Semi-elliptical Shape Research Articles

Basic research on the effect of distance between performers on ensemble performance

Due to the spread of COVID-19, the performers on stage were required to keep a certain distance among them. Because it was considered that the droplets come from performers rise a risk of infection with COVID-19 when they performed musical instruments. A distance of at least 2 m between wind instrument performers, and 1.5 m between string instrument performers was recommended. However, with these distances, the performers found it difficult to perform. Actually, in previous studies, it has been suggested that difficulties in listening to their performance can occur. However, the specific causes of these problems have not yet been clarified. Therefore, the purpose of this study is to clarify the effects of differences in distance between performers on acoustical properties and auditory perception by focusing on performers in an ensemble. In particular, targeting a group of five performers arranged in a semi-elliptical shape, the various acoustic physical quantities, and conducting subjective evaluation experiments were performed. As a result, it was found that changes in the distance between performers affect the acoustic properties and the auditory perception. This knowledge will contribute to creating a comfortable environment for performers.

Impinging ceiling flame behaviors induced by wall-attached gaseous fuel fires at one end in a narrow building corridor: Different phases and generalized correlations

This work investigated the flame extension behavior after impinging upon a ceiling induced by wall-attached fires at the closed end in a narrow building corridor. Experiments were conducted in a reduced scale corridor with one end closed and the other opened, under various fire heat release rates and source-ceiling heights (from 0.05 m to 0.50 m) of totally 353 test conditions. The flame morphological characteristic parameters involving the flame extension length in the center of the ceiling and in the two sides were measured and analyzed comprehensively. By a careful observation, it was found that, as the fire heat release rate increased or the source-ceiling height decreased, the ceiling flame extension behavior can be divided into different behavior phases: the flame spreads to the two sides after impinging the narrow building ceiling; flame extends longitudinally after reaching side walls, presenting a semi-elliptical shape; flame in the two sides extends farther than that in the center of the ceiling, presenting a “U” shape; and flame presents a cellular structure (the fire source is near the building ceiling). The dimensionless critical fire heat release rates for the transition of these phases were identified, and non-dimensional correlations were obtained for the prediction of flame extension lengths of different phases. This work provides new observations of different phases and generalized correlations for impinging ceiling flame behaviors induced by wall-attached gaseous fuel fires at one end in a corridor.

Analysis Of Semi Elliptical Multi Leaf Spring Using Ansys

A multi-leaf spring is one of the most important components of automobile suspension system. Leaves are basically a series of flat plates, usually of semi-elliptical shape. Generally, a multi leaf spring used in automobile suspension, consists of two types of leaves i.e. graduated- length leaves and full-length leaves. The present work is an attempt to estimate the magnitude of bending stresses in the above-mentioned leaves for a semi-elliptic multi- leaf spring made of structure steel and titanium alloy. A lot of research work has been carried out in the context of leaf spring considering its material and a significant progress has been observed in the field of weight reduction, improvement of load carrying capacity. This project includes the study of deflection and stress distribution of leaf spring for heavy duty vehicles, considering two materials. The results highlight the best suitable material for better dynamic behavior of leaf spring and its design optimization. Finally referring to the results obtained in these research studies, the present work proposes a new idea regarding the construction of multi-leaf spring based on practical applications and cost analysis. Keywords: Leaf spring, Torsion, Static analysis. Semi elliptical, Fatigue failure

Bioenergetic analysis and anthropometric evaluation of bra-breast interface for improved design and breast health

Bioenergetics analysis of bra-breast Interface is an important technique for improving the design of bras and promoting breast health and comfort during physical activity. The objective of this study is to evaluate the compatibility between the anatomy of the breasts and bra. The study encompasses breast anthropometry via measurement. A measurement topology was proposed to determine breast mass, volume, shape, and asymmetry under loading (with-bra) and unloading (without-bra). Using the anthropometric data, the bioenergetics of the breasts were determined and compared to the rest of the body. From the bioenergetic analysis, a larger breast could require up to 69 J of energy during walking. The average mass of a breast ranges from 500 to 1000 g. Assuming breast shape to be standard, semi-conical, semi-spherical and semi-elliptical, breast volume was determined where semi conical and semi spherical breast shapes consistently predicted lower bound volume for each breast, whereas the standard and semi elliptical breast shapes predicted higher volume for the same breasts measurements. Mathematically, the medial-lateral boundaries of the breast were described by a secant of a curve, aligned on the coronal plane, causing eccentric loading when the two breast nipples were on different transverse planes. When this variation was more than 5% volume change, asymmetric breast shapes occurred and was responsible to displace bra heterogeneously compromising fit and support. A non-linear, leaf-function describing the relationship between the breast radius and volume invoked at a given body weight. In general, the current design for a bra assumes that the breasts are symmetrical, though the current investigation proves that this is not the case. The bra needs to be redesigned to better fit women, since left and right sides are not symmetrical. This is a significant problem today, as it is estimated that nearly 80% of women wear incorrectly- sized bras; 70% wore bras that are too small, and 10% wore bras that are too big. Current investigation highlights the crucial importance of incorporating the distance between the nipples into bra design to achieve optimal support, comfort, symmetry, and minimize breast movement. It ensures that the bra cups are positioned optimally to provide effective support and enhance the natural shape of the breasts. If the current bra models are redesigned, the amount of discomfort in women could potentially decrease.

