scholarly journals Analysis of Damage Evolution in Concrete under Fatigue Loading by Acoustic Emission and Ultrasonic Testing

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 341
Author(s):  
Marc Thiele ◽  
Stephan Pirskawetz
Keyword(s):  
Acoustic Emission ◽  
Elastic Modulus ◽  
Cyclic Loading ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Measurement Methods ◽  
Material Structure ◽  
Fatigue Process ◽  
Acoustic Methods ◽  
Normal Strength

The fatigue process of concrete under compressive cyclic loading is still not completely explored. The corresponding damage processes within the material structure are especially not entirely investigated. The application of acoustic measurement methods enables a better insight into the processes of the fatigue in concrete. Normal strength concrete was investigated under compressive cyclic loading with regard to the fatigue process by using acoustic methods in combination with other nondestructive measurement methods. Acoustic emission and ultrasonic signal measurements were applied together with measurements of strains, elastic modulus, and static strength. It was possible to determine the anisotropic character of the fatigue damage caused by uniaxial loading based on the ultrasonic measurements. Furthermore, it was observed that the fatigue damage seems to consist not exclusively of load parallel oriented crack structures. Rather, crack structures perpendicular to the load as well as local compacting are likely components of the fatigue damage. Additionally, the ultrasonic velocity appears to be a good indicator for fatigue damage beside the elastic modulus. It can be concluded that acoustic methods allow an observation of the fatigue process in concrete and a better understanding, especially in combination with further measurement methods.

Study of Initial Stages of Fatigue Process Using Non-Destructive Testing Methods

2013 ◽  
Vol 592-593 ◽  
pp. 553-556
Author(s):  
František Vlasic ◽  
Josef Volák ◽  
Libor Nohál ◽  
Pavel Mazal ◽  
Filip Hort
Keyword(s):  
Acoustic Emission ◽  
Crack Nucleation ◽  
Electrical Potential ◽  
Fatigue Loading ◽  
Non Destructive Testing ◽  
Testing Methods ◽  
Destructive Testing ◽  
Fatigue Process ◽  
Cyclic Damage ◽  
Non Destructive

This paper deals with the basic research of cyclic damage during the initial stages of fatigue process using the non-destructive testing methods. The acoustic emission method was used for monitoring of the microstructure changes during fatigue loading. The electrical potential measurements of specimen and microscopic observation were used mainly to detect the first short cracks and their propagation. The fatigue tests at room temperature were conducted on titanium alloy and creep-resistant steel specimens under bending and tension loading. The aim of the study was to compare the acoustic emission signal at different types of loading until fracture and to analyze in detail the signal changes in initial stages of fatigue process. This analysis was primarily based on the waveform similarity and division into classes. The results show the high sensitivity of the acoustic emission technology in the transition from the stage of surface relief evolution to the stage of crack nucleation and propagation.

Experimental Damage Mechanics of Microelectronic Solder Joints Under Fatigue Loading

2002 ◽  
Author(s):  
Cemal Basaran ◽  
Hong Tang ◽  
Shihua Nie
Keyword(s):  
Elastic Modulus ◽  
Fatigue Life ◽  
Thermal Cycling ◽  
Fatigue Damage ◽  
Solder Joints ◽  
Fatigue Loading ◽  
Damage Mechanism ◽  
Load Drop ◽  
Material Degradation ◽  
Elastic Modulus Degradation

Fatigue damage is a progressive process of material degradation. The objective of this study is to experimentally qualify the damage mechanism in solder joints in electronic packaging under thermal fatigue loading. Another objective of this paper is to show that damage mechanism under thermal cycling and mechanical cycling is very different. Elastic modulus degradation under thermal cycling, which is considered as a physically detectable quantity of material degradation, was measured by Nano-indenter. It was compared with tendency of inelastic strain accumulation of solder joints in Ball Grid Array (BGA) package under thermal cycling, which was measured by Moire´ interferometry. Fatigue damage evolution in solder joints with traditional load-drop criterion was also investigated by shear-strain hysteresis loops from strain-controlled cyclic shear testing of thin layer solder joints. Load-drop behavior was compared with elastic modulus degradation of solder joints under thermal cycling. Following conventional Coffin-Manson approach, S-N curve was obtained from isothermal fatigue testing with load-drop criterion. Coffin-Manson curves obtained from strain controlled mechanical tests were used to predict fatigue life of solder joints. In this paper it is shown that this approach underestimates the fatigue life by an order of magnitude. Results obtained in this project indicate that thermal fatigue and isothermal mechanical fatigue are completely different damage mechanism for microstructurally evolving materials.

