Wave Peak Research Articles

Breaking wave field statistics with a multi-layer model

The statistics of breaking wave fields are characterised within a novel multi-layer framework, which generalises the single-layer Saint-Venant system into a multi-layer and non-hydrostatic formulation of the Navier–Stokes equations. We simulate an ensemble of phase-resolved surface wave fields in physical space, where strong nonlinearities, including directional wave breaking and the subsequent highly rotational flow motion, are modelled, without surface overturning. We extract the kinematics of wave breaking by identifying breaking fronts and their speed, for freely evolving wave fields initialised with typical wind wave spectra. The$\varLambda (c)$distribution, defined as the length of breaking fronts (per unit area) moving with speed$c$to$c+{\rm d}c$following Phillips (J. Fluid Mech., vol. 156, 1985, pp. 505–531), is reported for a broad range of conditions. We recover the$\varLambda (c) \propto c^{-6}$scaling without wind forcing for sufficiently steep wave fields. A scaling of$\varLambda (c)$based solely on the root-mean-square slope and peak wave phase speed is shown to describe the modelled breaking distributions well. The modelled breaking distributions are in good agreement with field measurements and the proposed scaling can be applied successfully to the observational data sets. The present work paves the way for simulations of the turbulent upper ocean directly coupled to a realistic breaking wave dynamics, including Langmuir turbulence, and other sub-mesoscale processes.

The Predictive Value of R Wave Peak Time to Detect Thrombus Burden in St-segment Elevation Myocardial Infarction: A Retrospective Cohort Study in a Tertiary Medical Center.

Background: Patients with higher thrombus burden have higher procedural complications and more long-term adverse cardiac events. Detecting patients with high thrombus burden (HTB) before coronary intervention could help avoid procedural complications. Objective: The research aimed to analyze the R wave peak time (RWPT) on the electrocardiogram to predict thrombus burden before coronary angiography in patients with acute ST-segment elevation myocardial infarction (STEMI). Materials and Methods: A total of 159 patients with STEMI were included in the study conducted at a tertiary medical center. The thrombolysis in myocardial infarction (TIMI) thrombus scale was applied to assess the thrombus burden. TIMI thrombus grades 0, 1, 2, and 3 were accepted as low; 4 and 5 had HTB. RWPT was measured from the beginning of the QRS complex to the R-peak from the leads pointing to the infarct-related artery. Results: Patients were divided into two groups according to their angiographically defined thrombus burden as low and high. The low thrombus burden group (LTB) comprised fifty-four patients, whereas the HTB group comprised 105 patients. In the LTB group, RWPT was 47.96 ± 9.17 ms, and in the HTB group was 53.58 ± 8.92 ms; it was significantly longer (p < 0.01). Receiver operating characteristic analysis showed that a cut-off value of preprocedural RWPT of > 46.5 ms predicted the occurrence of HTB with a sensitivity and specificity of 87.62% and 51.85%, respectively (AUC 0.682, 95% CI 0.590-0.774, p < 0.001). Conclusion: The present study evaluated the relationship between the RWPT and thrombus burden in STEMI patients. Based on the results, RWPT is an independent predictor of HTB.

Study on competition mechanism of deformation modes of U-shaped bellows under internal pressure

Bellows are widely used in various modern engineering fields, especially in storage and transportation of floating liquefied natural gas (FLNG) system on the sea. They are prominent pressure vessels with internal pressure load as a common working condition. Concerning common U-shaped bellows in this study, the cross-section of the bellows is divided into three segments, wave peak semicircle, straight ring plate, and wave trough semicircle, to establish mechanical models. Bellows with different design parameters have different mechanical properties, producing different deformation modes of the cross-section of the bellows under the action of internal pressure load. The competition mechanism of deformation modes of different parts in the cross-section under internal pressure is discussed. Furthermore, the sensitivity analysis of design parameters is performed and the bellows with competition balance between different parts were determined, which can keep the cross-section maintaining the “U” shape without global deformation under internal pressure. In addition, the radial displacement of bellows under internal pressure is theoretically derived to improve the deep discussion on competition mechanism of deformation modes. Accordingly, the relevant theoretical results are compared with finite element simulations, illustrating the reliability of the theoretical analysis. This study may serve as a reference for the design and analysis of the structure of bellows.

