

1993 ◽  
Vol 73 (4) ◽  
pp. 985-994 ◽  
Author(s):  
G. Saindon ◽  
G. B. Schaalje
Keyword(s):  
Cluster Analysis ◽  
Seed Yield ◽  
Seed Weight ◽  
Visual Assessment ◽  
Western Canada ◽  
Multiple Traits ◽  
Dry Bean ◽  
Biological Interpretation ◽  
Environmental Events ◽  
High Level

Genotype × environment (GE) effects in regional registration trials for dry beans in western Canada were studied to determine whether geographic distribution of sites could be rationalized. The structure of the GE effects on the maturity, seed weight and seed yield of seven dry bean check cultivars grown at eight locations during 4 yr was investigated using GE mean squares decomposition, cluster analysis and the additive main effect and multiplicative interaction (AMMI) method. The analyses revealed a high level of redundancy in the locations which suggested that most GE effects can be captured with fewer testing sites. The partition of the GE mean squares demonstrated the possibility of reproducing the GE structure of the entire data sets with as few as three sites; however, more locations may be needed to compensate for unpredictable environmental effects. Based on biological interpretation of groupings and visual assessment of the AMMI displays, a five-location set fully represented the GE effects on maturity, seed weight and seed yield and accounted for the inconsistent clustering of the Brooks site for the three traits. Also, the set should allow for site losses due to unpredictable environmental events. The dry bean industry in western Canada is expanding to non-traditional growing areas and the establishment of trials in these areas should be considered as they may create GE effects not considered to date. Key words: Phaseolus vulgaris L., genotype × environment interactions, cluster analysis, AMMI analysis

scholarly journals A Principal Component Analysis of Acoustic Emission Signals from a Landing Gear Component

2008 ◽  
Vol 13-14 ◽  
pp. 41-47 ◽  
Author(s):  
Rhys Pullin ◽  
Mark J. Eaton ◽  
James J. Hensman ◽  
Karen M. Holford ◽  
Keith Worden ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Acoustic Emission ◽  
Background Noise ◽  
Principal Component ◽  
Component Analysis ◽  
Landing Gear ◽  
Fracture Detection ◽  
Artificial Fracture ◽  
High Level ◽  
Ae Signals

This work forms part of a larger investigation into fracture detection using acoustic emission (AE) during landing gear airworthiness testing. It focuses on the use of principal component analysis (PCA) to differentiate between fracture signals and high levels of background noise. An artificial acoustic emission (AE) fracture source was developed and additionally five sources were used to generate differing AE signals. Signals were recorded from all six artificial sources in a real landing gear component subject to no load. Further to this, artificial fracture signals were recorded in the same component under airworthiness test load conditions. Principal component analysis (PCA) was used to automatically differentiate between AE signals from different source types. Furthermore, successful separation of artificial fracture signals from a very high level of background noise was achieved. The presence of a load was observed to affect the ultrasonic propagation of AE signals.

Acoustic Emission Studies of Alumina-13% Titania Free-Standing Forms during Four-Point Bend Tests

2005 ◽  
Vol 80 (9) ◽  
pp. 2382-2394 ◽  
Author(s):  
Chung-Kwei Lin ◽  
Christopher C. Berndt ◽  
Sang-Ha Leigh ◽  
Kenji Murakami
Keyword(s):  
Acoustic Emission ◽  
Free Standing ◽  
Bend Tests ◽  
Point Bend ◽  
Emission Studies

On the Reproducibility of Transducer Coupling for Acoustic Emission Testing

2006 ◽  
Vol 13-14 ◽  
pp. 117-124 ◽  
Author(s):  
James J. Hensman ◽  
C.V. Cristodaro ◽  
Gareth Pierce ◽  
Keith Worden
Keyword(s):  
Acoustic Emission ◽  
Test Results ◽  
Coupling Condition ◽  
Waveform Data ◽  
Three Point Bending ◽  
Emission Testing ◽  
Acoustic Emission Testing ◽  
Acoustic Emission Test ◽  
Point Bend ◽  
Ultrasonic Propagation

An acoustic emission test was simulated using a three point bend specimen and an artificial AE source. Waveform data was recorded as the sample was cyclically loaded in three point bending, and the cross correlation coefficient of the waveforms was used to measure the repeatability of the test. Results were twofold: the stress state of a specimen affects the ultrasonic propagation therein; and the coupling condition of a transducer may not remain constant during a test.

