bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical characterization of additive manufactured samples from biodegradable materials
Authors: Carausu C , Mazurchevici S-N , Mazurchevici A-D , Andrusca L , Comaneci R , Popa R-I , Nedelcu D 
Published: September 2020

Abstract
One of the biggest challenges facing engineers and designers in the field of additive manufacturing is to constantly develop and promote new products to meet the increasingly varied and demanding needs of customers. They must also “navigate” through a wide variety of technologies and materials available in order to determine the most appropriate solution for their application. The best and easiest way to determine if a particular technology or material is right for an application is to study and understand its behavior. This paper aims to mechanical characterize 3D printed samples from biodegradable materials through tensile, bending, and impact tests but also by determining the mechanical behavior in the dynamic regime and the tribological behavior (friction coefficient and wear). For the obtained results during the tensile test were performed a statistical analysis of the technological parameters’ influence on the output parameters (tensile strength, strain, and modulus of elasticity) and it has been developed and the optimization of these ones. The studied biodegradable thermoplastics were bioFila Linen, bioFila Silk and Fiber Wood which according to the highlighted results can be used in various fields of activity and can easily replacing polymers from fossil resources such as flexible filaments, high impact polystyrene, polypropylene, polypropylene reinforced with short glass fibers, polymers reinforced with metal or wood powder.
The optimization of container transport on a ship type PSV
Authors: Cojocaru R , Axinte T , Fratila C , Diaconu M , Berescu C 
Published: September 2020

Abstract
In this paper, we studied how containers need to be transported on a PSV ship. The deterioration of the containers during the transport can get a result in the destruction on the goods. All the drawings were made by us in the NX 12 software from Siemens. Furthermore, the analysis of the container clamping system was performed by the finite element method using the NX 12 Siemens software. Structural dimensions following an original project, were used to the achievement of a PSV (Platform Supply Vessel) ship in design. Although, PSV ships are relatively small, they have a complex design. The purpose of these ships types is to transport freight and weights bigger and bigger. This is the reason why we close to present in this work only the optimization of containers on PSV ships.
An accurate and fast iterative scheme for estimating the ship rolling and capsizing in regular waves
Authors: Deleanu D , Panaitescu M , Panaitescu F V 
Published: September 2020

Abstract
A short number of steep breaking waves hitting a ship from the side may affect its dynamic behaviour and to determine extreme roll angles and, eventually, capsizing. This last phenomenon is a challenging task for naval engineers because it is responsible not only for a lot of material damages, but also for human lives. It is therefore not surprising that there have been published many relevant theoretical and experimental studies on heavy rolling and capsizing but the problem is not yet fully resolved. Generally, the ship rolling in beam regular seas could be described by a second-order non-linear differential equation with the roll angle as dependent variable. Non-linearity comes from the restoring and damping moments, which are usually represented by (odd) polynomials of roll angle or of its time derivative. Numerical integrators incorporated in modern software packages (e.g. ode45 in Matlab) encounter efficiency problems for the unbounded solutions associated with capsizing, the running time being extremely high. The alternative is to write a computer software, appropriate to the topic to be solved. In the paper, the roll equation was solved using a simple, fast and accurate iterative scheme based on Taylor expansion. Compared with Runge-Kutta 4th order numerical technique, the used scheme demonstrated not only an excellent agreement of the results, but also a significant reduction of the CPU time. The rapidity of the scheme allowed us to conduct a comprehensive investigation on fractal erosion of safe basins and to represent the normalized integrity curves and the amplitude-frequency response curves for different combinations of wave parameters. The restoring and damping coefficients corresponded to a vehicle ferry model, considered to be either intact or damaged, on the one hand, and with or without bilge keels, on the other.
Materials used in a naval collision calculation with finite element software
Authors: Dumitrache C L , Faitar C , Buzbuchi N , Dumitrache R 
Published: September 2020

