bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and finite element analysis of the shear cutting process of electrical steel sheets under various process conditions
Authors: Slota J , Spišák E , Kaščák L’ , Majerníková J
Published: November 2019

Almost every electrical machine consists of the stator and rotor cores, which are made of stacked non-oriented electric steel sheets. Punching and blanking are the two commonly used shear cutting operations for manufacturing electrical machine components. The presented research was aimed to evaluate the shear cutting process of two grades of electrical steel sheets. The shear cutting process causes the formation of residual stresses in the cut segments from the non-oriented electric sheet metal, resulting in increased iron losses. Numerical modeling and experimental research were used to investigate the influence of cutting clearance as well as blunt cutting edge of the shear cutting tool on the residual stresses induced by shear cutting under different shear cutting parameters. The data derived from experiments were applied in finite element analysis of the shear cutting part in the shape of a toroid. Comparison between the results of the experiments and the FE simulations showed that the shear cutting process can be accurately predicted.
The Influence of Residual Stresses Induced by Near-Net-Shape Blanking Processes on the Fatigue Behavior under Bending Loads
Authors: Stahl J. , Müller D. , Pätzold I. , Golle R. , Tobie T. , Volk W. , Stahl K.
Published: November 2019

Gears manufactured by blanking can be found in many different products like hammer drills or automobiles. Here, only the functional surface, the clean shear, can be used to transmit torque. Therefore, parts in serial production demand a high amount of clean shear, so the required torque can be transmitted with a minimal thickness and part weight. To achieve this, these parts are usually manufactured by fineblanking or related Near-Net-Shape Blanking processes (NNSBPs). Furthermore, the gears are subjected to cyclic loading which can, especially in the highly stressed tooth root, lead to tooth breakage. The effect of different process variants and process parameters on the residual stresses and the fatigue behavior under a pulsating bending load has not been investigated yet. Due to the potential of endurance improvement of blanked gears, this topic is addressed in this paper. To accomplish this, C-shaped profiles are manufactured by five different Near-Net-Shape blanking processes. The investigated processes are fineblanking, precision blanking with and without blank holder, and blanking with a small die clearance with and without a v-ring. The sheet metal material, S355MC (material number 1.0976) with a thickness of 6 mm, is first subjected to a stress relief heat treatment to minimize residual stresses induced by the specimen preparation and to ensure a defined initial residual stress state. After blanking, the residual stresses of the parts are measured. Finally, fatigue strength tests are carried out under a pulsating bending load on the C-shaped profiles with shear-cut edges. The results show that the residual stress state, as well as the part’s fatigue behavior are strongly influenced by the chosen blanking process.
Investigation of a new sheet metal shear cutting tool design to increase the part quality by superposed compression stress
Authors: Senn S , Liewald M
Published: November 2019

Nowadays, a major criterion for the quality of shear cut workpieces is characterised by a smooth final cutting surface. Normally, this surface only can be manufactured by using fine cutting or trimming technology. Major disadvantage of these processes is the complex tooling design caused by a double-acting press and corresponding tool layout. Content of this study is to investigate the impact of a new sheet metal cutting tool design, also called concave nosed punch design, to increase the clean-cut portion in conventional shear cutting. The investigation focuses on sheet metal materials DP600, DC03 and HC420LA with a thickness of 1mm. Using FEA-Software DEFORM 2D, the models of conventional cutting and cutting with new tool design were mapped by comparing cutting surface results and stress distribution in the shearing zone. The main criterion of the optimization of tool design focuses on an enlarged clean-cut area along the cutting surface compared to conventional shear cutting. New tool design shows in numerical investigation a significant increase of clear-cut surface up to 73% compared to conventional cutting surfaces disclosing 35% when using tools according to standard design rules. With the result of the punch optimization in the numerical investigation, two cutting punches with different web widths were manufactured and experimentally investigated. The focus of the experimental investigation was the comparison of the cutting characteristics of smooth cut portion and cutting burr. The influence of the cutting clearance between 5% and 15% on the clean cut portion and the burr was investigated. Metallurgical micrographs show a significant increase in the percentage of smooth cut portion when punching with the new cutting method presented here. For DC03, these concave nose punch design was able to achieve smooth cut percentages of up to 95%. However, using this new punch design, it is possible to sheet metal materials revealing a noticeably performed shearing surface quality.
Prediction of necking & thinning behaviour during hot stamping conditions of 22MnB5 steel
Authors: Singh Amarjeet Kumar , Narasimhan K.
Published: November 2019