Static Liquefaction Assessment Combining Shear Wave Velocity, Peak Strength and Soil Grading

A large set of undrained compression triaxial tests was carried out on different types of cohesionless soils, from sands to silty sands and silts. Shear wave velocity measurements were also carried out. These tests exhibit distinct state transitions ranging from flow liquefaction to strain softening or strain hardening. With the purpose of defining a framework to assess soil liquefaction, it was found that the ratio between the shear wave velocity (VS0) and the peak undrained deviatoric stress (qpeak), VS0/qpeak, could be accurately used to define a boundary between liquefaction and strain hardening for sands and between strain softening and strain hardening for silty sands and silts. Since this ratio is a function of the tested material, the prediction of these boundaries can be made as a function of soil grading, namely via the coefficient of uniformity, CU. Despite not being regarded as a strong geomechanical parameter, CU is easily determined from a grain-size distribution test and has an empirically proven correlation with critical state parameters.

Dynamic Mechanical Behavior of Rock Specimens with Varying Joint Roughness and Inclination under Impact Load

The influence of joint roughness and inclination on the dynamic mechanical properties of rocks is a prominent research area. In order to investigate the effects of joint roughness and inclination on the dynamic mechanical properties of jointed rocks, impact tests were conducted using a spilt Hopkinson pressure bar (SHPB) apparatus for prefabricated serrated joint cement mortar specimens with varying joint roughness and inclination. The failure mode, stress wave propagation characteristics, peak stress, and stress wave energy transfer law under impact load were analyzed. The results indicate that both joint inclinations and joint roughness coefficients (JRC) have a strong influence on the failure mode, peak stress, and stress wave energy transfer of jointed specimens. The jointed specimens exhibit three distinct failure modes under impact load, namely splitting tensile failure, shear slip failure, and compound failure of splitting tensile and shear. The peak stress initially decreases then increases with the increase in joint inclination angle, namely a V-shape variation, while it gradually increases with JRC increasing from 0 to 20. Jointed specimens exhibit the lowest peak stress at an inclination angle of 45° and JRC of 0. The variation of transmitted energy coefficient is similar to the peak stress, while the variation of reflected energy coefficient is opposite to the peak stress. At joint inclination angles of 0° or 90°, the reflected energy coefficient increases with the increase of JRC from 0 to 20, while the transmitted energy decreases. However, when the joint inclination angle is in the range of 30° to 60°, the reflected energy coefficient gradually decreases with JRC increasing, while the transmitted energy coefficient gradually increases.

A Retrospective Clinico-demographic Study of SARS-CoV-2 Patients at a Tertiary Care Centre, Assam, North-East India during the Second Wave of the Pandemic

Assam along with the entire country of India experienced an unprecedented rise in SARS-CoV-2 infections and its fatal repercussions. Our earlier study during the first wave of the pandemic provided insight into the relationship between age and gender in COVID-19 cases. The present follow-up study is a retrospective Clinico-demographic Study of 1110 SARS-CoV-2 Patients during the Second Wave of the Pandemic. Out of the 1110 positive cases studied during the peak of the COVID-19 second wave, a total of 624 (56.21%) infected individuals were male, and 486 (43.7%) individuals were female. However, individuals in the age group 18-30 showed significant infection of COVID-19 cases (p&gt;0.00001) suggesting higher susceptibility in this age group irrespective of gender. In addition, the highest number of positive symptomatic cases in males were seen in the age group of 31-40 years followed by the age group of 18-20 years. The clinical profiles of all COVID-19-infected symptomatic patients were also analyzed. While females were more likely to experience symptoms like nausea, bodily aches, and abdominal pain (p&lt; 0.0001*). Male patients were substantially more likely than female patients to experience chest pain (p = 0.0006) and diarrhea (p &lt;0.0001*). Additionally, throughout the duration of the study, 115 samples were sent over for sequencing in which the delta variant [B.1.617.2] was found to be the most common strain during the Second Wave. Our research will add to the body of information that might help develop data-driven North-East India-centric recommendations to improve the preparedness to respond to similar future emergencies

Experimental analysis of Tsunami–Current interaction in river channel

The 2011 Tohoku Tsunami caused severe human and property damage along the east coast of Japan. In particular, the tsunami introduced through the river mouth damaged inland areas as it traveled up the river. In this study, a laboratory experiment was performed by applying funnel-shaped river mouth characteristics to investigate the hydraulic characteristics of a tsunami traveling up a river. In the river channel, the tsunami and wave heights were increased by the non-linear interaction between the tsunami and river current, which intensified as the river flow velocity increased. The river current in the opposite direction delayed tsunami propagation, thereby reducing the average celerity. The dispersion relation of the tsunami increased the time difference between the large first peak and small second peak. Additionally, the river current increased the effective volume of the tsunami wave peak. These hydraulic phenomena occurred because the flow characteristics of the tsunami are stronger than those of oscillating waves in the non-linear interaction between the tsunami and river current.

