Notch Position Research Articles

Fracture behavior, mechanical properties, and microstructural analysis of vacuum automated GMAW welded dissimilar A353 and A516 steels for pressure vessels

In this study, the performance of the automatic gas metal arc welding (GMAW) process in vacuum for similar and dissimilar joints of A353 and A516 steel plates with different thicknesses was intensively evaluated. Fracture of all vacuum-welded samples occurred in the heat-affected zone (HAZ) of A516 steel, highlighting the significant influence of HAZ microstructure and width on the cryogenic impact energy and strength of these joints. According to microscopic observations and impact tests, the fractures were fully ductile for notches in the weld and A353 HAZ, where dimples were observed on the fracture surfaces and the impact energy exceeded 50 J. This ductile behavior is particularly significant for notches in the weld due to the presence of a vacuum during welding prevents the formation of gas voids and oxide and hydride compounds that are normally the origin of cracks. However, for notches in the A516 HAZ, where the cleavage faces were observed on the fracture surfaces and the impact energy was less than 30 J, the fractures were quite brittle. For dissimilar vacuum-welded samples, the impact energy and fracture type for notches in the weld and A353 HAZ were nearly the same as those in similar A353 joints. However, for notches in the A516 HAZ, the impact energy and fracture type were close to those observed in the A516 joints. Yield strength and ultimate tensile strength (UTS) of A353-A353 non-vacuum-welded samples compared to vacuum-welded samples decreased by more than 78% and 40%, respectively. As well as, yield strengths and UTSs of A516-A516 non-vacuum samples compared to vacuum samples decreased by more than 34% and 4%, respectively. On the other side, the impact samples with a notch position in the weld suffered brittle fracture instead of ductile fracture because their impact energy decreased by about 40%.

Thick-wire GMAW for fusion welding of high-strength steels

The paper describes a high-current Gas Metal Arc Welding (GMAW) process using wire electrodes with diameters up to 4.0 mm for single-pass full penetration butt joint welding of 20 mm thick steel plates. Fundamental research aims to develop thick-wire GMAW into a high-efficiency method by identifying the limits of welding performance and achievable deposition rates. Current gaps in understanding include equipment requirements, process properties, application fields, and weld quality. The research project addresses these gaps through systematic investigations of basic technological analyses, application sample welding, and quality evaluations. The objective was to create a robust, cost-efficient gas-shielded high-performance welding technology with deposition rates comparable to Submerged Arc Welding. The fully mechanized, automatic welding setup included two parallel-connected welding power sources, one wire feeder and one high-power welding torch. Welding parameters and conditions were evaluated with the aim of achieving a high-quality weld. Optimal parameters were identified for one-sided single-pass welding on 20 mm thick plates. Validation of thick-wire GMAW for 20 mm thick high-strength steels was conducted via two-sided single-pass welding on S690Q grade plates. Testing of the weld joint included static tensile strength test (3x tensile specimen), a Charpy impact test at −40 °C (6x Charpy V-notch specimens respectively with notch position in weld metal, base material and heat-affected zone (HAZ)), microstructure examination and a hardness test. The lowest recorded impact energy was observed to be 50 J within the weld metal, in combination with hardness peaks in the HAZ reaching 415 HV1, and all tensile specimens failing outside the HAZ within the base material. The process achieved reliable, reproducible, and economical joint welding, meeting necessary mechanical-technological quality standards. The paper enhances the understanding of selected welding techniques tor thick plate joining and offers valuable industrial insights, demonstrating the technique's applicability and feasibility for high-strength applications.

The High-Cycle Tensile-Shear Fatigue Properties and Failure Mechanism of Resistance Spot-Welded Advanced High-Strength Steel with a Zn Coating.

