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In the present work, a detailed CFD (computational fluid dynamics) simulation is carried out to investigate the performance of a horizontal heat sink with vertical perforated pin-fin-array. The pin fins are embedded in a staggered arrangement on the base-plate of the horizontal sink. The objective of this study is to examine the effect of the orientation angle (β) on the performance of the heat sink. β is varied from 0° to 360° by rotating the horizontal sink about a vertical axis passing through the centre of the sink. Results are taken over a wide range of inflow Reynolds number (Re) to explore the possibility for obtaining an optimum orientation angle (β) for which thermal performance would be the maximum. The results are also generated for solid fin with same dimension. It is found that highest Nu is achieved at β=180° for perforated fin array, however, for solid fin optimum angle hovers around β = 120°. [ABSTRACT FROM AUTHOR]

Numerical simulations were carried out to study the ballistic resistance of double-layered metal plates subjected to normal impact by the ogive-nose projectiles. 12 mm thick Weldox 460E steel targets consisted of two 6 mm thick plates in contact were impacted by 20 mm diameter ogive-nose projectiles. The caliber radius head (CRH) of ogive-nose projectile was varied (0 - 5.0) and found to have obvious effect on the ballistic limit of 12 mm thick double-layered Weldox 460E steel plates. Double-layered plates were found to be less effective than the equivalent monolithic targets for CRH ≥ 0.5, and more effective with CRH = 0. LS-DYNA finite element code in conjunction with Johnson–Cook elasto-viscoplastic material model was employed to carry out the numerical simulations [ABSTRACT FROM AUTHOR]

The perforation channels are the only conduits between the reservoir in production and the producing well, so it is quite obvious that their parameters seriously affect the productivity. Under this highly volatile oil price environment aiming for the best productivity has the highest priority. For this reason, the need for understanding the effect of the perforation parameters on the inflow is urgent. In the previous years, Pasztor has proposed a new concept to calculate the pressure drop caused by the perforation geometry with promising results. However, to this day it was assumed that the pressure drop through the channels is negligible. In this paper a new method is presented, that can be used to eliminate all the uncertainties about the pressure drop through the perforation channels. This method makes it possible to get a better picture on the effect of perforation geometry on the productivity of producing wells, moreover it helps us to plan the best geometry. As an additional result, by understanding how the filtration goes in the vicinity of the well, it becomes easier to choose between reperforation or acidizing in case of a well with unsatisfactory productivity. [ABSTRACT FROM AUTHOR]

In 2016 Pasztor and Schultz[1] proposed an analytical method for calculating a perforation design's effect on hydrocarbon-well inflow, using a new concept to analyze the effect of the shape of the perforation channels' drainage area. The method compares well with standard industrial methods used to calculate the pressure drop caused by a given perforation design. In 2017 Toth and Pasztor[2] applied their model to investigate geothermal-well inflow, and achieved promising results. The model's complexity makes it unsuitable for optimizing the perforation design. Our aim was rather to develop a new algorithm based on the original model, one which could then be used for the optimization. In investigating the different perforation parameters' effect on productivity, we introduced a design coefficient which resulted in a new optimization method. This directly correlates to the well's productivity. [ABSTRACT FROM AUTHOR]

The report includes the updated results of analysis of buckling and vibrations of thin-walled structures previously reported in [1, 2]. Free vibrations of a thin plate with multiple cut-outs are modeled by means of analytic and numerical methods. The effect of the total area of holes, their positions and shapes, the shape of a plate shape and the plate side ratio on natural frequencies and modes of free vibrations is studied. It appeared that the natural frequencies may either increase or decrease with the total cut-outs area since the holes affects both the stiffness and the mass of a plate. The interaction between holes and modes of vibrations plays the crucial role. For small cutout area the asymptotic formula for natural frequencies has been obtained and the asymptotic results have been compared with the results of numerical analysis. [ABSTRACT FROM AUTHOR]

The article discusses research which investigated the effects of a higher Reynolds number and the perforation at a lower Reynolds number on flows past the conic cylinder. Topics discussed include the lack of effect of higher Reynolds number on qualitative variations of the drag and lift coefficients and hydrodynamic parameters resulting from the introduction of perforation.

