Using Acoustic Emission in Fracture Monitoring of Cementitious Composites

In order to predict the mechanical behavior of a material during its service life, it is important to evaluate its mechanical response under different types of external stresses by studying the initiation and development of cracks and the effects induced by damage and degradation. The non-destructive technique of analysis of acoustic emission, especially with source location and full wave-form analysis, provides excellent results on detecting and identifying initiations sites, cracking propagation and fracture mechanisms of polymer matrix composite, ceramic materials and rocks. For this study, loading tests in two different configurations were provided on specimens of same material and geometry. The significant AE features were monitored during each test and also locations of each AE event were estimated. Results of AE analysis are compared with a finite element analysis of the stress distribution and crack propagation within the specimens.

Download Full-text

Acoustic Emission Technique, an Overview as a Characterization Tool in Materials Science

Journal of Applied Research and Technology ◽

10.22201/icat.16656423.2011.9.03.431 ◽

2011 ◽

Vol 9 (03) ◽

Cited By ~ 4

Author(s):

C. R. Ríos-Soberanis

Keyword(s):

Acoustic Emission ◽

Composite Materials ◽

Mechanical Behavior ◽

Structural Integrity ◽

Materials Science ◽

Ceramic Materials ◽

Fracture Mechanisms ◽

External Stresses ◽

Characterization Of Materials ◽

Non Destructive

In order to predict the mechanical behavior of a composite during its service life, it is important to evaluate itsmechanical response under different types of external stresses by studying the initiation and development of cracksand the effects induced by damage and degradation. The onset of damage is related to the structural integrity of thecomponent and its fatigue life. For this, among other reasons, non-destructive techniques such as acoustic emission(AE) have been widely used nowadays for composite materials characterization. This method has demonstratedexcellent results on detecting and identifying initiations sites, cracking propagation and fracture mechanisms ofpolymer matrix composite and ceramic materials. This paper focuses on commenting the importance of the acousticemission technique as a unique tool for characterizing mechanical parameters in response to external stresses anddegradation processes by reviewing previous investigations carried out by the author as participant. Acoustic emissionwas employed to monitor the micro-failure mechanisms in composites in relation to the stress level in real-time duringthe tests carried out. Some results obtained from different analysis are discussed to support the significance of usingAE, technique that will be increasingly employed in the composite materials field due to its several alternatives forunderstanding the mechanical behavior; therefore, the objective of this manuscript is to involve the benefits andadvantages of AE in the characterization of materials.

Download Full-text

Research on Acoustic Emission Signal of Three Dimensional Braided Composite Material

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.48-49.1395 ◽

2011 ◽

Vol 48-49 ◽

pp. 1395-1400

Author(s):

Yi Li ◽

Zhen Kai Wan ◽

Jia Lu Li

Keyword(s):

Acoustic Emission ◽

Composite Material ◽

Mechanical Test ◽

Three Dimensional ◽

Emission Source ◽

Wave Form ◽

Form Analysis ◽

Braided Composite ◽

Emission Signal ◽

Acoustic Emission Source

This paper discusses the application and experimental method of acoustic emission for the three-dimensional (3D) braided composite material under flexural testing. It describes the feature of acoustic emission when applied to three-dimensional braided composite material under flexural testing. In order to know the materials damage position precisely, it is very important to collect the signal of acoustic emission source. The results of flexural experiment show that it is precise on the research of acoustic emission source location by the method of wave form analysis .During the collecting signal of acoustic emission , it is compared between parameter analysis and wave form analysis. According to the attenution degree of signal, it is selected signal of acoustic emission source exactly. It is the method to extract the precise acoustic emission signal by the different algorithm of wavelet analysis. We know that humans have been using materials by testing activities support, these tests have developed several centuries. From the traditional rough test to support materials and materials used in all aspects of science and technology, modern, scientific program, at present, there are mutual dependencies between the progress of scientific knowledge and the development of test methods. The 3D braided composite material is a kind of complex structure. Because of the many components and weaving material preparation process characteristic, material mechanics behavior is very complicated. It is characteristics of the 3D braided composite material, that the application on composites is widely more and more. The 3d braided composites have been used widely in aerospace, aviation, transportation, chemical, sports, medical care and other fields, so it is extremely vital significance for research on mechanics performance analysis of 3D braided composite material. Current studies of damage fracture behavior of composite materials are used in homogeneous materials research methods, namely the mechanical test and microscopic observation, but the research cannot distinguish and identify different damage fracture source, due to the combination of mechanical test parameters of the complex fracture micro-mechanism not sensitive. Microscopic observation is in fact observation later, local fracture surface morphology research, so can not observe the interaction of numerous fracture source and micro behavior, and can not study in the character of fracture source of composite materials, therefore the source faults already can not adapt to the traditional methods of composite material damage fracture process. From external or internal force effect material and structure produced deformation or fracture with elastic wave form, the strain energy release phenomenon called acoustic emission or stress wave [1]. Acoustic emission testing method is a kind of material internal defects or potential defects in the dynamic changes in movement, the damage detection method is real-time monitoring and can reflect the characteristics of acoustic emission sources in the load of the dynamic response. The AE information can directly reflect defects and changes [2, 3].

