Types Of Notches Research Articles

Predetermining glenoid dimensions using the scapular dimensions.

Variations of morphology of the glenoid cavity have been previously reported. These influence the surgical reconstruction or arthroplasty of the shoulder. This study aims to study the variation of the shape of suprascapular notch, shape of glenoid cavity, dimensions of both the scapular and the glenoid cavity, and predict the glenoid dimensions from the scapular dimension parameters. Adult-dried scapulae were collected. The shapes of each suprascapular notch and glenoid cavity were evaluated. The scapular height, scapular width, glenoid superoinferior distance, and glenoid anteroposterior distance were measured using a digital vernier caliper, and statistical analysis was conducted on the data that were obtained. There were 264 scapulae included in this study (166 male and 98 female). Most of the glenoid cavities were pear shaped (69.7%). The two most common types of suprascapular notches were small depression notches (31.8%) and the absence of notches (25.8%). The mean ± SD of scapular height, scapular width, glenoid superoinferior distance, and glenoid anteroposterior distance were 148.2 ± 10.0, 108.1 ± 6.4, 37.1 ± 2.2, and 27.4 ± 2.1mm, respectively, in the male samples and 133.0 ± 7.0, 97.0 ± 5.2, 33.2 ± 1.9, and 23.7 ± 1.7mm, respectively, in the female samples. The male scapulae were significantly larger than the female scapulae (p value < 0.05). However, there were no differences between the male and female scapulae in terms of scapular index or glenoid index (p value > 0.05). Scapular height and width were significantly associated with both the glenoid superoinferior distance (p = 0.0001) and glenoid anteroposterior distance (p value = 0.0001). Scapular height and width can predict the dimensions of the glenoid. In cases of glenoid bone loss or shoulder arthroplasty, the native normal glenoid dimensions can be determined from the scapular dimensions as visualized using a true scapular anteroposterior radiograph. The surgeon can use these preoperative parameters when performing glenoid reconstruction or shoulder arthroplasty.

Acoustic emission study on the effect of notch shape and temperature on elastic energy release during impact testing of 17Mn1Si pipe steel

Main fracture mechanisms are determined in 17Mn1Si steel during impact Charpy testing of specimens with three types of notches at different test temperatures covering ductile-to-brittle transition. The influence of the notch shape on the amount of expended mechanical energy (according to the loading diagram) and released elastic energy (according to the recorded acoustic emission signal) is analyzed. A combined application of fracture mechanics and acoustic emission methods is proven effective for better understanding of dynamic fracture and ductile-to-brittle transition from the viewpoint of energy-based approaches to crack initiation and propagation. It is suggested that the link between the AE signal and the ductile-to-brittle transition in dynamic loading can be established to develop a tool for in situ characterization of the fracture process.

Magnetoresistance effect in permalloy nanowires with various types of notches

Suppressing the stochastic domain wall (DW) motion in magnetic nanowires is of great importance for designing DW-related spintronic devices. In this work, we have investigated the pinning/depinning processes of DWs in permalloy nanowires with three different types of notches by using longitudinal magnetoresistance (MR) measurement. The averaged MR curves demonstrate that the stochastic DW depinning is suppressed partly or even completely by a transversely asymmetric notch. The single-shot MR curves show that how the resistance changes with the applied field also depends strongly on the notch type while the DW is pinned around the notch. In the case of two depinning fields, larger (smaller) change of resistance always corresponds to larger (smaller) depinning field, regardless of the notch type. These phenomena can be understood by that the spin structure around the notch changes differently with the notch type when the DW is traveling through the notch.