Application of Advanced Fatigue Damage Parameters in Comparison With Fatigue Analysis Included in Codes and Standards

2014 ◽  
Author(s):  
Philipp Rettenmeier ◽  
Karl-Heinz Herter ◽  
Xaver Schuler ◽  
Thomas Markus Fesich
Keyword(s):  
Cyclic Loading ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Fatigue Analysis ◽  
Damage Parameter ◽  
Fatigue Tests ◽  
Loading Conditions ◽  
Critical Plane ◽  
Fatigue Assessment ◽  
Fatigue Damage Parameter

Technical components are subjected to cyclic loading conditions that can be arbitrarily complex in the most general case. For analytical fatigue strength verifications in the finite life regime both the uniaxial material characteristics by means of Wöhler curves as well as a representative equivalent fatigue damage parameter (FDP) for multiaxial cyclic loadings have to be determined. For simple loading conditions, the fatigue assessment can be performed using well-known and verified strength hypotheses for quasi-static loading conditions. However, for complex non-proportional cyclic loading conditions with rotating principle stress directions the application of these hypotheses is not sufficiently verified. Hence, advanced stress, strain or energy based strength hypotheses in critical plane formulation are used. These hypotheses require considerable numerical efforts. The fatigue concept (MPA AIM-Life) enables an assessment of complex fatigue loading conditions with different advanced strength hypotheses. An interface to the finite element code ABAQUS allows the fatigue assessment of complex component geometries. Based on fatigue tests of specimens made from ferritic and austenitic materials under uniaxial and multiaxial loading conditions (tension/torsion) the accuracy of different strength hypotheses is demonstrated. Therefore the fatigue analysis assessment included in codes and standards is compared to different advanced fatigue damage parameters.

scholarly journals Fracture Characteristics and Fatigue Damage of Noncoplanar Fractured Rocklike Specimens under Uniaxial Graded Cyclic Loading and Unloading

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Gui-cheng He ◽  
Wen-yuan Wu ◽  
Yun Wang ◽  
Yong-ming Xue ◽  
Bing Dai ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Energy Dissipation ◽  
Cyclic Loading ◽  
Hysteresis Loop ◽  
Fatigue Damage ◽  
Damping Ratio ◽  
Fracture Characteristics ◽  
Cyclic Loading And Unloading ◽  
Loading And Unloading ◽  
Limit Stress

To study the fracture characteristics and fatigue damage of fractured rock masses, noncoplanar fractured rocklike specimens prepared using cement mortar were used for a graded cyclic loading–unloading test. The results showed that the two ends of the horizontal crack were the main stress concentration areas, and they inhibited crack initiation of the inclined fracture. With increasing crack inclination, the inhibitory effect became more obvious. Under the condition that the lower limit stress is constant, as the upper limit stress increases, energy dissipation of the specimen increases, becoming relatively stable in each stage of the cycle. With increasing crack inclination, the increase in the energy dissipation value decreases. Specimens with large changes in the shape of their hysteresis loop tend to exhibit large fluctuations in the elastic modulus. As the loading progressed, the elastic modulus exhibited a downward trend, and the damping ratio tended to be stable. The change in the damping ratio is affected by the dynamic elastic modulus and area of the hysteresis loop. Based on the Weibull probability distribution function, the evolution curve of the damage variable of the specimen can be obtained. This curve reflects the trend of the damage change of the rocklike specimens under various levels of cyclic loading and unloading.

scholarly journals New Nonlinear Cumulative Fatigue Damage Model Based on Ecological Quality Dissipation of Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hongsong Li ◽  
Yongbao Liu ◽  
Xing He ◽  
Wangtian Yin
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Fatigue Damage ◽  
Damage Model ◽  
Fatigue Loading ◽  
Ecological Quality ◽  
Aircraft Structures ◽  
Variable Amplitude ◽  
Fatigue Damage Accumulation ◽  
Cumulative Fatigue Damage

The failure of many aircraft structures and materials is caused by the accumulation of fatigue damage under variable-amplitude cyclic loading wherein the damage evolution of materials is complicated. Therefore, to study the cumulative fatigue damage of materials under variable-amplitude cyclic loading, a new nonlinear fatigue damage accumulation model is proposed based on the ecological quality dissipation of materials by considering the effects of load interaction and sequence. The proposed new model is validated by the test data obtained for three kinds of material under multilevel fatigue loading. Compared with the Miner model and Kwofie model, the proposed model can more effectively analyse the accumulative damage and predict fatigue life of different materials under variable-amplitude cyclic loading than others. The study provides a basis for predicting fatigue life accurately and determining reasonable maintenance periods of aircraft structures.

