Straight Profile Research Articles

Performance Evaluation of a Fin and Tube Heat Exchanger Based on Different Shapes of the Winglets

Abstract The present work investigates numerically the performance of a fin- and tube-type heat exchanger using the finite volume method. The effect of different winglet geometries, namely, straight profile, concave profile, convex profile, and their combinations are extensively examined under turbulent flow conditions to evaluate the pressure drop and heat transfer performance. These winglets are also tested for smaller leading-edge and larger trailing edge, and vice versa—it has been observed that the former winglet configuration outperforms the latter ones. The convex profiled winglets yield the highest heat transfer performance as well as pressure drops, whereas the winglet with a concave profile has the lowest heat transfer coefficient and pressure drop values. The enhancement factor—defined as the ratio of enhancement in heat transfer to the enhancement in pressure drop penalty—has also been calculated for all models. Conclusive results indicate that the convex profile and the concave–convex (a hybrid winglet) configuration, with a smaller leading edge, deliver the highest enhancement factor compared to other profiles. Following this, the study is further elaborated to find the optimum height for the convex winglet profile. General correlations have also been developed to estimate the Colburn factor, friction factor, and enhancement factor for variations in the leading edge of the convex profile.

Investigation on Modulation-Based Straightness Measurement

The concept of a novel non-contacting technique for measuring straightness and its practical realization in a mechanical device are presented in this article. The device, called InPlanT, is based on the acquisition of the luminous signal retroreflected by a spherical glass target and impinged on a photodiode after mechanical modulation. The received signal is reduced to the sought straightness profile using dedicated software. The system was characterized with a high-accuracy CMM and the maximum error of indication was derived.

Mixed Lubrication Analysis of Tapered Roller Bearings and Crowning Profile Optimization Based on Numerical Running-In Method

Tapered roller bearings (TRBs) are widely used in heavy-load rotating machinery. One of the technical problems in TRBs is the existence of sharp spikes of the contact pressure in the vicinity of the two ends of the tapered rollers. To suppress the pressure spikes at the roller ends, a straight roller profile is crowned in cylindrical and tapered roller bearings. However, compared to cylindrical roller bearings, there are few studies on the profile modification of TRBs in the literature, and most of the publications on the EHD analysis of tapered rollers focused on a single roller, using traditional profiles such as logarithmic profiles, dub-off profiles and chamfer profiles. By using the numerical running-in method proposed and used in crowning profiles of cylindrical rollers by the authors, this paper provides the first ever asymmetric optimized profile solution for all TRBs rather than for just a single roller. The results show that the optimized profile has the best performance in smoothing contact pressure distribution in the axial direction compared with the conventional logarithmic profile and is a useful profile form with respect to the elimination of sharp pressure spikes. In addition, considering the effect of temperature and mixed lubrication, this paper analyzes the influences of different axial profiles under radial load (Fr), rotation speed (N) and standard deviation of roughness (Rq) conditions.

Experimental study on the collapse-resistant performance of unbonded prestressed PC beam-column sub-assemblages with pinned connections

In precast concrete frame structures, it is imperative that beam-to-column connection has appropriate robustness and reliable axial resistance to defense against progressive collapse. Hence, a method of using pinned connection and unbonded posttensioning strands (UPSs) to mutually improve the collapse-resistant performance of precast concrete structures was proposed in this study. The pinned connections are used for connecting precast beams with columns at precast beam ends, and UPSs with straight profile are placed at the bottom of beam cross-section. In order to investigate whether the proposed method can enhance collapse-resistant capacity of precast concrete structures, static progressive collapse tests were conducted for the newly proposed precast concrete frame substructures with UPSs (UPPC frame substructures) and without UPSs (PC frame substructure). Moreover, influences of effective prestress level upon the collapse-resistant capacity of UPPC substructure were also investigated. Test results demonstrated that, similar to conventional RC frame structure, the compressive arch action (CAA) and catenary action (CTA) could also develop in the proposed UPPC substructures to avert progressive collapse. The UPPC substructure was able to develop 32% higher CAA capacity and 162% larger CTA capacity as compared to the PC substructure, indicating that the UPSs play a positive role in enhancing both its CAA and CTA. The CTA capacity of the PC substructure was 53.8% higher than that of CAA, which signifies that the pinned connection can be employed to improve structural robustness to mitigate progressive collapse. In addition, the increase of effective prestress level of UPSs is beneficial to the enhancement of CAA capacity of the UPPC substructure. However, higher effective prestress level is limited to improve its CTA capacity due to lower deformation capacity of UPSs. Subsequently, three-dimensional finite element models (FEMs) of the UPPC and PC substructures were developed by using ABAQUS software. By comparing experimental data with FEM results, it was concluded that the FEM could accurately predict the load–displacement curves, crack patterns and reinforcing ruptures of all the test specimens.