Local strain energy density for the fracture assessment of polyurethane specimens weakened by notches of different shape

Recent studies on local stress fields in proximity of crack and notch tips have shown that Strain Energy Density (SED), averaged in a circular control volume surrounding the point of stress singularities, represents a reliable engineering approach for assessing the brittle fracture of several brittle materials. It is worthy of notice that the application of SED criterion and the reliability of its results are strictly related to the proper determination of fracture parameters, i.e. the critical value of deformation energy Wc and the radius Rc of the control volume. This work presents an experimental methodology for their determination by means of notched specimens for different polyurethane densities, ranging from 100 to 651 kg/m3. Then, once obtained these critical parameters, the failure load in different types of notches and cracked specimens under mode I have been predicted. Moreover, for cracked specimens under mixed mode and mode II, the authors propose a personal approach that confirms PUR foams can be treated as brittle materials

Non-local plasticity effects on notch fracture mechanics

We investigate the influence of gradient-enhanced dislocation hardening on the mechanics of notch-induced failure. The role of geometrically necessary dislocations (GNDs) in enhancing cracking is assessed by means of a mechanism-based strain gradient plasticity theory. Both stationary and propagating cracks from notch-like defects are investigated through the finite element method. A cohesive zone formulation incorporating monotonic and cyclic damage contributions is employed to address both loading conditions. Computations are performed for a very wide range of length scale parameters and numerous geometries are addressed, covering the main types of notches. Results reveal a strong influence of the plastic strain gradients in all the scenarios considered. Transitional combinations of notch angle, radius and length scale parameter are identified that establish the regimes of GNDs-relevance, laying the foundations for the rational application of gradient plasticity models in damage assessment of notched components.

The Analysis of the Machining Influence of the Surface Layer on Durability

The paper deals with the influence of the properties surface layer of notched components. This material is widely used in the automotive industry. This material is subject to different kinds of processing, and therefore present a different quality of the surface layer. For many manufactured components, we find diverse types of notches, such as slots, recesses and holes. They are the place where is stress concentrated, so called the macroscopic stress concentrator. When we focus more on the surface profile, we find the diversity of technologies in the surface, which creates different sizes and shapes of microscopic notches. In these places, there is a higher risk of the destruction of the components. Many designers prescribe unnecessarily high surface quality. It is important to maintain adequate quality of the surface to achieved high durability.

On the fracture behavior of polyurethane notched components

Local Strain Energy Density represents an engineering approach for assessing the brittle fracture of cracked and notched components. Experimental determination of fracture parameters (critical value of deformation energy Wc in a local finite volume around the notch tip and the radius of the control volume Rc) represents a key issue. The paper presents a methodology to determine these parameters using a notched tensile specimen. The obtained values will be used to predict the fracture load in different types of notches and cracked specimens under mode I; for cracked specimens under mixed mode and mode II has defined a personal approach that confirms PUR foams can be treated as brittle materials. The considered specimens are made of polyurethane materials of different densities from 100 to 651 kg/m3.

Stochastic domain wall depinning in permalloy nanowires with various types of notches

Stochastic phenomena in magnetic nanowires based on domain wall (DW) motion is scientifically important thus to understand and control such behaviors are very meaningful. Here we report on the investigation of pinning and depinning of DWs in permalloy nanowires with six types of longitudinally asymmetric notches using focused magneto-optic Kerr effect (FMOKE) magnetometer and magnetic force microscopy (MFM). The hysteresis loops obtained by FMOKE indicate the generation of one or two distinct depinning fields by creating one notch close to the edge of the nanowires, in comparison multiple depinning processes occur in the nanowires with two identical notches symmetrically placed along the transverse direction, indicating more remarkable stochastic DW depinning phenomena. The MFM images verify the existence of DW in each type of nanowires and the DW sizes in the latter kind of nanowires are generally larger than those in the former ones. These observations can be explained by considering the thermal perturbation and edge or surface roughness effects in nanowires.

Occupational noise exposure, hearing loss, and notched audiograms in the HUNT Nord-Trøndelag hearing loss study, 1996-1998.