Hot stamping is a high-temperature forming operation in which the blank is heated to austenitization temperature, and subsequent forming and quenching operations are done simultaneously. In the current research, forming limits were determined using a thickness gradient-based criterion. For this purpose, the tensile and plane strain mode of deformation were considered. The study was carried out in a wide range of temperatures, viz. 750 °C,800 °C and 850 °C at a constant strain rate of 0.01/s. The experiments were carried out in the thermomechanical simulator (Gleeble-3800), and subsequent measurement of thinning evolution for all the deformed specimens were carried out. It was observed that with the increase in temperature, thickness reduction was less and the distribution of thickness was uniform in tensile specimens and at the point of necking thickness gradient ratio is below 0.92 at various temperatures.
Numerical and experimental study of strain distribution of trip steel sheet using hydraulic bulge test
Authors: Spišák E , Majerníková J , Slota J , Kaščák L’
Published: November 2019

This paper presents a numerical and experimental study of strain distribution in a spherical cup drawn from TRIP steel RAK 40/70 by hydraulic bulge test. The strain distribution was measured based on the data obtained by coordinate measuring machine (CMM) to identify the wall thickness and plastic anisotropy through measuring the circularity. Numerical modelling of hydraulic bulge test was performed in two types of finite element code – explicit as well as implicit. Hill’s family plasticity models with a combination of two types of the hardening curves were used in the simulation model of the bulging process. The FE analysis was compared with the experimental study. The results indicate that the model is applicable to describe the wall thickness, strain distribution and bulged profile.
On the Design of Novel Multi-failure Specimens for Ductile Failure Testing
Authors: Williams Bruce W. , M. Simha C. Hari
Published: November 2019

To quantify uncertainty in the failure response of metallic alloys, conventional experiments may not be suitable owing to the lack of significant scatter in stress states that lead to ductile tearing. In contrast, our testing experience indicates with structures containing strategically located cutouts lead to multiple failure paths and display sufficient scatter in the failure response. Accordingly, we describe the design of dog-bone shaped structures with an ensemble of cutouts, so that at least three different failure paths are observed. In conjunction with Digital Image correlation for full-field displacement measurement and numerical computations, we show how multiple failure paths are obtained when these samples are used. Tests on 2-mm thick 6061-T61 aluminum sheets were conducted using a novel guillotine-style fixture that allows the use of high-speed press. The latter allows testing at strain rates as high as 1 1/s. The primary purpose of this article is to make the case for the use of these samples that not only minimize number of tests required to garner data to calibrate stress-based damage models that capture the entire failure envelope of the material, but also display sufficient scatter that allows quantification of uncertainty in the failure response.
AA1100-O cylindrical cup-drawing using 3D servo-press
Authors: Ha J , Breunig A , Fones J , Hoppe F , Korkolis Y P , Groche P , Kinsey B L
Published: November 2019

In this paper, the flexibility of a 3D servo-press is used as the inspiration to numerically demonstrate the ability to improve the final product, in this case reduced equivalent plastic strain, increased forming depth, and reduced punch force, during cylindrical cup-drawing. The material investigated is AA1100-O which exhibits significant anisotropy, i.e., r-values of 0.45 to 1.2 in 45 degree and transverse direction to rolling, respectively. This leads to earing during cup-drawing, which is used to validate numerical simulation efforts. A unique 3D servo-press at the Institute for Production Engineering and Forming Machines at the Technische Universität Darmstadt allows for tilting and orbital motion of the blank holder and with this a variation of the blank-holding force during the punch progression. Numerical simulations are used to demonstrate improvements with respect to equivalent plastic strain and forming depth.
Bayesian Model-based State Estimation for Mass Production Metal Forming
Authors: Havinga Jos , Mandal Pranab K , Boogaard Ton van den
Published: November 2019

Modern metal forming factories produce large amounts of data, such as process forces and product geometries. These data contain indirect information about fluctuations in the manufacturing process, such as changes in temperature, material properties and lubrication conditions. In this work, Bayesian inference is used to obtain a probabilistic estimate of the process state based on force measurements in mass production metal forming. The procedure requires statistical assumptions about process state variations, which are often not known as it is usually not possible to directly measure the process state in-line. It is shown that unknown statistical model parameters can be estimated simultaneously with the process state. This leads to an improvement in the accuracy of the state estimate. The procedure is studied using pseudo-data from a mass production sheet bending process, using a finite element model with ten parameters. The material, friction and process parameters are estimated based on process force measurements.
Finite element modeling and durability evaluation for rubber pad forming process
Authors: Park J , Kim Y , Yoon J W , So H , Lee J , Ko S
Published: November 2019

Elastomer (or rubber pad) forming is a dieless forming process. The forming process has several advantages compared to general press forming process in terms of tool cost and scratch problem. However, when the elastomer is subjected to severe deformation during forming process, it can result in an expensive cost for the replacements of elastomer. Therefore, it is necessary to evaluate accurate tool life. In this study, the FE analysis was conducted for the rubber pad forming process and the fatigue life evaluation of the elastomer tool was investigated numerically using the reference experimental data. For the FE analysis, uniaxial and equibiaxial tension tests of natural rubber 50 were carried out in order to obtain the mechanical material properties of the elastomer. The hyperelastic behavior of the elastomer was characterized using Ogden model. The elastomer forming process was modeled using a commercial software LS-DYNA 3D. Two important factors of FE modeling were to calibrate the simulation conditions and to obtain the target product shape with a preformed elastomer. With the result of FE analysis, a durability of the elastomer was conducted focusing on fatigue life, because the elastomer is applied for repeated loadings during the forming process. Unlike general fatigue analysis, the fatigue life of the elastomer is predicted with respect to the strain measures due to Mullins effect. Furthermore, the Polar Effective Plastic Strain (PEPS) diagram [6] considering the strain path changes was used to check the failure of the blank during the forming process.
A new approach for advanced plasticity and fracture modelling
Authors: Park N , Stoughton T B , Yoon J W
Published: November 2019