Abstract
Collisions and groundings have a significant contribution to structural damages occurring to ships. For collision calculation are used non-linear relations between strains and deformations, considering a significant difference between the initial shape and final deformed shape of the structure, and the mechanical equilibrium equations are written on the deformed shape of the structure. Using a mechanical test to a material sample will result the connection between the engineering strain and engineering deformation. During numerical simulation, we are using the real mechanical characteristic curve, which represents the reliance between real strains and real deformations, those being calculated from the distorted material sample. For calculation, we are using Johnson – Cook plasticity model, frequently used by other authors as well during collision calculation. There is included new information, also tabular calculations using specific formulas, resulted during carried out studies, to establish the model parameters considering the measured data or using information from another material model (exponential law). Considering the materials used within ANSYS software and calculus processor LS-DYNA, are presented types of materials useful for collision calculation, describing the elasticity, plasticity and yielding. Following, it is used a procedure for dynamic explicit calculus because it is suitable for solving of nonlinear systems. During simulation with finite element of the collision, there are no strains and deformations concentrations and it is necessary to generate an artificial curve, which leads to same results, as in reality and as well finite element analysis.
Mathematical modelling of the composite materials structure used for leisure crafts
Authors: Dumitrache C L , Dumitrache R , Faitar C , Buzbuchi N 
Published: September 2020

Abstract
For a leisure craft, chosen materials are mainly made of fibre reinforced composite. This type of materials have more advantages than disadvantages, having a good resistance to corrosion, resistance to impact, are reducing vibrations, are light and are easy to use during construction including maintenance and repairing. In the practice of using composite materials, the most common structural element is the lamina. Within the calculation of a composite material structure, there can be various approaches: to ignore the layering of the composite laminae, considering them isothropic or orthotropic and they can be calculated as standard metallic structures or to consider the layering of the composite laminae, but to ignore the exact orientation of fibers into the matrix. For the calculation with finite element method is used COSMOSM/MATLAB software and it includes several types of laminae, with or without layers. It is carried out a comparison of the results from COSMOSM software, MATLAB software and finite element, being observed a good consistency between the results of the software and the calculated results by other authors. It is worth noting that the study of the specialty literature shows that several programs have been designed to calculate the strength of laminates, but they are meant for internal use. Given that the strengths of laminates can be efficiently calculated, although the calculations may be complicated, it becomes obvious the importance to design such a software program.
Prediction of cutting forces in drilling AL6082-T6 by using artificial neural networks
Authors: Efkolidis N , Dinopoulou V , Kakoulis K 
Published: September 2020

Abstract
This research investigates the comparison of the thrust force (Fz) and cutting torque (Mz) predictive models based on artificial neural networks (ANN). The models were developed based on three-level full factorial design of experiments conducted when drilling of Al6082-T6 alloy material with cutting speed, feed rate and tool diameter as the process parameters. The predictive ANN models of thrust force (Fz) and cutting torque (Mz) were developed using a multilayer feed forward neural network, trained using an error back propagation learning algorithm. The developed models are shown capable of predicting them (Fz and Mz) to a great level. The confirmation experiments provided favorable results with accuracy of 4% and 4.5%, for the thrust force (Fz) and the cutting torque (Mz) respectively. Furthermore the R coefficient for the prediction model of the thrust force is 0.99608 and 0.9946 for the cutting torque. As a result they can be considered as very accurate and appropriate for their prediction. This study promotes the better machining quality and the sustainability of the process that are achieved at the same time
Doubling the power of a wood boiler with fixed grill
Authors: Garleanu G , Garleanu D , Borda C , Luchian C , Dumitras M 
Published: September 2020