scholarly journals Study on the relation between damage and permeability of sandstone at depth under cyclic loading

2019 ◽  
Vol 6 (4) ◽  
pp. 479-492 ◽  
Author(s):  
Yang Zhao ◽  
Hongwei Zhou ◽  
Jiangcheng Zhong ◽  
Di Liu
Keyword(s):  
Acoustic Emission ◽  
Elastic Modulus ◽  
Cyclic Loading ◽  
Rock Damage ◽  
Permeability Evolution ◽  
Damage State ◽  
Evolution Law ◽  
Fractal Characteristic ◽  
Characteristic Value ◽  
Compression Parameter

Abstract The damage and permeability evolution of rock under stress is of great significance to engineering safety. In this paper, the evolution law of rock damage and permeability is studied by means of acoustic emission (AE) seepage experiment on deep roof sandstone with cyclic loading. Characterization of damage uses the changes in acoustic emission fractal characteristics and compression parameter which based on elastic modulus. The experimental results show that the AE events has fractal characteristic, in which the AE b-value and correlation dimension can represent the damage of rock. When the fractal characteristic value of AE increases, it indicates that the rock is in the compaction stage and the damage is not obvious. When the fractal characteristic value of AE drops, it indicates that the rock was damaged, and the permeability increase. Under the cyclic load increasing step by step, the elastic modulus first increases and then decrease. Introducing compression parameter C to characterize the state of compaction and damage, it is obtained that the rock damage state and hydrostatic permeability show a power law function relationship with porosity and have the same monotonicity. When compression parameter is less than zero, the evolution law of permeability and damage can be described by functional relationship between hydrostatic permeability K and compression parameter C.

Application of Acoustic Emission for Identification of Differences in Fatigue Damage of Selected Materials for Power Plants

2014 ◽  
Vol 627 ◽  
pp. 313-316 ◽  
Author(s):  
Vaclav Mentl ◽  
Frantisek Vlasic ◽  
Denisa Bartkova ◽  
Pavel Mazal
Keyword(s):  
Acoustic Emission ◽  
Fatigue Damage ◽  
Power Plants ◽  
New Technologies ◽  
Fatigue Loading ◽  
Damage Mechanism ◽  
Emission Signal ◽  
West Bohemia ◽  
Industry And Commerce ◽  
Diagnostic Complex

An acoustic emission is remarkable source of information about the fatigue process and its intensity under cyclic loading. Specimens made of reactor steel and INCONEL 713LC were subjected to bending fatigue loading in the high-cycle range. This study presents results of acoustic emission signal analysis. The main aim of this study is to propose a methodology for evaluation of the early manifestations of fatigue damage and to identify material changes in both materials by AE parameters. Signal comparison material indicates differences of damage mechanism in observed. An examination of crack initiation sites and microstructure has been also performed.Experiments were realized in cooperation between laboratories of Brno University of Technology and University of West Bohemia in Pilsen and its related to solving of project of the Czech Ministry of Industry and Commerce: “A diagnostic complex for the detection of pressure media and material defects in pressure components of nuclear and classic power plants“ and project New Technologies for Mechanical Engineering (NETME +).

Nondestructive Evaluation of Fiberglass Reinforced Plastic Subjected to Combined Localized Heat Damage and Fatigue Damage Using Acoustic Emission

1999 ◽  
Author(s):  
H. Nayeb-Hashemi ◽  
P. Kasomino ◽  
Nader Saniei
Keyword(s):  
Acoustic Emission ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Tensile Tests ◽  
Cyclic Stress ◽  
Damage Parameter ◽  
Contact Heat ◽  
Heat Damage ◽  
Early Rise

