Notch Deformation Research Articles

Effect of plastic anisotropy on notch deformation behavior of 7075 high-strength aluminum alloy sheet subjected to axial tension

The notch is an inevitable geometric characteristic in thin-walled structural components. However, the anisotropy in the notch deformation behavior of metal sheets has not been thoroughly investigated. To address this gap, we explored the effect of plastic anisotropy on the notch deformation behavior of the AA7075-T6 sheet subjected to axial tension at room temperature and quasi-static conditions. For this purpose, four types of notched tensile specimens are designed and tested along the rolling, diagonal, and transverse directions. The plastic anisotropy is examined by the dog-bone sample every 15° from the rolling to transverse directions. Full-scale numerical simulations for each notch tensile test were performed in ABAQUS/Standard based on the elastic–plastic constitutive framework with yielding depicted by the Yld2004-18p criterion. The results show that the established numerical models high fidelity reproduced the experimental measurements. It is found that the plastic anisotropy strongly affects the notch deformation of the sheet specimen subjected to axial tension, including strain concentration, plastic localization, stress state, and fracture initiation. Besides, the critical location of cracking in the material depends on the notch geometry parameter w/ρ, viz., the ratio of the half distance between roots of two notch (w) to the radius of the depth notch root (ρ). Another crucial contribution is to provide ideas for a researcher to control or design the path of strain localization by producing metals with specific textures to promote or delay fracture initiation. Accordingly, through the investigation of this work, we provide an essential reference for further engineering applications of high-strength aluminum alloy sheet products with notches.

Eyelid malposition after orbital fracture surgery

: Orbital fractures generally do not cause eyelid malposition. Studies have shown that mostly eyelid malposition is mainly due to the choice of surgical approaches of orbital fracture repair. Approaches are divided into transcutaneous and transconjunctival ones. The application of orbital fracture approaches depends on fractures’ range and the surgeons’ preferences. Eyelid malposition after orbital fracture surgery is not only an aesthetic concern but also a functional complication, which will cause eyes discomfort, such as corneal exposure and ocular irritation. Some patients may have multiple types of eyelid malposition. In this review, we summarized the surgical approaches of orbital fractures and the complications including scar, ectropion, retraction, entropion, flattening, laceration and lacrimal canaliculus avulsion and notch deformity that associated with eyelid, especially the lower eyelid. Reports revealed that the scar usually occurred in infraorbital incisions compared with subtarsal and subciliary incisions, and the transconjunctival approach had a higher incidence of entropion and flattening, and less ectropion than the transcutaneous approach. Meanwhile, pathogenesis of eyelid malposition after orbital fracture surgery are discussed. Furthermore, to prevent eyelid malposition complications, doctors should choose the appropriate orbital fracture approach according to the patient’s needs, and delicate tissue management, technical expertise, and meticulous hemostasis are necessary. Conservative treatment with taping, lubricating ointment, and steroid for eyelid malposition complications should be performed first, and then surgical intervention when the conservative treatment fails.

Traction Applying Technique on Bicanalicular Crawford Silicone Tube to Overcome the Notching Deformity After Lacrimal Canalicular Repair.

Lower eyelid avulsion injury with lower canalicular laceration generally occur just medial to the punctum with insufficient skin remnant for repair causing tension on repair margins. The inevitable blinking force, along with the tension widens the repair margin, resulting in an aesthetically challenging notch at the medial lower lid. The authors attempted to minimize this notching deformity with a traction applying technique on bicanalicular silicone tube.Fifteen patients were enrolled and divided into 2 groups: the experimental group with 10 patients which received the traction technique, and the control group with 5 patients which the traction technique was omitted. Each end of the bicanalicular silicone tube was intubated through both puncta and the lacerated canaliculus. No canalicular anastomosis was performed. The tube ends were retrieved through the nostril, followed by medial canthal tendon, orbicularis oculi muscle, and skin repair. The tube ends were pulled to create a tension on the loop, until upper and lower puncta apposed each other, creating a dimple in the medial canthal area. The tube ends were tied and anchored at internal valve of the nostril to maintain the traction tension. Medial lower lid notching (>2 mm width), epiphora, and conjunctival injection were evaluated and compared in the 2 groups.Patients with traction technique showed symmetric medial canthal angle and minimized lower lid notching deformity when compared with the control group (P = 0.025). No conjunctival injections and epiphora were observed in either group. Symmetric and aesthetically satisfactory results were achieved by traction applying technique on bicanalicular silicone tube.