Aesthetic preferences of individuals when evaluating photographs of facial profiles with different sagittal and vertical growth patterns. A cross-sectional study

To evaluate the aesthetic preferences of individuals by observing photographs of different facial profiles with different sagittal and vertical growth patterns. Cross-sectional study that evaluated 300 students from a private university. Edited photographs of a man and a woman were used. The maxilla being moved in a vertical direction while the mandible was moved in a sagittal direction, various combinations of the photographic profile of the two individuals were created. These movements created 9 photographic profiles for the woman and the man; for intra-observer reliability, two photo profiles of both sexes were duplicated. Chi square tests and binary logistic regression were used. P<0.05. In general, the evaluated individuals mostly preferred the type 6 profile (65.7%), followed by the type 5 profile (21.7%) (slightly convex). It was found that for every year of age that an individual increases, there is a 31% greater chance of choosing one of these profiles. Both sexes prefer a straight or slightly convex profile, and as age increases, individuals prefer a straight profile.

Esthetic preferences of orthodontists, dentists, and plastic surgeons for balanced facial profiles.

The aim of this investigation was to determine whether the facial esthetics of subjects rated as "attractive" can be related to specific cephalometric soft tissue parameters. The profile silhouettes of 100 subjects (45 males and 55 females) were rated by 60 esthetics specialists (20 orthodontists, 20 dentists, and 20 plastic surgeons) using a Likert scale, and 30 of the subjects were selected as being "attractive". The cephalometric measurements of the attractive group were then compared with norms for the general Caucasian population. The effects of specific measured parameters on profile beauty grades were assessed using the median test, and the following variables were found to show significant correlations between the Caucasian norms and the attractive profile group: the ratio of the upper to lower face height (P = 0.011), the ratio of the subnasale - labrale inferius (Sn-Li) and labrale inferius - menton (Li-Me`) lines (P = 0.011), the distance between the chin and the subnasale perpendicular (P = 0.002), upper lip thickness (P = 0.021), soft tissue chin thickness (P = 0.021), vertical height ratio (P = 0.021), and nasolabial angle (P = 0.021). A straight profile with a fuller and more protruded upper lip, a higher nasal tip, and a smaller lower facial third are considered to be the most attractive facial features, and may be useful for improvement of facial esthetics.

An experimental study of friction stir welding parameters effect on joint properties of aluminium alloy and copper plate

Joining dissimilar metals like copper and aluminium is a complex area of research for the manufacturing industry. To effectively join the AA7075 with copper plates, an experimental investigation on friction stir welding was carried out. A straight cylindrical pin profile tool of H13 tool steel was chosen for this study. On the advancing direction, the AA7075 plates were fixed under the condition of zero tool offset. The tool was positioned at a 2° tilt angle for the entire experiment. Tensile test, microhardness test, SEM and EDS analysis were completed to investigate the effectiveness of the process parameters (tool traverse and rotational speed) in combination with a modified set-up on the microstructure, tensile strength and microhardness of the joint. Fractography was conducted on fractured specimens to identify the mode of failure. Complex microstructures of swirl and vortex-type material flow patterns were created in the stir zone. As a result of SEM analysis, one of the samples (S5) had finer grains at intermediate heat input, which produced excellent microhardness and tensile strength. Fractography identified ductile failure as the predominant mode of failure in the joints. The results of this study include an ultimate tensile strength value of 221.091 MPa with a joint efficiency of 95.05%, yield strength of 159.035 MPa, maximum elongation of 9.335% and a microhardness value of 271 HV for specimen welded at a traverse speed of 60 mm min−1 and a rotational speed of 1400 rpm.