Abstract
The article presents one technological modality of doubling the thermal power of a wood boiler. The base of departure is a wood boiler with fixed grill with a power of 30 kW and a yield of 62%. The technological variant is to increase with maximum 50% of the value of the heat transfer surfaces and modify the water circuit. For this, a FEM thermal transfer simulation program was used. In the first part of the article is presented the initial 30 kW wood boiler with the heat transfer surfaces. With the help of the FEM program, a thermal transfer simulation was performed. The results of the program were compared with those of the technical characteristics of the wood boiler. The authors of the article carried out different simulations with new surface types, changes in the water circuit, heat transfer calculations, fluid flow angles, so that the efficiency reaches over 75%. The design results were put into practice and the new wood boiler was built. The power of the wood boiler reached a maximum of 75 kW. The article presents some of the intermediate stages of execution. The wood boiler was tested in a specialized installation. It can be seen that the efficiency increased by 18%, from 62 to 80 and the thermal power reaches a maximum of 75 kW. The hot water flow is about 60 l / min, a very good value considering the type of wood boiler. Using the experimental results presented in this paper, wood boilers can be designed with much smaller dimensions having the same characteristics of power and water flow.
Considerations about the friction inside on a transversal coupling
Authors: Gavrila C C , Lates M T 
Published: September 2020

Abstract
The paper presents, starting from some kinematic aspects as rotations and translations between the Oldham coupling parts, some kinematic equations useful in determining of intermediary element position depending by the transversal misalignments. Then, using the inside translational movements between parts, the friction coefficient between adequate materials to be used are studied. The friction which appears between the coupling parts has an important influence on their dynamic behaviour, wear and lifetime. The most significant friction and also wear is given by the translational movements between parts. Due to this, the study of the friction between some materials to be used in coupling manufacturing is required, but also difficult because of some particularities, as reduced parts translational movements for reduced transversal misalignments between shafts, or the alternative translational movement in translational joints. In the paper final part the results and conclusions are presented.
Modeling of mechanical properties of dissimilar joints using the FEM approach
Authors: Gwiazda A. , Topolska S. 
Published: September 2020

Abstract
Modeling of connections in CAD class systems enables conducting simulation tests of entire structures. It gives the opportunity to reduce costs and speeds up the design process itself. Programs using the finite element method (FEM) are the oldest (over 40 years of history) and the most popular tools for modeling objects and physical processes. It is an absolutely necessary component of the knowledge of every modern engineer. In contrast to physical modeling (see below), in which quite approximate models are used, the MES program can model structures in great detail. But the calculation time for this reason can be relatively long. However the advantage of using CAE systems is the ability to understand the behavior of the object in real conditions, to conduct a numerical experiment under the influence of: load, vibration, temperature, etc. with the use of computer calculations and simulations. The paper presents the use of an advanced CAD / CAE class system for modeling complex technological joints of mechanized mining supports manufactured using the welding technology. One of the most important problems in manufacturing and repairing of mining support using the welding technology is the method of welding the dissimilar joints and analysis of its characteristics. It is particular important for the repairing procedures. A case of such approach is presented in the present paper.
Mathematical development of an efficient three-dimensional workflow for industrial manufacturing systems
Authors: Ibrahim A J , Abduljaleel Y W , Al-Maliki S J B , Al-Khayat Z Q , Albaali G 
Published: September 2020

Abstract
The increasing rate of challenges and competitions that face industrial projects alongside the vast fluctuations in the various related variable, whether human, material or economic nature, have forced decision-makers and researchers to examine all the related technological production dimensions. The three-dimensional 3D array of technological production is formalized and examined in comparison with the relevant two dimensional 2D and one-dimensional 1D ones. The analysis of the general principals of conventional technological systems and the theoretical productivity of technological systems with different types of capacity technological areas were used as the base in order to develop a qualitatively new high efficient, continuous action, low-cost technological system. Flow-helical technological module FHTM was developed in order to ensure an effective solution for a complex automated production processes scheme that ensures sufficient rising of technical and economic indices of manufacturing for a wide range of industries.
Reconditioning by Welding of the Spiral Heat Exchangers Made of Austenitic Stainless Steel - X2CRNIMO17-12-2
Authors: Ionescu F , Solomon Ghe , Gârleanu G , Gârleanu D , Dijmărescu MR 
Published: September 2020