Accurate Detection and Analysis of Pore Defects in Laser Powder Bed Fusion WE43 Magnesium Alloys.

To explore the size, morphology, and distribution patterns of internal pore defects in WE43 magnesium alloy formed by laser powder bed fusion (LPBF), as well as their impact on its mechanical properties, computer tomography (CT), metallographic microscopy, and scanning electron microscopy were used to observe the material's microstructure and the morphology of tensile test fractures. The study revealed that a large number of randomly distributed non-circular pore defects exist internally in the LPBF-formed WE43 magnesium alloy, with a defect volume fraction of 0.16%. Approximately 80% of the defects had equivalent diameters concentrated in the range of 10∼40 μm, and 56.2% of the defects had sphericity values between 0.65∼0.7 μm, with the maximum defect equivalent diameter being 122 μm. There were a few spherical pores around 20 μm in diameter in the specimens, and unfused powder particles were found in pore defects near the edges of the parts. Under the test conditions, the fusion pool structure of LPBF-formed WE43 magnesium alloy resembled a semi-elliptical shape with a height of around 66 μm, capable of fusion three layers of powder material in a single pass. Columnar grains formed at the edge of individual fusion pools, while the central area exhibited equiaxed grains. The "scale-like pattern" formed by overlapping fusion pool structures resulted in the microstructure of LPBF-formed WE43 magnesium alloy mainly consisting of fine equiaxed grains with a size of 2.5 μm and columnar grains distributed in a band-like manner.

Detection of a Submillimeter Notch-Type Defect at Multiple Orientations by a Lamb Wave A0 Mode at 550 kHz for Long-Range Structural Health Monitoring Applications.

The early detection of small cracks in large metal structures is a crucial requirement for the implementation of a structural health monitoring (SHM) system with a low transducers density. This work tackles the challenging problem of the early detection of submillimeter notch-type defects with a semielliptical shape and a groove at a constant width of 100 µm and 3 mm depth in a 4.1 mm thick aluminum plate. This defect is investigated with an ultrasonic guided wave (UGW) A0 mode at 550 kHz to investigate the long range in thick metal plates. The mode selection is obtained by interdigital transducers (IDTs) designed to operate with a 5 mm central wavelength. The novel contribution is the validation of the detection by pulse-echo and pitch and catch with UGW transducers to cover a distance up to 70 cm to reduce the transducers density. The analysis of scattering from this submillimeter defect at different orientations is carried out using simulations with a Finite Element Model (FEM). The detection of the defect is obtained by comparing the scattered signals from the defect with baseline signals of the pristine laminate. Finally, the paper shows that the simulated results are in good agreement with the experimental ones, demonstrating the possible implementation in an SHM system based on the efficient propagation of an antisymmetric mode by IDTs.

Upgraded VKI Plasmatron capabilities with supersonic nozzles for extended material characterization methods

In the domain of re-entry and hypersonic vehicles, advancing material development requires comprehensive material testing to thoroughly understand the aero-thermo-chemistry at the surface. This paper overviews hypersonic, high-temperature activities conducted at the von Karman Institute for Fluid Dynamics (VKI) Plasmatron facility, employing three recently developed supersonic nozzles. These activities aim to augment VKI’s experimental and numerical capabilities in high-temperature material research, contributing to a deeper understanding of the chemical surface interactions, at stagnation and off-stagnation locations, during re-entry. The newly developed nozzles were 3D printed using an additive manufacturing aluminum alloy. The three nozzles serve distinct purposes: two conical ones of varying lengths are designed for stagnation point testing, while the third nozzle, adopting a semi-elliptical shape, is tailored for off-stagnation point testing. The initial section of the paper focuses on designing, manufacturing, and simulating these nozzles, then we characterize the nozzle flow and compare with simulations, while the subsequent part will delve into showcases of recent activities conducted in the Plasmatron facility utilizing these distinct nozzle configurations.