Orthodontic Camouflage of Borderline Skeletal Class III MalocclusionA Report of Two Cases

Camouflage treatment in borderline Class III patients, especially those who refuse a surgical line of treatment, remains a challenge to the orthodontists. Such patients were usually treated using Class III elastics and lower premolar extractions. Mandibular arch distalisation is an alternative option for non extraction Class III camouflage. Temporary Anchorage Devices (TADs) help in achieving effective mandibular molar distalisation and are more accepted by adult patients. This case report discusses the diagnosis and management of two different presentations of borderline skeletal Class III malocclusion treated with miniscrew assisted mandibular arch distalisation. Two adult female patients between 18-20 years of age presented with a skeletal Class III malocclusion, average growth pattern, super Class I molar relationship and straight facial profile. The patients did not agree for a surgical line of treatment. Camouflage treatment by distalisation of mandibular arch using buccal miniscrew implants was done. Inter-radicular miniscrews were placed between mandibular second premolar and first molar to apply distalisation force of 250 gm/side. Lower arch distalisation of 2-3 mm was achieved in an average of 4.6 months. The outcomes were well retained 3 years post-treatment.

Design of Roll Sheet Metal Forming Machine with Material Thickness of 0.3 mm

The role of wood as a choice of roof frames for houses is increasingly being abandoned due to high costs, wood materials are easily exposed to flying termites so that they corrode. aluminum, and zinc. So, it is more resistant to corrosion and made according to ISO standards, mild steel sheet material / metal sheet for roof truss construction is formed by profiles where the process of forming these profiles is by cold rolling, known commonly as a metal forming process or cold metal forming with external force emphasis. on the plastic condition of the steel sheet, due to the high market demand which is promising now efforts to build a light steel profile factory are springing up rapidly. The prospect of the metal forming process industry still has a good chance, therefore the initiative was taken to design a metal roll forming machine with a straight triangular groove profile with galvalume steel sheet material with a thickness of 0.3 mm and used for practical purposes in the production process. The metal forming process is a work process. metal by changing the shape of the workpiece by applying an external force so that plastic deformation occurs and the resulting mild steel profile is generally intended to be carried out at room temperature without heating the steel sheet. The design of the roll machine along with the frame to be constructed has dimensions of 200x400x275 mm and a frame of 310x400x750 mm, with the rotary wheel of the roll machine.

Исследование взаимосвязи режущей способности инструмента с параметрами акустического сигнала в процессе профильного шлифования

Introduction. Modern mechanical engineering is closely connected with digital production management technologies, for which an important aspect is the collection of reliable information about the current state of the systems. Acoustic methods of current control of the tool cutting ability possess significant potential due to the possibility of continuously obtaining up-to-date data on the parameters of machining process. Profile grinding is one of the widespread methods of machining surfaces of complex configuration. The high importance of this method lies in the high degree of responsibility of shaped parts obtained with it. The wear parameter of profiled grinding wheels needs current control to the same extent as other types of cutting tools. At the same time, acoustic methods of research have not found wide application in relation to profile grinding. In view of this, the present work is aimed at studying the influence of the tool wear rate on the acoustic characteristics of grinding when using grinding wheels of different profiles. Purpose of work is to determine the acoustic parameters of profile grinding with application of planar grinding scheme as it wears out in comparison with analogical process with application of straight profile grinding wheel. As the basic methods of research an experiment is used to study the acoustic phenomena accompanying grinding with application of wheels of different profile. An analysis of the acoustic signal of grinding is carried out, as well as an analysis of the spectrum of its frequency composition. The frequencies of natural vibrations of grinding wheels of different profiles are investigated, its sound index is determined as a criterion for evaluating its characteristics. Acoustic characteristics of the grinding process with the use of grinding wheels of different profiles are compared. Regression analysis of acoustic data obtained as a result of the experiment is also used. Results and discussion. Spectrograms of frequencies of natural vibrations of the wheels under research, as well as a number of spectrograms of the acoustic signal accompanying the processing process for various technological conditions are received. As a result of comparing the obtained spectrograms, the informative frequencies of the grinding processes are determined. Mathematical models of sound level dependence on the value of periodic vertical feed St at depth t and processing time T are developed. It is established that the value of periodic vertical feed St at depth t has a greater influence on the acoustic index in comparison with the machining duration T. Practical significance and prospects of the results of the work lies in the possibility of increasing the efficiency of profile grinding processes due to the rational use of the tool availability.

