bluuebunny/crossref_metadata_2025_split huggingface dataset:
Processing effects on tensile superelastic behaviour of Fe43.5Mn34Al15 ± XNi7.5∓X shape memory alloys
Authors: Popa M , Pricop B , Comaneci R-I , Gurau G , Vollmer M , Krooss P , Niendorf T , Bujoreanu L-G 
Published: August 2019

Abstract
Fe43.5Mn34Al15Ni7.5 was introduced in the current decade as a new superelastic alloy with great applicative potential due to: (i) superelastic behaviour over a thermal range of 200°C and (ii) recoverable strains up to 9.7 %. One of the key factors in enhancing the superelastic response of several shape memory alloys (SMAs) is the formation of an oligocrystalline structure, i.e. without triple junctions between grains, which is the result of an abnormal grain growth (AGG) process that can be induced by cyclic heat treatment (CHT). Considering that, up to present date, no systematic observations were reported on the effects of Al substitution with Ni, the present study aims to analyse precisely these effects of on the structure and properties of Fe43.5Mn34Al15-xNi7.5+x, where x = 0; 1.5 and 3 at. %. The ingots with the five above mentioned compositions were: (i) cut by wire electrical discharge machining (WEDM); (ii) hot rolled (HR) at 1060°C with 43.7-70 % thickness reduction degrees; (iii) annealed (A) at 900°C/1h/water, (iv) cold rolled (CR) with 60-92.7 % thickness reduction degrees; (v) cut by WEDM under the configuration of tensile specimens; (vi) subjected to CHT between 1225 and 900°C with heating-cooling rates of 10°C/min (repeated three times) and final water cooling to 80°C before being subjected to (vii) final ageing (AT) at 200°C for 3 hours/water. After applying this complex thermomechanical procedure, the specimens were analysed by optical microscopy (OM) and the average diameter of crystalline grains was calculated based on dimensional measurements. Considering that the approximate specimen thickness was 1 mm, since the average grain size of thermomechanically treated specimens ranged between 1.3 and 3.7 mm, it can be concluded that oligocrystalline structure, characterized by grain size larger than specimen’s thickness/diameter has been obtained. Tensile tests were performed on thermomechanically treated specimens, both up to failure and by loading-unloading. The evolution of average hardness, during the five processing stages, HR-A-CR-CHT and AT was determined and discussed.
Modelling of the visco-elastic pendular hybrid system with dissipative rolling elements
Authors: Scheaua F 
Published: August 2019

Abstract
The construction industry has seen a remarkable development in recent decades, making it possible to build infrastructure elements capable of withstanding considerable demands on traffic, wind or seismic actions. These achievements have been made due to the solutions used for isolation against dynamic actions that may require the structure at a given time. In order to ensure the protection of construction structures against seismic actions, many constructive solutions have been developed which can be mounted inside the resistance structure. These are mechanical systems used for isolation and seismic energy dissipation, which by operation are able to modify structural behaviour at earthquake. A hybrid seismic isolation model is described which is classified under the building base isolation systems category. This system consists of concave roller elements in combination with elastomeric shock absorbing elements. An experimental model has been developed and analysed, and the results are presented in terms of accelerations in time and frequency at the level of the structural elements at which the recordings are made during excitation simulating the action of a seismic event. The isolation system is used on the low model of a bridge or viaduct structure. Analyses are made for different models of insulation system layout at the isolated structure and distinct cases regarding the construction of the component parts regarding the rolling elements in contact with the concave surface. The results are presented for each structural element in part describing the registered values of acceleration due to the excitation on the supporting pier and the superstructure over the three main directions of movement according to the constructive type of the rolling elements that are included in the isolating system. Experimental analysis was performed on a small-scale system under laboratory conditions, based on a set of simplified assumptions. The advantage of this approach is supported by multiple possibilities of simulation of real dynamic loading situations, static and dynamic loading states, structural and functional schemes and functional configurations of the supporting and isolation systems against dynamic actions. Thus, the transfer of experimental results from reduced models to real systems through mathematical and computer models associated with them is ensured by appropriate transfer functions.
Study on reducing pollutant gases and particulate content inside the passenger car
Authors: Vranau A M , Bujoreanu C 
Published: August 2019