A solution to the challenge of modelling the general yielding behaviour including fracture initiation is proposed based on non-associated flow rule. A decoupled formulation with employment of a Lagrangian interpolation function is established to develop a general fracture criterion that considers the mutual effect of the material anisotropy, the strain rate, and the temperature on the onset of fracture. An advanced constitutive law is also developed to accurately describe the evolution of the anisotropy/asymmetry-induced distortional yielding behaviour, using neither any interpolation nor optimization techniques for the calibration of the yield surface. The proposed models are successfully applied to various types of metallic materials to validate their noticeable flexibility and applicability in describing the general material behaviour during various forming processes.
Spring-Back Analysis Method Considering the Die Deformation Due to the Stamping Pressure of the Ultra-High Strength Steel
Authors: Bae Gihyun , Song Junghan
Published: November 2019

This paper proposes a spring-back analysis method for investigating the effect of the stamping pressure on the final shape of a B-pillar outer panel manufactured with the ultra-high strength steel. The conventional sheet metal forming simulation of the B-pillar outer panel was conducted with rigid tool surfaces and a deformable blank of CR1180TRIP. Press and die structure was modelled with three dimensional tetrahedral solid elements for the structural analysis. The stamping pressure obtained from the forming simulation was mapped to the tool surfaces in the tool structure model. From the implicit structural analysis, the deformation amount of the press and die structure was investigated quantitatively. The structural analysis method was verified by comparing the total stamping force of rigid surface model and deformable tool structure model. Finally, the conventional sheet metal forming simulation with modified rigid tool surfaces was conducted to investigate the effect of the tool deformation on spring-back. The simulation result shows that the deformation amount due to the stamping pressure can have significant effect on the final product shape.
A robust experimental technique to determine the strain to fracture for plane strain tension
Authors: Roth C C , Grolleau V , Mohr D
Published: November 2019

The stress state of plane strain tension plays a crucial role in many forming and crash applications. Under plane stress conditions (in thickness direction), most micromechanical and phenomenological models predict a minimum in ductility for a plane strain tension loading (in the plane of the sheet). When looking at Forming Limit Diagrams (FLD) or at modern stress state dependent fracture initiation models, a “plane strain ductility valley” exists between uniaxial and equi-biaxial tension. Given that the ductility reaches a minimum for plane strain tension, the reliable measurement of the strain to fracture for plane strain tension is particularly crucial when calibrating modern fracture initiation models. Many experimental techniques have been proposed in the past, but a standardized universal experimental technique for plane strain tension testing is still missing to date. It is the goal of the present work to develop a robust experimental technique for determining the strain to fracture for plane strain tension. Emphasis is placed on finding a technique that is universally applicable i.e. that provides reliable results irrespective of the material thickness or ductility. In addition, it should be easily automatized in order to be included in up-to-date test protocol dedicated to the prediction of the behavior from large database analysis. The experiments are designed such that the material is subject to proportional loading, i.e. the stress state remains constant throughout the entire loading history until fracture initiates. After identifying a suitable specimen geometry through finite element simulations, experiments are performed on specimens extracted from aluminum alloys and steels sheets. The experimental campaign includes three different types of plane strain tension experiments (flat notched tension, V-bending and the newly-proposed stretch-bending of mini-Nakazima specimens) to elucidate their differences and limitations, and to demonstrate that the newly-proposed technique is the only one that yields meaningful results for all three materials.
Numerical evaluation of mechanical performance for self-piercing riveted fiber-reinforced plastic and metal sheets
Authors: Noh W , Park K Y , Kim C , Lee M G , Jung C Y , Song J H
Published: November 2019

Finite element analysis is presented to evaluate the mechanical performance of self-piercing riveted fiber-reinforced plastic and metal sheets. The mechanical properties of the rivet and the sheets subjected to joining are considered for reliable simulation. Yielding and hardening behaviour of the rivet was inversely characterized by a coupled experimental-numerical analysis of a compression test, while those of the sheets were deduced by directional tensile test as usual. Fracture criterion was characterized and considered only in the sheets. The geometric features of the die and the rivet were also quantitatively measured and applied to the simulation as the boundary conditions. Consecutive simulations of riveting process and tensile shear test were carried out, which leads to determining sensitivity of peak load to characteristic rivet-joining features such as interlock and bottom thickness.
Processing of videos of the fatigue cracks propagation in the rotor blades of the helicopter
Authors: Kurokhtin V Yu
Published: November 2019

