Effect Of Hole Size Research Articles

The effect of hole size on failure loads of the distal humerus fenestration in Outerbridge-Kashiwagi arthroplasty: A biomechanical study.

The aim of this study was to biomechanically assess the effect of humeral-fenestration size in the Outerbridge-Kashiwagi arthroplasty on the ultimate failure load of the distal humerus in a synthetic bone model. We biomechanically tested the influence of different humeral-fenestration sizes on the failure load of the distal humerus in Outerbridge-Kashiwagi arthroplasty. A total of 50 synthetic humerus models were divided into 5 groups based on the fenestration size: 10 mm, 12 mm, 15 mm, 18 mm, and 20 mm. All the samples were randomly assigned to receive either axial or anteroposterior (AP) loading and then loaded to failure at a rate of 2 mm/min on a material testing machine. The data regarding ultimate failure loads under the axial and AP loading were analyzed. Under the AP loading, the mean ultimate failure loads of the 18 mm and 20 mm groups were lower than those of the other groups. Under the axial loading, the mean ultimate failure load of the 10 mm group was significantly greater than that of the 15 mm, 18 mm, and 20 mm groups. Additionally, the ultimate failure load of the 20 mm group was significantly lower than that of the 12 mm, 15 mm, and 18 mm groups. The distal humeral fenestrations with a size greater than 18 mm may offer poor biomechanical properties in the Outerbridge-Kashiwagi ulnohumeral arthroplasty.

Theoretical study and physical tests of circular hole-edge stress concentration in long glass fiber reinforced polypropylene composite

The long glass fiber reinforced polypropylene (LGFRP) composite has been widely used in automotive components due to its remarkable advantages of high mechanical properties and flexible design features. Automotive structural components usually suffer various intrinsic hole-edge stress concentration in mechanical joints. Thus, the objective of this work is to investigate the circular hole-edge stress concentration of the LGFRP composite. A theoretical model, which is in view of cutting area and damage factor, is originally developed to predict the hole-edge stress concentration in LGFRP composite with regard to the hole size effect. Corresponding physical tests were conducted under tensile loading monitored by a digital image correlation (DIC) system. The experimental results reveal that the influenced area of the stress concentration is within the range of four times of the hole radius. The theoretical predictions are in good agreement with the experimental results. The stress concentration factor (SCF) is calculated to demonstrate that SCF increases with the increasing circular hole radius. The conclusions obtained from this work lay the basis on the mechanical performance of the LGFRP composite subject to hole-edge stress concentrations, and is of importance to rationalize appropriate design of the LGFRP composite in automotive components.

Application of planting hole sizes, seedling sizes of meranti (Shorea johorensis) and planting media for the rehabilitation of skidding road

Timber harvesting in natural forest caused damage along the skidding roads. This research studied the effects of planting hole sizes, seedling sizes and culture media on the growth of Meranti (Shorea johorensis) at skidding roads. This study used factorial in completely randomized block design 3 × 2 × 2 in three replicates. The first factor was planting hole sizes (A1 :, A2 : 40 × 40 × 40 cm, A3: 40 × 40 × 50 cm), second was seedling size (B1 : decapitated seedlings for 10 cm, B2 : non-decapitated seedlings) and third was culture media (C1 :, C2: soil and wood charcoal). The results showed that the growth of Shorea johorensis plantation coming from 10 cm decapitated seedlings at 3-year-old after planting grew well and better than non-decapitated one. The appropriate planting hole size and culture media for planting Shorea johorensis were 40 × 40 ×30 cm and soil and top soil. The success of seedling regrowth is one of solutions to overcome seedling damage during seedling transportation.

INSIGHTS INTO THE CONTRIBUTION OF RARE NONCODING VARIATION IN AUTISM SPECTRUM DISORDER THROUGH FAMILY-BASED WHOLE-GENOME SEQUENCING

This work is devoted to numerical investigation for buckling of functionally graded plates (FGPs) with internal holes using an efficient adaptive isogeometric analysis (IGA). The locally refined (LR) B-splines, which possess the local refinement ability, are used as basis functions in IGA. Kinematics of plate structures are derived using the simple quasi-3D hyperbolic shear deformation theory (S-Q3HSDT), which has few unknowns, free from shear locking, and suitable for considering the shear deformation and thickness-stretching effect. The high-order continuity of LR B-splines directly meets the requirement of C1-continuity in the S-Q3HSDT. Internal holes are described by the level set method, and the physical mesh is independent of the hole boundaries. Local refinement is guided by a posterior error estimation based on strain recovery of the first buckling mode and the structural mesh refinement strategy. Several numerical examples considering different types of cutouts are studied, and the computed results are compared with reference solutions available in the literature to show the accuracy and performance of the developed method. The present method automatically identifies the required local refinement zones, improves the computational accuracy at a low cost, possesses high convergence speed, and avoids the usage of trimmed surfaces in the analysis. The effects of boundary condition, hole shape, hole size, load direction, and multiple holes on the buckling behavior of FGPs are investigated in detail.