DETERMINATION OF CHARACTERISTICS OF FATIGUE CRACKS GROWTH IN THE AXLES OF RAILWAY CARRIAGES

Providing damage resistance is the most important requirement presented to railway axles. This paper provides a detailed review of the characteristics of resistance to fatigue crack growth in axles made of EA4T steel (25CrMo4). This steel is typical for axles of high-speed rolling stock. Resistance to fatigue crack growth is defined by the nature of the Paris-Erdogan curve da/dN=CKm, the parameters of which are the coefficient C and the exponent m. Determination of these parameters is based on the results of fatigue tests with the samples or with full-scale axles having cracks. The analysis of numerous scientific papers has shown that for the specified steel there is a significant scatter in the values of these parameters. This scatter is caused by a number of factors, the main of which are: the difference in test objects (from small samples of the SE(B) type to full-scale rolling axles 190 mm in diameter); the difference in loading methods (tension-compression, flat bending, circular bending); the variation of mechanical properties of EA4T steel. In the paper the models of surface fatigue crack geometry are analyzed and semi-elliptical shape of crack front line is selected as the most acceptable. The significant scatter in the values of the parameters m and C prevents to establish reliably the residual life of axles with cracks, which is an important characteristic for practical forecasting of axle survivability. The technique for parameters m and C optimization in view of semi-elliptical shape of the crack front line has been developed. The relationship linking the parameters m and C has been established. The method for determining the residual life of the axle by the criterion of non-destruction is proposed. The dependence between the residual life and the value of the parameters of the Paris-Erdogan equation in the development of fatigue failure is established. The procedure for axles monitoring timeframes setting to prevent their fatigue failure is discussed. Keywords: parameters of Paris-Erdogan equation, fatigue crack, residual life of axle.

Evolution law of coal and gas outburst hole shapes with varying underground stress conditions: Numerical analysis and on-scene evidence

A rock-coal-rock excavation model was established, and a coal and gas outburst (Abbreviated as CAGO) numerical simulation was carried out, which takes into account the dual-pore model and the desorption of gas. The plastic zone expansion was simulated under the different gas pressures and lateral pressure coefficients, and the variation in hole shape was characterized by the change in the plastic zone and compared with the actual engineering. The results indicate that: (1) There is a critical time in the CAGO process that divides the gas action into two stages: the first stage is the energy that causes the destruction of the coal body and throws out the crushed coal, the pressure difference between atmospheric and gas provides energy for this. The second stage is that the pressure difference will only provide energy for the throwing of broken coal. (2) Under the same loading conditions, gas pressure is set from 0.5 MPa to 0.9 MPa in 0.1 MPa increments, the area of the plastic zone around the exposed surface increases from 1.323 m2 to 1.3238 m2, and the peak velocity is reached faster. Meanwhile, the plastic zone increased from 1.319 m2 to 1.3238 m2 under the gas pressure of 0.9 MPa. This suggests that gas also has an effect on coal seam damage, but it is relatively weak compared to the geo-stress. (3) Pre-destruction of coal by geo-stress determines the size and shape of the hole, and the lateral pressure coefficient determines the pre-destruction situation. When the coefficient is small, the hole develops into an asymmetrical butterfly shape with a larger upper part and a smaller lower part, and when the coefficient is close to 1, the hole tends to develop into a semi-elliptical shape. Finally, the simulation result was compared with the experiment and the on-scene evidence. This study has guiding significance for the prevention and control of CAGOs at different depths.

Numerical Study of Bottom Shape Effect on the Mixing for Stirred Tank

Abstract In this work, computational fluid dynamics (CFD) was used to investigate the effect of the bottom shape on the flow field and mixing characteristics in an agitated vessel stirred by six-pitched blade turbine (PBT6). The simulation was based on the resolution of the Navier-Stokes equations using standard k-ε turbulence model. Hydrodynamic behavior of the stirred vessel with four types of bottom shapes was investigated, a flat bottom and three different semi-elliptical bottoms. The results show reasonably satisfactory agreement with the experimental data. The CFD simulation also showed that the semi-elliptical bottom shapes had a significant influence on the velocity profiles and on the turbulent kinetic energy distributions of the local flow generated at the bottom region of the vessel.

