Cumulative acoustic emission energy for damage detection in composites reinforced by carbon fibers within low-cycle fatigue regime at various displacement amplitudes and rates

Abstract Low cycle fatigue (LCF) behavior of unidirectional polymer matrix composites (PMCs) reinforced with glass fibers is investigated. LCF conditions involve high loads reaching up to 90% of the material ultimate strength. LCF characterization of PMCs is carried out under tension-tension fatigue loading to identify the key physical phenomena occurring in PMCs under LCF conditions and to determine their unique characteristics. Analysis of experimental data indicates that finite strain rates, large strains and stress ratios may affect LCF behavior of PMC structures and the property degradation rates.

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Prediction of fiber breakage and matrix cracking in polymeric composites under low-cycle fatigue regimes by fuzzy and wavelet clustering of acoustic emission signals

10.21203/rs.3.rs-364618/v2 ◽

2021 ◽

Author(s):

Sattar Mohammadi Esfarjani ◽

Mohammad Azadi ◽

Mohsen Alizadeh ◽

Hassan Sayar

Keyword(s):

Acoustic Emission ◽

Composite Structures ◽

Mechanical Test ◽

Low Cycle Fatigue ◽

Polymeric Composites ◽

Matrix Cracking ◽

Fiber Breakage ◽

Cycle Fatigue ◽

Emission Data ◽

Pull Out

Abstract One of methods for detecting cracks and estimating their growth in materials such as composites is the acoustic emission technique. The detection of damages, cracks and their growth in industrial composite structures, under static and dynamic loads, has a significant importance, in order to prevent any damages and increase the reliability. Therefore, achieving required technical knowledge in this field, can be helpful in repairing and the maintenance of the part in industries. The prediction of the damage in polymeric composites under static loads has been already investigated by researchers; however, under cyclic loadings, researches about this behavior are still rare. In this study, by acoustic emission sensors and analyzing experimental data, the damage, including matrix cracking, the fiber breakage and other damages (debonding, fiber pull-out and delamination) during dynamic loading was investigated. At the first stage, standard specimens were made by the pure resin epoxy and the pure carbon fiber, subjected to monotonic tensile loading and then, the frequency of the failure was extracted. Then, composite specimens were loaded in the low-cycle fatigue regime. Mechanical test results and acoustic emission data were analyzed by fuzzy C-Means and wavelet transform methods and then compared to each other to find the percentage of failures in first, mid- and last cycles by the differentiation of failure types. Results clearly indicated that the acoustic emission approach is useful and an effective tool for identifying and detecting damages in polymeric composites.

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Prediction of fiber breakage and matrix cracking in polymeric composites under low-cycle fatigue regimes by fuzzy and wavelet clustering of acoustic emission signals

Composites Mechanics Computations Applications An International Journal ◽

10.1615/compmechcomputapplintj.2021038550 ◽

2021 ◽

Author(s):

Satar Mohammadi Esfarjani ◽

Mohammad Azadi ◽

Mohsen Alizadeh ◽

Hassan Sayar

Keyword(s):

Acoustic Emission ◽

Low Cycle Fatigue ◽

Polymeric Composites ◽

Matrix Cracking ◽

Fiber Breakage ◽

Cycle Fatigue

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Low Cycle Fatigue of Unidirectional Laminates: Stress Ratio Effects1

Journal of Engineering Materials and Technology ◽

10.1115/1.1289024 ◽

2000 ◽

Vol 122 (4) ◽

pp. 415-419 ◽

Cited By ~ 6

Author(s):

V. M. Harik ◽

J. R. Klinger ◽

T. A. Bogetti

Keyword(s):

Composite Laminates ◽

Stress Ratio ◽

Polymer Matrix Composites ◽

Low Cycle Fatigue ◽

Strain Rates ◽

Matrix Composites ◽

Cycle Fatigue ◽

Degradation Rates ◽

Stress Ratios

Low cycle fatigue (LCF) of unidirectional glass/epoxy composite laminates is investigated. LCF conditions involve high loads that may reach up to 90 percent of the material ultimate strength. LCF has unique features that require some modifications to the existing fatigue models and engineering S-N curves. LCF characterization of polymer matrix composites (PMCs) is carried out to determine unique characteristics of the S-N curves corresponding to distinct loading conditions (e.g., stress ratios). LCF behavior of the PMCs studied is characterized by finite strains (1–3 percent), finite strain rates (0.05–10 s−1), and high property degradation rates, which are higher than those seen during high cycle fatigue of the glass/epoxy laminates. [S0094-4289(00)02504-4]

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Prediction of fiber breakage and matrix cracking in polymeric composites under low-cycle fatigue regimes by fuzzy and wavelet clustering of acoustic emission signals

