Nose Angle Research Articles

Influence of tool nose angle on cutting performance in hot machining of Inconel 718

Superalloy Inconel718 is an important material for aircraft preparation because of its excellent performance at high temperatures. However, when cutting Inconel718, a large amount of cutting heat will be generated, resulting in excessive tool temperature and serious wear, which accelerates the tool failure. In order to solve this problem, the influence of tool angle on the process of thermal aided machining was studied by simulation model combined with thermal aided machining technology. During the cutting process, the workpiece preheating temperature rises from room temperature 20° C to 500° C, the front tool angle range is − 5° to 10°, and the rear tool angle range is 4° to 16°. By analyzing various parameters, it was found that a smaller tool rake angle can effectively reduce the tool temperature. Additionally, a flank angle of around 12° was found to decrease the maximum wear area of the tool by approximately 10.5%. Moreover, it was observed that implementing heat-assisted machining can result in a significant reduction of tool temperature by 11.1%, as well as a decrease in cutting force ranging from 18 to 22%, particularly at temperatures exceeding 500 °C.

Flow around single and two tandem rectangular cylinders with various single-side fairings

The shape of single-side wind fairing, which is the longitudinal triangular prism that tailors the outer side of a bridge deck, is key to the aerodynamic performances of double streamlined box girders used in long-span bridges. Uniform flow past single and double 4:1 rectangular cylinders with various single-side fairings are investigated using large-eddy simulation at a Reynolds number of 1.1 × 104. Various fairing nose angles and heights are compared. The wind loading and flow characteristics of the cylinders are discussed. The upstream fairing shows a larger reduction of mean drag and fluctuating lift on double cylinders than on a single cylinder. The fairing nose angle has a stronger influence on the wind loading than the nose height. By adding the fairing, sharpening the fairing nose, or lifting the fairing nose, the lateral recirculation zones are shortened while the rear recirculation zone barely changes, leading to different influences on the surface pressure. The upstream fairing is effective in reducing the vertical range and complexity of vortex structures around single and double cylinders.

Influence of nose angle on performance of dense medium cyclones with volute inlet

Dense medium cyclones (DMCs) are widely used in coal mine sorting processes to improve the quality of coal products and reduce pollution. The conventional linear inlet DMCs has the problems of unstable flow field, high turbulence density and low separation efficiency. Based on these concerns, the volute inlet DMCs was proposed, however the nose angle as one of the most critical parameters has not yet been investigated in depth. In this paper, a DMC with volute inlet is investigated, and the effect of nose angle is studied by a computational fluid dynamics model in terms of flow field, particle motion and the forces acting on the particles. The performance of the DMC is evaluated with respect to the inlet nose angle. As the nose angle increases from 0 to 180 deg., the separation efficiency has a tendency to increase and then decrease with the inflection point founding when nose angle is 180 deg. Then the flow field, particle distribution and particle force are analyzed respectively. The results show that the symmetry and stability of the flow field can be significantly improved as nose angle increases from 0 to 180 deg., but they remain almost constant when nose angle is 270°. In addition, a quantification method of the short-circuiting flow is established and it has been found that increasing the nose angle can notably reduce the short-circuiting flow. In terms of particle phase, increasing the nose angle causes heavier particle distribution tends to concentrate. During this period, the variation pattern of forces on particles with different nose angles is also analyzed. The DMC with a nose angle of 180 deg. has a longer acceleration zone at the entrance height and an increased radial force on the particles, which results in better performance. This study provides a theoretical basis and reference for the structure optimization of dense medium cyclones.

Improved Facial and Skull-Base Symmetry following Osteotomy and Distraction of Unilateral Coronal Synostosis.