Abstract
The pollutant gases entering the car through the ventilation system are very harmful and the effect they have on the human body is often lethal. The European Environmental Agency is talking about over 45000 “premature deaths” that occur annually due to the particles in the atmosphere. A rigorous monitoring of pollutant content in the passenger compartment is absolutely necessary, therefore the appearance of the first pollen filter in 1940 by Nash Motors on the Weather Eye ventilation system. Studies conducted by researchers in Germany show that not all systems work the same way, and the degree of air filtration is only 40% for some cars, while other cars filter outdoor air up to 90%. The most car manufacturers recommend the filters replacing, and huge gaps exist between a classic particle filter (it captures and retains dust, pollen and soot) and one with active carbon that also captures unpleasant odours. In reducing the amount of pollutant gases entering the passenger compartment, the air quality sensor (AUC), mounted in the pollen filter housing, also controls the activation of the recirculation function when the car enters a polluted area. Our paper presents an overview in the field of pollution in the passenger compartment, the main types of passenger car filters launched on the market and the importance of their use according to the manufacturer’s indications.
The behaviour of “liquid wood” when exposed to some physico-chemical factors
Authors: Barhalescu M L , Jarcau M , Poroch–Seritan M , Costescu E , Vaideanu Dorin , Petrescu T C 
Published: August 2019

Abstract
Because of an ever-increasing demand of non-toxic, biodegradable, naturally-sourced materials and products, the human society is always searching for new materials with specific applications, which are able to fulfil the above-mentioned requirements. Consequently, it is essential to identify the qualities of these materials and their behaviour when subjected to various external factors, in order to find their optimal solutions for application in various domains. Such a material, obtained from renewable resources, is known as “liquid wood”, a material which exhibits composite polymer-like properties, having a lignin matrix. “Liquid wood” can be found in three different forms: Arboform, Arbofill and Arboblend, depending on the natural substances (besides or associated with lignin), which are to be found in the material – resins, wax, vegetable fibres etc. As such, “liquid wood” has been subjected to various external factors, the aim being to determine the degradation of the material when acted upon by environmental factors. Thus, “liquid wood” has been immersed in distilled water and then in an alkaline environment and in an acid environment for 210 days. Measurements were periodically performed to determine the mass variation and the change of electrical properties when subjected to the specific environmental factors and to UV radiation. The changes were determined by comparison with standard samples. Following this study, it has been observed that the main degradation factor is water, which leads to cracking and then fracture in the material. Furthermore, significant changes have been observed in the electrical properties of the material and in the pH of the environments in which it has been immersed. These observations lead to the idea that the material is hydrophilic. The results obtained following the immersion of “liquid wood” in distilled water and then in an alkaline environment and in an acid environment point towards some of the possible application of this material in various fields of activity, which may have a significant positive impact upon the environment.
Experimental researches on the tribological analysis of composite materials sintered with iron matrix
Authors: Caliman R 
Published: August 2019

Abstract
In this paper a study is conducted on the abrasion wear behavior of iron matrix composite materials, testing of samples obtained by sintering was made for different values of the applied load as for the relative speed of sliding. Starting from the studied literature, recipes of sintered sintered metal composite materials having iron matrix have been developed which have been tested for their physico-chemical and tribological properties. The prepared powders were dosed according to the formulations (Fe 68%, Cu 13%, Ni 5-7%, Graphite 6%, SiC 8%, SiO 2 8%), and the resulting mixtures were homogenized to achieve homogeneous mixtures to ensure, finally, a good reproducibility of the physico-mechanical properties of the sintered material. For forming, a cylindrical die having a surface area of 2cm2 was used. Working pressures ranged from 5000 ÷ 6000daN/cm2. The densities obtained for the compressed samples were determined by weighing the METTLER analytical balance and measured with the micrometer for the volume calculation. The values of „raw” densities range from 5.12 to 6.3g/cm3.
Numerical modelling of structural behaviour of URM panels strengthened with cement matrix composites
Authors: Ghiga D A , Taranu N , Ungureanu D , Isopescu DN , Scutaru MC , Hudisteanu I 
Published: August 2019

Abstract
Unreinforced masonry (URM) structures represent a large share of the dwelling stock, traditional industrial buildings and historical heritage of mankind. Most of the URM structures have been built with little or, in some cases, no seismic provisions. In order to overcome this drawback, the application of external reinforcement layers, especially those made of composites, to improve the structural behavior of masonry structures has been a research focus area during the past decades.
The aim of this paper is to propose and assess a simplified and accepted Finite Element (FE) modelling strategy to simulate the diagonal compression test of the URM walls strengthened with glass fibre meshes embedded in a cement-based mortar. In the case of masonry walls strengthened with composites reinforced with glass fibre meshes, both the masonry material model and the modelling and the meshing of the composite strengthening system need to be addressed by taking into account the complex phenomena that characterise the bond interaction between the glass fibre mesh, mortar and the masonry support. The FE analyses were developed with reference to the experimental tests available in the current literature and, according to the preliminary outcomes of an experimental program which is currently under development at the Faculty of Civil Engineering and Building Services, Iasi.
Interlaminar failure investigations on delamination growth of composite laminates
Authors: Hudisteanu I , Taranu N , Isopescu D N , Munteanu V , Ungureanu D , Scutaru M C 
Published: August 2019