10.21203/rs.3.rs-364618/v1 ◽

2021 ◽

Author(s):

Sattar Mohammadi Esfarjani ◽

Mohammad Azadi ◽

Mohsen Alizadeh ◽

Hassan Sayar

Keyword(s):

Acoustic Emission ◽

Composite Structures ◽

Mechanical Test ◽

Low Cycle Fatigue ◽

Polymeric Composites ◽

Matrix Cracking ◽

Fiber Breakage ◽

Cycle Fatigue ◽

Emission Data ◽

Pull Out

Abstract One of methods for detecting cracks and estimating their growth in materials such as composites is the acoustic emission technique. The detection of damages, cracks and their growth in industrial composite structures, under static and dynamic loads, has a significant importance, in order to prevent any damages and increase the reliability. Therefore, achieving required technical knowledge in this field, can be helpful in repairing and the maintenance of the part in industries. The prediction of the damage in polymeric composites under static loads has been already investigated by researchers; however, under cyclic loadings, researches about this behavior are still rare. In this study, by acoustic emission sensors and analyzing experimental data, the damage, including matrix cracking, the fiber breakage and other damages (debonding, fiber pull-out and delamination) during dynamic loading was investigated. At the first stage, standard specimens were made by the pure resin epoxy and the pure carbon fiber, subjected to monotonic tensile loading and then, the frequency of the failure was extracted. Then, composite specimens were loaded in the low-cycle fatigue regime. Mechanical test results and acoustic emission data were analyzed by fuzzy C-Means and wavelet transform methods and then compared to each other to find the percentage of failures in first, mid- and last cycles by the differentiation of failure types. Results clearly indicated that the acoustic emission approach is useful and an effective tool for identifying and detecting damages in polymeric composites.

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Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽

10.3390/ma14154070 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4070

Author(s):

Andrea Karen Persons ◽

John E. Ball ◽

Charles Freeman ◽

David M. Macias ◽

Chartrisa LaShan Simpson ◽

...

Keyword(s):

Fatigue Life ◽

Prediction Models ◽

Fatigue Testing ◽

Low Cycle Fatigue ◽

Wearable Sensors ◽

Fatigue Tests ◽

Proof Of Concept ◽

Cycle Fatigue ◽

Wearable Sensing ◽

Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

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The Investigation of the Optimization Scheme of the Low-cycle Fatigue Cropping Based on the Acoustic Emission Technique

10.21203/rs.3.rs-509322/v1 ◽

2021 ◽

Author(s):

Yujian Ren ◽

Jingxiang Li ◽

Yuanzhe Dong ◽

Dong Jin ◽

Shengdun Zhao

Keyword(s):

Acoustic Emission ◽

High Frequency ◽

Control Method ◽

Low Cycle Fatigue ◽

Control Strategies ◽

Low Frequency ◽

Loading Frequency ◽

Cycle Fatigue ◽

Al 6061 ◽

Whole Process

Abstract High efficiency and good section quality are two main objectives of metal bar cropping. A suitable control method can help to achieve both goals. An investigation of the control method of low-cycle fatigue cropping (LCFC) based on the acoustic emission (AE) technique has been proposed in this study. Ring-down counts and kurtosis are used to monitor the whole process of LCFC. The results showed that kurtosis is more suitable for monitoring the LCFC process and as a critical parameter to optimize the control method than ring-down counts in the noisy factory environment.Moreover, three types of materials are studied in this experiment; by combine with the AE results, macroscopic images and microscopic images of sections, characteristics of various LCFC stages are obtained. The results also indicated reduce the area of the transient fracture zone is the key to improve the section quality. Reducing the load frequency before the unstable crack propagation stage will beneficial to realize the goals. Based on the evaluation of kurtosis, an optimized control method is presented, and two control parameters: transient time T and the critical value of the slope of kurtosis C are determined. For 16Mn, 1045 and Al 6061, the T is 5s, 10s, and 1s, respectively. For 16Mn, 1045, and Al 6061, the C is 100, 300, and 0, respectively. Two parameters, h and S, are used to evaluate the section quality and four control strategies are compared. The results indicate the optimal control methods can improve the section quality effectively. The influence trend of reducing loading frequency is investigated by further comparison. It can be seen as the frequency decreases, the efficiency of the section quality improving decreases. In order to realize the optimal results, different control strategies are adopted for different materials. Strategy 1 (high frequency is 20Hz，high frequency thought the whole process), strategy 2 (high frequency is 20Hz，low frequency is 8.33Hz), and strategy 3 (high frequency is 20Hz，low frequency is 6.67Hz) is suitable for Al 6061, 1045, and 16Mn, respectively.