Unilateral coronal synostosis (UCS) results in a surgically demanding deformation, as the deformity is asymmetric in the calvaria but also presents with facial scoliosis and orbital dystopia. Traditional cranioplasties correct the forehead but have little effect on the face and orbits. In this article, the authors describe a consecutive series of patients operated on for UCS with osteotomy of the fused suture combined with distraction osteogenesis. Fourteen patients (mean age, 8.0 months; range, 4.3 to 16.6 months) were included in this study. The authors measured and compared the orbital dystopia angle, anterior cranial fossa deviation, and anterior cranial fossa cant between preoperative computed tomography results and those at distractor removal. Blood loss was 6.1 mL/kg (range, 2.0 to 15.2 mL/kg), and length of stay was 4.4 days (range, 3.0 to 6.0 days). The authors observed significant improvements in the median orbital dystopia angle from 9.8 degrees (95% CI, 7.0 to 12.6 degrees) to 1.1 degrees (95% CI, -1.5 to 3.7 degrees) ( P < 0.001), anterior cranial fossa deviation from 12.9 degrees (95% CI, 9.2 to 16.6 degrees) to 4.7 degrees (95% CI, 1.5 to 7.9 degrees) ( P < 0.001), and anterior cranial fossa cant from 2.5 degrees (95% CI, 1.5 to 3.5 degrees) to 1.7 degrees (95% CI, 0.0 to 3.4 degrees) ( P = 0.003). Osteotomy combined with a distractor for UCS straightened the face and relieved orbital dystopia by affecting the nose angle relative to the orbits, correcting the deviation of the cranial base in the anterior fossa, and lowering the orbit on the affected side. Furthermore, this technique demonstrated a favorable morbidity profile with low perioperative bleeding and a short inpatient period, suggesting its potential to improve the surgical treatment of UCS. Therapeutic, IV.

Modal Instabilities over Blunted Cones at Angle of Attack in Hypersonic Flow

The effects of nose radius and angle of attack on the linear modal amplification over blunt circular cones at hypersonic speeds are computationally investigated. The three-dimensional laminar flow solutions over a 1.5-m-long, 7°-half-angle cone with 5.080, 9.525, and 25.40 mm nosetip radii are computed for selected angle-of-attack values and freestream conditions that match the Mach 10 experiments at a freestream unit Reynolds number of 17.1 million per meter conducted within the Hypervelocity Wind Tunnel 9 at the Air Force Arnold Engineering Development Complex (AEDC). Results indicate that the linear amplification of stationary and traveling crossflow waves along inflection lines increases with the angle of attack and decreases with the nosetip radius. The trend in transition front with respect to increasing angle of attack and bluntness is found to be consistent with the predicted increase in the amplification factors for Mack’s second mode (MM) disturbances along the streamline trajectories for the small and medium bluntness cases. The increase in the MM amplification along the windward ray for higher angles of attack is shown to be the result of a progressively earlier entropy-layer swallowing. Computations also indicate that the transition amplification factor along the windward ray increases with the angle of attack and decreases with the nosetip radius. Furthermore, the transition -factors along the leeward ray are below 2 and, therefore, rather small to lead to transition.

Soft tissue parameters variability in patients with normal dental occlusion

Facial aesthetics can be characterized by both subjective and objective data. The subjective view depends on many factors: gender, age, education level, population, race, ethnic group, fashion.Aim. Determine of soft tissue variability parameters in individuals with physiological occlusion.Materials and methods: a photometric examination of 20 persons with normal occlusion aged 20-24 years was carried out. There were used 12 soft tissue points on face profile and 6 front points for the photometric study. We researched soft tissue’s transversal parameters in full face structures and the angular parameters. Also we researched soft tissue profile’s ratio of points and planes to the true vertical and horizontal, and the face parts ratio reflecting indices.Results. It was determined that papameters have the maximum variability: under/beard line rotation, cervical-chin angle, cervical angle, cervical index, nose, middle and lower heights face ratio rotation angle. Facial Changes index shows that 35% of the studied subjects were classified as mild, 45% as moderate, and 20% as severe.Conclusions. The of the standards narrow framework does not allow taking into account the individual, ethnic, gender and age components of the face aesthetic perception. There is needed norms Greater individualization, an index evaluation increase role and face parts ratio analysis.