The Role of the Inframammary Fold (IMF) in Aesthetic and Reconstructive Surgery: A Critical Analysis and Surgical Solution

IntroductionThe inframammary fold (IMF) is a critical structure in breast aesthetics and is affected by various types of breast surgery. The ideal IMF has a semi-elliptical shape, which may become attenuated with age and descends in macromastia. The aim of this study was to analyse the IMF and retain/restore its shape with sutures.MethodsA retrospective study was conducted on breast surgeries performed over a four-year period (2019–2022). The morphometry of the IMF was evaluated preoperatively while the patients were standing. In cases where the IMF was symmetrical, sutures were used to reinforce it during surgery. When the loss of the semi-elliptical shape was clinically indicated, the IMF was mobilized, repositioned, and then sutured into place.ResultsThe study included 56 patients: 43 undergoing immediate breast reconstruction, and 13 undergoing bilateral breast reductions. In over two thirds of the patients, the lateral IMF was inferiorly displaced compared to the medial IMF.ConclusionIt is recommended to reinforce the IMF in all patients undergoing breast surgery. Where the IMF has an elliptical shape preoperatively, it is reinforced. Where IMF is inferiorly displaced, mobilization and superior advancement of the IMF, followed by suture reinforcement, are necessary. This approach results in a well-defined IMF with improved breast aesthetics.Level of Evidence IVThis 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.

Research on the Melt Pool Shape Formation Mechanism of the Laser Surface Remelting of Nickel-Based Single-Crystal Superalloy

By numerical simulation and experimental analysis, the melt pool shapes for the laser surface remelting of nickel-based single-crystal superalloy under different processing parameters are investigated. The results show that heat conduction and heat convection work together to determine the formation of the melt pool during the laser surface remelting, and the melt pool shape can be controlled by adjusting the laser power and laser scanning speed. For processing with large laser power and low scanning speed, the alloy vaporizes in the melt pool, which makes the melt pool shape unstable. For laser surface remelting with smaller laser power or higher scanning speed, one can have a stable “ω” shape melt pool, which is because the Peclet number is large, and the heat convection plays the dominant role. For the condition with further smaller laser power or higher scanning speed, the Peclet number in the melt pool is much lower, and the heat convection is the weakest, which produces the semi-elliptical melt pool shape that has no essential difference from that of the pure heat conduction model. The present study offers theoretical support to our previous research and the future parameters selection of processing parameters for the laser repairing of nickel-based single-crystal superalloys.

Flexural-slip folding in buckling phases of orogenic belts: Insight into the tectonic evolution of fault splays in the East Iran orogen

Introduction: The East Iran orogen has experienced multiple buckling phases resulting in the formation of strike-slip fault splays. The geometric and kinematic characteristics of these splays are influenced by folding mechanisms. This study focuses on investigating the structural characteristics and tectonic evolution model of the Khousf splay, located in the northern terminus of the Nehbandan right-lateral strike-slip fault system.Methods: Field visits and geometrical properties from map views were used to analyze the structural features of the Khousf splay. The splay was found to consist of a multi-plunging anticline and syncline, referred to as the Khousf anticline and Khousf syncline, respectively. Flexural slip was identified as a significant mechanism for the formation of these structures. Structural evidence, including parasitic folds, active folds, and strike-slip duplexes, suggested that flexural slip occurred on discrete movement horizons among the rock units.Results: Analysis of the parasitic folds in the cores and limbs of the Khousf anticline and syncline revealed M, W, Z, and S shapes, with complex slicken-line patterns observed on faults parallel to the beds at the limbs. The analysis results indicated strain partitioning and inclined left- and right-lateral transpressional zones. Shortening estimates obtained from profiles in the Shekarab inclined transpressional zone were approximately 33%, 65%, and 68% for NE-SW, N-S, and NW-SE profiles, respectively. In the Arc area, which is the core of the anticline, shortening estimates from NE-SW and N-S profiles ranged from 14% to 10%. Structural analysis of the folds in this area revealed broad, close, semi-elliptical, and parabolic shapes, suggesting that secondary folds with NW-SE axis directions have been superimposed on the first-generation folds with E-W axis directions in the Khousf refolded splay.Discussion: The findings of this study highlight the structural characteristics and tectonic evolution model of the Khousf splay in the northern terminus of the Nehbandan right-lateral strike-slip fault system. The results suggest that flexural slip played a crucial role in the formation of the multi-plunging anticline and syncline in the Khousf splay. The presence of parasitic folds and complex slicken-line patterns on faults indicate the complexity of deformation processes. The observed strain partitioning and inclined transpressional zones suggest a complex tectonic history in the study area. The superimposition of secondary folds with different axis directions on first-generation folds adds further complexity to the structural evolution of the Khousf refolded splay. Overall, this study provides new insights into the structural characteristics and tectonic evolution of the Khousf splay in the East Iran orogen.