Advanced high-strength steels (AHSSs) with Zn coatings are commonly joined by the resistance spot welding (RSW) technique. However, Zn coatings could possibly cause the formation of liquid metal embrittlement (LME) cracks during the RSW process. The role of a Zn coating in the tensile-shear fatigue properties of a welding joint has not been systematically explored. In this study, the fatigue properties of tensile-shear RSW joints for bare and Zn-coated advanced high-strength steel (AHSS) specimens were comparatively studied. In particular, more severe LME cracks were triggered by employing a tilted welding electrode because much more stress was caused in the joint. LME cracks had clearly occurred in the Zn-coated steel RSW joints, as observed via optical microscopy. On the contrary, no LME cracks could be found in the RSW joints prepared with the bare steel sheets. The fatigue test results showed that the tensile-shear fatigue properties remained nearly unchanged, regardless of whether bare or Zn-coated steel was used for the RSW joints. Furthermore, Zn mapping adjacent to the crack initiation source was obtained by an electron probe micro-analyzer (EPMA), and it showed no segregation of the Zn element. Thus, the failure of the RSW joints with the Zn coating had not initiated from the LME cracks. It was concluded that the fatigue cracks were initiated by the stress concentration in the notch position between the two bonded steel sheets.

Performance degradation evaluation of square steel tubes with local penetration damage

Steel tubular structures are susceptible to welding defects, cracking defects and environmental corrosion, which can negatively affect the stability and reliability of structure. This study tested the axial compression performance of twenty-six square steel tubular stubs with localized penetration damage simulated by artificial notch, considering the influence of notch length, orientation, and position. The test results showed that the failure mode of the specimens was dominated by the local buckling along the direction of the notch axis. The failure mode of the specimen with vertical notch showed notch opening, while those with horizontal notch showed notch closing, resulting in the secondary peak value in the load-displacement curve. The existence of local penetration damage reduced the ultimate strength and ductility of the tubular stubs. Compared to the ultimate strength of the specimens with middle notch, those with corner notch were weakened more, up to 27 %. Furthermore, the effects of notch dimension, position, orientation, and tube wall thickness on the axial bearing capacity of square steel tubular stubs are discussed by using a validated finite element model. Owing to the analysis, the ultimate strength of the stubs is reduced by increasing notch length, width and depth, whereas the reduction effect tends to be weakened as the notch orientation angle increases. The notch located in the corner is the most unfavorable for the axial compression performance of the square steel tubular stubs. A semi-empirical formula for evaluating the ultimate strength of square steel tubular stubs with local penetration damage is proposed by introducing the strength reduction factor. An artificial neural network-based ultimate strength prediction model is developed that can consider the effects of wide-range parameters, achieving high accuracy.

Investigation of notch position and fiber ratio on the fracture mode and energy of sfrc beam under the impact load

When the literature is examined, it is seen that a lot of study has been done on the crack propagation and fracture modes that occur under the influence of static loads in reinforced concrete (RC) structures. Studies in the literature show the effect of crack initiation, concrete compressive strength, and fiber volume fraction on the tension mode (Mode-I), shear mode (Mode-II), and mixed fracture mode that occurs in crack propagation under static load. However, the literature has not found a comprehensive study in which the fracture modes are examined under the effect of dynamic impact loading. For this reason, an experimental study has been planned in which hybrid steel fiber reinforced concrete (SFRC) notched beams with varying compressive strength will be tested under impact loading with a free-fall drop weight device designed by the authors. The experimental variables studied were determined as the change of the crack initiation point in the beams, the compressive strength of the concrete used to produce the beams, and the fiber volume fraction in the concrete mixture. The acceleration and impact load-time histories under the constant-energy-level impact loading applied to the beams were measured. Also, the crack shape, fracture mode, crack angle, and energy absorption capacities of the beams under impact load were interpreted. While the transition from Mode-I fracture form to Mode-II fracture form occurs under impact loading, the effects of concrete compressive strength and steel fiber ratio variables on energy absorption capacity, crack angle, and crack shape are studied. Increasing the distance of the notch from the beam midpoint in notched beams produced with concrete without fiber from 0 to 40, 80 and 120 mm caused the energy absorption capacity values to increase by an average of 39 %, 66 % and 86 %, respectively. Increasing the distance of the notch to the beam midpoint from 0 to 40, 80 and 120 mm in beams with 0.75 % and 1.5 % fiber ratio increased the energy absorption capacity values by an average of 40 %, 65 % and 86 %, respectively. In beams with 2.25 % fiber ratio, increasing the notch distance from 0 to 40, 80 and 120 mm increased the energy absorption capacity values by an average of 38 %, 62 % and 83 %, respectively.