This paper reviews the results of recent laboratory research studies focusing on the behavior of hybrid fiber Engineered Cementitious Composite (ECC) panels subjected to low- and high-velocity projectile impact. The reviewed laboratory studies include high-velocity (300-700 m/s) small-size projectiles impact tests conducted on 0.30 x 0.17 m hybrid fiber ECC prismatic panels of various thicknesses (representing a section of a door or wall), low-velocity large projectile impact tests conducted on both full scale hybrid fiber ECC blast/shelter panels (2.0 x 1.0 x 0.05-0.1 m), and 1/3 scale hybrid fiber ECC strengthened masonry wall panels (1.0 x 1.0 x 0.1 m). Recent results obtained from dynamic tensile tests of hybrid fiber ECC coupon specimens are also reviewed to assess the effect of strain rate on the material uniaxial tensile behavior. The reviewed test results demonstrate the potential value of hybrid fiber ECC for providing better functionality as protective material in aspects such as increased shatter resistance with damage reduction due to scabbing and spalling, as well as significantly-improved cracking behavior, resistance against multiple impacts, and energy absorption associated with distributed microcracking in comparison to concrete. [ABSTRACT FROM AUTHOR]

The formation of cellular building constructions made of perforated steel band is presented in the paper. The information about the main mechanical properties of perforated tapes and plates is provided. Basic technological methods for obtaining cellular structures from perforated metallic tape achieved from waste material by stamping are suggested. The main attention is focused on the analysis of the compressive strength of key elements of cellular structures. Examples of the use of cellular structures made of perforated metallic materials in building construction are given. Special attention is paid to the manufacturing of sandwich panels based on a honeycomb structure made of perforated metal tape. [ABSTRACT FROM AUTHOR]

In this study, the perforation failure of honeycomb sandwich structures is numerically simulated by using homogenized equivalent model. The high velocity impact behavior of aluminum honeycomb core with reinforced carbon/epoxy face sheets is modeled by using commercial finite element (FE) analysis code AUTODYN-3D. It is observed that the detailed three dimensional FE modeling of honeycomb core is complex, time consuming and computationally expensive. A simplified hexagonal honeycomb equivalent numerical model with relatively less computational time and acceptable degree of accuracy is proposed in this paper. The equivalent numerical model is based on P-alpha (Pα) equation of state for porous materials. In this model, it is assumed that honeycomb core is isotropic homogeneous porous medium in which all the pores are uniformly distributed. For the purpose of validation, the simulation results of detailed and equivalent honeycomb numerical models are compared with available experimental results in terms of ballistic limit, energy absorption, residual velocity and contact time. The results show that the equivalent honeycomb model closely predicts the perforation behavior for various impact velocities and takes considerably less computational time than detailed honeycomb model. [ABSTRACT FROM PUBLISHER]

The wellbore dynamic pressure waves are produced in the perforation liquid after the shaped charges are initiated and then fiercely strike the gunstring, packer, casing and artificial bottom. The impact and damage effect only depend on the amplitude and holding time of dynamic pressures. This paper discusses the simplification of perforators' explosion with gun in the oil well. On the basis of simplification model, the finite element method is applied to compute the wellbore dynamic pressure under different working conditions. The simulation results indicate that peak compression enhances and the duration of platform pressures obviously prolongs with the perforators' amount once detonated increasing. The holding time of platform pressure clearly prolongs with the accretion of perforator's explosive charge mass. The peak compression and holding time of reflection waves decrease with the augment of distance between the end of tubing and artificial bottom. The peak compression and holding time must be lowered if possible to avoid undesirable failures and damage during perforating operation. [ABSTRACT FROM PUBLISHER]