Redefining QRS transition to confirm left bundle branch capture during left bundle branch area pacing.

QRS transition criteria during dynamic manoeuvers are the gold-standard for non-invasive confirmation of left bundle branch (LBB) capture, but they are seen in <50% of LBB area pacing (LBBAP) procedures. We hypothesized that transition from left ventricular septal pacing (LVSP) to LBB pacing (LBBP), when observed during lead penetration into the deep interventricular septum (IVS) with interrupted pacemapping, can suggest LBB capture. QRS transition during lead screwing-in was defined as shortening of paced V6-R wave peak time (RWPT) by ≥10 ms from LVSP to non-selective LBBP (ns-LBBP) obtained during mid to deep septal lead progression at the same target area, between two consecutive pacing manoeuvres. ECG-based criteria were used to compared LVSP and ns-LBBP morphologies obtained by interrupted pacemapping. Sixty patients with demonstrated transition from LVSP to ns-LBBP during dynamic manoeuvers were compared to 44 patients with the same transition during lead screwing-in. Average shortening in paced V6-RWPT was similar among study groups (17.3 ± 6.8 ms vs. 18.8 ± 4.9 ms for transition during dynamic manoeuvres and lead screwing-in, respectively; p = 0.719). Paced V6-RWPT and aVL-RWPT, V6-V1 interpeak interval and the recently described LBBP score, were also similar for ns-LBBP morphologies in both groups. LVSP morphologies showed longer V6-RWPT and aVL-RWPT, shorter V6-V1 interpeak interval and lower LBBP score punctuation, without differences among the two QRS transition groups. V6-RWPT < 75 ms or V6-V1 interpeak interval > 44 ms criterion was more frequently achieved in ns-LBBP morphologies obtained during lead screwing-in compared to those obtained during dynamic manoeuvres (70.5% vs. 50%, respectively p = 0.036). During LBBAP procedure, QRS transition from LVSP to ns-LBBP can be observed as the lead penetrates deep into the IVS with interrupted pacemapping. Shortening of at least 10 ms in paced V6-RWPT may serve as marker of LBB capture.

The reverse prediction of the ship principal dimensions based on the Kelvin ship waves

This study examines the impact of the ship’s principal dimensions on the steady waves generated by the ship, and practical approaches are subsequently proposed to reverse-predict the ship’s length, width, draught, and related parameters. The ship length Ls and the related Froude number Fr=Vs/gLs are found to relate with the quasi-period of the divergent wave amplitude function. The ship length can be predicted within an accuracy of ±5% overall based on the two-point wake model considered here. The effects of the ship width and the ship draught are different, and a practical method is proposed here to predict the ship width and the ship draught based on the simplification of the Hogner theory. A noteworthy discovery of this research is that the hull form details have a more pronounced impact on the trough of the divergent waves compared to the transverse waves and the peaks of the divergent waves.

Wave forces and moments on concave and vertical front caissons supported on piles

ABSTRACT The present paper details the total wave-induced forces and moments on the circular cum parabola shape (CPS-PSB) and vertical front pile-supported breakwaters (VF-PSB) through a comprehensive experimental investigation under intermediate to deep water conditions. The model was subjected to the action of random waves with peak wave periods ranging from 1s to 2.6s. The total wave forces and moments were measured using a six-component force balance. VF-PSB experiences maximum wave force at lower submergence and the vertical force decreases exponentially as relative depth increases. In the case of CPS-PSB, the variation of vertical force with relative depth is similar to the energy loss. The horizontal wave forces on both PSB models decrease with their relative submergence as the wave exposure frontal area. The induced moments are higher for longer waves and higher submergence. CPS-PSB experiences lesser force and moment than VF-PSB.