Improving the photovoltaic performance of CIGS solar cells with the modified 3-stage co-evaporation process

The 3-stage co-evaporation process has been adopted as one of the standard deposition techniques for developing high efficiency CuIn1-xGaxSe2 (CIGS) thin film solar cells. This method often results in a double-graded [Ga]/([Ga] + [In]) or x value, leading to a double-graded bandgap in the CIGS films. The main challenge is to increase open-circuit voltage (Voc) without losing short-circuit current density (Jsc) of the devices. To achieve this goal without extra elemental sources or processes during fabrication, the standard 3-stage co-evaporation process could be modified by adjusting the deposition rate of Ga in the 1st and 3rd stages to enhance the double-graded profile of x. In the 1st stage, x1 is varied in the range of 0.37–0.60, whereas x3 is varied in the range of 0.15–0.37 in the 3rd stage. This is to be compared with our reference 3-stage process using constant x1 = x3 = 0.37. The effects of the x values on the photovoltaic properties of the CIGS devices and the elemental depth profiles of the CIGS absorber have been examined. In this work, the champion device has a maximum efficiency of 17.61 %, a Voc of 698.4 mV, a Jsc of 33.81 mA/cm2 and a fill factor (FF) of 76.12 %. This was achieved by using x1 = 0.55 and x3 = 0.25. These parameters demonstrate a significant beneficial improvement over reference 3-stage process and result in the notch position (the minimum of the x value) being approximately 500–800 nm below the surface of the CIGS films.

Controllable Double Gradient Bandgap Strategy Enables High Efficiency Solution‐Processed Kesterite Solar Cells

AbstractThe double gradient bandgap absorber has the potential to enhance carrier collection, improve light collection efficiency, and make the performance of solar cells more competitive. However, achieving the double gradient bandgap structure is challenging due to the comparable diffusion rates of cations during high‐temperature selenization in kesterite Cu2ZnSn(S,Se)4 (CZTSSe) films. Here, it has successfully achieved a double gradient bandgap in the CZTSSe absorber by spin‐coating the K2S solution during the preparation process of the precursor film. The K2S insertion serves as an additional S source for the absorber, and the high‐affinity energy of K‐Se causes the position of the spin‐coated K2S solution locally Se‐rich and S‐poor. More importantly, the position of the bandgap minimum (notch) and the depth of the notch can be controlled by varying the concentration of K2S solution and its deposition stage, thereby avoiding the electronic potential barrier produced by an inadvertent notch position and depth. In addition, the K─Se liquid phase expedites the selenization process to the elimination of the fine grain layer. The champion CZTSSe device achieved an efficiency of 13.70%, indicating the potential of double gradient bandgap engineering for the future development of high‐efficiency kesterite solar cells.

Clustered photoplethysmogram pulse wave shapes and their associations with clinical data.

Photopletysmography (PPG) is a non-invasive and well known technology that enables the recording of the digital volume pulse (DVP). Although PPG is largely employed in research, several aspects remain unknown. One of these is represented by the lack of information about how many waveform classes best express the variability in shape. In the literature, it is common to classify DVPs into four classes based on the dicrotic notch position. However, when working with real data, labelling waveforms with one of these four classes is no longer straightforward and may be challenging. The correct identification of the DVP shape could enhance the precision and the reliability of the extracted bio markers. In this work we proposed unsupervised machine learning and deep learning approaches to overcome the data labelling limitations. Concretely we performed a K-medoids based clustering that takes as input 1) DVP handcrafted features, 2) similarity matrix computed with the Derivative Dynamic Time Warping and 3) DVP features extracted from a CNN AutoEncoder. All the cited methods have been tested first by imposing four medoids representative of the Dawber classes, and after by automatically searching four clusters. We then searched the optimal number of clusters for each method using silhouette score, the prediction strength and inertia. To validate the proposed approaches we analyse the dissimilarities in the clinical data related to obtained clusters.