Алгоритм маршового розрахунку надзвукового обтікання ракети з відхиля-ємою носовою частиною

This paper presents a marching algorithm for the calculation of supersonic flow past a tilting-nose rocket. A feature of the algorithm is that the marching direction of supersonic flow calculation for the nose does not coincide with that for the main part of the rocket surface. Because of this, at first flow past the nose is calculated in a cylindrical coordinate system, the flow field parameters being stored at marching cross-sections. The start and the end of the parameter storage interval in the flow field are determined from the condition of the intersection of the bow shock wave with a plane in which an initial flow field is to be specified for the calculation of flow past the main part of the rocket surface. The flow field is interpolated in two stages, First, in the cylindrical coordinate system bound to the main part of the rocket surface in the initial data plane, the radial coordinates of the bow shock wave are determined at meridional sections. From the radial coordinates of points on the rocket surface and the bow shock wave, new computational grid node coordinates are determined at meridional sections in the cylindrical coordinate system of the main part. Using the new computational grid coordinates specified in the cylindrical coordinate system of the main part, old coordinates specified in the cylindrical coordinate system of the nose are determined with the use of expressions that relate the two coordinate systems to each other. The flow parameters at a point with the calculated coordinates are calculated using linear interpolation of the stored flow field parameters in the cylindrical coordinate system bound to the nose. The calculated flow field is used as initial data for the marching calculation of the main part of the rocket, The paper presents the results of calculation of the aerodynamic characteristics of a tilting-nose rocket in a supersonic flow at different values of the nose angle. The proposed algorithm may be used in a prompt calculation of the aerodynamic characteristics of rockets with tilting elements. In doing so, use may be made of a standard program of rocket flow calculation with an added block for the storage and interpolation of the flow field in a tilted cylindrical coordinate system with a shifted origin, which allows the marching direction to be changed.

Ideal Reference Lines for Assessment of Facial Asymmetry in Rhinoplasty Patients.

Assessing facial asymmetry is important to prevent unsatisfactory results in rhinoplasty. There has yet to be a consensus on reference lines for determining asymmetry. This study aimed to determine ideal reference lines to assess facial asymmetry and identify predictors of subjective perceptions of facial asymmetry. Preoperative photographs of 47 patients who underwent rhinoplasty were adjusted according to two reference lines (vertical line from the mid-glabella to Cupid's bow and horizontal interpupillary line). In total, 94 photographs were generated, randomly ordered, and evaluated by two independent observers for anthropometric measurements including six distances (distances from the midline to the medial and lateral canthi, ala, oral commissure, width of midface at maximum distance, and mandible width) and three angles (lateral canthal, lateral alar, and lip margin angles). Photographs were rated by 18 independent observers for subjective perceptions of facial asymmetry. Observers perceived faces as asymmetric if accompanied by nasal deviation, irrespective of the reference line (p < 0.001). Based on the horizontal reference line, subjective perceptions of asymmetry were correlated with the midline to lateral alar margin distance (r = 0.489, p = 0.003) and sum of the distance ratios (r = 0.354, p = 0.037). None of the objective parameters correlated with subjective perceptions when adopting the vertical reference line. A deviated nose and lateral alar angle were significant predictors of subjective perceptions of facial asymmetry. To assess facial asymmetry, the horizontal reference line should be determined first followed by the perpendicular vertical line. The nose is the most important feature determining overall facial asymmetry. LEVEL OF EVIDENCE V: "This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 ."

Investigation of geometric parameters with HSS tools in machining polyamide 6 using Taguchi method

The present investigation shows a suitable geometry for high-speed steel cutting tools for turning and facing operations. Different angles were considered such as the tip, free, attack and nose radius angle in the Polyamide PA-6 material, which allowed to perform a clean machining, with the least roughness possible. This investigation was carried out using orthogonal arrangements of the Taguchi method, followed for each stage of the corresponding variance analysis, ANOVA. The analysis allowed to decide the best variable for each parameter in order to propose the lowest possible roughness, for the turning tool the determined values were nose angle 45°, 6° free, 8° attack, and nose radius 0.7 mm. For the facing tool, the determined values were nose angle 3°, 4° free, 8° attack, and nose radius 0.5 mm. Also, the factor of the greatest influence was established, being for the turning tool, the nose angle with 22.7 %, free angle with 14 %, side rake angle with 6.4 % and the nose radius with 5.9 %. For the facing tool, the parameter with the greatest influence was the side rake angle with 12 %, followed by the free angle and the nose radius with 11 %.