Abstract
The investigation of the interlaminar damage evolution on multi-layered composites as well as the numerical modelling techniques available for the simulation of the interface delamination are still a current concern. The complexity of modelling the mechanical behaviour and fracture modes of composite laminates is increased because of the anisotropic behaviour of the material, the fibre arrangement or other important parameters, such as stacking sequence, fibre orientation angle and the configuration of the composite laminates. Different failure modes may occur on multi-layered composites, which can lead to significant stiffness and strength reduction or to the complete loss of the load carrying capacity. The interlaminar stresses are the main factors responsible for the initiation and growth of the interlaminar failures such as delamination. They may occur as a result of manufacturing defects, low-velocity impacts or as an effect of the presence of the free edges. The delamination onset can lead to serious problems such as the premature buckling of the laminates, moisture infiltration, and stiffness degradation or even to progressive delamination growth and the separation of the layers of the composite laminates. The paper presents the numerical modelling of a multi-layered composite subjected to the tensile opening fracture mode as well as the investigation of the delamination growth. The purpose of the analysis is to study the delamination evolution on a symmetric composite laminate, starting from a pre-existing initial crack, at the interface between the adjacent layers from the middle plane. Thenumerical modelling approach for the simulation of the delamination evolution is conducted based on the Cohesive Zone Method. The results are presented in terms of the total displacement jump and equivalent stress distributions on the layers of the composite laminates.
Assessment of the rehabilitation benefits by finite element method
Authors: Dimitrescu A , Babis C , Chivu O , Dascalu L 
Published: August 2019

Abstract
Cruciform fillet welded joints are found in many industrial applications. Welded structures are often subjected to load cycles due to loads that can vary in position and value. As a result of these loads, the phenomenon of fatigue occurs. Fatigue consists in the occurrence of failures, after applying a large number of load cycles, of loads below the yield limit of the material from which the structure is made. Fatigue mattempts have to be carried out over very long periods of time and are very expensive because of the expensive machines. A method by which the fatigue behavior of fillet welded joints can be predicted is the finite element method. The paper proposes to investigate by the finite element method, the fatigue life of some cruciform-fillet-welded specimens, making a comparison of two applied rehabilitation techniques.
Modeling of stress and strain states induced by torsion of straight rods with elliptical cross sections
Authors: Glovnea M , Manolache-Rusu C , Suciu C 
Published: August 2019

Abstract
Torsion of bars of various cross-section is of great practical utility in engineering, structural design and mechanical work. It is applied in machine construction, steel bridge or railway construction. Many publications can be found in literature that present the stress-strain analysis in the case of straight rods with constant profiles subjected to torsion. Most of these works were however directed to the case of rods with simple connected domains as cross sections. The present work uses a semi-inverse method which permits to determine general equations for stress-strain analysis in the case of rods having a multiple connected domain as cross section, subjected to torsion. For the present study, the general equations were customized for two particular cases that of an elliptical cross section and that of an elliptical ring.The determined analytical equations were implemented to a specific situation by aid of Mathcad software. This permitted to graphically represent the distribution of torsion stresses and cross-section deflection.
CFD analysis of a hybrid, Darrieus-Savonius, horizontal wind turbine, using static and moving mesh
Authors: Grabowski L , Sobek M , Baier A 
Published: August 2019

Abstract
Changes in the ecological spirit of the world lead to the need for usage of additional ways of obtaining clean energy. With help comes solutions to use wind energy. In the world, there are numerous commonly used, various kinds of wind turbines of different sizes, numbers of generated power and the different place of use. They are increasingly used as household wind turbines to improve the ecology and a marked decrease in household spending. Moreover, it was decided to use an innovative, previously unused connection of two separate types of wind turbines. The approach to turbine positioning is also innovative. Due to the use of its horizontal orientation and purpose to mounting on the roofs of the buildings, to do not exceed the specified size limits in building regulations. It also allows increasing the number of applications of this solution. With the use of Darrieus - Savonius turbine increasing of the range of the wind speeds, which are able to spin a turbine is achieved. In the case of higher efficiency, the Darrieus turbine operates at high wind speeds, while the Savonius turbine at lower wind speeds. Two separate solutions have been coupled with each other by claw clutch, which allows the rotation of only one part or two parts of the turbine depending on the prevailing wind conditions. The CAD model of the turbine was made and then the turbine was subjected to advanced CFD analysis. Initially, analysis of the air course around the turbine was performed, using statistical and analytical data on wind speeds prevailing in Poland, within the areas of single-family houses. The approximate values of the wind flow streams and the torque which ultimately is moving the electric generator were determined. The subsequent CFD analysis was performed using the moving FEM mesh, mapping the actual velocities of the turbine blades. The turbine blades revolved at velocities close to the obtained analytical speed of the shaft and turbine components. Airspeeds were analysed in the case of the shape of the flow of streams. The pressure of the air around the turbine was also analysed, the value of which could be used to add strength analysis using FEM method. The main purpose of the test was to determine the torque acting on the engine. Thanks to this information, it was possible to determine the energy efficiency of the turbine and select the appropriate elements, such as the generator, bearings etc. The obtained information has also had an impact on the final shape of the turbine’s executive elements. Thanks to performed analysis, it was possible to obtain proper turbine performance parameters without conducting expensive, real, experiments. In the end, the prototype of this Darrieus – Savonius turbine was manufactured.
Nondestructive testing sensor using semiregular architecture with folding ligaments
Authors: Iftimie N , Savin A , Steigmann R , Stanciu M D 
Published: August 2019

