scholarly journals Research on Residual Life Estimation Method for KMN Steel Based on Nonlinear Ultrasonic Testing

2021 ◽  
Vol 11 (23) ◽  
pp. 11385
Author(s):  
Pengfei Wang ◽  
Weiqiang Wang ◽  
Sanlong Zheng ◽  
Zengliang Gao
Keyword(s):  
Fatigue Life ◽  
Ultrasonic Testing ◽  
Residual Life ◽  
Fatigue Cracks ◽  
Nonlinear Coefficient ◽  
Estimation Method ◽  
Microscopic Analysis ◽  
Gumbel Distribution ◽  
Micro Cracks ◽  
Nonlinear Ultrasonic

The testing of KMN steel bending fatigue with different cycles was carried out using a nonlinear ultrasonic detector to obtain its nonlinear coefficient. The experimental results show that the nonlinear coefficient first increases and then decreases with an increase in fatigue cycles. The relationship between the propagation of the micro-cracks inside the material and the nonlinear coefficient was researched by microscopic analysis in the dangerous position of the specimens. As the fatigue cycles increase, the microstructure of the specimen gradually deteriorates and cracks occur, which proves that nonlinear ultrasonic detection can be used to characterize the initiation of micro-cracks in the early fatigue stages of the material and that the nonlinear coefficient β of the material can be used to reflect the fatigue damage degree and fatigue life of the interior of the material. An analysis of the numerical statistics of the fatigue cracks inside the specimens was carried out, and the extreme value of fatigue cracks was calculated using the Gumbel distribution. An empirical formula for the nonlinear coefficient and crack growth size of KMN steel was established and then a method for estimating the fatigue life of KMN steel based on nonlinear ultrasonic testing was proposed.

Metal Surface Fatigue Detection Using Nonlinear Ultrasonic

2014 ◽  
Vol 510 ◽  
pp. 156-162 ◽  
Author(s):  
Hong Juan Yan ◽  
Chun Guang Xu ◽  
Qi Lin ◽  
Hai Chao Cai
Keyword(s):  
Fatigue Life ◽  
Nonlinear Coefficient ◽  
304 Stainless Steel ◽  
2024 Aluminum Alloy ◽  
Surface Fatigue ◽  
Micro Cracks ◽  
Nonlinear Ultrasonic ◽  
Ultrasonic Propagation ◽  
Fatigue Detection ◽  
The Relationship

Based on theory of ultrasonic nondestructive testing on surface fatigue damage of metal components, the wave law of ultrasonic nonlinearity caused by fatigue is studied. When there are lattice defects in metal material, second-order nonlinear coefficient β changes during ultrasonic propagation. According to the point, the system of nonlinear ultrasonic testing is build. The change trends of harmonic amplitudes and ultrasonic coefficients are measured during fatigue bending testing of materials such as 45 steel, 2024 aluminum alloy and 304 stainless steel. The results shows: in elastic phase, the ratios of harmonic and fundamental waves monotonically increase with fatigue life, and in plastic phase, deformations appear and micro-cracks expand into macro-cracks in materials, the ratios firstly decrease and then increase with fatigue life. However the quadratic sums of nonlinear coefficient are approximately linear with the fatigue life. Therefore, when the relationship between the quadratic sums and fatigue life is known, it can be used to characterize fatigue state of metal materials.

scholarly journals Fatigue Damage Evaluation of Compressor Blade Based on Nonlinear Ultrasonic Nondestructive Testing

2021 ◽  
Vol 9 (12) ◽  
pp. 1358
Author(s):  
Pengfei Wang ◽  
Weiqiang Wang ◽  
Sanlong Zheng ◽  
Bingbing Chen ◽  
Zengliang Gao
Keyword(s):  
Fatigue Damage ◽  
Ultrasonic Testing ◽  
Evaluation Method ◽  
Early Stage ◽  
Nonlinear Coefficient ◽  
Crack Size ◽  
Compressor Blade ◽  
Three Dimensional Model ◽  
Micro Cracks ◽  
Nonlinear Ultrasonic