Evolution mechanism of fracture interface wave and microstructure during resistance butt spot welding

In this work, the interface wave was first shown in resistance butt spot welding of titanium (Ti) alloy and stainless steel (SS) as in explosive welding and magnetic pulse welding. Interface wave exhibited a fracture mode in the joint, so which were called fracture interface waves. The wavelength and the peak of the fracture interface wave weaken from the center of the joint to the outer edge. The formation of the wave is closely related to the interface microstructure. Fracture interface wave would have a direct impact on the joint properties. Analysis of the formation of fracture interface wave is helpful to improve the quality of the joint. Thermo-electric-mechanical-magnetic-flow coupling in resistance butt spot welding makes it difficult to explain the forming mechanism completely by existing theory and experiment methods. The key conditions of fracture interface wave propagation were analyzed by means of thermo-electric-mechanical numerical simulation. The formation process was explained in addition to the microstructure, mechanical properties.

Intimate Partner Violence among women living in families with children under the poverty line and its association with common mental disorders during COVID-19 pandemics in Ceará, Brazil

BackgroundIntimate partner violence (IPV) is a pervasive public health issue that affects millions of women worldwide. Women living below the poverty line experience higher rates of violence and fewer resources to escape or cope with the abuse, and the COVID-19 pandemic has significantly impacted women’s economic well-being worldwide. We conducted a cross-sectional study in Ceará, Brazil, on women in families with children living below the poverty line at the peak of the second wave of COVID to assess the prevalence of IPV and its association with common mental disorders(CMD).MethodsThe study population comprised families with children up to six years of age who participated in the cash transfer program “Mais Infância”. The families selected to participate in this program must meet a poverty criterion: families must live in rural areas, in addition to a monthly per capita income of less than US$16.50 per month. We applied specific instruments to evaluate IPV and CMD. To access IPV, we used the Partner Violence Screen (PVS). The Self-Reporting Questionnaire (SRQ-20) was used to assess CMD. To verify the association between IPV and the other evaluated factors with CMD, simple and hierarchical multiple logistic models were used.ResultsOf the 479 participant women, 22% were positively screened for IPV (95% CI 18.2–26.2). After multivariate adjustment, the chances of CMD are 2.32 higher in women exposed to IPV than in those not exposed to IPV ((95%CI 1.30–4.13), p value = 0.004). CMD was also associated with job loss during the COVID-19 pandemic (ORa 2.13 (95% CI 1.09–4.35), p-value 0.029). In addition to these, separate or single marital status, as well as non-presence of the father at home and food insecurity were associated with CMD.ConclusionWe conclude that the prevalence of intimate partner violence in families with children up to six years of age living below the poverty line in Ceará is high and is associated with greater chances of common mental disorders in mothers. Also, job loss and reduced access to food caused by the Covid 19 pandemic exacerbated both phenomena, constituting a double burden generator factor on mothers.

Perturbation indicator for Hall effect thruster operating state based on statistical characteristics of breathing oscillation time scale signals

The failure of Hall effect thruster (HET) is usually the result of the accumulation of several tiny abnormal disturbances during operation. Timely and accurate early warning of perturbations is an important guarantee for the normal operation of thrusters. In this study, when the perturbation rate of HET signal (anode voltage or anode flow rate) is −4% to 4%, the time scale signal of breathing oscillation (BO) in the frequency range of 10 kHz to 100 kHz is statistically analyzed. Experiments show that when the signal is perturbed, the balance between ionization and acceleration of plasma in the discharge channel is destroyed, resulting in the dwell time of the wave peaks and valleys of BO in the far-zero region with the perturbation law, which visually shows that the number of scattered points at the corresponding current value changes regularly. According to the above statistical characteristics, this paper proposes a new condition monitoring index, namely the number of scattered points in the wave peaks side of the far-zero point area, and designs a perturbation indicator for the operating condition of the HET. Compared with direct monitoring of discharge current in engineering, this indicator can amplify the influence of the perturbation signal on BO, and has better identification and accuracy. Meanwhile, the indicator does not use invasive measurement and complex equipment, and is promising to be applied to the monitoring and diagnosis of the perturbation operation state of the on-orbit thruster.

Right ventricle injury in RCA occlusion: Exploration using precordial bipolar leads and surrogate vectorcardiograms.