Investigation of the Staging of Damage Accumulation in Polymer Composite Materials during Bending and Tensile Tests

2021 ◽  
Vol 887 ◽  
pp. 116-122
Author(s):  
A.A. Bryansky ◽  
O.V. Bashkov ◽  
Daria P. Malysheva ◽  
Denis B. Solovev
Keyword(s):  
Acoustic Emission ◽  
Composite Materials ◽  
Polymer Composite ◽  
Loading Rate ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Rate Effect ◽  
Polymer Composite Materials ◽  
Static Tension ◽  
Point Bend

The paper presents the results of the study of registered acoustic emission (AE) parameters during static deformation and damaging of polymer composite materials (PCM). Mechanical tests were done by a static tension and a static three-point bend, accompanied by an acoustic emission method. The assessment of the loading rate effect on defects formation processes was done by additional static tension test at rate equal half of recommended by the standard and static three-point bend test at rate ten times lower than that calculated by the standard. Clustering by frequency components of the recorded AE signals with a self-organizing Kohonen map was performed. The characteristics of the types of PCM structure damage by the centroids of the obtained clusters are given. Based on the clusters accumulation during mechanical tests, the stages of damage formation for static tension and static three-point bend, the loading rate effect on the process of damage formation are described.

Hyperbolic Source Location of Crack Related Acoustic Emission in Bone

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
John O'Toole ◽  
Leo Creedon ◽  
John Hession ◽  
Gordon Muir
Keyword(s):  
Acoustic Emission ◽  
Constant Velocity ◽  
Good Accuracy ◽  
Source Location ◽  
Bovine Bone ◽  
Accuracy And Precision ◽  
Median Error ◽  
Acoustic Emission Source ◽  
Three Point Bend Test ◽  
Point Bend

Little work has been done on the localization of microcracks in bone using acoustic emission. Microcrack localization is useful to study the fracture process in bone and to prevent fractures in patients. Locating microcracks that occur before fracture allows one to predict where fracture will occur if continued stress is applied to the bone. Two source location algorithms were developed to locate microcracks on rectangular bovine bone samples. The first algorithm uses a constant velocity approach which has some difficulty dealing with the anisotropic nature of bone. However, the second algorithm uses an iterative technique to estimate the correct velocity for the acoustic emission source location being located. In tests with simulated microcracks, the constant velocity algorithm achieves a median error of 1.78 mm (IQR 1.51 mm) and the variable velocity algorithm improves this to a median error of 0.70 mm (IQR 0.79 mm). An experiment in which the bone samples were loaded in a three point bend test until they fractured showed a good correlation between the computed location of detected microcracks and where the final fracture occurred. Microcracks can be located on bovine bone samples using acoustic emission with good accuracy and precision.

Strategic orientations, knowledge management (KM) and business performance

Kybernetes ◽  
2019 ◽  
Vol 48 (9) ◽  
pp. 1942-1964 ◽  
Author(s):  
Mona Jami Pour ◽  
Mohammad Asarian
Keyword(s):  
Cluster Analysis ◽  
Knowledge Management ◽  
Business Performance ◽  
High Performance ◽  
Strategic Orientation ◽  
Content Type ◽  
Strategic Orientations ◽  
Strategy Performance ◽  
High Level ◽  
The Relationship

Purpose Despite the huge amount of studies that have investigated the strategy–performance relationships and knowledge management (KM)–performance relationships, there is little consensus regarding the nature of these connections. By reviewing related literature, some notable limitations and inconsistent results are highlighted in extant studies. To address these challenges, this study aims to explore the effects of strategic orientation and KM mechanisms on business performance. Design/methodology/approach The study conducted an empirical investigation of 227 small- and medium-sized enterprises (SMEs) to explore the relationship between strategy−performance and KM−performance. Business strategy is conceptualized as a comparative construct with six dimensions, KM is conceptualized by two types of KM mechanisms of technical and non-technical KM mechanisms and business performance is measured by four dimensions of balanced scorecard (BSC). The cluster analysis was used to explore different aspects of these three constructs. Findings Using cluster analysis, the results indicate that firms with high level of analysis, defensiveness, futurity and proactiveness in strategic orientation have better performance and also the high level of both KM mechanisms another important finding shows that firms with more KM mechanisms have high performance and technical mechanisms have more predictor role on performance. Practical implications This research also has prescriptive implications for strategic managers and KM practitioners. The finding enhanced the understanding of the relationship between strategic orientations, KM and performance. The results assist managers to assess business performance regarding strategic orientations and KM mechanisms of the firms. Therefore, it helps firms to improve strategic resource allocation and exploit KM investment by considering ideal pattern of the performance. Originality/value By reviewing strategic management and KM literature, it is revealed that there are little studies about how the interaction of strategic orientation and KM influences business performance. The main contribution of the study is exploring the profile of the firms by considering their strategic orientation and KM mechanisms and their impact on business performance. This study provides an empirical evidence about interaction of strategic orientations, KM mechanisms and business performance in SME context, which is merely investigated in previous researches.