Corrosion Characterization of Friction Stir Weld Dissimilar Aluminium Alloy Joints

The course of contact mix welding is quick acquiring conspicuousness in aviation, marine and car industry because of its benefits as far as mechanical strength, effect and hardness characteristics. There is as yet a requirement for sure fire consideration from the exploration local area to erosion in grating mix welding zones, hence the work introduced here centres around the consumption portrayal of the grinding mix weld divergent aluminium composite. This study looks into friction stir welding under various parametric settings and shows how corrosion happens in a sodium chloride electrolytic media under potentio-dynamic conditions. The friction stir weld joints of dissimilar alloys aluminium are constructed using three sets of parameters. Straight cylinder, taper cylinder, and straight triangular tool profiles; tool rotational speeds of 800, 1000, and 1200 rpm; tool feed rates of 100, 120, and 140 mm/min; and tool offsets of 0.5, 0 mm, and -1.5 mm. The corrosion current (Icorr) reduces as tool rotating speed increases up to 1200 rpm, after which it slightly increases due to the creation of ridges all around the periphery of the friction stir weld area.

Optimisation of underwater friction stir welding parameters of aluminum alloy AA5083 using RSM and GRA

Friction stir welding (FSW) is a non-traditional welding procedure for joining identical and divergent substances that are comparatively hard to weld using fusion techniques. The FSW is more competent and eco-responsive when correlated with the traditional processes. The tensile characteristics of thermally susceptible alloys are minimized as a result of heat iterations. The roughening of the consolidated deposits in friction stir welding induces joint moderation. For non-heat-treatable alloys, intergranular and stress corrosion cracking are developed in grain boundaries during the FSW. Because of this, the overall performance and mechanical properties were reduced. Underwater friction stir welding (UWFSW) is preferred to prevail over the problems. UWFSW is appropriate for both heat-treatable and non-heat-treatable alloys that are receptive to thermal activity throughout the procedure. This research examines the effects of response surface methodology (RSM)-based grey relational methods on the optimization of UWFSW procedural characteristics such as the straight hexagonal tool profile (SH), tool rotational speed (TRS) of 1200 rpm, tool transverse velocity (TTV) of 20 mm/min, and water head (WH) of 10 mm in military-grade AA5083 alloy. The mechanical properties of the AA5083 UWFSW joint, such as its average ultimate tensile strength (UTS) and hardness, have been greatly improved. Grey Relation Analysis was used to determine welding specifics such as UTS and hardness. The ANOVA was used to assess the formulation's significance. The micro-structural behaviour and grain structure of different weld zones were investigated with the help of the scanning electron microscope (SEM). The image processing technique can be used to quantitatively assess the UWFSW process using the non-destructive testing (NDT) ultrasonic B-scan image and radiographic image. Confirmation tests at the optimal parameter level improved the performance of each response.

Last Glacial Maximum Microblade Production at Shizitan 29 and its Implications for North China Pressure Technology

ABSTRACT A techno-functional approach applied to the lithics of the Late Upper Palaeolithic Shizitan 29 site allows the identification of previously unrecognized technical features of microblade pressure production and new behavioral understanding of its evolution beginning ca. 26,000 cal b.p. These technical features may relate to the evolution of so-called boat-shaped cores, including the development of two blade scar sequences and the 8-like contour of the striking platform (likely related to fixing cores in a holding device). Counter to traditional typological lithic analyses centered on final core morphologies, we seek to identify technical objectives related to the required pressure production. In doing so, we argue that earlier semi-conical cores may have maximized the exploitation of the core volume, while subsequent boat-shaped cores developed to maximize the efficiency of the production of straight profile, regular blades. This allowed microblades to become a critical adaptation for final Pleistocene hunter-gatherers in northern East Asia.

Phenotypic Characterization and Reproductive Performance of Blackhead Somali Sheep in Fafen Zone of Somali Regional State, Ethiopia

Objective. The study aimed to characterize the reproductive performances and physical characteristics of Blackhead Somali indigenous sheep breeds. Methods. The data from 460 sheep were used for the determination of morphometric characterization while 110 male sheep and 150 females were used to characterize the reproductive performance of Blackhead Somali sheep breeds. Results. Accordingly, about 86% of sheep have a white body with a blackhead as the dominant coat color and about 81% of sheep have a straight facial head profile. Dewlap was present in 92.7% (91.8% for males and 92.7% for females). The overall average body weight, body length, height at wither, height at the rump, heart girth, chest depth, pelvic width, and tail circumference differs significantly (p&lt;0.05) among males and females with the advancement of age. The average age at first service, age at first lambing, lambing interval, and life lamb crop in ewe were 13.75 ± 2.44, 19.12 ± 2.41, 9.66 ± 1.56, and 6.18 ± 2.01, respectively. The average reproductive life span of ewe and ram was 6.04 ± 1.43 and 6.63 ± 1.49 years, respectively. On average Blackhead Somali ewe delivers 13.1 ± 4.3 lambs in her lifetime. The twinning and triplet rate were recorded to be 12.30% and 1.90%, respectively. Conclusion. In conclusion, shorter lambing intervals, higher adult body weight, and frequent twinning are the most desirable features which may also be used as selection criteria. It is recommended to do further detailed analyses to determine the genetic variation between and within these small populations to develop an effective conservation and utilization program.