Effect of notch location on flexural and fracture behaviors of UHPGC notched beam based on four-point bending test and acoustic emission monitoring

Ultra-high performance glass sand concrete (UHPGC) is a new composite material with superior mechanical properties and durability made by replacing quartz sand in traditional ultra-high performance concrete (UHPC) with environmentally friendly and economical glass sand recycled from waste glass. This study investigated the flexural and fracture characteristics of UHPGC notched beams with prefabricated notches at three different locations (mid-span, 100 mm off mid-span and 145 mm off mid-span) using four-point bending tests. Meanwhile, the damage evolution processes of notched beams under flexural load were monitored in real time and characterized by acoustic emission (AE) technology. Fracture modes were automatically classified based on Gaussian mixture model (GMM) and support vector machine (SVM) of rise angle (RA) and average frequency (AF). Outlier analysis of b-value were applied to provide a warning prior to complete failure of UHPGC notched specimen. The results revealed that notched position presents significant effects on flexural strength, flexural toughness and fracture energy, and exhibit considerable influence on AE parameters and cracking patterns. The farther the notch is away from the mid-span, the greater the flexural strength, flexural toughness and fracture energy exhibit due to the weakened stress concentration. As it takes longer to gather enough strain energy at the tip of the notch to crack, AE monitoring shows that higher amplitude and hysteretic nature of AE parameters such as accumulated energy and information entropy, etc., can be recorded as notch position away from the mid-span. The farther the notch is away from mid-span, the more shear cracks predominate at the later stages of damage. Cumulative AE energy and fracture energy throughout the damage process are found to exhibit a favorable exponential relationship. In addition, the b-value outlier analysis can provide failure warning for UHPGC notched beams. This study is of great significance in exploring the fracture behavior of UHPGC and providing reference for engineering applications related to UHPGC failure.

Grain Size Distribution of DP 600 Steel Using Single-Pass Asymmetrical Wedge Test

Grain size distribution after the completion of a phase transformation was studied through the laboratory-controlled hot-plastic deformation of dual phase 600 (DP 600) steel using a specially prepared asymmetric single-pass hot-rolling wedge test with a refined reheating grain size instead of the usual coarse-grained starting microstructure observed in practice. The experiment was performed to reduce generally needed experimental trials to observe the microstructure development at elevated temperatures, where stable and unstable conditions could be observed as in the industrial hot-rolling practice. For this purpose, experimental stress–strain curves and softening behaviors were used concerning FEM simulations to reproduce in situ hot-rolling conditions to interpret the grain size distribution. The presented study revealed that the usual approach found in the literature for microstructure investigation and evolution with a hot-rolling wedge test was deficient concerning the observed field of interest. The degree of potential error concerning the implemented deformation per notch position, as well as the stress–strain rate and related mean flow stresses, were highly related to the geometry of the specimen and the material behavior itself, which could be defined by the actual hardening and softening kinetics (recrystallization and grain growth at elevated temperatures and longer interpass times). The grain size distribution at 1100–1070 °C was observed up to a 3.45 s−1 strain rate and, based on its stable forming behavior according to the FEM simulations and the optimal refined grain size, the optimal deformation was positioned between e = 0.2 and e = 0.5.