The article describes the processing of videos of growing fatigue cracks in the main rotor blades of a helicopter, which are formed during their fatigue tests on the stand. A specially created computer program allows to determine the geometrical parameters of a crack based on video recording (length, width, extreme points, center of gravity). Each frame of the video is binarized, after which a binary matrix is created on its basis, which is subject to element-by-element processing. The obtained data are presented in the form of a graph showing the dependence of the crack growth rate on the time of its growth. The graph is traced in the Mathcad program, as a result, two data vectors are created — the time and crack growth rate, which undergo an interpolation procedure with the construction of a third-degree polynomial. According to the results of the integration of the polynomial, the critical length of the crack is determined, after reaching which its rapid growth begins.
Research on the technology of paste boronizing for H13 die steel
Authors: Yan-Wei Zhang , Quan Zhen , Lygdenov Burial , Guriev A M , Shun-Qi Mei
Published: November 2019

In this paper, the boronizing effect of H13 hot work die steel is studied. The experiment is carried out to compare the boronizing effect of H13 steel at 850 °C, 900 °C and 950 °C. The heating time is set to 4 hours. The experimental results indicate that the temperature at 950 °C is suitable for boronizing of H13 steel. At 950 °C the boronized layer is more tightly bonded to the matrix, and the depth of the layer is deeper than at 850 °C and 900 °C. The hardness of the layer at 950 °C is better than at 850 °C and 900 °C in terms of the hardness of the layer. Therefore, 950 °C is a suitable temperature for boronizing the H13 hot work die steel.
Study on the bending property of shirt sleeve slits
Authors: Yi-Chuang Gu , Shun-Qi Mei
Published: November 2019

Shirts are the clothing products that people need in all seasons. The folding effect of shirt sleeves directly affects the quality of the sleeves. In this paper by controlling the fabric of the shirt, the folding pressure and the additional pressure time, the fold recovery performance of the sleeves are studied from three aspects: bending stiffness, wrinkle recovery angle and bending recovery force. The experimental results show that the greater the areal density of the fabric is, the greater the restoring force is, the less likely the sleeves are folded. Under operation time of 5 minutes, the pressure of 30 N, 40 N, 50 N is applied to the wool fabric and the polyester fabric respectively, the restoring force was 1.0 cN, 0.75 cN, 0.5 cN and 1.2 cN, 0.8 cN, 0.6 cN respectively. At the same time the experimental results show that, the greater the additional pressure is, the smaller the resilience is, and the better the folding effect of the sleeves is. The research in this paper provides a theoretical basis for the actual production of the folding of the shirt sleeves and improves production efficiency by controlling the relationship between negative pressure and negative pressure time.
Complex saturation of corrosion resistant steels AISI430 and AISI303 with boron and carbon
Authors: Shunqi Mei , Guriev A M , Ivanov S G , Guriev M A , Lygdenov B D
Published: November 2019

Studies have been conducted on the effect of the degree of doping with chromium and nickel on the formation of boride coatings on steels AISI430 and AISI303. The saturation was carried out in a SNOL-type chamber furnace equipped with a PID controller from a powder saturating medium in an unsealed crucible. A mixture of boron carbide powders (70 wt. %), potassium tetraborate KBF4 (7 wt. %) and graphite – up to 100 % was used as a saturating medium. The process temperature was 900 ºC, the saturation time was 2.5 hours. Upon completion of the high-temperature exposure, the crucibles were removed from the furnace and cooled in air to the 50–60 ºC temperature. Diffusion coatings with a total thickness of 120 μm were formed on steel AISI430 and 75–85 μm on steel AISI303. The thickness of the boride layer for both steels was 45–50 µm.
Study on physical properties of dispersed silica
Authors: Tserenjav E , Jigmeddorj V , Lygdenov B D , Bayraa U , Tsevelmaa D D
Published: November 2019

The paper deals with the physical properties of colloidal silica dispersed system such as distribution width (Q
x, %) and density (q
x, %) defined by photon cross correlation spectroscopy (PCCS) at an average size of 17.06 nm for D
50 % and the area of specific surface of 349.96 m2 cm−3 depending on molar (R
m2) optimal ratio of silica stone mineral to alkali ash powder. The change of crystal structure to amorphous state was determined by X-ray diffraction analysis. The results of their kinematic viscosity, liquid density, UV light adsorption inspections show possibility to produce the colloidal silica by using the wetting and ultrasonic vibration method for that fusible alloy.
3D aerosol printing as method to obtain low-temperature ceramic layers of printed circuit boards
Authors: Ivanov A A , Chermoshentseva A S
Published: November 2019