On-machine workpiece straightness profile measurement using a hybrid Fourier 3-sensor method

To compensate for the straightness error of the slide of a machine tool efficiently and precisely, on-machine self-calibrating measurement of the manufacturing error is critical. The Fourier 3-sensor (F3S) method proposed by Fung is promising in measuring the straightness profile of a workpiece accurately on a machine. However, it still suffers from two main challenges: the height difference between the second and the third probes and the stochastic uncertainty, both of which can significantly decrease the measurement precision. In this paper, we counter these two challenges, respectively, and propose the solutions accordingly. First of all, by resorting to the Laplace transform, an algorithm for the F3S method is proposed. Second, the adverse effect of the height difference between the second and the third probes is demonstrated. An approach is presented for estimating the height difference, and compensating for this. Third, to alleviate the stochastic uncertainty, a hybrid F3S method is developed: several F3S measurements are first performed under different probe spacings; then, the optimal Fourier coefficients of the straightness profile are individually selected from the candidate estimates in accordance to the determinant of the transfer matrix. Finally, practical straightness profile measurements were performed, respectively, on a grinding machine by adopting the hybrid F3S method and on a Taylor Hobson surface profiler. The results show that compared with the conventional F3S method, the hybrid F3S method reduced the measurement uncertainty significantly, and the straightness profiles estimated by the hybrid method and by the surface profiler were consistent with each other.

Surgical Orthodontic Treatment of Class II Malocclusion with Facial Asymmetry

This case report describes a successful surgical orthodontic treatment of a Class II malocclusion with facial asymmetry. An 18-year-old female visited our dental clinic due to proclined anterior teeth and facial asymmetry. Straight facial profile and skeletal Class II was observed. The frontal cephalometric analysis showed that the left ramus length was longer and the left ramal angle was greater than the right. After extraction of the maxillary and mandibular second premolars, dental arch was decompensated. After presurgical orthodontic treatment, bilateral sagittal split ramus osteotomy (BSSRO) was performed. Facial asymmetry was improved, but posterior open bite on the right was occurred by insufficient dental decompensation. To prevent recurrence of the mandible, a bite stop was made by bonding resin on the lingual side of the right maxillary canine. This prevented the recurrence of the mandibular rolling and yawing with the use of bilateral intermaxillary elastics. The right mandibular posterior part with open bite was segmented from the main arch wire and was extruded with intermaxillary elastic. Fast occlusal stabilization was achieved by using the rapid tooth movement after surgery. Since intermaxillary elastic was used while applying an intrusion force with a micro-implant to the left posterior region, it was possible to stabilize the mandible while prevent tooth extrusion. After treatment, facial symmetry and good occlusal relationship were achieved.

Characteristics of Sciatic Scoliotic List in Lumbar Disc Herniation.

Retrospective radiological study. Physical examination reveals sciatic scoliotic list (SSL) in some patients with lumbar disc herniation (LDH). We aimed to evaluate the coronal and sagittal parameters of the SSL curve, describe their characteristics, and establish a new classification system. We retrospectively reviewed 230 patients (SSL group = 96; non-SSL group = 134) diagnosed with single-segment LDH from January 2018 to December 2020. The control group comprised 70 healthy volunteers. Radiographic parameters were compared between the groups. In the SSL group, the Cobb's angle was 12.5 ± 5.3° (4.2-31.2), trunk shift 26.2 ± 17.9mm (.0-88.2mm), and apical vertebral translation 31.7 ± 16.0mm (1.18-8.58mm). Further, 62.5% of patients had L4/5 disc herniation, 76.0% had disc herniation at the convex side of the lumbosacral scoliosis, and 81.3% had disc herniation at the opposite side of the trunk shift. Compared to the control group, lumbar lordosis and thoracic kyphosis decreased, pelvic tilt increased, and the sagittal vertical axis moved forward in the other patients. The sagittal imbalance in the SSL group exacerbated. Using the positional relationship between vertebrae and the central sacral vertical line (CSVL), we identified two main SSL patterns with which 95.8% of the patients were defined as Type 1. The SSL curve is characterized by a long thoracic or thoracolumbar curve, with a relatively straight sagittal profile and little rotation. Further, the lumbar and thoracic vertebrae shifts are on the same side as the CSVL. These features of the SSL curve differentiate it from other types of structural scoliosis.