A Comparative Study on Aerodynamic Drag Reduction of a Blunt Nose Body using Aerospike and Aerodisk – Numerical Approach

A spike attached to a hemispherical body drastically changes its flow field and influences aerodynamic drag in supersonic and hypersonic flow. It is, therefore a potential candidate for drag reduction of a future high-speed vehicle. The effect of spike nose configuration and angle of attack on the reduction of drag is studied. The studies show that the aerodisk is superior to the aerospike. The aerodisk of appropriate length, diameter and nose configuration may have the capability for the drag reduction. Design criteria is studied and the aerodisk attached to the blunt nose body are designed using CATIA. Numerical solutions are obtained using a commercial CFD software ANSYS-Fluent. Flow observations on the blunt body with a conical, hemispherical aerodisk and flat-faced aerodisk are carried out at Mach number of 2. The flow fields show different flow features between the conical spike, the hemispherical aerodisk and the flat-faced aerodisk. The effects of the aerospike and aerodisk on the lift and drag coefficient are studied. Finally, it is found that A forward-facing spike attached to a hemispherical body alters significantly the structure of the flow field and serves to reduce drag by the formation of a recirculation region around the stagnation point of the blunt body. The flow field, immediately behind the aerodisk shows a complex flow field due to back-disk geometry as compared to the conical spike. To take advantage of the forward-facing spike for more efficient drag reduction, the reattachment point of the shear layer on the body should be moved backward by choosing the optimal spike length with suitable geometrical configuration of the nose.

Sweep-Soil Interaction: a Mathematical Model

Cutting-edge tillage machinery design involves the evolving theory of implement-soil interaction. This paper proposes a mathematical model that represents the performance indicators of a sweep (soil deformation, draught, contact pressure) as a function of design and operating factors (note: this paper covers low-crown sweeps). Analysis of these equations and the results of field experiments show that increasing the nose angle will reduce the drag and require less force to cut the stubbles. As the cutting angle increases, more force is required to cut through; the penetration ability is directly proportional to cosα.

Design and test of a new step drill to reduce the operation time and increase the hole quality for CFRP materials

The usage of the composite materials, which is light and strong, has been rising thanks to the technological developments in the aerospace industries. The most important operation in the assembly process of the parts in producing the aircraft components is drilling which constitutes 50% of the total operation time. The reduction in the workmanship costs of the drilling operation is very important for the competition. In this study, a new step drill was designed to reduce the drilling operation time for drilling of O5.94-mm holes on carbon fiber reinforced plastic (CFRP) parts. The tests were applied by using a 12,000 rpm drill motor manually to simulate the actual process and to inspect the impact of new drill geometry on the hole quality. The result indicates that double step drill geometry with 18° nose angle reduces the drilling operation time by making the O5.94-mm hole in two steps instead of three steps. The cylindricity and delamination results of existing and newly designed drill geometry were compared. From results, the established new design geometry could be employed for drilling operations of CFRP materials. The time saving for one hole can be obtained as 30 s by using newly designed double step drill. The operation time can be reduced as 33% with this new drill.

Modeling the surface roughness in face-end milling process by using general insert at stable cutting conditions

Predicting the quality of the machined components is the grandiose signification in industrial manufacturing. Calculation of the surface roughness is one of the most important elements to predict the quality of machined parts. In this paper, the surface roughness was modeled in the face-end mill process by using general rhombu insert. In the proposed mathematical model, with the stable milling condition, the surface roughness is formulated by a function of feed rate, and insert geometry such as nose radius and nose angle. An experimental method is proposed based on the stable milling condition to estimate the surface roughness. The developed surface roughness calculation model has been successfully verified by both simulation and experiment with very promising results. The average difference between predicted and experimental results is 7.59%. The proposed model can be applied to predict the surface roughness in face-end mill processes by using general insert at stable cutting condition.