Precordial Bipolar Leads (PBL) provide new electrocardiographic information derived from standard 12‑lead ECG recordings. To explore the usefulness of PBL in patients with acute right coronary artery (RCA) occlusion. Sixteen patients undergoing elective percutaneous transluminal coronary angioplasty (PTCA) were studied before and after RCA occlusion and their data were processed with new methods based on PBL. The findings were: 1. In PBL V2-V1, strong systolic currents of injury moving in the left to right direction coexist with those directed towards leads II, III and aVF. 2. Changes in the time of the peaks of the QRS waves do not alter the duration of the QRS. 3. The QRS loops of the surrogate VCG generated show that, during ischemia, the time changes in the peak of the QRS waves displayed in one axis are the consequence of an increase in the amplitude of the waves observed in the perpendicular axis. 4. The use of two simultaneous dimensions (transverse and frontal planes) facilitates the location of the J-point. 5. In the surrogate VCGs of this group of patients, J-point and ST segment shifts produced an image that reminded the Greek letter omega (Ω). 6. The QRS wave changes, in time and amplitude, explained the rotational changes and the ischemic distortions of the surrogate VCG loops. Computerized processing of ECG data appears to provide new and valuable diagnostic data in patients with acute RCA occlusion. The loops revealed important information related to systolic currents of injury. Because these methods use routine 12‑lead ECG data, the procedure is based only in software applications.

Investigation of Acoustic Emission Wave Propagation Pattern with Defect Locations in a Multilayer Structure

Acoustic emission (AE) is used to monitor conditions of various structures across many industrial sectors, including containment vessel or storage tank of nuclear materials. Periodic monitoring, inspection, and analysis of structure conditions can help prevent failure and accidents. Understanding the transient elastic waves in multi-layered structures (planar or rounded types) has long been of great interest. This paper experimentally investigates changes in AE wave propagation patterns in multilayer planar structures (detecting and assessing the effect of coating layers, assumed surrogate of deposits or protective layer). Epoxy phenolic coated two mild steel plates were assembled (without any adhesion), and two piezoelectric AE sensors were placed on the coating layer. The pencil lead break (PLB) test was used to initiate the AE waves from the surface and cross-section of different layers. From wavelet transforms (WT) analysis, significant energy zone changes were observed up to the 450 kHz frequency level with PLB on the surface and cross-section of different layers. Love wave propagation on the coated plate structure resulted in wave pattern changes with PLB locations and layers. Wave duration, energy, energy ratio, and peak amplitude levels were also analysed to characterise the AE wave pattern relationship with defect location in a multilayer plate-like (planar) structure. The approaches used in this work could potentially be useful in providing a greater understanding of defects within multilayer nuclear containment structures, and also offering an alternative way to monitor corrosion related degradation of structures with insulations.

Non-Invasive Pressure-Only Aortic Wave Intensity Evaluation Using Hybrid Fourier Decomposition-Machine Learning Approach.

The clinical significance of the wave intensity (WI) analysis for the diagnosis and prognosis of the cardiovascular and cerebrovascular diseases is well-established. However, this method has not been fully translated into clinical practice. From practical point of view, the main limitation of WI method is the need for concurrent measurements of both pressure and flow waveforms. To overcome this limitation, we developed a Fourier-based machine learning (F-ML) approach to evaluate WI using only the pressure waveform measurement. Tonometry recordings of the carotid pressure and ultrasound measurements for the aortic flow waveforms from the Framingham Heart Study (2640 individuals; 55% women) were used for developing the F-ML model and the blind testing. Method-derived estimates are significantly correlated for the first and second forward wave peak amplitudes (Wf1, r = 0.88, p 0.05; Wf2, r = 0.84, p 0.05) and the corresponding peak times (Wf1, r = 0.80, p < 0.05; Wf2, r = 0.97, p 0.05). For backward components of WI (Wb1), F-ML estimates correlated strongly for the amplitude (r = 0.71, p 0.05) and moderately for the peak time (r = 0.60, p 0.05). The results show that the pressure-only F-ML model significantly outperforms the analytical pressure-only approach based on the reservoir model. In all cases, the Bland-Altman analysis shows negligible bias in the estimations. The proposed pressure-only F-ML approach provides accurate estimates for WI parameters. The pressure only F-ML approach introduced in this work expand the clinical usage of WI into inexpensive and non-invasive settings such as wearable telemedicine.

Diagnostic accuracy of different ECG-based algorithms in wide QRS complex tachycardia: a systematic review and meta-analysis

ObjectiveSeveral ECG-based algorithms have been proposed to enhance the effectiveness of distinguishing Wide QRS complex tachycardia (WCT), but a comprehensive comparison of their accuracy is still lacking. This meta-analysis aimed...