Microstructure and Mechanical Properties of Inconel 617/AISI 310 Electron Beam Welds

The aim of this research was to analyze the relationship between the microstructure and mechanical properties of Inconel 617/AISI 310 stainless steel electron beam welds. The microstructure of the weldments was studied using scanning electron microscopy and the electron backscatter diffraction (EBSD) technique. Mechanical properties of the weldments, including tensile behavior, hardness and impact toughness resistance, were evaluated. The results indicated that the electron beam welding process led to the segregation of elements in the weld metals, and the formation of secondary phases rich in Co, Nb and Mo was recorded too. EBSD studies also showed that the grains of the weldment had a variety of orientations. In addition, the fraction of coincident-site lattice boundaries was non-uniformly distributed across the weldments. The tensile strength of the weldments was similar to that of the AISI 310 parent metal, and the tensile samples underwent the ductile fracture mode. Upon Charpy impact testing, the weldments underwent notch deformation and the ductile mode of fracture; however, the impact toughness resistance was lower, as compared with the base metals. Based on the performed tests, the heat input of 168 kJ/m could be recommended.

Notch deformation and stress gradient effects in multiaxial fatigue

This paper investigates notch mechanics under multiaxial fatigue loading conditions with respect to notch stress–strain estimation rules and stress gradient effects. A pseudo stress-based plasticity modeling technique, incorporating a structural yield surface concept, was applied to predict local stress distributions for a 2024-T3 aluminum alloy notched tubular specimen, as well as for two different AISI 1141 steel alloy notched shaft specimen geometries. Stress–strain predictions were generated for several nominal loading conditions and compared to nonlinear FEA solutions. Most predictions were found to be within ±15% error for loading levels relevant to typical fatigue loading applications. To evaluate stress gradient models, fatigue life predictions were performed for each specimen geometry using Neuber’s rule with fatigue notch factor, as well as several different interpretations of Theory of Critical Distances (TCD) approaches. The effect of critical distance value on life predictions was also studied. The Fatemi–Socie critical plane damage parameter was used to calculate fatigue lives. While the TCD approaches were found to provide improved multiaxial fatigue data correlation when compared to fatigue notch factor, negligible differences between the different TCD approaches were observed. Life prediction trends were found to be consistent regardless of notch geometry and material, thus suggesting some generality of the findings.

Effects of mean stress and stress concentration on fatigue behavior of short fiber reinforced polymer composites

AbstractAn experimental study was conducted to evaluate the effect of mean stress on fatigue behavior of two short glass fiber reinforced thermoplastic composites and the effect of stress concentration on fatigue behavior of an unreinforced and a short glass fiber reinforced thermoplastic. Load‐controlled fatigue tests were conducted on unnotched (smooth) specimens at R ratios of −1, 0.1, and 0.3 in different mold flow directions or fiber orientations and at a range of temperatures between −40 and 125 °C. Effect of mean stress on fatigue life was found to be significant at all temperatures. Several mean stress parameters including modified Goodman, Walker, and Smith–Watson–Topper were evaluated for their ability to correlate mean stress data. A general fatigue life prediction model was also used to account for the effect of mean stress, temperature, and fiber orientation. Notched fatigue tests of an unreinforced polymer and a short glass fiber thermoplastic composite were also conducted using plate type specimens with a central circular hole and with or without the presence of mean stress. Effect of stress concentration was found to be considerable, with or without mean stress and in both the longitudinal and transverse directions. The commonly used Neuber's rule for metallic materials, nonlinear finite element analysis, as well as critical distance approaches were utilized for notch deformation and fatigue life analyses.

Hard palate graft for repair of eyelid notch deformity

A single case description of a novel surgical treatment using hard palate to correct an upper eyelid deformity after traumatic laceraton. The surgical procedure is described with accompanying diagram to illustrate the technique. The eyelid margin was successfully restored with proper anatomical outcome, as seen up to at least eighteen months post-operatively in the presented case. Our technique can be applied to the correction of small eyelid defects in other patients.