Behavior of High Strength Reinforced Concrete Hollow Circular Short Columns under Axial Loads

This work deals with investigating the capacity of high strength columns, under axial compression loads. A total of nine circular column with 600 mm length and 150 mm outer diameter were tested, three of them were solid as a reference, the remaining six columns were with internal hole of 50 and 75 mm dimeter. The effect of hole size as well as area of longitudinal steel reinforcement was studied. Area of steel used where 0, 301 and 471 mm2 and two hole size were 50 and 75 mm. The results showed that the increasing of longitudinal reinforcement ratio from 0 % (plain) to 2.67% (steel reinforcement area of 471 mm2) for solid column cause an increase in the ultimate strength by 33.6%, while for hollow columns with 75 mm internal hole the ultimate strength increased up to 33.2 %. Increase in hole dimeter from 50 to 75 mm caused a reduction of columns capacity in all cause, the decrease was up 33 % for columns with 301 mm2 steel area was up to 32 %, for columns with 417 mm2

Experimental and Analytical Investigations of the Effect of Hole Size on Borehole Breakout Geometries for Estimation of In Situ Stresses

Borehole breakout is a natural phenomenon in boreholes drilled in rock due to the induced stress concentration. Many researchers have attempted to correlate this phenomenon with in situ stress magnitudes. In this paper, a series of true triaxial tests on sandstone blocks (120 × 120 × 120 mm3) with different diameter pre-drilled holes have been carried out. Results confirmed that breakout geometries (angular span and depth) are dependent on the relative stress magnitudes. It is also noticed that a larger hole size (hole radius) yielded a wider angular span and deeper normalised depth (breakout depth/hole size), which indicates that hole size is an important parameter for breakout geometries. In addition, the analysis on previous experimental studies suggested that the relationship between two breakout geometries is not unique and is heavily influenced by the horizontal stress magnitudes. The analysis of the existing model also revealed the angular span may be narrowed with increasing horizontal stress ratio under a certain stress–strength condition. Both analyses indicate the breakout geometries are not only dependent on each other but also on the horizontal stress magnitudes. This leads to a tentative conclusion that breakout geometries may not be redundant factors and might be used for horizontal stress estimation.

Acoustic characterization of additive manufactured perforated panel backed by honeycomb structure with circular and non-circular perforations

This paper studies the acoustic properties of an additive manufactured micro-perforated panel backed by a periodic honeycomb structure. Extrusion-based Fused Filament Fabrication (FFF) technique of Additive Manufacturing (AM) is used to fabricate the integrated honeycomb structures with a perforated face sheet. Normal absorption coefficient of the fabricated structure is measured in impedance tube using two microphone transfer function method. A generalized analytical formulation based on unit section analysis applicable to various cross sections of perforations has been proposed to predict the absorption coefficient, where shape dependent viscous effects in the perforation are incorporated by deriving effective complex density of the medium. To study the effect of perforation shape, three geometries viz., circular, triangular and square perforations are considered for analysis where triangular shape found to have more absorption coefficient and lower frequency of peak absorption. In addition, broadband absorption coefficient of proposed structure has been demonstrated by deploying hexagonal cells of different lengths in a unit section. The analytical results are compared with experimental results and a good agreement is observed between them. A parametric study is conducted to understand effect of perforated hole size and cell length on the absorption coefficient and peak frequency. Results show that the proposed structures can be tuned to desired frequency range by altering geometric parameters like cell length, shape and size of perforation hole. Technique and methodology presented in the current study gives an alternative way to design and fabricate honeycomb structures with perforations for acoustic applications such as aircraft cabins, ship structures and building acoustics.