R wave peak time and no reflow following primary percutaneous coronary intervention: Immediate and short-term outcomes.

No reflow (NR) remains an important constraint in management of ST elevation myocardial Infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI). Most ECG parameters validated till date including ST resolution are postprocedural. R wave peak time (RWPT) is a dynamic parameter and reflects conduction delay in ischaemic myocardium in selected leads supplied by infarct related artery (IRA). The present study was undertaken to see whether preprocedural RWPT per se or RWPT following primary PCI can predict persistence of NR along with immediate and short-term clinical outcome. 200 patients were enrolled after exclusion. Clinical, Biochemical, ECG parameters including RPWT and angiographic parameters (pre- and post-procedure) were recorded. ECG papers was analysed using digital image processing software (http://imagej.nih.gov/ij/). All patients were followed up for 6months. NR was observed in 35% of the patients. Age, Diabetes, symptom to balloon time, higher thrombus burden, peak CPK-MB level (pre and post procedure) were significantly higher in NR group. On ECG analysis, baseline RWPT, QRS duration and pathological Q wave were significantly higher in NR group. On multivariate analysis, age (OR 1.10 CI 1.00-1.21 P=0.04), thrombus grade≥3 in IRA (OR 12.38 CI 2.08-73.58 P=0.006), symptom to balloon time (OR 2.18 CI 1.6-3.0 P<0.001) and baseline RWPT on ECG [OR 1.86 CI 1.24-2.78, P=0.003] were found to be independent predictors of NR. Increase in RWPT following primary PCI was found to both highly sensitive and specific for diagnosing persistence of NR after primary PCI. Follow up at the end of 6months has shown that patients with increased RWPT following primary PCI had worse short-term cardiovascular outcomes compared to those with decreased RWPT following primary PCI. Baseline RWPT is a significant predictor of NR in patients of STEMI undergoing primary PCI. A persistently increased RWPT following primary PCI is also a highly sensitive and specific ECG marker of persistence of NR which is associated with adverse short-term clinical outcome.

Performance evaluation of a global CMIP6 single forcing, multi wave model ensemble of wave climate simulations

A performance evaluation is conducted for a state-of-the-art Coupled Model Intercomparison Project Phase 6 (CMIP6)-derived ensemble of global wave climate simulations. A single-model (forcing), single-scenario approach is considered to build the ensemble, where the differentiating factor between each member is the wave model or physics parameterization used to simulate waves. The 7-member ensemble is evaluated for the 1995-2014 historical period, highlighting the impact of the multiple source terms on its robustness. The ensemble’s ability to accurately represent the present wave climate is assessed through an extensive comparison with long-term ERA5 reanalysis and in-situ observational data. Relevant aspects such as the depiction of extremes and natural wave climate variability are analyzed, and inter-member uncertainties are quantified. Overall, the results indicate that the ensemble is able to accurately simulate the global wave climate, regarding the significant wave height (HS), mean and peak wave periods (Tm and Tp, respectively) and mean wave direction (MWD). However, we show that using multiple wave models and parameterizations should be cautiously considered when building ensembles, even under the same forcing conditions. Model-parameterization-induced ensemble spreads during the historical period are found to be high, compromising the robustness of projected changes in wave parameters towards the end of the 21st century across several areas of the global ocean.

Identification of Subsurface Mesoscale Crack in Full Ceramic Ball Bearings Based on Strain Energy Theory

Subsurface mesoscale cracks exist widely in the outer ring of full ceramic ball bearings (FCBBs), which is a potential threat for the stable operation of related devices such as aero engines, food processing machinery, and artificial replacement hip joints. This paper establishes a dynamic model of subsurface mesoscale cracks in the outer ring of FCBBs based on strain energy theory, and the influence of different crack lengths on the running state is analyzed. The existence of mesoscale cracks is regarded as weakening on the stiffness coefficient, and the deterioration degree of outer ring stiffness of subsurface cracks is thereby quantified. It is found that a small wave peak appears in the vibration time-domain signal when there is a mesoscale crack on the outer ring subsurface, and the crack evolution is evaluated by the amplitude of the corresponding feature frequency. Finally, the accuracy of the model is verified by experiments. The model realizes the identification and degree evaluation of subsurface mesoscale cracks in FCBBs, and provides theoretical references for the diagnosis and status monitoring for FCBB rotor systems.