Separation of the Effects of Notch and Macroresidual Stress on the MFL Signal Characteristics

Magnetic flux leakage (MFL) distribution for three configurations of samples has been investigated in order to study the influence of notch and plastic deformation separately as well as together. Samples have been made of S355 steel. The MFL signal measurements were carried out along the longest dimension of the sample over a length of 120 mm. Two components of magnetic field were measured: 1) tangential to the main axis and 2) normal to the largest surface of the sample. Study has shown that geometrical effect, related to the notch presence, as well as plastic deformation with associated compressive macroresidual stresses, together are responsible for the specific MFL distribution above the sample. In order to confirm the assumption that the decrease of the permeability in the central part of the sample and the change of cross section are the main sources of the MFL anomaly, disrupting flux from demagnetization field, a series of simulations has been made. Simulation results coincide with those obtained experimentally and thus confirming the above hypothesis.

Clinical Experience of the Modifi ed Transconjunctival Lower Lid Approach for Orbital Fractures with Lateral Peri-Canthal Incision

INTRODUCTION: Optimal repair of orbital fractures requires adequate exposure of the fracture area. The transconjunctival approach with lateral canthotomy has gained increasing popularity. This technique offers arguably improved visualization with lower risk of lid retraction. However, if the lateral canthotomy area is improperly repaired, it may cause lower lid malposition and deformity.1 The authors report the use of a modified transconjunctival incision method with a lateral peri-canthal incision to overcome this problem in the cantholysis. METHODS: Between January 2011 and December 2012, the authors used this technique in 30 patients with orbital fractures. When the transconjunctival approach was performed, an inferolateral incision of the lower eyelid near the lateral canthus including the tarsal plate was added instead of the common lateral canthotomy incision for the cantholysis (Figure 1).Figure 1: Transconjunctival incision with lateral peri-canthal incision.RESULTS: Average follow-up was 6 months. There were no functional complications (no webbing, no ectropion, no entropion, etc) related to the operation. In 28 of 30 cases (93%) they were rated as having an excellent cosmetic outcome; however, there were two cases (7%) with complications. One patient had a subcutaneous preseptal hematoma, which required reoperation to obtain hemostasis. In another patient, there was a notch deformity on the lower eyelid margin, but the patient was satisfied and did not choose to have it revised. CONCLUSION: The authors believe that for orbital fracture repair the modified transconjunctival incision with lateral peri-canthal incision can be easily performed and reliably repaired as opposed to the more traditional lateral canthotomy technique. We believe that there is more anatomical reliability in repairing the tarsal plate rather than the attachment of the lateral canthus. Furthermore, in our experience this modified technique provided more than adequate exposure for fracture repair, with excellent cosmetic and functional result on long-term follow-up.

Correction of secondary vermilion notching deformity in unilateral cleft lip patients: Complete revision of two errors

Background Vermilion notching deformity is one of the most common secondary deformities in unilateral cleft lip patients. Two errors during primary cheiloplasty seem to cause notching deformity. The first one is insufficiently lengthened oral lining of the medial lip compared to the cutaneous surface, and the other is medialized marking of the height of cupid’s bow on cleft side rather than marking it at the thickest portion of the vermilion. The authors were able to obtain satisfactory results after revising notching deformities by correcting these two errors. Methods A total of 104 patients (median age: 13) with secondary notching deformity underwent revision surgery from 1987 to 2009. After the new height of cupid’s bow on the cleft side was marked on the white roll with the greatest vermilion fullness, the notched vermilion including the cutaneous scar was elevated. For sufficient lengthening of the oral lining, the elevated tissue was interposed as an inferior pedicled flap into a relaxing incision of the central portion of the oral sulcus. Results The follow-up period ranged from 1 year to 12 years. The patients were satisfied with the aesthetic outcomes. Seven patients experienced lateral vermilion bulging which was easily corrected by an elliptical excision. Conclusion Complete revision by lengthening the oral lining of the central lip portion, and lateralizing the height of cupid’s bow of cleft side to the region where vermilion is thickest, is an effective method for correction of secondary notching deformity.