Effects of notch-load-defect interactions on the local stress-strain fields and strain hardening of additively manufactured 18Ni300 steel

This study investigates the influence of geometrical notches on the local (true) stress-strain curves, deformations, and strain hardening behavior of maraging tool steel 18Ni300 processed via the laser powder-bed fusion method as an additive manufacturing approach. For this purpose, five types of specimens with different notch designs were manufactured; these samples were considered to study the effects of the notch stress concentration factor and the notch position on the material's mechanical response against the applied external load. Accordingly, using the digital image correlation technique, true stress-logarithmic strain curves were plotted and compared for various points in the vicinities of the notches while the specimens were subjected to quasi-static tensile loads. Further, the strain (work) hardening behavior of the material at each point was then evaluated and compared with other points by plotting their strain hardening diagrams from the first derivative of the stress-strain curves. The results showed that the strain hardening of the samples increased with the stress concentration factor (notch sharpness) while its ductility decreased accordingly. Furthermore, notch location and shape also showed determining roles in defining the material behavior. Ultimately, higher stress concentrations, internal positioning, and less gradual changes in geometric features (C-shaped notches compared to V-shaped ones) can result in higher defect sensitivity, more decrease in ductility, and more likely catastrophic failures in metals processed by additive manufacturing.

Model-Based Parametric Study of Surface-Breaking Defect Characterization Using Half-Skip Total Focusing Method

As the demand of structural integrity in manufacturing industries is increasing, the ultrasonic array technique has drawn more attention thanks to its inspection flexibility and versatility. By taking advantage of the possibility of individual triggering of each array element, full matrix capture (FMC) data acquisition strategy has been developed that contains the entire information of an inspection scenario. Total focusing method (TFM) as one of the ultrasonic imaging algorithms, is preferably applied to FMC dataset since it uses all information in FMC to synthetically focus the sound energy at every image pixel in the region of interest. Half-skip TFM (HSTFM) is proposed in multi-mode TFM imaging that involves a backwall reflection wave path, so that the defect profile could be reconstructed for accurate defect characterization. In this paper, a method involving Snell’s law-based wave mode conversion is proposed to account for more reasonable wave propagation time when wave mode conversion happens at backwall reflection in HSTFM. A series of model based simulations (in software simSUNDT) are performed for parametric studies, with the intention of investigating the capability of defect characterization using HSTFM with varying tilt angle and relative position of surface-breaking notch to array probe. The results show that certain TFM modes could help with defect characterization, but the effectiveness is limited with varying defect features. It is inappropriate to address a certain mode for all characterization perspectives but rather a combination, i.e., multi-mode TFM, should be adopted for possible interpretation and characterization of defect features.

Photoplethysmography waveform analysis for classification of vascular tone and arterial blood pressure: Study based on neural networks

To test whether a Shallow Neural Network (S-NN) can detect and classify vascular tone dependent changes in arterial blood pressure (ABP) by advanced photopletysmographic (PPG) waveform analysis. PPG and invasive ABP signals were recorded in 26 patients undergoing scheduled general surgery. We studied the occurrence of episodes of hypertension (systolic arterial pressure (SAP) >140 mmHg), normotension and hypotension (SAP < 90 mmHg). Vascular tone according to PPG was classified in two ways: 1) By visual inspection of changes in PPG waveform amplitude and dichrotic notch position; where Classes I-II represent vasoconstriction (notch placed >50% of PPG amplitude in small amplitude waves), Class III normal vascular tone (notch placed between 20-50% of PPG amplitude in normal waves) and Classes IV-V-VI vasodilation (notch <20% of PPG amplitude in large waves). 2) By an automated analysis, using S-NN trained and validated system that combines seven PPG derived parameters. The visual assessment was precise in detecting hypotension (sensitivity 91%, specificity 86% and accuracy 88%) and hypertension (sensitivity 93%, specificity 88% and accuracy 90%). Normotension presented as a visual Class III (III-III) (median and 1st-3rd quartiles), hypotension as a Class V (IV-VI) and hypertension as a Class II (I-III); all p < .0001. The automated S-NN performed well in classifying ABP conditions. The percentage of data with correct classification by S-ANN was 83% for normotension, 94% for hypotension, and 90% for hypertension. Changes in ABP were correctly classified automatically by S-NN analysis of the PPG waveform contour.