Influence of pin profile on formability of friction stir-welded aluminum tailor-welded blanks: an experimental and finite element simulation analysis

In sheet metal forming processes, the forming limit diagram is frequently employed as a criterion for predicting necking initiation. This is one of the most useful and effective methods for the evaluation of the formability of tailor-welded blanks. The goal of this study was to determine the formability of friction stir-welded (FSW) aluminium alloy 6061-temper 6 (AA6061-T6) and aluminium alloy 2017-temper 6 (AA2017-T6) by employing five dissimilar tool pin profiles. To evaluate the limiting dome height, five different combinations of dissimilar blanks were used in experimental and simulation experiments. Material characteristics such as density, elastic modulus, and all multilinear behaviors of blanks were manually assigned for simulation from the test results of true stress versus true strain plots. The punch with die supports was considered as a rigid body, whereas the metallic blanks were considered as plastic material. To carry out the simulation, the entire blank was divided into three zones. The results obtained from the experimental and simulation results showed that the straight square tool pin profile is the optimal tool pin profile for the formability of FSW AA6061-T6 and AA2017-T6. The tested height values obtained from the limiting dome height were 20.5 and 20.9 mm in experimentation and simulation, respectively. The straight cylindrical tool pin profile exhibited the worst formability properties in both experimentation and simulation.

Investigation of the imbibition/drainage of two immiscible fluids in capillaries with arbitrary axisymmetric cross-sections: a generalized model

Abstract In this work, we investigate the problem of imbibition/drainage of a fluid in capillaries of arbitrary axisymmetric cross-sections filled initially with another immiscible one. The model predicts the location of the meniscus and its speed along the tube length with time. The two immiscible fluids may assume any density and viscosity contrasts. In addition, the axisymmetric profile of the tube maintains a relatively small angle of tangency to warrant that the axial velocity distribution assumes, approximately, a parabolic profile. The driving forces that may be encountered in this system include the capillary force, pressure force, gravitational force and an opposing viscous force. The orientation of the capillary force can be in the direction of the flow (e.g. during imbibition) or opposite to the flow (e.g. during drainage). Likewise, the gravitational force can be in the direction of the flow or opposite to it. In this work we account for all these possibilities. A differential equation is developed that defines the location of the meniscus with time. A fourth-order-accurate Runge–Kutta scheme has been developed to provide solutions for the different scenarios associated with this system. It is shown that the developed model reduces to those appropriate for straight tubes, which builds confidence in the modelling approach. The effects of changing the tangent along the profile of the tube, which influences the calculation of the radius of curvature of the meniscus, is also considered. Unlike the cases of straight capillary tubes, in tubes with arbitrary symmetric profiles, the friction force depends on the variations of the tube profile. Examples of converging/diverging capillary tubes that follow straight and power law profiles are investigated. In addition, the case of sinusoidal profiles has also been considered.

Influence of age, sex and occupation on the aesthetic perception of the facial profile

Objective: To study the influence of age, sex, and occupation in determining the aesthetic perception of the facial profile in the Chilean population through the analysis of silhouettes. Methods: From a profile photograph, a digital silhouette was designed, which was modified with 2mm movements from the original position of the chin, simulating mandibular protrusion and retrusion. The use of silhouettes allows for eliminating various distractions, prejudices, and predispositions when making an aesthetic judgment. All participants accepted informed consent. Results: 112 participants with a mean age of 33.99 ± 8.28 years were surveyed. When analyzing the most aesthetic option was a straight profile, followed by a slight retrusion of -2mm and a protrusion of +2mm. The least esthetic option was a severe protrusion of +12mm. Both results were repeated in all the groups analyzed. Conclusions: The results present similarities with the literature, however, the low concordance in this study may be due to possible indirect influences due to the contrast of the images that made up each set and the limited size of the studied sample. The present study was the first of these characteristics in a Chilean population.