Abstract The effect of fatigue damage to unidirectional fiberglass composite specimens with prior contact heat damage was investigated. After damaging the specimens by contacting them to a hot tip at 360 °C, the specimens were subjected to fatigue loading at cyclic stress amplitude corresponding to 65% of the specimens’ ultimate tensile strength. The fatigue experiments was halted after 3000 cycles. The specimens were then subjected to tensile tests while monitoring their Acoustic Emission activity. In addition, acoustic emission activities of undamaged and contact heat damaged specimens were monitored during tensile tests for comparison with specimens with combined fatigue and heat damage. AE activities of all specimens can be categorized into three regions: an early rise in activity, a relatively dormant period in activity and a high exponential activity before failure. The early rise in activity did not appear on the specimens with combined contact heat and fatigue damage. For undamaged and contact heat damaged specimens, the period of the dormant activity was independent of the contact heat duration of less than 15 minutes. However, the period was a function of the contact heat duration for combined contact heat and fatigue damaged specimens. Analyzing event duration distribution identified micro-mechanisms of the damage growth upon tensile loading. AE-stress delay concept was used to predict the state of the damage in the composite. A correlation between stress delay parameter and damage parameter was obtained for all of the specimens. Fatigue life of contact heat damaged specimen was also studied. It was found that localized heat damage reduced the fatigue life significantly. Loss of matrix to transfer the load to the fibers uniformly was believed to be responsible for the reduction in the fatigue life.

Study of Initial Stages of Fatigue Process in Selective Laser Melting Material Using Acoustic Emission Method

2016 ◽  
Vol 258 ◽  
pp. 477-480
Author(s):  
Vendula Kratochvilova ◽  
Lucie Zemanova ◽  
František Vlasic ◽  
Pavel Mazal
Keyword(s):  
Acoustic Emission ◽  
Selective Laser Melting ◽  
Crack Nucleation ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Acoustic Emission Method ◽  
Laser Melting ◽  
Emission Method ◽  
Fatigue Process ◽  
Wide Range

This paper deals with the evaluation of the fatigue tests and subsequent analyses of damage processes in selective laser melting (SLM) materials under bending loading. Compared to conventional production technologies (casting, forming and machining), SLM offers a wide range of benefits, e.g. production with no need for expensive molds, very low material waste and the possibility to create complex geometric shapes. The acoustic emission method was used to fully understand the processes which appear in the stages preceding the crack initiation. The fatigue tests at room temperature were conducted on standard wrought 2618A aluminium alloy as a representative testing material and the same material created by SLM. The main aim of the study was to compare the acoustic emission signal during fatigue loading at different manufacturing parameters of SLM material and to analyze in detail the signal changes in initial stages of fatigue process. The results show the high sensitivity of the acoustic emission technique to the fracture behaviour of SLM material and transition from the stage of surface relief evolution to the stage of crack nucleation and propagation. After completion of dynamic mechanical tests, a detailed fractographic analysis was conducted to assess material response to mechanical loading. Attention was focused on determining the predominant failure mechanisms and the influence of defects or inhomogeneities such as pores, cavities, etc. resulting from the production of materials using SLM method.

scholarly journals Experimental Research on Acoustic Emission Characteristics and Felicity Effects during Coal Fatigue Failure under Cyclic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yongjie Yang ◽  
Luyi Xing
Keyword(s):  
Acoustic Emission ◽  
Cyclic Loading ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Stress Level ◽  
Counting Rate ◽  
Test System ◽  
Emission Characteristics ◽  
Evolution Law ◽  
Felicity Effect

In order to study the acoustic emission characteristics and Felicity effect in the process of coal fatigue failure and reveal the internal relationship between the fatigue damage evolution law and the acoustic emission activity, with the help of MTS815.02 electrohydraulic servo rock mechanics test system and PCI-2 acoustic emission detection and analysis system, a triaxial cycling loading acoustic emission test was carried out on the coal samples. The results show that the higher the upper limit stress is, the more obvious the degree of fatigue damage will be caused by coal samples. At the same time, the more active acoustic emission signal will appear. The coal samples under linear loading are on the initial damage state, and slight fatigue, moderate fatigue, deep fatigue, and ultimate fatigue failure under cyclic loading. The acoustic emission shows the “L-” type development evolution law in any previous stress level range, while at the last stress level, it shows the obvious “U-” type development evolution law. The higher the frequency of the cyclic loading is, the higher the rate of initiation and expansion of the microcrack will be, while the more obvious acoustic emission phenomenon will appear. Furthermore, the ringing counting rate is basically the same as that of the energy counting rate. Under triaxial cyclic loading, a shear failure mode that extends along different directions of fracture surface will be presented. The acoustic emission in the range of different stress levels shows a different degree of Felicity effect. In contrast, it is more reasonable to use the principal stress difference as a parameter to study the Felicity effect of coal under cyclic loading.

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