A method for the synthesis of the polyaluminosilicates (PAS) with the macromolecules of dendrimer morphology has been developed. A quantum-chemical assessment of thermodynamically possible mechanisms to develop the populations of short-chain aluminosilicates (nuclei of dendrimer macromolecules) has been carried out followed by the domains generation from the dendrimer assemblies capable to contain up to 80 % wt of the dispersed filler particles into their interdomain spaces by means of the GAUSSIAN B3LYP/6-31G (d) software package. A quantitative calculation of the parameters determining the composition of PAS macromolecules and the size of the dendrimer assemblies has been carried out. A method for the synthesis of monomeric precursor-powder has been developed. A new low-temperature ceramic composite material for 3D aerosol printing has been developed on the basis of the PAS and highly dispersed precursor-powder. The processes of 3D aerosol printing of the PAS filled with monomeric precursor-powder have been researched. An optimal method for aerosol generation has been chosen that does not affect the PAS supramolecular structure. The ceramic dielectric layers with high consumer properties have been obtained by means of 3D aerosol printing.
On improving the operational properties of metal-fluoroplastic plain bearings
Authors: Rogov V E , Baldanov A B
Published: November 2019

The analysis of metal-fluoroplastic materials was carried out. Domestic metal-fluoroplastic materials do not meet the requirements of regulatory and technical documentation adopted in domestic engineering. A review of patents on technologies for the production of metal fluoroplastic materials (MFM) was carried out. Promising methods for producing MFM have been identified. New methods can significantly increase the operational characteristics of fluoroplastic materials. For widespread use of metal-fluoroplastic plain bearings it is necessary to increase their performance. Reducing the linear wear parameter is possible by increasing the nominal area of the metal contact.
Design of rectangular sandwich panels with metal skins based on post-buckling state in compression and shear
Authors: Mitrofanov O V
Published: November 2019

Solutions of geometrically non-linear tasks concerning post-buckling behavior of sandwich panels with thin metal skins and lightweight filler loaded by compression and shear flows are shown. Based on obtained solutions methods of aircraft structures sandwich panels design based on post-buckling state with acceptable global buckling in case of ultimate loading are suggested.
Experimental study of continuous welded rails deformation under the effect of axial force
Authors: Novoseltsev P V , Bokhoeva L A
Published: November 2019

On the Russian railways there is a transition from conventional rail to a continuous welded rail track, however during its operation, occasional track disturbances occur due to internal stresses in the rails caused by the temperature and longitudinal stresses generated by passing rolling stock and creepage of the railway. Stresses can be tensile in winter and compressive in summer. They can reach dangerous values leading to rupture of the track at low temperatures and its ejection at high temperatures. To ensure traffic safety, it is necessary to develop a technology for monitoring stresses arising during operation. The authors created and obtained a patent for a device which made it possible to determine the generated stresses. Studies were carried out on welded rail behaviour and the dependence of displacements and stresses on the action of an external force was obtained.
Accounting for shear deformations with bending a round plate
Authors: Bokhoeva L A , Chermoshentseva A S
Published: November 2019

This paper presents a solution of the stability problem of a round plate taking into account the influence of shear deformations. The critical load of a round plate is determined taking into account shear deformations and without taking into account the shear deformations. The critical load taking into account the transverse shear with a local stability loss of a round plate is less than the critical load without taking into account the transverse shear. The inclusion of shear deformations in the study of the supercritical behavior of a round plate for isotropic materials does not have practical value, but it makes sense with extremely strong anisotropy of the elastic properties of the material.
On the results of integrated researches of the initial raw material and fenced glass structure with the application of modern physical and chemical methods
Authors: Anchiloev N N , Rogov V E
Published: November 2019

Studies have been conducted on the structures of the initial raw material and obtained on their basis foam glass of the “aluminosilicate rock –cullet – sodium hydroxide” systems with the use of X-ray and thermal analysis. The interrelation of the prescription-technological parameters and the physical and mechanical properties of the foam glass of the system “cullet – aluminosilicate rock – sodium hydroxide” has been established. Compositions of foam-forming mixtures have been developed, thus making it possible to obtain foam glass with the density from 412 to 1200 kg m−3 and strength from 2.0 to 16.1 MPa.
Thermal conductivity improvement of Al alloy with Nb nanopowder using SPS for transmission conductor
Authors: Ujah C O , Popoola A P , Popoola O M
Published: November 2019

Aluminium 1000 alloy has high purity and good electrical conductivity required for high power transmission conductors but lacks adequate thermal conductivity which induces sagging in service. To augment this deficiency, Nb nanopowder was incorporated into it as a reinforcement and consolidated with spark plasma sintering (SPS). The SPS was conducted with pre-optimized processing parameters of 630 °C, 30 MPa, 10 mine and 200 °C/min. The sintering was conducted in a vacuum with graphite die of 20 mm in diameter. Thereafter, the sintered samples were metallographically prepared and subjected to thermal conductivity testing. A laser flash analyzer was used to generate the thermal diffusivity of the samples. Then their thermal conductivities were computed. Results obtained showed that Al-4Nb had the highest thermal conductivity of 115. 95 ± 6.9 W/mK which represented 42% improvement. So, it follows that Al-Nb composite is a better replacement for monolithic Aluminium 1000 alloy in power transmission conductors with a potential property of low sag.
Numerical and experimental analysis of the rotor eccentric effect on the labyrinth seal
Authors: Mo Jintao , Yu Zhiwei , Luo Ying , Du Hua
Published: November 2019