Objectives/HypothesisTo study the prevalence and usefulness of audiometric notches in the diagnosis of noise‐induced hearing loss (NIHL).Study DesignAudiograms and data on noise exposure from 23,297 men and 26,477 women, aged 20 to 101 years, from the Nord‐Trøndelag Hearing Loss Study, 1996–1998.MethodsThe prevalence of four types of audiometric notches (Coles, Hoffman, Wilson) and 4 kHz notch were computed in relation to occupational noise exposure, age, sex, and report of recurrent ear infections.ResultsThe prevalence of notches in the 3 to 6 kHz range (Wilson, Hoffman, and Coles) ranged from 50% to 60% in subjects without occupational noise exposure, and 60% to 70% in the most occupationally noise‐exposed men. The differences were statistically significant only for bilateral notches. For 4 kHz notches, the prevalence varied from 25% in occupationally nonexposed to 35% in the most occupationally exposed men, and the differences were statistically significant for both bilateral and unilateral notches. For women, the prevalence of notches was lower than in men, especially for 4 kHz notches, and the differences between occupationally noise exposed and nonexposed were smaller. Recreational exposure to high music was not associated with notched audiograms.ConclusionsThe detection of bilateral notches and unilateral 4 kHz notches is of some value in diagnosing NIHL, especially in men.Level of Evidence4 Laryngoscope, 127:1442–1450, 2017

A Prediction Model for Mode-III Fatigue Crack Growth

In the fracture mechanics, the failure of mode-III crack belongs to the anti-plane shear (also called out-plane shear or longitudinal shear). Fatigue crack growth (FCG) behavior under mode-III reversed load (load ratio R=-1) was studied by using 30Cr2Ni4MoV rotor steel with types of circumferential notches. Under the remote cyclic torsional load, the precrack process was applied to specimens with notch in the round bar, and the ideal sharp-crack was obtained. Then, mode-III FCG test under the remote cyclic torsional load and the axial constant small load was carried out until to fatigue failure. The axial constant small load is aimed at reducing the cracks interaction in the mode-III FCG experiment. Due to experimental data of 30Cr2Ni4MoV rotor steel, the mode-III FCG rate in the range of KIII from 12MPa·m1/2 to 40 MPa·m1/2 and the threshold value were got. Furthermore, a prediction model for mode-III FCG is proposed with considering the small scale yield of plane stress crack tip zone and the plastic strain energy density failure criteria. The predicted mode-III FCG rate is found to agree well with the experimental curves of 30Cr2Ni4MoV rotor steel.

Effect of notch position on creep damage for brazed joint

In this paper, we investigated the effect of notch position on creep damage for Hastelloy C276-BNi2 brazed joint. Three different types of notches locate in edge of base metal (base notch), edge of filler metal (surface notch) and center of filler metal (inside notch) were compared, and the influence of notch geometric parameters on creep damage was also investigated. The results show that the different notch position and dimension generate different creep damage distributions and have a great influence on creep life. The creep failure is the easiest to occur in surface notch, then the base notch, and the last is inside notch. The brazed joint with higher maximum principal stress and von Mises stress generates creep failure easier. For the base notch, the failure time increases with the increase of base notch distance and the creep failure location moves gradually from the center of filler metal to notch tip. The notch locating away from filler metal is beneficial to reduce the creep damage in filler metal and enhance the creep life. For the inside notch, the failure time decreases with notch length increases and the maximum creep damage locates at notch tip. With the increase of inside notch width, the failure time increases first and then keep steadiness, and the failure location moves away from notch tip. The effects of notch position and dimension should be fully considered in creep failure analyses and life assessments of brazed joints.

Creep failure prediction of brazing joints with double notches

This paper predicts the creep ductile failure of brazing joints with three different types of double notches by continuum damage mechanics simulation, and the effects of distance between the double notches (notch distance) and inside notch radius have been discussed. The results show that the different double notches have different creep failure lives and notch sensitivity effects due to the different notch strength ratios. For the notches in the surface of base metal and filler metal, the creep failure time decreases with the notch distance increases. Compared with single notch, the smaller notch distance shows a strengthening effect because of the larger notch strength ratio, otherwise it is a weakening effect. For the notches in the surface and center of filler metal, the creep failure time increases firstly then decreases with the increase of inside notch radius. Opposite to the notch distance effect, the smaller inside notch radius shows a weakening effect, while the bigger inside notch radius shows a strengthening effect. As the notch radius increases, the strengthening effect becomes not obvious. For the notches in the center of filler metal and the surface of base metal, the creep failure location moves from base metal to filler metal, and the failure time decreases with the increase of inside notch radius. The creep life of smaller inside notch radius is the same as single base notch, showing an insensitive effect. Nevertheless, it is a weakening effect for the bigger inside notch radius.