Structural integrity assessment for a component of the bucket-wheel excavator

2014 ◽  
Vol 5 (2) ◽  
pp. 129-140 ◽  
Author(s):  
Anghel Cernescu ◽  
Liviu Marsavina ◽  
Ion Dumitru
Keyword(s):  
Risk Factor ◽  
Fatigue Life ◽  
Crack Length ◽  
Structural Integrity ◽  
Evaluation Procedure ◽  
Content Type ◽  
Integrity Assessment ◽  
Material Component ◽  
High Level ◽  
Remaining Fatigue Life

Purpose – The purpose of this paper is to present a methodology for assessing the structural integrity of a tie member from a bucket-wheel excavator, ESRC 470 model, which was in operation for about 20 years. The tie member is made of S355J2N structural steel. Following the period of operation, the occurrence of microcracks which can propagate by fatigue is almost inevitable. It is therefore necessary to analyze the structural integrity and the remaining life of the component analyzed. Design/methodology/approach – In principle, the assessment methodology is based on three steps: first, the evaluation of mechanical properties of the material component; second, a BEM analysis using FRANC 3D software package to estimate the evolution of the stress intensity factor based on crack length and applied stress; third, risk factor estimation and remaining fatigue life predictions based on failure assessment diagram and fatigue damage tolerance concept. Findings – Following the evaluation procedure were made predictions of failure risk factor and remaining fatigue life function of crack length and variable stress range, for a high level of confidence. Originality/value – As results of this analysis was implemented a program for verification and inspection of the tie member for the loading state and development of small cracks during operation.

scholarly journals Spatial-Temporal Pattern and Its Influencing Factors on Urban Tourism Competitiveness in City Agglomerations Across the Guanzhong Plain

2019 ◽  
Vol 11 (23) ◽  
pp. 6743
Author(s):  
Jia Wan ◽  
Junping Yan ◽  
Xiaomeng Wang ◽  
Ziqiang Liu ◽  
Hui Wang ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Influencing Factors ◽  
Temporal Pattern ◽  
Explanatory Power ◽  
Urban Tourism ◽  
Ecological Environment ◽  
Single Factor ◽  
Tourism Resources ◽  
High Level ◽  
Environment Condition

Strengthening research on urban tourism competitiveness is vital in evaluating the current situation and potential of urban tourism, maintaining the sustainable development of the tourism economy and assisting in the regional macro decision making. In this study, an index system evaluation of urban tourism competitiveness in city agglomerations across the Guanzhong Plain is established by collecting cross-section data from the years 2017 and 2010. The entropy value method is adopted to determine the index weight. Cluster analysis is performed and the spatial-temporal pattern and evolution laws of urban tourism competitiveness among city agglomerations in the Guanzhong Plain are analyzed and the geographic detector utilized to discuss the influencing factors. Results show that the spatial gradient difference of urban tourism competitiveness of agglomerations in the Guanzhong Plain is significant. In 2010, it presented the characteristic of ‘the high and middle levels having a zonal distribution from east to west, and the low level was distributed along the north and south wings’. In 2017, the characteristic of ‘polarization’ became highly prominent, that is, the scope of high-level and low-level cities expanded and the scope of medium-level cities decreased. Urban tourism competitiveness in city agglomerations across the Guanzhong Plain exhibited a trend of ‘strengthening in the east, weakening in the west’. The competitiveness of resources and management shifted aggressively and supporting factors competitiveness underwent a slight change. The urban tourism competitiveness of city agglomerations in the Guanzhong Plain is generally low, while the urban tourism competitiveness of Xi’an had an absolute advantage in city agglomerations of the Guanzhong Plain. According to the cluster analysis results, resources and management competitiveness, supporting factors competitiveness, demand conditions competitiveness, situational conditions competitiveness and urban tourism competitiveness of Xi’an in 2010 and 2017 were all at an extremely high level, which was relatively higher than the index values of other cities in the city agglomerations of the Guanzhong Plain. Tourism resources, service support capacity, infrastructure support capacity, tourism income scale, tourism reception scale and economic development power are the core influencing factors of urban tourism competitiveness among city agglomerations in the Guanzhong Plain. The single factor explanatory power of destination management indicates a downward trend while the single factor explanatory power of the ecological environment condition shows an upward trend. Tourism resources are the leading interactive factor of urban tourism competitiveness, and destination management and ecological environment condition are the most significant indicators for the collaborative effect.

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