Effectiveness of hole plate-type sand barriers in reducing aeolian sediment flux: Evaluation of effect of hole size

Abstract Hole plate-type sand barriers can effectively control wind-sand disasters along the railways running through the windy Gobi desert region, and the hole diameter of hole plate is the key geometric parameter influencing their protective effect. To determine the effect of hole diameter on the wind-sand flow field of hole plate-type sand barriers, in this study, numerical simulations and wind tunnel tests were conducted on hole plate-type sand barriers with different hole diameters (1.03 cm, 2.06 cm, and 4.12 cm) but the same porosity (30%). The results showed that the protective effect of sand barriers presented regular changes with the change in hole diameter. Regarding the flow field, an increase in hole diameter increased the wind penetration rate of sand barrier, decreased the area of acceleration zone above the sand barrier, shortened the length of vortex zone on the leeward side, and lowered the degree of wind velocity reduction by sand barrier. Regarding the distribution of sand deposit, an increase in hole diameter decreased the sand deposits on the windward side of sand barrier, increased the sand deposits on the leeward side, and overall shifted the sand deposit on the leeward side towards the downwind direction. Moreover, hole diameter and sand interception of sand barrier showed a negative correlation. The sand interception of sand barrier with the smallest hole diameter (1.03 cm) exceeded the sand interceptions of the other two sand barriers by 5.41% and 13.43%, respectively. At different heights, the sand barrier with a relatively small hole diameter maintained a relatively high sand-retaining efficiency. The advantage was particularly significant within the height range of 0.5–1H. Moreover, the effective protection ranges of the three sand barriers were approximately the same. The effective protection interval approximately ranged from 1H on the windward side to 10H on the leeward side, and the effective protection height was found to be 1H.

Effect of the surface treatment and hole size of pure titanium mesh on new bone formation

The purpose of this study is to investigate the effect of surface modification and hole size of pure titanium (Ti) mesh on the enhancement of bioactivity and new bone formation for the dental application of guided bone regeneration. Three types of titanium meshes with different hole sizes and distributions were used for surface treatments, which were anodization, silicate pretreatment, cyclic precalcification and heat treatment. Improvement of bioactivity as a result of the surface modifications and the tendency to new bone regeneration by the different designs of titanium meshes were identified through an immersion test in simulated body fluid and an in vivo test using the rat calvarial defect model, respectively. It was confirmed that the bioactivity of the titanium mesh was enhanced through the formation of multiple layers by anodization and precalcification treatments at the initial stage after implantation of the titanium mesh, and the hole size and distribution of the titanium mesh affected the new bone formation in the bone defect with implantation period differently.

A phase-field model for strength and fracture analyses of fiber-reinforced composites

A phase-field model for brittle fracture is proposed and evaluated for strength and fracture analyses of composites. In addition to the elastic properties, this approach makes use of only the fracture toughness and the strength of the material. The capability of the method is shown in analyses of composites at two scales. In laminates, strengths of notched laminates are estimated, including hole size effects. In a lamina, cracks developed in both transverse tension and compression are analyzed and compared to other numerical methods in the literature. The effects of a spectral and a hydrostatic-deviatoric decomposition of the strain energy density, two variants often used in phase-field formulations, are studied. It is shown that the choice of the decomposition affects the fracture development. Results are compared to experiments and simulations in the literature showing the capabilities of the phase-field approach.

Push-out test of large perfobond connectors in steel–concrete joints of hybrid bridges

The size of perfobond connectors in steel–concrete joints of hybrid bridges is typically less than 75 mm. Given the limited capacity of connectors, it is essential to tightly arrange the connectors for transmitting large internal forces. Large-sized perfobond connectors with increased capacity act as an excellent alternative to reduce the number of connections, thereby simplifying the structure in steel–concrete joints. Additionally, an increased diameter can contribute to the flow of concrete coarse aggregate. To verify the mechanical properties of large perfobond connectors, 13 groups of 39 push-out specimens are introduced. The effects of hole size, hole shape, perforating rebar, concrete strength, and lateral confinement are investigated on the failure modes and load–slip curves of large perfobond connectors. The test results indicated that, under a high level of confinement of a concrete dowel, increases the geometrical size of the hole significantly improve its bearing capacity without weakening its ductility. Finally, an empirical formula is proposed for the shear capacity considering various influencing factors.

Size Effect of Defects on the Mechanical Properties of Graphene

Graphene, a two-dimensional material, has been studied and utilized for its excellent material properties. In reality, achieving a pure single-crystalline structure in graphene is difficult, so usually graphene may have various types of defects in it. Vacancies, Stone-Wales defects, and grain boundaries can drastically change the material properties of graphene. Graphene with vacancy defects has been of interest because it is a two-dimensional analogy of three-dimensional porous materials. It has efficient material properties, and can function as a part of modern devices. The mechanical properties have been studied by using molecular dynamics for either a single vacancy defect with various sizes or multiple vacancy defects with same defect ratios. However, it is not clear which one has more influence on the mechanical properties between the size of the defects and the defect ratio. Therefore, we investigated the hole-size effect on the mechanical properties of single-crystalline graphene at various defect ratios. A void defect with large size can have a rather high tensile modulus with a low fracture strain compared to a void defect with small size. We numerically found that the tensile properties of scattered single vacancies is similar to that of amorphous graphene. We suspect that this is due to the local orbital change of the carbon atoms near the boundary of the void defects, so-called the interfacial phase.