Nonlinear ultrasonic testing is highly sensitive to micro-defects and can be used to detect hidden damage and defects inside materials. At present, most tests are carried out on specimens, and there are few nonlinear ultrasonic tests for fatigue damage of compressor blades. A vibration fatigue test was carried out on compressor blade steel KMN, and blade specimens with different damage degrees were obtained. Then, the nonlinear coefficients of blade specimens were obtained by nonlinear ultrasonic testing. The results showed that the nonlinear coefficient increased with the increase in the number of fatigue cycles in the early stage of fatigue, and then the nonlinear coefficient decreased. The microstructures were observed by scanning electron microscopy (SEM). It was proven that the nonlinear ultrasonic testing can be used for the detection of micro-cracks in the early stage of fatigue. Through the statistical analysis of the size of the micro-cracks inside the material, the empirical formula of the nonlinear coefficient β and the equivalent crack size were obtained. Combined with the β–S–N three-dimensional model, an evaluation method based on the nonlinear ultrasonic testing for the early fatigue damage of the blade was proposed.

scholarly journals Research on Fatigue Damage of Compressor Blade Steel KMN-I Using Nonlinear Ultrasonic Testing

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Pengfei Wang ◽  
Weiqiang Wang ◽  
Jianfeng Li
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Ultrasonic Testing ◽  
Early Stage ◽  
Compressor Blade ◽  
Nonlinearity Parameter ◽  
Nonlinear Ultrasonic ◽  
Blade Steel ◽  
Scanning Electron ◽  
Peak Value

The fatigue damage of compressor blade steel KMN-I was investigated using nonlinear ultrasonic testing and the relation curve between the material nonlinearity parameter β and the fatigue life was obtained. The results showed that the nonlinearity parameter increased first and then decreased with the increase of the fatigue cycles. The microstructures were observed by scanning electron microscopy (SEM). It was found that some small defects like holes and pits appeared in the material matrix with the increase of the fatigue cycles, and the nonlinearity parameter increased correspondingly. The nonlinearity parameter reached the peak value when the microcracks initiated, and the nonlinearity parameter began to decrease when the microcracks further propagated to macrocracks. Therefore, it is proved that the nonlinearity parameter can be used to characterize the initiation of microcracks at the early stage of fatigue, and a method of evaluating the fatigue life of materials by nonlinear ultrasonic testing is proposed.

scholarly journals Combined Damage Index to Detect Plastic Deformation in Metals Using Acoustic Emission and Nonlinear Ultrasonics

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2151 ◽  
Author(s):  
Lu Zhang ◽  
Sepideh Oskoe ◽  
Hongyu Li ◽  
Didem Ozevin
Keyword(s):  
Plastic Deformation ◽  
Acoustic Emission ◽  
Residual Life ◽  
Nonlinear Coefficient ◽  
Damage Index ◽  
Microscopic Analysis ◽  
Sensor Data ◽  
Structural Components ◽  
Nonlinear Ultrasonics ◽  
Absolute Energy

Understanding the amount of degradation using nondestructive evaluation (NDE) methods provides an effective way of determining the fitness to service and the residual life of structural components. Due to uncertainties introduced by the single NDE method, a combined damage index using multi-sensor data increases the reliability of damage assessment. In this paper, the outputs of three NDE methods including acoustic emission (AE), linear ultrasonics (LUT), and nonlinear ultrasonics (NLUT) are merged to identify the amount of plastic deformation in aluminum 1100. The sensitivities of individual and combined methods to microstructural changes are evaluated. The coupon samples are loaded up to different strain levels and then unloaded. AE data is recorded in real time and ultrasonic data is recorded from the unloaded samples. The major features combined in the damage index are cumulative AE absolute energy and nonlinear coefficient. The microstructural state is verified with microscopic analysis and hardness testing. The developed damage index can nondestructively assess the amount of plastic deformation with higher reliability.

scholarly journals HCF Failure Modes and Mechanisms of Dissimilar Welds of Martensite/Austenite Metals at Elevated Temperature

2019 ◽  
Vol 269 ◽  
pp. 03004
Author(s):  
Chendong Shao ◽  
Haichao Cui ◽  
Fenggui Lu ◽  
Zhuguo Li
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
Fatigue Cracks ◽  
High Stress ◽  
Crack Origin ◽  
Dissimilar Welds ◽  
Micro Cracks ◽  
High Stress Level