Abstract
In present, much more studies on patterned structures composed of periodic unit-structures have been performed. These studies mainly based on the electromagnetic wave propagation, because the variation of physical properties of the patterned structure depends on the change in the unit-structure. Structural topology optimization has made remarkable progress over the past decades. The periodic topology of many periodic cellular makes the analysis of their wave propagation characteristics particularly interesting. This paper presents the results obtained at the electromagnetic testing using a structure in a semiregular arrangement with “exotic” behavior. The CAD/CAM models of reconfigurable folding architecture were designed in the multiple flat unit cells structure considering that the kinematics of a structure with ligaments is function of the angle in the XY horizontal plane. It was followed in response to the modification of the architecture and the size of the structure, their response to the interaction with the electromagnetic field. The simulation of the operation of the wavelength excitation process, first realized theoretically using the Finite Difference Time Domain (FDTD) method, was performed using specialized XFDTD software.
A sliding grid based method for the roll decay simulation
Authors: Lungu A 
Published: August 2019

Abstract
The paper describes a novel technique meant to support the numerical prediction of the roll decay for a ship hull equipped with bilge keels in an attempt of establishing a methodology for accurate prediction of the damping forces which occur during the oscillation. The numerical simulation is achieved by making use of the ISIS-CFD solver, part of the FineTM/Marine package available in the NUMECA suite. The solver is based on finite volume method to build the spatial discretization for the governing equation to solve the incompressible unsteady RANSE in a global approach. Closure to the turbulence is achieved by making use of the detached eddy simulation model which has been found as being enough accurate. All the computations are performed in respect to an earth-fixed Cartesian reference frame with only one degree of freedom i.e. roll motion. The validation of the computed solution is done through the comparisons with the experimental data.
DES-based computation of the flow around the DARPA suboff
Authors: Lungu A 
Published: August 2019

Abstract
Flow modelling is a key issue not only for the correct prediction of hull-propeller interactions, manoeuvring characteristics and the flow field in the stern region of any marine vehicle, but also for the correct estimation of the fuel consumption. The paper describes a thorough investigation of the hydrodynamic performances of the DARPA suboff hull. The flow is numerically simulated by integrating in time the unsteady Navier-Stokes equations in which closure to the turbulence is achieved by means of a modified detached eddy simulation (DES hereafter) technique. The solver used for the purpose is the ISIS-CFD, part of the Numeca FineTM/Marine suite, which employs the finite volume of fluid technique. A comparative analysis between the numerical solutions based on the DES and explicit algebraic stress model (EASM hereafter) are provided in an attempt to sustain the choice for the turbulence model in the present study. Extensive parallel computations are carried out on 120 processors for which comparisons with the experimental data prove the accuracy of the chosen investigation methodology. A grid convergence test is performed for verification and validation purposes.
On the bending vibration of a train driving wheelset
Authors: Mazilu T , Gheti M A 
Published: August 2019

Abstract
The driving wheelset is used on the traction railway vehicle to support a part of the vehicle’s weight and for traction and braking purpose. The driving wheelset consists of the axle on which the two wheels and the driving gear are rigidly attached. The bending vibrations in the driving wheelset may be caused by variations of the vertical wheel/rail contact force. In this paper, a mechanical model of the driving wheelset, consisting of a free-free uniform beam with three rigid bodies, representing the axle, the two wheels and the driving gear, is considered. Using an analytical method for solving the equations of motion for the model, the steady-state harmonic behaviour of the bending vibrations is analysed. The frequency response function and the impact of the position of the driving gear upon this function are pointed out.