Numerical Investigations of Cavitation Nose Structure of a High-Speed Projectile Impact on Water-Entry Characteristics

In this study, a detailed analysis of the influences of cavitation nose structure of a high-speed projectile on the trajectory stability during the water-entry process was investigated numerically. The Zwart-Gerber-Belamri (Z-G-B) cavitation model and the Shear Stress Ttransport (SST)k-ω turbulence model based on the Reynolds Averaged Navier–Stokes (RANS) method were employed. The numerical methodology was validated by comparing the numerical simulation results with the experimental photograph of cavitation shape and the experimental underwater velocity. Based on the numerical methodology, the disk and the conical cavitation noses were selected to investigate the water-entry characteristics. The influences of cavitation nose angle and cavitation nose diameter of the projectile on the trajectory stability and flow characteristics were carried out in detail. The variation features of projectile trajectory, velocity attenuation and drag were conducted, respectively. In addition, the cavitation characteristics of water-entry is presented and analyzed. Results show that the trajectory stability can be improved by increasing the cavitation nose angle, but the drag reduction performance will be reduced simultaneously. Additionally, due to the weakening of drag reduction performance, the lower velocity of the projectile will cause the damage of the cavitation shape and the trajectory instability. Furthermore, the conical cavitation nose has preferable trajectory stability and drag reduction performance than the disk cavitation nose.

Aerodynamic Optimization Design on Supersonic Transports Considering Sonic Boom Intensity

It is key points to improve the aerodynamic efficiency and decrease the sonic-boom intensity for the supersonic aircraft design. Sonic-boom prediction method with high precision combining the near-field sonic-boom prediction based on Reynolds-Averaged Navier-Stokes equations and the far-field sonic-boom prediction based on waveform parameter method is firstly established. Then the gradient of sonic boom with respect to the design variables is calculated by the finite difference method and is combined with the gradient of the aerodynamic object by the discrete adjoint technique, acting as the gradient of the weighed object function. Assembling two gradients, the optimization system couples Free Form Deform method、the dynamic mesh technique based on Inverse Distance Weighting interpolation method、the gradient-based optimization algorithm based on the sequential quadratic programming. Using the aerodynamic optimization system considering the sonic boom intensity, the paper conducts a nose angle deflection optimization design and an elaborate aerodynamic optimization including huge design variables and constraints on a supersonic business jet, while the optimization objects are the weighed object and the supersonic cruise drag coefficient. The results show that the nose is deflected downward and the shock wave pattern is changed, leading to a lower far-field maximum overpressure; the drag is decreased by 15.8 counts, and the wing load is moved inboard, also, the pressure drag of the outer wing reduces. Meanwhile, the pressure distribution in the outer wing has a weaker adverse pressure gradient and a more gentle pressure recovery. After optimization, the low-drag and low-sonic boom configuration is obtained, which verified the effectiveness of the optimization system.

Experimental and Numerical Analysis of Conical Projectile Impact on Inconel 718 Plates

This paper analyses the impact behavior of Inconel 718 through experimental and numerical approach. Different conical projectiles were tested in order to obtain the ballistic curves and failure mechanisms. A three-dimensional (3D) numerical model corresponding to the experimental tests was developed using the Johnson–Cook constitutive model. The experimental data (residual velocities, global, and local perforation mechanisms) were successfully predicted with the numerical simulations. The influence of the projectile’s nose angle was found to be important when designing ballistic protections. The projectile with the narrowest angle, 40°, developed a ballistic limit approximately 10 m/s lower than the projectile with a 72° nose. The use of double-nose projectile for the same nose angle, 72°, led to a ballistic limit 12 m/s lower than that obtained for the single nose.

Numerical Simulations of Projectile Nose Angle Effect in Ballistic Perforation of Double-Layered Steel Plates

The purpose of this paper is to study the ballistic perforation resistance of double-layered steel plates subjected to impact by conical projectiles with different nose angles. Based on nonlinear finite element theory, different rigid projectiles vertically penetrating into double-layered Weldox 460E steel plates are simulated with LS-DYNA code. The configurations in the penetration process and failure modes of steel plates are given. The results of monolithic and layered targets are studied and compared for projectiles with different nose angles. It is revealed that compared to the monolithic plate, the double layer configuration is able to improve the ballistic limit for the target under impact by blunt-nose projectiles, and for sharp-nose projectiles the double layer configuration obviously weakens the ballistic resistance.