In this paper, the high cycle fatigue (HCF) behavior and failure mechanism of welded joint for martensite/austenite dissimilar metals were systematically investigated at elevated temperature. The HCF tests were performed at different elevated temperatures of 550, 600 and 630°C with stress ratio of -1. Most tested specimens failed in the heat affected zone (HAZ) of martensite metal, while minor failure occurred on the weld metal (WM) with comparatively more scattered fatigue life. Fatigue crack in the WM initiated from welding defects like porosities and non-metallic inclusions. For failures in the 10Cr-HAZ, fatigue cracks nucleated from the interior matrix of HAZ, which possessed lower hardness. The initiation of cracks was divided into facet type crack origin (FTCO) and rough type crack origin (RTCO). FTCO was observed for specimens tested at high stress amplitude with fatigue life below 107 cycles. Micro-cracks were observed at prior austenite grain boundaries (PAGBs) at high stress level. Micro-cracks preferred to form at martensite lath boundaries and coalesced into macro-crack leading to the formation of RTCO under the condition of lower stress.

Evaluation of the Fatigue Life in Aluminum Alloy Welded Joint by Nonlinear Ultrasonic Testing

2013 ◽  
Vol 762 ◽  
pp. 673-679
Author(s):  
Tie Gang ◽  
Chu Hao Wan ◽  
Rong Hua Zhu ◽  
Li Bin Zhao
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Ultrasonic Testing ◽  
Welded Joint ◽  
Ultrasonic Waves ◽  
Second Order ◽  
Testing Method ◽  
Nonlinear Ultrasonic ◽  
6N01 Aluminum Alloy

Fatigue is a common phenomenon in welded structures. Prediction of fatigue life of welded joints in-service is still an unsolved puzzle by the conventional linear ultrasonic testing method. However, the nonlinear ultrasonic waves or the acoustic nonlinear signal can provide clear signs of the accumulative fatigue damage in materials, as reported by a number of researchers. Hence, the nonlinear ultrasonic testing method has revealed a tremendous potential for fatigue damage evaluation. This paper presents a study to characterize the fatigue damage using the analysis of the signal characteristics and a new nonlinear parameter. Based on the very high-cycle fatigue testing results for a 6N01 aluminum alloy welded joint, the relationship between the amplitude of the second-order harmonic and fatigue cycling has been established. The nonlinear ultrasonic system test results show that the amplitude of the second-order harmonic increases at the early fatigue stage, with further increase in cyclic loading until reaching a peak. Metallographic examinations show that a fatigue crack will nucleate in the weld joint in the stage as the amplitude reaches the peak value. Finally, theoretical and experimental results confirm that the amplitude of the second-order harmonic is useful for assessing the fatigue life of a 6N01 aluminum alloy welded joint.

scholarly journals Properties of GH4169 Superalloy Characterized by Nonlinear Ultrasonic Waves

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Hongjuan Yan ◽  
Chunguang Xu ◽  
Dingguo Xiao ◽  
Haichao Cai
Keyword(s):  
Fatigue Life ◽  
Yield Strength ◽  
Tensile Stress ◽  
Fatigue Testing ◽  
Extreme Values ◽  
Nonlinear Coefficient ◽  
Ultrasonic Waves ◽  
Nonlinear Ultrasonic ◽  
Nonlinear Wave Motion ◽  
Gh4169 Superalloy

The nonlinear wave motion equation is solved by the perturbation method. The nonlinear ultrasonic coefficientsβandδare related to the fundamental and harmonic amplitudes. The nonlinear ultrasonic testing system is used to detect received signals during tensile testing and bending fatigue testing of GH4169 superalloy. The results show that the curves of nonlinear ultrasonic parameters as a function of tensile stress or fatigue life are approximately saddle. There are two stages in relationship curves of relative nonlinear coefficientsβ′ andδ′ versus stress and fatigue life. The relative nonlinear coefficientsβ′ andδ′ increase with tensile stress when tensile stress is lower than 65.8% of the yield strength, and they decrease with tensile stress when tensile stress is higher than 65.8% of the yield strength. The nonlinear coefficients have the extreme values at 53.3% of fatigue life. For the second order relative nonlinear coefficientβ′, there is good agreement between the experimental data and the comprehensive model. For the third order relative nonlinear coefficientδ′, however, the experiment data does not accord with the theoretical model.