When Chirophotonic Film Meets Wrinkles: Viewing Angle Independent Corrugated Photonic Crystal Paper.

Light manipulation strategies of nature have fascinated humans for centuries. In particular, structural colors are of considerable interest due to their ability to control the interaction between light and matter. Here, wrinkled photonic crystal papers (PCPs) are fabricated to demonstrate the consistent reflection of colors regardless of viewing angles. The nanoscale molecular self-assembly of a cholesteric liquid crystal (CLC) with a microscale corrugated surface is combined. Fully polymerizable CLC paints are uniaxially coated onto a wrinkled interpenetrating polymer network (IPN) substrate. Photopolymerization of the helicoidal nanostructures results in a flexible and free-standing PCP. The facile method of fabricating the wrinkled PCPs provides a scalable route for the development of novel chirophotonic materials with precisely controlled helical pitch and curvature dimensions. The reflection notch position of the flat PCP shifts to a lower wavelength when the viewing angle increased, while the selective reflection wavelength of wrinkled PCP is remained consistent regardless of viewing angles. The optical reflection of the 1D stripe-wrinkled PCP is dependent on the wrinkle direction. PCPs with different corrugated directions can be patterned to reduce the angular-dependent optical reflection of wrinkles. Furthermore, 2D wavy-wrinkled PCP is successfully developed that exhibit directionally independent reflection of color.

Athermal Microwave Photonic Sensor Based on Single Microring Resonance Assisted by Machine Learning

We propose a machine learning (ML) assisted athermal microwave photonic (MWP) sensing scheme with high resolution based on a single microring resonance. The immunity of temperature interference of the high-resolution sensing is achieved by employing MWP sideband processing based interrogation, and supervised machine learning based on support vector regression (SVR) and neural tangent kernel (NTK) that are effective on small datasets. The MWP sideband processing transforms the variation of the target measurand into the shift of an ultra-deep notch in the radio frequency (RF) spectrum relieving the fabrication requirements on the microresonators, while ML accurately predicts the measurand by using the modulator bias voltage or RF passband transmission together with the RF notch position. The proposed sensor is demonstrated for relative humidity (RH) measurements using a silicon-on-insulator microring coated with polymethyl methacrylate. About 50 dB high RF rejection ratio is achieved over the sensing process, indicating a high sensing resolution. Despite the small experimental datasets, the established SVR and NTK models consistently exhibit lower mean absolute errors (MAEs) than the linear regression model in the RH prediction in the presence of temperature drifts. The NTK models achieve the lowest MAEs of 1.01% RH and 1.03% RH when the RF passband transmission and modulator bias are selected as the model input, respectively. The equivalent performances of the RF passband transmission and modulator bias voltage further demonstrate the feasibility of athermal sensing based solely on the MWP interrogation results of a single microring resonance, which simplifies the design and reduces the complexity.

Effect of the notch location on the Charpy-V toughness results for robotic flux-cored arc welded multipass joints

Abstract In this study, the effect of the notch locations on the Charpy-V toughness values of the all-welded joint obtained using robotic flux-cored arc welding was investigated with respect to microstructures at the notch locations. Charpy impact tests were performed through the thickness with notch location at the centerline as well as off-set regions of the weld metal in addition to the microhardness measurements conducted. The detailed weld metal characterization was conducted using a stereo microscope, optical microscope, and scanning electron microscope at the same location where the Charpy tests and microhardness tests were performed. The sub-zero impact toughness test results indicated that the columnar weld metal regions exhibited low toughness values while the centerline microstructure consisting of mainly reheated regions displayed much higher toughness values even at the test temperature of −60 °C, satisfying the toughness requirement of the requested 47 J value. It is concluded that a small variation of the through-thickness notch position may result in different toughness values for the same weld metal. On this basis, the notching procedure of the Charpy-V samples for the multi-pass weld metal should be conducted with care and obtained results should be explained with respective notch position and microstructure.