Labyrinth seals are widely used in turbomachines. In this paper, a transit simulation method is introduced to model the relationship between the journal offset in Labyrinth seals and the system stability based on Fluent UDF. A special dynamic mesh method has been adopted to ensure fine mesh quality during the arbitrary motion of the journal. In each time step, the transient fluid seal force on the journal surface is obtained by the solving Navier-Stokes equations. Then the displacement of the journal in the next step can be numerically solved by the FEM model of the rotor system. For every transient time step, the computed fluid seal force and the rotor motion displacement were coupled by data exchange. The experiment is carried out in a steam turbine with a position adjustable labyrinth seal. The experimental results show that the amplitude of the vibration decreases after the change of the relative position between the journal and the labyrinth seals and the numerical results show that the locus of the journal under different labyrinth seal offsets has some half-frequency components. Both the simulation and the experiment validates that the relative position between the journal and the labyrinth seals can greatly affect the stability in the coupled rotor-seal system.
Heavy Object Lifting Platform to Correct Human Balance and Posture
Authors: Raymundo F , Quispe G , Raymundo-Ibañez C
Published: November 2019

This research document on technological development is aimed at workers in small companies, those that are developing well and soon to emerge as companies that will be positioned at the top of their labor sector. Starting from the problem at present with respect to the bad manipulation of loads it is arranged to solve the problem with established objectives to try to correct the corporal posture at the time of lifting an object with a machine that replaces the functions of the worker. The design and the solution was made based on the requirements of the worker, workers who have the need to load objects at a certain height, here the man-machine relationship, demands and desires that help to achieve the general objective are analyzed. In addition, it has the main function of this machine: to lift heavy objects of up to 150 kg of mass, this due to the implementation of a hydraulic piston in the lifting platform. The appropriate solution is an adaptation of a platform in the form of a truck forming an angle of 47.17 between the structure of the truck and the horizontal surface, this position is the most adequate so that the back does not suffer injuries during the handling of loads at work. The results give assurance that it is a machine of reliability and easy handling since it only requires an operator to control the objects and a flat position on the back without damaging the spine.
Controlled Trim-Blasting Model to Improve Stability and Reduce Vibrations at a Production Gallery of the San Ignacio de Morococha S.A.A. Mining Company
Authors: Camallanqui-Alborque C , Quispe G , Raymundo-Ibañez C
Published: November 2019

This paper presents a blasting method called controlled trim blasting, in which the rock mass of an unstable gallery where high levels of vibration have been detected is analyzed. This methodology comprises a drilling mesh with two-contour gallery assessment, producing its drilling machines and determining the type of explosive used and burden and spacing, which will be detonated after the internal blasting. Further, the internal blasting will possess its drilling machines, burden, spacing, and a second type of explosive. The separation of the gallery into smaller parts will improve the blasting, as verified in the recorded simulation. In addition, the rock-mass stability improves because the explosives used in the perimeter of the gallery are low-power with mild detonation pressure, which does not generate high levels of vibration. This is a practical and efficient method in areas where the rock mass is not good or there is a mixture of rock types.
Variation Propagation in Multistage Machining Processes Using Dual Quaternions
Authors: Yacob F , Semere D
Published: November 2019

The application of rigid transformations matrices in variation propagation has a long tradition in manufacturing community. However, the matrix-based modeling of variation propagation in multistage machining processes is complicated. Moreover, there is a need to improve the computational efficiency of manipulation of geometrical models for variation analysis purposes. This paper introduces the representation of rigid transformation by dual quaternions, which have a computational advantage and mathematical elegance compared to matrices. In comparison to a commercial tool, the implementation of the purposed method predicted parallelism with an average error of 4.3 % in a hypothetical two stage machining process. The proposed approach has a potential to be an alternative to matrix based rigid transformation practices in variation and tolerance analysis.
Testing of a new transport and installation method for offshore wind turbines
Authors: Haugvaldstad J , Gudmestad O T
Published: November 2019