Study on Fatigue Life of Cement Stabilized Macadam Base during Crack Expanding Phase Based on Accelerated Loading Test

2020 ◽  
Vol 846 ◽  
pp. 213-219
Author(s):  
Wei Zeng ◽  
Rong Ma ◽  
Fei Chen ◽  
Ke Zhong ◽  
Xiao Chen Ma
Keyword(s):  
Fatigue Life ◽  
Residual Life ◽  
Fatigue Cracks ◽  
Base Layer ◽  
Fatigue Properties ◽  
Rigid Base ◽  
Correction Coefficient ◽  
Loading Test ◽  
Degradation Model ◽  
Pavement Maintenance

The evaluation for remaining life of semi-rigid base layer has a significant effect on pavement maintenance scheduling like resurface or rehabilitation. An accurate evaluation can obviously improve the pavement maintenance, which could also utilize the original pavement structure in a rationally way, and optimize the entire maintenance plan. In this study, a series of laboratory investigation were conducted on the cement stabilized macadam materials. The fatigue life and deterioration characteristics of cement stabilized macadam materials were analyzed during the pre-cracked (fatigue cracks occurring) phase and crack expanding phase by laboratory fatigue test and full-scale accelerated loading test, respectively. Then, a fatigue life correction coefficient of the crack expanding phase was used to analyze the fatigue properties of the semi-rigid base, and a modulus degradation model of the semi-rigid base life was characterized. It proved to be convenient to evaluate the residual life of semi-rigid base according to the modulus.

Online fatigue crack prognosis using nonlinear ultrasonic modulation

2019 ◽  
Vol 18 (5-6) ◽  
pp. 1889-1902 ◽  
Author(s):  
Hyung Jin Lim ◽  
Hoon Sohn
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Power Function ◽  
Estimation Method ◽  
Target Structure ◽  
Fatigue Index ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Nonlinear Ultrasonic ◽  
Remaining Fatigue Life

This article presents an online remaining fatigue life estimation (prognosis) technique using nonlinear ultrasonic modulation. When two ultrasonic inputs at two distinct frequencies are introduced to a structure with a fatigue crack, modulation components at the sum and difference of input frequencies are generated owing to crack opening and closing. First, a fatigue index is defined for prognosis and extracted from nonlinear ultrasonic modulation measurement. Subsequently, it is shown that the fatigue index is expressed as a simple power function of loading cycles applied to a target structure based on the Nazarov–Sutin and Paris–Erdogan theories. Then, the real-time remaining fatigue life estimation method is proposed by fitting the power function to online data obtained from the target structure. The performance of the proposed prognosis technique is evaluated using either notched or welded aluminum (6061-T6) plate specimens.

scholarly journals Evaluation of Damage Process of a Coating by Using Nonlinear Ultrasonic Method

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 440
Author(s):  
Chunguang Xu ◽  
Lei He ◽  
Shiyuan Zhou ◽  
Dingguo Xiao ◽  
Pengzhi Ma
Keyword(s):  
Tensile Stress ◽  
Order Parameter ◽  
Evaluation Method ◽  
Early Stage ◽  
Ultrasonic Method ◽  
Nonlinear Coefficient ◽  
Damage Index ◽  
Second Order ◽  
External Loading ◽  
Nonlinear Ultrasonic

During the service or external loading of the surface coating, the damage accumulation may develop in the coating or at the interface between the substrate and the coating, but it is difficult to measure directly in the early stage, so the acoustic nonlinear parameters are used as the early damage index of the coating. In this paper, the nonlinear wave motion equation is solved by the perturbation method and the new relationship between the relative ratio of second-order parameter and third-order parameter was derived. The nonlinear ultrasonic testing system is used to detect received signals during tensile testing of for the specimen with Al2O3 coatings. It is found that when the stress is less than 260 MPa, the appearance of the coating has no obvious change, but the nonlinear coefficients measured by the experiment increase with the increase of the tensile stress. By comparing the curves of nonlinear coefficients and stress respectively, the fluctuation of curves the second-order nonlinear coefficient A2 and the relative nonlinear coefficient β′ to stress is relatively small, and close to the linear relationship with the tensile stress, which indicates that the two parameters of the specimen with Al2O3 coatings are more sensitive to the bonding conditions, and can be used as an evaluation method to track the coating damage.

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