150 In-Situ観察と空孔拡散解析によるW添加9Cr鋼のクリープ損傷形成挙動と変形特性(材料力学IV,一般講演)

150 In-Situ観察と空孔拡散解析によるW添加9Cr鋼のクリープ損傷形成挙動と変形特性(材料力学IV,一般講演)

Mixed mode (I and II) crack tip fields in bulk metallic glasses

Stationary crack tip fields in bulk metallic glasses under mixed mode (I and II) loading are studied through detailed finite element simulations assuming plane strain, small scale yielding conditions. The influence of internal friction or pressure sensitivity on the plastic zones, notch deformation, stress and plastic strain fields is examined for different mode mixities. Under mixed mode loading, the notch deforms into a shape such that one part of its surface sharpens while the other part blunts. Increase in mode II component of loading dramatically enhances the normalized plastic zone size, lowers the stresses but significantly elevates the plastic strain levels near the notch tip. Higher internal friction reduces the peak tangential stress but increases the plastic strain and stretching near the blunted part of the notch. The simulated shear bands are straight and extend over a long distance ahead of the notch tip under mode II dominant loading. The possible variations of fracture toughness with mode mixity corresponding to failure by brittle micro-cracking and ductile shear banding are predicted employing two simple fracture criteria. The salient results from finite element simulations are validated by comparison with those from mixed mode (I and II) fracture experiments on a Zr-based bulk metallic glass.

124 In-Situ観察と空孔拡散解析によるW添加9Cr鋼のクリープ損傷形成挙動と変形特性(材料力学I)

124 In-Situ観察と空孔拡散解析によるW添加9Cr鋼のクリープ損傷形成挙動と変形特性(材料力学I)

Tunability of notch angles in quantum cascade microlasers with highly deformed spiral resonators

We study the mode spectra and lasing thresholds of spiral-shaped quantum cascade lasers with a deformation in the range of 10%–45% with respect to the radius and with various notch angles. We observe that the initial lasing wavelength and the threshold of a laser are correlated with each other, and they can be jointly tuned by both the deformation coefficient and notch angle. The dependence of the cavity loss on the deformation coefficient is analyzed via the measured lasing thresholds and frequency dependent gain coefficients. Moreover, we achieve single mode emission by tuning the notch angle and deformation coefficients.

The Clinical Characteristics of Peyronie’s Patients with Notching Deformity

Peyronie's patients with notching deformity represent a small percentage of disease population, and the features of these patients have not been well established yet. To analyze the characteristics of Peyronie's patients with notching deformity. Peyronie's patients with notching deformity were compared with those with other type of penile deformities with regard to clinical features. During a 13-year period, a total of 703 patients with Peyronie's disease were evaluated at our institution. The patients were divided into two groups: group I consists of Peyronie's patients with notching deformity (N = 89) and group II patients with any other kind of penile curvature (N = 614). The clinical characteristics, presence of co-morbidities including diabetes mellitus, hypercholesterolemia, hypertriglyceridemia, hypertension, and ischemic heart disease, erectile status, and penile deformities were compared between the two groups. Pure notching deformity was detected in 12.6% (N = 89) of the patients. The mean age of men was 53.1 +/- 10.2 and 52.7 +/- 10.7 years in groups I and II, respectively, (P = 0.8). The leading presenting symptom was erectile dysfunction (68.5%), followed by penile deformity (51.6%), and pain on erection (17.9%) in group I, while it was penile curvature (77.1%), erectile dysfunction (54.6%), and pain on erection (14.4%) in group II. In group I, 27 patients (30.3%) were diagnosed during a standard evaluation for erectile dysfunction. Hypertension was significantly higher in group I (25.8%) than in group II (15.4%) (P = 0.022); whereas hypercholesterolemia was more common in group II (P = 0.008). There was no significant correlation between the presence or the number of co-morbid conditions and the presence of the notching deformity. Combined injection and stimulation test revealed a diminished erectile capacity in 46.1% of the patients in group I, while it was 31.7% in group II (P = 0.008). In group I, 62.9% had unilateral notching deformity, 34.8% had hourglass deformity, and 2.2% had combined hourglass and notching deformity. Overall, the notching deformity was localized in the distal penile shaft in 50.5%, proximal shaft in 40.4%, and mid-shaft in 8.9% of the patients in group I. In this large-scale series, pure notching deformity was detected in about one-tenth of patients with Peyronie's disease. Patients presented at the first half of the sixth decade of life and more than half of the patients were in the acute phase of the disease. The most common presenting symptom was erectile dysfunction. The notching deformity was more frequently localized at the base and tip of the penis.