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Evaluation of the Heat Treatment Role for Light Aluminum Alloys Subjected to Creep and Low Cycle Fatigue

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.455 ◽

2010 ◽

Vol 638-642 ◽

pp. 455-460 ◽

Cited By ~ 1

Author(s):

A. Rutecka ◽

L. Dietrich ◽

Zbigniew L. Kowalewski

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Low Cycle Fatigue ◽

Numerical Models ◽

Cyclic Hardening ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Lower Stress ◽

Creep Tests ◽

Different Temperatures

The AlSi8Cu3 and AlSi7MgCu0.5 cast aluminium alloys of different composition and heat treatment were investigated to verify their applicability as cylinder heads in the car engines [1]. Creep tests under the step-increased stresses at different temperatures, and low cycle fatigue (LCF) tests for a range of strain amplitudes and temperatures were carried out. The results exhibit a significant influence of the heat treatment on the mechanical properties of the AlSi8Cu3 and AlSi7MgCu0.5. An interesting fact is that the properties strongly depend on the type of quenching. Lower creep resistance (higher strain rates) and lower stress response during fatigue tests were observed for the air quenched materials in comparison to those in the water quenched. Cyclic hardening/softening were also observed during the LCF tests due to the heat treatment applied. The mechanical properties determined during the tests can be used to identify new constitutive equations and to verify existing numerical models.

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Effect of Different Welded Structures on Mechanical Properties of TA2 Tube-to-Tubesheet Joints

Journal of Pressure Vessel Technology ◽

10.1115/1.4026566 ◽

2014 ◽

Vol 136 (4) ◽

Cited By ~ 1

Author(s):

Xinlong Wei ◽

Yang Qian ◽

Junhui Wang ◽

Jianxin Zhou ◽

Xiang Ling

Keyword(s):

Applied Load ◽

Low Cycle Fatigue ◽

Weld Zone ◽

Steel Tube ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Welded Structures ◽

Pull Out ◽

Weld Toe ◽

Welded Tube

Four types of TA2 welded tube-to-tubesheet joints prepared by manual tungsten arc argon-shielded welding technique are studied in this paper. The pull-out tests and low cycle fatigue tests were performed to optimize welded structures of tube and tubesheet. The results show that fractures of welded TA2 tube and tubesheet samples occur at weld zone of TA2 steel tube for the pull-out tests and low cycle fatigue tests. The extension-tubesheet welded joints have the maximum pull-out forces and the best fatigue resistance, and the internal-bore welded joint with 45 deg bevel occupies second place. Fractures are both initiated from weld toe of the outside of tube for the pull-out tests and low cycle fatigue tests. Crack propagates along the direction of 45 deg for the pull-out test. However, crack propagates perpendicularly to the direction of the applied load for low cycle fatigue test, and then fractures immediately parallel to the direction of the applied load. Fatigue striations with a spacing of about 10 μm can be observed on the fatigue crack propagation zone. However, hemispheroidal dimples exist on instant rupture zone.

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Damage in Adhesive Joints During Low Cycle Fatigue

Volume 9: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2010-40676 ◽

2010 ◽

Author(s):

Iva´n C. Ca´bulo-Pe´rez ◽

Juan P. Casas-Rodri´guez

Keyword(s):

Plastic Strain ◽

Low Cycle Fatigue ◽

Stress Test ◽

Damage Model ◽

Fatigue Tests ◽

Constant Stress ◽

Cycle Fatigue ◽

Damage Behavior ◽

Non Linear ◽

Compressive Loads

The objective of this research is to study the damage behavior of bulk adhesive and single lap joint (SLJ) specimens during low cycle fatigue (LCF). Fatigue tests under constant stress amplitude were done and strain response was measured through cycles to failure using the bulk adhesive and SLJ data. A non linear damage model was used to fit experimental results. Identification of the damage parameters for bulk adhesive was obtained from the damage against accumulated plastic strain plot. It is shown that the plastic strain can be obtained from the constant stress test if the instantaneous elastic modulus, i.e. modulus affected by damage, is evaluated for each cycle. On the other hand, damage in SLJ was seen mainly in the adhesive for itself — no substrate failure — this fact is used to propose that fatigue response in the joint is due to continuum damage accumulation in the adhesive as the number of cycles increases. Damage behavior under compressive loads was not taken into account but good correlation of numerical and experimental data was obtained. It was found that damage evolution behaves in a non linear manner as the plastic deformation grows for each cycle: on fatigue onset an accelerated damage grow is observed, then a proportional evolution, and finally a rapid failure occurs; this characteristics were seen in both the SLJ and bulk adhesive specimen. So far, this research takes the damage model found in a standard adhesive specimen and assumes it is accurate enough to represent the damage behavior of the SLJ configuration.

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