Two-dimensional numerical modelling of viscous emulsion drops coalescence in a constricted capillary channel

We study numerically the coalescence of viscous emulsion drops in a two-dimensional semi-elliptical shape constricted channel. The Navier-Stokes equations are solved using the finite element method and the oil-water interface is tracked using the level-set techniques. Effects of interfacial tension, inertia, viscosity ratio, droplet size, and constriction shape on the droplet coalescence and average viscous pressure drop along the channel are investigated. It is found that at high interfacial tension, droplets are circular, approach each other more quickly, coalesce at the constriction entrance, and give higher pressure drops. At intermediate interfacial tension, the onset of coalescence occurs downstream of the constriction entrance while at very low interfacial tension, no coalescence of the droplets was observed. Inertia is found to be negligible effects on the coalescence of the droplets. High inertia gives less viscous pressure drop. Less viscous droplets are more likely to quickly coalesce compared to high viscous drops. Higher viscous drops create more resistance to flow. Moreover, larger size drops are responsible for more quick coalescence and tend to create more viscous pressure drops. In addition, we found that circular constriction offers less resistance to fluid flow. We hope that these numerical results would be beneficial while displacing oil from the underground reservoirs.

Experimental method and application of the slurry “diffusion-bleeding-seepage” of isolated overburden grout injection

Isolated overburden grout injection (IOGI) is a green mining method to control surface subsidence. Slurry water significantly influences grouting effectiveness and mining safety. This study establishes a three-dimensional visualization experimental system for slurry “diffusion-bleeding-seepage” to investigate the seepage law of slurry water. The system is composed primarily of a transparent box (1.2 m × 0.5 m × 0.25 m) and support, with the solid–liquid coupling seepage similar material and modules for mining, grouting injection, slurry pressure and displacement monitoring, overburden saturation monitoring, and water leakage monitoring of the working face. A similar material with good permeability and non-disintegration is obtained by hydrophilic, water absorption, and permeability tests. Grouting and mining are simulated by pulling acrylic sheets and pumping slurry. With the fly ash slurry entering the injection layer, the slurry undergoes water–cement separation, and the water bleeding is formed to seep into the similar material. The volumetric water content of the similar material is obtained by arranging multiple groups of volumetric water content sensors into the similar material. The corresponding saturation is obtained by theoretical calculation. The experimental system is used to simulate the seepage of slurry water in a high initial saturation overburden, and the characteristics of injection slurry diffusion and water bleeding are obtained. The profile distribution of seepage of slurry water is found to possess a semi-elliptical shape. Under the condition of high initial saturation, slurry water appears in the working face. The system provides a convenient method for further research of IOGI slurry water seepage.

Determination of the dependence of the humidification circuit parameters during drip irrigation on the properties of irrigation water

To ensure the optimal water-air balance of the plant, agro-reclamation measures are required, including the organization of irrigation. The advantage of drip irrigation is the most rational consumption of irrigation water. To realize this advantage, it is necessary to calculate the irrigation rate taking into account the dynamics of moisture distribution in the soil. During irrigation, the humidification circuit takes on a semi-elliptical shape. To determine the geometrical parameters of the humidification circuit, one should take into account the physical and mechanical properties of the soil and irrigation water, the mineralization of which varies widely. Having identified the numerical dependences and the nature of the distribution of moisture in the soil and having calculated the parameters of the irrigation circuit, it is necessary to determine the flow rate per dripper and subsequently calculate the irrigation rate, taking into account all of the above factors. The proposed method for calculating the irrigation contour will make it possible to rationally use water for irrigation, minimizing losses due to filtration into deep soil layers. Optimizing the water regime of plants during the growing season will not only save water and energy resources, but also maintain an optimal water and air regime, which will increase the yield and improve the quality of grown products.