Single staged, z-plasty supported, wedge excision modification for treatment of auricular lesions under local anesthesia: a technical note

Following wedge-excision of auricular lesions, a triangular-cartilage only-excision is planned at the tip of the wedge. The dimensions and the angles of this cartilage can be modified as much as the required helical rotation. After approximating the cartilage edges a notching deformity may be observed which can be improved using single or multiple z-plasties.

Anatomic basis of notch deformity in open rhinoplasty.

Notch deformity at the columella after the stairstep incision is an unsightly sequel that fuels negativism for open rhinoplasty critics. Obvious causes cited include surgical misadventures involving division of the foot of the medial crus and poor healing. The authors offer yet an additional etiology based on the contraction distortion caused by the depressor septi nasi muscle. The purpose of this study is to investigate the anatomic basis for notch deformity after stairstep technique in open rhinoplasty. For this anatomic study, 10 fresh cadavers were used. Dissections were performed, exposing the columellar components. The macroscopic and microscopic photo documentation gathered supports the authors' theory that depressor septi nasi action causes skin-edge deformation that leads to closure malalignment and notch deformity. Pre-incision landmark defining tattoo or sutures will assure proper alignment at closure.

On the influence of stress triaxiality and strain rate on the behaviour of a structural steel. Part I. Experiments

Abstract Notched axisymmetric specimens of the structural steel Weldox 460 E have been tested at high strain rates in a Split Hopkinson Tension Bar. The aim was to study the combined effects of strain rate and stress triaxiality on the material's behaviour. It is further considered important to obtain experimental data that can be used in validation of constitutive relations and fracture criteria. The force and elongation of the specimens were measured by strain gauges during the high strain rate tests, while the fracture strain was calculated based on measurements of the fracture area in the microscope. Optical recordings of the notch deformation were obtained using a digital high-speed camera system. Using image processing of the digital images, it was possible to estimate the true strain against time at minimum cross-section. The strength of the material was found to increase with increasing strain rate, while for the ductility no significant effect of strain rate could be ascertained from the notched specimen tests. The ductility of the material was found to depend considerably on the stress triaxiality.

Elasto-plastic stress and strain behaviour at notch roots under monotonic and cyclic loadings

Notch deformation behaviour under monotonic and cyclic loading conditions was investigated using circumferentially notched round bar and double-notched flat plate geometries, each with two different notch concentration factors. Notch strains for the double-notched plate geometry were measured with the use of miniature strain gauges bonded to specimens made of a vanadium-based microalloyed steel. Elastic as well as elasto-plastic finite element analyses of the two geometries were performed. Notch root strains and stresses were predicted by employing the linear rule, Neuber's rule and Glinka's rule relationships under both monotonic and cyclic loading conditions. The predicted results are compared with those from elastic—plastic finite element analyses and strain gauge measurements. Effects of notch constraint and the material stress-strain curve on the notch root stress and strain predictions are also discussed.

A modified Bell-Tawse Proceduter for surgical correction of congenital elbow luxation in a Dalmatian puppy

SummaryA four month old Dalmatian puppy affected by congenital luxation of the radial head was very lame on the right front limb and was not weight bearing after little exercise. The radiological examination revealed humero-radial articular incongruity, excessive humeral trochlea development, trochlear notch deformation, and medial deviation of the olecranon. The surgery performed was derived from a modification of a human orthopaedic procedure, the Bell-Tawse technique. It was intended to increase the articular contact surface between the humerus and radius, with ostectomy, rotation, and osteosynthesis of the radius; to treat the luxation, by reduction and elbow annular ligament reconstruction; to prevent its recurrence, by means of a Kirschner pin inserted through the lateral humeral epicondyle to the radial head. Over six months the patient completely recovered.A congenital luxation of the radial head in a puppy was treated successfully employing a technique reported in human orthopaedics.