Turbulent flame propagation with pressure oscillation in the end gas region of confined combustion chamber equipped with different perforated plates

Experiments were conducted in a newly designed constant volume combustion chamber with a perforated plate by varying the initial conditions. Hydrogen–air mixtures were used and the turbulent flame, shock wave, and the processes of flame–shock interactions were tracked via high-speed Schlieren photography. The effects of hole size and porosities on flame and shock wave propagation, intensity of the shock wave and pressure oscillation in closed combustion chamber were analyzed in detail. The effect of interactions between the turbulent flame and reflected shock or acoustic wave on the turbulent flame propagation was comprehensively studied during the present experiment. The results demonstrated that flame front propagation velocity and pressure oscillation strongly depend on the hole size and porosities of the perforated plate. The flame front propagation velocity in the end gas region increases as hole size increases and porosity decreases. The flame front propagation intensity in the end region of a confined space is strongly relevant to two competing effects: the initial turbulent formation and turbulent flame development. The experimental results indicated that an oscillating flame is associated with both the reflected shock wave and the acoustic wave. Meanwhile, different turbulent flame propagations and combustion modes were observed.

Elastic and inelastic buckling of square and skew FGM plates with cutout resting on elastic foundation using isoparametric spline finite strip method

The elastic buckling of square and skew thin functionally graded material (FGM) plates with cutout resting on an elastic foundation is investigated using the isoparametric spline finite strip method. It is assumed that the material properties of FGM plates vary smoothly through the thickness according to the power law model. The elastic foundation is simulated by the Winkler and two-parameter Pasternak models. The isoparametric spline finite strip method is also applied to investigate initial inelastic local buckling loads of skew homogenous plates with cutout based on the Ramberg–Osgood representation of the stress–strain curve using the deformation theory of plasticity. The critical buckling load of the plate is achieved by minimizing its total potential energy and solving the corresponding eigenvalue problem. In addition, the effects of elastic foundation coefficients and hole size on the local buckling of plates with different boundary conditions are determined and discussed.

Effect of TiO2 Nanofiller on Electrical Conductivity of ABS/TiO2 Polymer Nanocomposites: A Free Volume Study

Acrylonitrile Butadiene Styrene (ABS) / Titanium dioxide (TiO2) Polymer nanocomposites with different TiO2 wt % were prepared by solution casting method. Microstructural characterization of ABS/TiO2 polymer nanocomposites was performed by Positron Lifetime Spectroscopy. The increased positron lifetime parameters viz., o-Ps lifetime (τ3) and free volume size (Vf) from 0.2 to 1.0 wt% of TiO2 loading suggests the formation of interfaces due to the increased agglomeration of TiO2 nanoparticles. The increase of two orders of magnitude change in electrical conductivity (σ) of ABS/TiO2 polymer nanocomposites with the increasing free volume hole size (Vf) as a function of TiO2 nanoparticles loading . The increased electrical conductivity (σ) with the increased free volume hole sizes (Vf) indicates the increased interfacial space for the movements of charge carriers and TiO2 ions. Miyamoto and Shibayma model for ion conduction has been used to explore the effect of free volume hole size (Vf) on the electrical conductivity (σ) in ABS/TiO2 polymer nanocomposites. Fourier Transform Infrared Spectroscopy (FTIR) suggests the improved chemical and physical interaction between the functional groups of TiO2 and ABS polymer side chain

Experimental and numerical investigation of stress concentration and strength prediction of carbon/epoxy composites

Unidirectional composites are very popular structural materials used in aerospace, marine, energy and automotive industries, thanks to their superior material properties. However, the mechanical behavior of composite materials is more complicated than isotropic materials because of their anisotropic nature. Also, stress concentration presence on the structure, like a hole, makes the problem further complicated. Therefore, enormous numbers of tests are required in understanding the mechanical behavior and strength of composites which contain stress concentration. Accurate finite element analysis and analytical models enable us to understand mechanical behavior and predict the strength of composites without enormous number of tests which cost serious time and money. In this study, unidirectional Carbon/Epoxy composite specimens with central circular holes were investigated in terms of stress concentration factor and strength prediction. The composite specimens which had different specimen width (W) to hole diameter (D) ratio were tested to investigate the effect of hole size on the stress concentration and strength. Also, specimens which had same specimen width to hole diameter ratio, but different sizes were tested to investigate the size effect. Finite element analysis were performed to determine the stress concentration factor for all specimen configurations. Also, Point stress criteria (PSC) was used to predict strength of the specimens. For quasi-isotropic laminate, it was found that the stress concentration factor at the hole tip increases approximately %15 as W/D ratio decreased from 6 to 3. Also, it is observed that as W/D ratio quadrupled with constant specimen width the failure strength increases by %62.4. For the specimens which had same width to hole diameter ratio but different (scaled) dimensions, the stress concentration factor at the hole tip was seen to be identical as expected. For these specimens, as W/D ratio doubled the specimen failure strength reduces by %13.2 because of the size effect. For all type of specimens, the PSC method could predict the strength of specimens with maximum %8 error.