Transport and installation of offshore wind turbines require considerable efforts and can be time consuming, in particular when jackups are used for lifting operations. This is mainly due to the specific weather window requirements for towing and locating the jackups. A goal is ultimately to finalize all turbine assembly work onshore and at quayside and to transport the completed turbine to the site for easy installation. We suggest that this can be achieved by a transport and installation method we denote “the MINT method” whereby the wind turbine foundation is located on a barge while the tower is resting on a support system, a “MINT” system that is located at the stern of a mid-size standard offshore support vessel. The MINT is specifically designed for the transport and installation operations allowing relative motions and rotations between the tower and the transport vessel. In order to qualify the “MINT installation method”, a numerical study of the feasibility of the transport and installation was carried out by Sintef Ocean using their SIMO software package [1]. The method was found feasible in favourable weather conditions. To further document feasibility, it was decided to carry out a proof of concept test in a wave tank to identify concerns with respect to the suggested method for transport and installation. This paper reports the findings of this test. The test is to be considered to represent an initial activity in the concept qualification process, see [2], and is not a full wave tank test carried out to measure stresses and strains for member sizing. The objective of the paper is therefore, to show how an initial wave tank test can be useful for concept qualification.
The influence of an unstable turbulent wind spectrum on the loads and motions on floating Offshore Wind Turbines
Authors: Knight J M , Obhrai C
Published: November 2019

Floating offshore wind turbines (FOWT) are exposed to harsh environmental conditions and often experience unstable atmospheric conditions. Including the effects of atmospheric stability should improve the accuracy of fatigue load calculations, and subsequently, the design of the wind turbine. The current standards recommend two turbulence spectral models that are valid for neutral atmospheric conditions only. The objective of this study is to investigate the influence of Hejstrup’s 1981 Unstable Spectra Model on the loads and motions on a spar and a semi-submersible FOWT. This study focuses on the effect of unstable atmospheric conditions in the free stream wind and does not include the effect of wakes. The most significant differences observed in this study were for the tower top torsion loads, where very unstable conditions gave 47% larger loads than neutral conditions for OC3-Hywind turbine and 30.4% larger for OC4-DeepCwind turbine. Since very unstable conditions corresponded to the highest turbulence intensities and larger turbulent fluctuations, they also resulted in higher fatigue loads. The blade root flap-wise loads were also observed to be higher under unstable conditions compared to neutral conditions, but the differences were smaller with 7.5% for OC3-Hywind and 23% for OC4-DeepCwind.
Investigation of transitional turbulence models for CFD simulation of the drag crisis for flow over a sphere
Authors: Nakhostin S M , Giljarhus K E T
Published: November 2019

The drag crisis is an interesting physical phenomenon for flow over bluff bodies, where the drag coefficient suddenly drops as the Reynolds number increases. This behavior is caused by the flow transitioning from laminar to turbulent flow in the boundary layer. The turbulent flow remains attached to the surface longer than the laminar flow, thereby reducing the size of the wake behind the body. The phenomenon has been extensively studied experimentally for simple geometries such as flow over a sphere or a cylinder. Numerical simulations, however, have mainly been performed in either the subcritical or the supercritical region. In this study, we investigate the ability of steady-state RANS CFD models to predict the drag crisis for flow around a sphere. Experiments using oil-film visualization are performed to determine the type of transition for flow over a sphere. Simulations are performed using OpenFOAM, with the k-ω shear stress transport (SST) turbulence model. For transition modelling, the Langtry-Menter modification to the SST model is considered. The simulations show improved prediction of the drag coefficient in the subcritical regime, but the implementation of the model is found to be unstable in the critical and supercritical range.
Effects of an inserted circular cylinder on a steady lid-driven rectangular cavity flow
Authors: Zhu J , Holmedal L E , Myrhaug D
Published: November 2019

This paper provides numerical investigations of flow in a steady lid-driven cavity of depth to width ratio 1/3 containing a circular cylinder. The inner cylinder is treated using a direct-forcing immersed boundary method, and a project method is applied to solve the incompressible Navier-Stokes equations. Three different Reynolds numbers and positions of the cylinder are considered; for a lower Reynolds number, flow structures are weakly affected by the cylinder near the left wall while two clockwise vortices attached to the cylinder are formed as the cylinder moves rightwards; for a moderate Reynolds number, an anticlockwise bottom vortex is formed for the cylinder near the left wall, and it disappears as the cylinder is shifted rightwards; for the largest Reynolds number, two anti-clockwise vortices attached the cylinder are formed for the cylinder close to the left wall, and as the cylinder moves gradually closer to the left wall a bottom vortex is formed and disappears together with the clockwise vortex to the right side of the cylinder.
Environmental and sustainable aspects of green building: A review
Authors: Çiner F , Doğan-Sağlamtimur N
Published: November 2019