Fracture parameters determination of polyurethane materials for application of SED criteria to notched components

Local Strain Energy Density represents an engineering approach for assessing the brittle fracture of cracked and notched components. Experimental determination of fracture parameters (critical value of deformation energy Wc in a local finite volume around the notch tip and the radius of the control volume Rc) represents a key issue. The paper presents a methodology to determine these parameters using a notched tensile specimen. The obtained values will be used to predict the fracture for different types of notches and cracked specimens under mode I; for cracked specimens under mixed mode and mode II has proposed a new approach which confirms that PUR foams can be treated as brittle materials. The considered specimens are made of rigid polyurethane foams having different densities from 100 to 651 kg/m3.

Bionics - Natural but Innovative Methods Improve the Aeroacoustic Engineering

This paper presents the aeroacoustics result of the trailing edge noise prepared wings two species of owl - Barn owl (Tyto alba), called “good hearing” and Northern hawk-owl (Surnia ulula), called “good seeing”. The acoustic performance comparisons between the Barn owl and Northern hawk-owl show that there are differences between the sound intensity the studied wings. These results prove that the special sound suppression characteristics of wing feather play an important role for their silent flight. Therefore the flat plates with the cutting trailing edge have been studied. At lower speeds, a better noise reduction effect was obtained for the plates with edges as elliptical arcs. On the basis of the above tests it can be concluded that other types of notches on the trailing edge (not just a sawtooth) also reduce the aerodynamic noise of flat plate.

Modelling the Temperature Aging Effect on Tensile Fracture Load of Notched High Density Polyethylene Material Using the Planning Design Experiment Approach

This article addresses the experimental characterization of the temperature aging effect on tensile fracture load behavior of notched and unnotched high density polyethylene material. The samples were cut from a HDPE pipe. After mechanizing the tensile specimens with a numerical controlled machine, two series of samples were mechanized with different types of notches. The first series was drilled with a different central hole of diameter 4,6 and 8 mm. In the second series, one group of specimens the V shape notches were carried out on one side of samples, while for the second group the V shape notches were carried out on the double sided of specimens. Once the notches mechanized, the samples were exposed into a room temperature to positive and a negative temperatures -40?C and 100?C during 72 hours. The planning design experiment approach was applied to obtain a mathematical model taking account all the influencing parameters on tensile fracture load of the material. The fracture tensile load and the elongation in cases of V and circular notch were modeled as function of temperature aging effect. From the response surfaces of both cases, we note that the temperature had a significant effect on fracture load tensile and elongation with respect on type of number of V notch and hole diameter. The ultimate tensile load decrease and the elongation increases.

Strain analysis at notch root in laser welded samples using material properties of individual weld zones

This paper presents results of the strain analysis at a notch root in a laser-welded joint subjected to cyclically variable stresses. The examined welds were made of S355JR (PN-EN 10025-2) ferritic steel. A theoretical analysis of strain was performed using cyclic material properties determined for individual weld zones. For the purpose of comparison, values of strains at a notch root were also determined using base metal properties. Experimental verification of determined strain values was performed using the laser grating interferometry method. Cyclic variations of material properties for base metal and welded joint zones were determined as per the standard and the methodology presented in previous study and described with the Ramberg–Osgood relationship. The above material properties were used to calculate strain at the root of two types of geometric notches machined in a laser-welded joint. Analytical calculations were performed using the Neuber’s rule, while numerical calculations with the use of the finite element method by means of the ABAQUS software.Test results confirmed good efficiency of the numerical strain analysis using cyclic material properties of the individual weld zones in low cycle fatigue.