Perspective method for construction of drying and watering network for growing potatoes

In the Central region of the Russian Federation, precipitation is uneven both during the growing season of plants and during the calendar year. Therefore, to obtain sustainable yields and ensure the optimal water-air balance of the soil, agro-reclamation measures are required, including the organization of additional irrigation. During the winter period, a significant amount of snow accumulates, which during the melting period does not have time to soak into the soil, forming surface runoff. The construction of a drainage and water supply network will make it possible to accumulate excess moisture in reservoirs to moisten the soil during the rainless period. The joint use of the drainage network and the drip irrigation system is recommended. Using such a system will allow at the estimated time to supply or divert water to a specific area, removing excess moisture from the soil by drainage to storage tanks and then directing irrigation water to the drip irrigation system during the dry period. The calculation of the irrigation rate, taking into account the semi-elliptical shape of the humidification contour, showed that the required volume of water could be accumulated in special storage tanks. Drip tape laying can be carried out mechanized using a special stacker based on a ridge former.

Experimental investigation of fracture process zone of rock in dynamic mode I fracturing and its effect on dynamic crack initiation toughness

Fracture process zone (FPZ) is critical to the applicability of linear fracture mechanics (LEFM) in rock fracturing, but little attention has been given to quantify the FPZ under dynamic loading condition in previous studies. This study presents the experimental results of notched semi-circular bending (NSCB) tests undertaken by split Hopkinson pressure bar (SHPB) to investigate the FPZ evolution for red sandstone under dynamic mode I fracturing and its effect on dynamic crack initiation toughness. A hybrid displacement–strain calibration method was proposed to characterize the FPZ with high-speed digital image correlation (DIC) technique. Results show that the FPZ initiation in dynamic fracturing is much earlier than that in quasi-static cases, and the FPZ length fully develops when crack initiation taking place at the pre-peak stage. The FPZ in dynamic fracturing is of a semi-elliptical shape with a width independent from the loading rate. The opening displacement exhibits a nonlinear decreasing trend along the FPZ boundary. LEFM theory underestimates the inherent dynamic crack initiation toughness, and the corrected dynamic crack initiation toughness was approximately 1.6 ∼ 2.1 times the uncorrected one within the loading rate ranging from 8.5 ∼ 78.2 GPa•m1/2/s in present study. The FPZ length in dynamic mode I fracturing lies in between the values predicted by Schmidt model and Irwin model, which indicates a non-linear cohesive stress with higher gradient near the FPZ tip is distributed along the FPZ.

Numerical simulation on molten pool flow of Inconel718 alloy based on VOF during additive manufacturing

In this paper, the discrete element method is used to establish the model of the powder bed. The numerical simulation model is established by the finite volume method. The results shows that the heat diffusion is relatively slow when the laser act on the powder bed, which result in a small heat-affected zone of the powder bed and the base metal. The molten pool is a semi-elliptical shape, and the cladding layer formed after the molten pool solidifies is flat. As the heat source get closer to a certain point on the scanning path, the flow direction of the molten pool became uniform gradually from random at the beginning. The initial temperature of the powder bed become higher when the second track is deposited, and the depth of the molten pool is deeper than that of the first track. The second cladding layer overlap the first one well. The flow direction of the molten pool at a fixed point gradually change from disorder to uniform with the approach of the heat source. The flow direction of the molten pool in the remelting part always remain uniform.

A Study On Effects of Flaw Shape Idealization On the Interaction of Co-Planar Surface Flaws Subjected to Tension Load

Abstract Engineering Critical Assessment (ECA) guidelines contain rules to assess flaw interaction. Major flaw dimensions (depth or height and length) are typically characterized assuming the flaws to be contained entirely within a bounding rectangle through a procedure known as flaw idealization. In fracture mechanics based calculations, flaws are often assumed to be (semi-)elliptical when evaluating possible interaction. This paper investigates the implication of this simplification for the specific case of two identical co-planar surface breaking flaws. Two flaw shapes are considered and compared: semi-elliptical and canoe-shaped (quarter-circular ends with constant depth elsewhere). Especially for long and shallow flaws, the canoe-shaped configuration best approximates the bounding rectangle, whereas the semi-elliptical shape only touches the bounding rectangle at three points (deepest point and two points at the surface). Several flaw dimensions and spacing distances are studied through an extensive parametric study comprising both linear elastic and elastic-plastic finite element simulations. The results, evaluated in terms of stress intensity factor (SIF) and J-integral, show that the flaw shape idealization, particularly for long and shallow flaws, can significantly affect the degree of interaction between identical co-planar flaws. The inconsistency between semi-elliptical and canoe-shaped flaw shapes is observed in a linear elastic analysis and becomes more pronounced at higher loading levels evaluated in elastic-plastic analyses