Public and scientific focus of interest on climate changes, population increase, rapid urbanization is rising day by day. Thus, increased demand for green buildings that reduces negative impacts, and can creates positive impacts on climate, natural environment and sustainable development is a new topic. Green buildings must be not only eco-friendly (efficiently use energy, water, and other resources, use renewable energy, reduce pollution and waste, enable reuse and recycling, have good indoor environmental quality, use of materials that are non-toxic, ethical and sustainable) but also function as the key part to provide a comfortable working/living environment for human activities and improve quality of life. It is realised that green buildings as a worldwide response to raise awareness of the role of human activity in global climate changes, with maximum expression in Leadership in Energy and Environmental Design (LEED) Certification and its five basic requirements: Sustainable Space (SS), Materials and Resources (MR), Energy and Atmosphere (EA), Environmental Quality (EQ), and Water Efficiency (WE).The aim of this study is to review the environmental and sustainable aspects of green buildings. For this goal, environmental and sustainable aspects of green building including its origin, concept, eco-friendly properties, benefits, tools, rating systems, certifications are given and discussed in detail in this study.
Building panel production incorporated with fly ash
Authors: Yıldırım G , Keser H , Doğan-Sağlamtimur N , Çelik F
Published: November 2019

With the increase in industrialization, the amount of fly ash (FA), which is one of the industrial solid wastes causing environmental and human health problems, is increasing day by day. Waste valorization and reuse methods need to be developed for this waste ash. The construction industry is the main sector where it is used. In this study, it is aimed to evaluate the usability of industrial FA in the production of economical and useful building panels and to determine their physical-mechanical properties. FA supplied from İsken Sugözü Thermal Power Plant (ISTPP), ordinary Portland cement (OPC) supplied from ÇİMSA Cement Industry and Trade Inc., molding plaster (MP) and lime are the materials of this study. Particle distribution curves were determined by using laser scattering method for FAISTPP. In this study, compressive and flexural strengths, water absorption, bulk density and porosity as mechanical and physical tests were made in the building panels having the combination of FAISTPP+cement FAISTPP+MP and FAISTPP+lime in contribution ratios of 10, 30, 50, 70 and 90%FAISTPP. The results of the experiments show that the highest compressive strengths values in 7 and 28 days found in the building panels having combination of 90% cement+10% FAISTPP are 57.30 and 64.20 MPa, respectively. It was determined that the value-added building panels could be produced from FAISTPP, an industrial solid waste, in the appropriate proportions of cement contribution.
Fly ash as a raw material for geopolymerisation-mineralogical composition and morphology
Authors: Korniejenko K , Łach M , Marczyk J , Ziejewska C , Halyag NP , Mucsi G
Published: November 2019

The article discusses the main features fly ashes (FAs) as a raw material for geopolymerisation taking into consideration mineralogical composition and morphology. It is continuation the previous research connected with chemical composition and physical properties. This article is focused on the examination of a FA from the CHP plant in Skawina (Poland) and assessment it as a main component for geopolymers production. The characteristic of the FA is presented, including the morphology and mineralogical structure. The morphology was examined using Scanning Electron Microscopy (SEM). The structure of the FA was monitored also by Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray diffraction (XRD).
Evaluation of fire, high-temperature and water erosion resistance of fiber-reinforced lightweight pozzolana-based geopolymer mortars
Authors: Silva G , Salirrosas J , Ruiz G , Kim S , Nakamatsu J , Aguilar R
Published: November 2019

The development of new building materials requires intensive analyses of their durability under aggressive conditions. Therefore, the current study evaluated the capacity of a fiber-reinforced lightweight pozzolana-based geopolymer mortar to resist the action of fire, high temperatures and water erosion. The fire resistance and heat absorption capacity were evaluated through the exposure of disc samples to a direct flame at 1000 °C and the measurement of reverse-side temperature, respectively. To evaluate the high-temperature resistance, uniaxial compression tests were performed on cubic samples after their exposure to oven-temperatures of 300°C, 500°C, 800°C, and 1000°C. Finally, water jet erosion and permeability tests were performed to analyze the interaction of the material with water. The results of the fire tests indicate that fiber-reinforced lightweight pozzolana-based geopolymer mortars are able to absorb up to approximately 65% of heat flame with only slight degradation. On the other hand, uniaxial compression tests showed a temperature resistance up to 800°C, above this temperature the cubic samples experimented significant volumetric changes that might have been caused by a reaction of remaining hydrogen peroxide or gas expansion. Finally, water exposure tests showed that the material is highly permeable and has a remarkable resistance to water erosion.
Utilization of innovative system for coke oven wastewater treatment as an element of stabilization technology for post-process waste from municipal incineration plants
Authors: Mierzwiński D , Łach M , Mikuła J , Furtos G , Korniejenko K
Published: November 2019

The article discuss the possibility of using the system for coke oven wastewater treatment process that has been developed within the framework of the project: The innovative system for coke oven wastewater treatment and water recovery with the use of clean technologies — INNOWATREAT that has received funding from the Research Fund for Coal and Steel under Grant Agreement No. 710078 and from the Ministry of Science and Higher Education Poland from financial resources on science in 2016-2019, for the removing the hazardous elements and compounds from wastewater from leaching ashes from municipal waste incineration plants. The results achieved in the project are compared with analysis provided for two different sources of ash from Poland and one Lithuania. The article discuss predicted effectiveness of the method and possibility their use in wider method of post-process waste stabilization technology as well as potential risk connected with implementation this solution into practice.