This paper describes the development of a HIFU irradiation system with the goal of devising an intrauterine means of preventing hypoplastic left heart syndrome (HLHS) or balloon atrial septostomy (BAS). Four large confocal ultrasound transducers were adopted in a large animal experiment to simulate an intervention for the treatment of fetuses in utero. [ABSTRACT FROM AUTHOR]

This paper presents a series of numerical predictions of the perforation behaviour of glass fibre laminates subjected to quasi-static and low-velocity impact loading. Both shear and tensile failure criteria were used in the finite element models to simulate the post-failure processes via an automatic element removal procedure. The appropriate material properties, obtained through a series of uniaxial tension and bending tests on the composites, were used in the numerical models. Four, eight and sixteen ply glass fibre laminates panels were perforated at quasi-static rates and under low-velocity impact loading. Reasonably good correlation was obtained between the numerical simulations and the experimental results, both in terms of the failure modes and the load-deflection relationships before and during the penetration phase. The predicted impact energies of the GFRP panels were compared with the experimental data and reasonable agreement was observed. [ABSTRACT FROM AUTHOR]

It is well known that tissue perforation is performed by the shock waves generated by the collapse of micro bubbles due to HIFU irradiation. However, the angle-dependency between the HIFU irradiation beam and the tissue membrane has not been studied in detail so far. The objective of this study was to investigate the HIFU parameters which were the most effective in perforating the tissues with the heart beating, especially the angle dependency of the beam with the observation using high speed video camera. The result shows that the ultrasound beam should be at right angle to the membrane to perforate the tissue membrane effectively. [ABSTRACT FROM AUTHOR]

When a projectile approaches the back surface of a target, complicated mechanics and different failure modes ensue that can lead to perforation. There have been a number of attempts to model these different failure modes, for example models due to Ravid and Bodner [1] and Walker [2]. Of particular interest are analytic models (as opposed to hydrocode models) where the model attempts to explicitly identify relevant failure modes and back surface breakout modes. This paper examines back surface breakout and target failure models with different failure modes to see how they are invoked in specific impact geometries and scenarios. Comparisons are made of thresholds and sensitivities for the different failure modes to gain a greater understanding of their usefulness and applicability. The model results are compared to data to ensure reasonableness of the computations. Good agreement is shown with a relatively simple back-surface-strain target failure mode for predicting ballistic limit velocity for large aspect-ratio projectiles and relatively thick targets as compared to the projectile diameter. [ABSTRACT FROM AUTHOR]

Calculation of perforated beams with account of plastic properties of material has been made in an analytical form. The holes of perforation were hexagonal and rectangular. The value of limit load of beam-wall with two rows of holes was determined also. The obtained results were compared with the solution by the finite element method. Estimation of advantages of one or another scheme of perforation is made after analysis of rigidity of beams with different systems of location of holes. Beams with hexagonal and rectangular holes are considered. [ABSTRACT FROM AUTHOR]

Review of structure designs indicates that more useful holes applied in civil engineering structures are the round and hexagonal ones. In this work an analysis of stress state of a beam wall near hexagonal and round holes is performed both analitically and with the finite element method. It was suggested a simplified formula for determination of stress concentration factor in beam with hexagonal hole. Investigation with FEM of influence of width of shelves of double-T beam on stress concentration near hexagonal hole was performed. [ABSTRACT FROM AUTHOR]

Calculation of deformations of beams with different kind of the wall perforation has been performed by the method of composed bar and by the finite element method. Estimation of advantages of one or another scheme of perforation is made after analysis of rigidity of beams with different systems of location of holes. Beams with circular, hexagonal and rectangular holes are considered. [ABSTRACT FROM AUTHOR]

The calculation of perforated beam-walls with the finite element method (FEM) and with the theory of composed bars (TCB) is considering. The form of cutouts is rectangular. On the base of FEM calculation it was obtained factor of rigidity of elastic lay, formed with intercostals between holes. A comparison of calculations has been made with FEM and with TCB and indicates on good correlation of results. [ABSTRACT FROM AUTHOR]