Download Full-text

IMPROVEMENTS IN LIDAR BATHYMETRY DATA ANALYSIS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w10-113-2019 ◽

2019 ◽

Vol XLII-2/W10 ◽

pp. 113-117 ◽

Cited By ~ 1

Author(s):

H.-G. Maas ◽

D. Mader ◽

K. Richter ◽

P. Westfeld

Keyword(s):

Laser Scanning ◽

Bottom Topography ◽

Airborne Lidar ◽

Wave Form ◽

Form Analysis ◽

Full Waveform ◽

Full Wave ◽

Systematic Effects ◽

Airborne Lidar Bathymetry ◽

Coordinate Correction

<p><strong>Abstract.</strong> Airborne Lidar Bathymetry is a laser scanning technique to measure waterbody bottom topography in shallow waterbodies with limited turbidity. The topic has recently gained relevance due to the advent of new sensor technologies allowing for much higher spatial resolution in bathymetry data capture and due to guidelines demanding regular monitoring of waterbodies. In our contribution, we focus on three important aspects of lidar bathymetry: In the first part, systematic effects of wave patterns will be analysed in order to derive waterbody coordinate correction terms. In the second part, we will apply waveform-stacking techniques to enhance the detectability of water bottom points in lidar bathymetry full waveform signals. In the third part, a dedicated full wave-form analysis procedure is shown, which allows for deriving turbidity information from the decay of the signal intensity in the waterbody.</p>

Download Full-text

Динамическая прочность керамических материалов на основе ZrO-=SUB=-2-=/SUB=-, изготовленных по аддитивной технологии

Письма в журнал технической физики ◽

10.21883/pjtf.2019.19.48314.17926 ◽

2019 ◽

Vol 45 (19) ◽

pp. 28

Author(s):

В.В. Промахов ◽

А.С. Савиных ◽

Я.А. Дубкова ◽

Н.А. Шульц ◽

А.С. Жуков ◽

...

Keyword(s):

Elastic Limit ◽

Spall Strength ◽

Composite Ceramic ◽

Ceramic Materials ◽

Experimental Investigations ◽

Wave Loading ◽

Hugoniot Elastic Limit ◽

Full Wave ◽

Ceramic Samples ◽

Wave Profiles

The ceramic and composite ceramic materials based on ZrO2 have been prepared by the additive manufacturing. The experimental investigations on the shock-wave loading of the fabricated samples were carried out. The Hugoniot elastic limit and spall strength of the ceramic samples were determined by analyzing the full wave profiles recorded by means of the laser velocimeter under their shock compression.

Download Full-text

Discrete element analysis of the punching behaviour of a secured drapery system: from laboratory characterization to idealized in situ conditions

Acta Geotechnica ◽

10.1007/s11440-020-01119-z ◽

2021 ◽

Author(s):

Antonio Pol ◽

Fabio Gabrieli ◽

Lorenzo Brezzi

Keyword(s):