Soft tissue growth changes from 8 to 16 years of age: A cross-sectional study.

Objective:The present cross-sectional study was conducted to evaluate and compare the soft tissue growth changes between males and females of two groups from 8 to 16 years.Materials and Methods:One hundred sixty skeletal class I lateral head cephalograms were screened aged between 8 to 16 years-Subjects were divided into two groups. Group I (8 to 12 years) and Group II (12 to 16 years) and further these groups were subdivided into male and female subgroups. Total eight linear and four angular parameters were studied.Results:All the parameters increased in their dimension while angle of total facial convexity including nose and Nasolabialangle decreases. Among the linear variables, Noseheight, Lip thickness at laberale inferious, Lip thickness at B point, Soft tissue chin thickness and Measurements of lips to E-plane were found significant for both subgroups. While rest of the linear variables like Upper lip height, Lower lip height, Nose depth and Sagittal depth also increased but this increase wasfound non-significant. Among the angular parameters angle of total facial convexity including nose and Nasolabialangle decreases and angle of facial convexity excluding nose, and Nose inclination increases with the age, and these changes were found non-significant.Conclusion:In this study, we observed that males showed a greater value of all parameters in comparison to females, and with the advancement of age, all the parameters increased, except for angle of total facial convexity and nasolabial angle.

Effect of preemptive dexamethasone and etoricoxib on postoperative period following impacted third molar surgery - a randomized clinical trial.

Background The aim of this study was to compare the anti-inflammatory effects of dexamethasone and etoricoxib after third molar extraction. Material and Methods A prospective, randomized, controlled, split-mouth study was conducted. 19 volunteers were allocated randomly to receive 90mg etoricoxib 1 hour prior to the procedure or 4mg intramuscular dexamethasone immediately after anesthesia. Baseline measurements were obtained preoperatively, and subsequent assessments were made on immediate postoperative, at 72 hours and 7 days after surgery to measure postoperative facial swelling by use of linear measurements, interincisal mouth opening width and visual analog scale score for pain. The amount of analgesics consumed was recorded. Descriptive statistics and the independent-samples t-test were used to compare the two groups at P < 0.05. Results Dexamethasone was effective in the control roasted edema for measurements of the mandibular angle - wing of the nose and mandibular angle - labial commissure 72 hours after surgery. And for the measurement mandibular angle - mentum, in the time of 72 hours and 7 days. There was no statistically significant difference in relation to pain and trismus. Conclusions Considering significant results for some measures of the variable edema for the group that used intramuscular dexamethasone and the difference without statistical significance between groups for the other variables studied, we seem to reflect the intramuscular indication of the corticosteroid in a single dosage in relation to the use of etoricoxib as pre-emptive medication. Key words:Corticosteroids, COX-2 selective, third-molar surgery.

Debris dispersion analysis for the determination of impact conditions via traceback technology

A method for predicting the initial impact conditions including projectile shape and impact velocity is presented through analysis of the dispersion characteristics of debris by means of a traceback methodology. For the determination of the impact conditions, the diameter of the penetration hole in the target, and the dispersion area of the debris on the witness plate were investigated. Based on the results, the projectile configuration defined by the nose angle (NA) and the length to diameter ratio (L/D) together with the initial impact velocity was obtained. NA is associated with the penetration diameter DP and also debris dispersion diameter D50. D50 means 50% containing debris of all dispersions from the center of witness structure. Furthermore, L/D is related to DP and D95, in which D95 is the dispersion diameter containing 95% debris. The projectile diameter can be determined by the relationship between the projectile shape (NA and L/D) and debris dispersion (D50 and D95). Meanwhile, the shape factors identified from the contact surface between the projectile and the structure were designed to modify the de Marré’s ballistic limit equation. From the results, it was found that DP increased linearly with increasing impact velocity, and the slopes of DP against impact velocity also increased as NA increase. The initial velocity has been then finally determined by the DP-impact velocity slope and the modified de Marré’s equation. Based on the methodology, the shape and initial impact velocity of the projectile could be predicted within 5% error.