Modelling and assessment of accidental oil release from damaged subsea pipelines

This paper develops a 3D, transient, mathematical model to estimate the oil release rate and simulate the oil dispersion behavior. The Euler-Euler method is used to estimate the subsea oil release rate, while the Eulerian-Lagrangian method is employed to track the migration trajectory of oil droplets. This model accounts for the quantitative effect of backpressure and hole size on oil release rate, and the influence of oil release rate, oil density, current speed, water depth and leakage position on oil migration is also investigated in this paper. Eventually, the results, e.g. transient release rate of oil, the rise time of oil and dispersion distance are determined by above-mentioned model, and the oil release and dispersion behavior under different scenarios is revealed. Essentially, the assessment results could provide a useful guidance for detection of leakage positon and placement of oil containment boom.

Open‐hole tensile behaviour and failure prediction of carbon fibre reinforced aluminium laminates

In this article, the open‐hole tensile behaviour of carbon fibre reinforced aluminium laminates (CARALL) were investigated experimentally and numerically. Two specimens with different fibre orientations ([0°/90°/0°] and [45°/0°/−45°]), consisting of T700 carbon fibre/epoxy prepreg and 2024‐T3 aluminium with a 3/2 configuration, were manufactured by the autoclave process. Damage initiation and progression were considered in modelling the CFRP layers and interface bonding layers. Isotropic hardening behaviour was defined for aluminium layers. A major contribution of this study was to reveal the failure mechanisms and failure sequences of notched CARALL with different fibre orientations by numerical method. Damage evolution processes of the two specimens were compared. Effects of hole sizes and laminate configurations (stacking sequences & stacking structures) on both the specimens were further evaluated based on simulation. Point stress failure criterion and Wu's modified point stress failure criterion were applied in comparison with the numerical method as well. POLYM. COMPOS., 39:4123–4138, 2018. © 2017 Society of Plastics Engineers

Mixed-mode fracture in open-hole composite plates of finite-width: An asymptotic coupled stress and energy approach

In the present work, brittle failure of finite-width composite plates containing a circular hole under uniaxial tension loading is investigated using a coupled stress and energy criterion within the framework of finite fracture mechanics. Depending on the material anisotropy, the onsets of symmetric and antisymmetric crack patterns are investigated considering mixed-mode fracture. In order to provide an efficient finite fracture mechanics analysis, a semi-analytical approach is proposed combining the method of complex potentials with a two-scale asymptotic solution procedure. Within the asymptotic framework, higher-order terms and the application of Padé approximation are implemented allowing for an extended applicability of asymptotic solutions. In addition, full-numerical analyses are performed and the accuracy of the asymptotic approach, in particular with regard to the finite-width, is thoroughly examined. The effects of hole size and fibre orientation on the plate’s effective strength are studied using the proposed finite fracture mechanics approach and theoretical strength predictions are compared to experimental results from literature.

Spray characteristics of pressure-swirl nozzles at different nozzle diameters

The spray characteristics from a pressure-swirl nozzle, a widely used device in agriculture, combustion and aerospace, have been investigated in this study experimentally with focus on the effects of nozzle hole size and injection pressure on spray morphology, velocity distribution, and spray angle. Particle image velocimetry (PIV) is used to measure the velocity distribution of the fuel (jet-fuel No. 3) sprays generated by the nozzles with orifice diameter of 0.3mm, 0.5mm, and 0.8mm at a fixed orifice length of 1.0mm, under injection pressure ranging from 0.1MPa to 2.0MPa. It is found from this study that there exists a critical injection pressure of 1.5MPa beyond which the spray angle becomes independent of pressure, meanwhile; the sprays from nozzle with an orifice length/diameter ratio of 2 have larger spray angles associated with higher velocities. From the data obtained by this study and Buckingham π theorem, a correlation of the spray angle (θ) and Reynolds number (Re) has been developed, as Re=1.4Re0.39, where is defined by orifice diameter and exit velocity estimated by fuel mass flow rate and orifice area.