Mechanical Response ◽

Steel Wire ◽

Discrete Element ◽

Wire Mesh ◽

Steel Plates ◽

Loading Conditions ◽

Element Analysis ◽

In Situ Conditions ◽

Wire Meshes

AbstractIn this work, the mechanical response of a steel wire mesh panel against a punching load is studied starting from laboratory test conditions and extending the results to field applications. Wire meshes anchored with bolts and steel plates are extensively used in rockfall protection and slope stabilization. Their performances are evaluated through laboratory tests, but the mechanical constraints, the geometry and the loading conditions may strongly differ from the in situ conditions leading to incorrect estimations of the strength of the mesh. In this work, the discrete element method is used to simulate a wire mesh. After validation of the numerical mesh model against experimental data, the punching behaviour of an anchored mesh panel is investigated in order to obtain a more realistic characterization of the mesh mechanical response in field conditions. The dimension of the punching element, its position, the anchor plate size and the anchor spacing are varied, providing analytical relationships able to predict the panel response in different loading conditions. Furthermore, the mesh panel aspect ratio is analysed showing the existence of an optimal value. The results of this study can provide useful information to practitioners for designing secured drapery systems, as well as for the assessment of their safety conditions.

Download Full-text

Scanner influence on the mechanical response of QCT-based finite element analysis of long bones

Journal of Biomechanics ◽

10.1016/j.jbiomech.2019.01.049 ◽

2019 ◽

Vol 86 ◽

pp. 149-159 ◽

Cited By ~ 7

Author(s):

Yekutiel Katz ◽

Gal Dahan ◽

Jacob Sosna ◽

Ilan Shelef ◽

Evgenia Cherniavsky ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Mechanical Response ◽

Long Bones ◽

Element Analysis

Download Full-text

Finite Element Analysis of Composite Ceramic-Concrete Slab Constructions Exposed to Fire

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.861.88 ◽

2016 ◽

Vol 861 ◽

pp. 88-95

Author(s):

Balázs Nagy ◽

Elek Tóth

Keyword(s):

Composite Structures ◽

Elevated Temperatures ◽

Cfd Simulation ◽

Concrete Slab ◽

Composite Ceramic ◽

Reinforced Concrete Beam ◽

Element Analysis ◽

Standard Fire ◽

Using Data ◽

Dynamics Simulations

In this research, conjugated thermal and fluid dynamics simulations are presented on a modern hollow clay slab blocks filled pre-stressed reinforced concrete beam slab construction. The simulation parameters were set from Eurocode standards and calibrated using data from standardized fire tests of the same slab construction. We evaluated the temperature distributions of the slabs under transient conditions against standard fire load. Knowing the temperature distribution against time at certain points of the structure, the loss of load bearing capacity of the structure is definable at elevated temperatures. The results demonstrated that we could pre-establish the thermal behavior of complex composite structures exposed to fire using thermal and CFD simulation tools. Our results and method of fire resistance tests can contribute to fire safety planning of buildings.

Download Full-text

An XYZ Parallel Kinematic Flexure Mechanism With Geometrically Decoupled Degrees of Freedom

Volume 6: 35th Mechanisms and Robotics Conference, Parts A and B ◽

10.1115/detc2011-47713 ◽

2011 ◽

Cited By ~ 1

Author(s):

Shorya Awtar ◽

John Ustick ◽

Shiladitya Sen

Keyword(s):

Degrees Of Freedom ◽

Element Analysis ◽

Motion Direction ◽

Form Analysis ◽

Flexure Mechanism ◽

Non Linear ◽

Decoupled Motion ◽

Motion Range ◽

Parallel Kinematic ◽

Cross Axis

We present the constraint-based design of a novel parallel kinematic flexure mechanism that provides highly decoupled motions along the three translational directions (X, Y, and Z) and high stiffness along the three rotational directions (θx, θy, and θz). The geometric decoupling ensures large motion range along each translational direction and enables integration with large-stroke ground-mounted linear actuators or generators, depending on the application. The proposed design, which is based on a systematic arrangement of multiple rigid stages and parallelogram flexure modules, is analyzed via non-linear finite element analysis. A proof-of-concept prototype of the flexure mechanism is fabricated to validate its large range and decoupled motion capability. The analyses as well as the hardware demonstrate an XYZ motion range of 10 mm × 10 mm × 10 mm. Over this motion range, the non-linear FEA predicts a cross-axis error of less than 3%, parasitic rotations less than 2 mrad, less than 4% lost motion, actuator isolation less than 1.5%, and no perceptible motion direction stiffness variation. Ongoing work includes non-linear closed-form analysis and experimental measurement of these error motion and stiffness characteristics.

Download Full-text