Morfometrical and morphological analysis of the suprascapular notch with multidetector computerized tomography

IntroductionSuprascapular notch is situated in lateral section of margo superior of scapula as adjacent to substratum of processus coracoideus. Suprascapular nerve compression is characterized with chronic localized pain spreading to shoulder posterior and/or lateral areas, to under brachion and into the neck; and with weakness in shoulder abduction, and also atrophy of supraspinatus and infraspinatus muscles. In our study, we aimed to exhibit notch suprascapularis morphology and the variations of this structure which creates an important passage for suprascapular nerve. MethodsThis study was conducted on 100 patients (35 females–65 males). Average age of individuals included into the study was 17–87 years. ResultsThe morphological study of the suprascapular notch revealed six different types of notches. DiscussionThe data we have obtained in our study are important to constitute a reference space of Turkish society. Furthermore, the fact that the differences between genders and right-left are exhibited will be helpful for surgeons who perform surgery in this region. Therefore, we conclude that the exhibited results will provide a better detail of information regarding morphometry of suprascapular notch and will aid in diagnosing and surgical treatment for shoulder pain.

Effect of Machining the Load Capacity Notched Components

Nowadays is issue investigation the notch problems and their influence on component durability. For many manufactured components, we find various types of notches, such as grooves, step and holes. They have a tend to be the place where is concentrated stress, so called the macroscopic stress concentrator. In this area is higher risk of part destruction. Nowadays, there are hypotheses that are based on the assumption that the higher the roughness, the lower the durability. In many cases the designers prescribe unnecessarily high surface quality. It is necessary to maintain adequate quality of the surface, and also necessary that the component has attained a high durability. The paper deals with the influence of machining technology carrying capacity of notched components. As the test material was used steel Fe510 according to EN ISO (11523, according to CSN 42 0002).

Fatigue life prediction in the damaged and un-damaged compressor blades

Article history: Received September 20, 2013 Received in Revised form October, 14, 2013 Accepted 25 November 2013 Available online 4 December 2013 A land-based gas turbine may operate at the different environment including corrosive and dusty environments. These conditions can cause early damages in the “cold” parts as well as in the “hot” parts of the gas turbine. In this research, fatigue life of a compressor blade is predicted with and without damages. Damage is considered as a notch at the blade and is classified as three types of short, medium and long notches. These are numerically simulated in the compressor blade and fatigue crack initiation life is calculated. Stress analysis is carried out using finite element analysis followed by fatigue life calculations. Furthermore, the influence of blade tip displacement on life of the undamaged and damaged blade is investigated. Moreover, the effect of damage's size and location on blade’s life is reported. This procedure can be tuned with corrosion damages observed during the minor inspection where the gas turbines are operating in the unusual environments. © 2013 Growing Science Ltd. All rights reserved.

Morphometric study of suprascapular notch in Indian dry scapulae with specific reference to the incidence of completely ossified superior transverse scapular ligament.

The suprascapular notch, a depression on the lateral part of the superior border of the scapula, medial to the coracoid process, is bridged by the superior transverse scapular ligament, which is sometimes ossified and the foramen which is thus completed, transmits the suprascapular nerve to the supraspinatus fossa. Variations in the morphology of suprascapular notch have been identified as one of the causes of suprascapular nerve entrapment. Rengachary et al. classified this notch into six types, based on its shape. To study morphological variations of suprascapular notch in Indian dry scapulae and to analyze the incidence of completely ossified superior transverse scapular ligament with other ethnic populations which have been cited earlier. A total of 400 human dry scapulae which were obtained from the Department of Anatomy of selected eight medical colleges were analyzed. The type of suprascapular notch was noted and it was recorded as per the description given by Rengachary et al. The results of the present study were compared with the results of previous authors in different populations. In our study, out of 400 scapulae, 40 (10%), were identified to have completely ossified superior transverse scapular ligaments. The frequencies of various types of suprascapular notches were: Type I -20%, Type II -10%, Type III -52%, Type IV -4%, Type V -4%, Type VI -10%. Since the suprascapular nerve entrapment syndrome might be caused by complete ossification of superior transverse scapular ligament with formation of suprascapular foramen and other morphometric variations of suprascapular notch, the knowledge on such variations is essential for clinicians, for making a proper diagnosis and for planning the most suitable surgical intervention.