Inversion of elastic constants of composite materials by single test based on virtual fields method

In this paper, a method of obtaining four elastic constants of orthotropic composites by single tensile test is proposed. The principle of this method is to obtain the full field strain on the surface of the specimen through the tensile test of the specimen with a specific geometry, and to invert the measured in-plane strain field into the virtual fields method (VFM) to obtain the elastic constants. Based on the deformation field data generated by finite element numerical simulation, the effects of design parameters such as effective length, notch position, notch size and fillet radius on the identification results of elastic parameters of V-notch tensile specimen are studied. The results show that the inversion results of symmetrical V-notch specimen with 50 mm length, 12 mm notch size and 3.1 mm fillet radius are the best, and the sum of absolute relative errors of four elastic constants is less than 3%, which verifies the feasibility of the method.

Effects of notch position on the fatigue crack growth behavior of dissimilar laser welded DP980/QP980 joint

AbstractLaser welding of heterogeneous high‐strength steels (AHSSs) is increasingly used in the automotive industry, while the inhomogeneous microstructure of the joint could affect its fatigue crack growth (FCG) behavior. Therefore, fiber laser welding experiments were performed in this study to evaluate the microstructure, mechanical properties, and effects of notch position on FCG behavior of dissimilar laser welded DP980/QP980 joint. Results show that the hardness of fusion zone (FZ) near the QP980 side was higher and softening zones were observed in the heat affect zone (HAZ) on both sides of the joint. The stress–strain curves of all the samples show continuous yield and follow the two‐stage work hardening mechanism. The weld overmatch effect induced by laser welding could hinder the propagation of fatigue crack. The microstructural inhomogeneity, weld mismatch effect, and crack closure contribute to the variety of FCG rates. Ductile fracture mechanism became more dominant with the increase of ΔK.

Research on fracture parameters of asphalt mixture based on XFEM and J Integral method

The fracture toughness and load displacement relationship of the three point bending (3pb) asphalt mixture specimens with different notch position were experimentally and numerical investigated. Firstly, the extended finite element was used to simulate the three-point bending and fracture process of asphalt mixture beam, and the load and displacement curves were obtained, which were compared with the test results to verify the accuracy of the XFEM model. Secondly, J contour integral method in ABAQUS software was used to solve the stress intensity factor under the three-point bending of asphalt mixture, and the fracture parameters of asphalt mixture were provided by the numerical calculation results. The results showed that the offset distance increases, the influence of the type II crack in the fracture process increases, but the type I crack still was dominant.

Recognition of dicrotic notch in arterial blood pressure pulses using signal processing techniques

The Physiological condition of cardiovascular system is analyzed by arterial blood pressure pulse wave. The arterial pulse wave displays the genetic traits of the heart, average records of a heartbeat and variation in pressure as the heart spouts blood. This pulse monitoringis a standard process used to assess the cardiovascular system’s medical history. A waveform ofthe Arterial blood pressure usually involves a systolic level, diastolic occurrence, and dicrotic spike and dicrotic notch. The cardiac cavity contracting and relaxing leads to systolic and diastolic blood pressure respectively. The dicrotic notch which is a drop on the down slope shows systole termination and depicts the aorta closure of successive backward stream. The position of the dicrotic notch throughout the cardiac activity differs as per the duration of aortic closure. Dicrotic notch plays an essential part in sclerosis, occlusion, stenosis, arterial spasm and erythromelalgia diagnostic test. Hence Discrete Wavelet transform is utilized in this proposed work to examine and assess the dicrotic notch in arterial pulse wave form. Arterial pulse data are processed using a data acquisition system consisting of multiple channels sensor signal processing and a computer to collect the necessary data for future examination. The uniform peer group of 22 patients has been evaluated utilizing two distinct Haar and Daubuchies4 (db4) wavelet transformations. The peripheral wave in the patients seems to have a sharp rise and a notch on dropping slope, has been identified. The data collected are contrasted between the two techniques, and the Haar wavelet is observed to reasonably represent the best outcome.