Abstract
The heat exchangers are playing an essential role in some widely used systems including automobiles, heating, refrigeration, air conditioning, distillation, in thermal power plants, district heating and as annexes to thermal machines. During the use of the heat exchanger, different phenomena occur due to the flow velocity of the fluids, the viscosity and the hardness of the microparticles in the fluid. The main causes of defects are corrosion and rubbing. In the presentation of heat exchanger repairs is considered a problem in terms of cost, time and efficiency. The method of repairing a spiral heat exchanger is the uncovering, which is cut outside the inside towards a sheet (s) of the exchanger when it is defective. The repair is performed by cutting the changing sheets from close to the access to the defective area. This paper presents a new method of repairing the heat exchanger, namely the intervention from the inside to the outside. The experimental plan consists of the following steps: choosing the basic material; choice of the reconditioning by welding; choice of filler material; re-welding and non-destructive examination of the samples.
Hydrodynamic loads and wake dynamics of a propeller working in oblique flow
Authors: Lungu A 
Published: September 2020

Abstract
Most of the small crafts and navy ships are equipped with propellers mounted on inclined shafts as thrusters. In spite of its importance, the information on the forces generated by inclined shaft propellers is scarce. To help the designers of small craft and navy ships, the present research describes a systematic numerical program undertaken to evaluate the propeller performances when inclined in respect to the oncoming flow. Scale resolved incompressible Detached Eddy Simulation (DES hereafter) or Delayed Detached Eddy Simulation (DDES) technique are employed by using a volume of fluid approach to study the four-blade propeller recommended in 2015 Tokyo Workshop on CFD Ship Hydrodynamics for the ONR tumblehome ship model 5613. A series of three working conditions are numerically analyzed over a range of shaft inclinations and advance coefficients. Besides, the usual shaftline thrust and torque, horizontal and vertical side forces are computed. The results of these simulations confirm the expectations that a propeller mounted on an inclined shaft produces less thrust than the same propeller on a horizontal shaft. This paper contains propeller characteristic curves and lift- and side-force data which are directly applicable in the design of both high-performance small craft and commercial ships.
Numerical Investigation of the Minimum Gap Impact on the Screw Compressor Efficiency
Authors: Malael I , Bucur I O , Slujitoru C 
Published: September 2020

Abstract
The screw compressor is a positive displacement machine, with two rotors - driver and driven. In this paper, the influence of minimum gap, between the rotors of an oil injection screw compressor, on the efficiency was investigated. Two cases were analysed, in which the minimum gap ranged from 40 to 60μm, respectively 20 to 40μm. The geometrical model, the physical properties and the initial values represent the input data for the used thermodynamic model. Starting from the 3D CAD model, the computational domain for the stator part was defined, which is composed of three subdomains: suction side, oil inlet and pressure side. The grids for the stator were generated with Ansys Meshing, whereas the meshes for the rotor subdomains were made using the TwinMesh software. In the end, smoothing functions were used to increase the mesh quality. To simulate the flow through the screw compressor, the commercial software of CFD ANSYS CFX was used, employing the SST turbulence model. In the analysis the rotational speed was 6000rpm, with a suction pressure of 2bar and a discharge of 10bar. Using the “opening” type limit conditions with the required pressure, both the air flow variation and the oil flow variation were determined.
New methods and equipment for the machining of cross-axes parts- Case study
Authors: Malea C I , Iordache M D 
Published: September 2020

Abstract
The processes and equipment for manufacturing, assembly, and control operations, adapted to the needs of modern industry, shall be determined according to the volume of production and the technical conditions imposed, at a level which ensures economic effects on the recovery of costs for their design and execution. The design-optimization algorithm, with the four working steps, applied on the case study presented, allows the determination of the optimal number and succession of technological processes, but also of new processing methods, based on a technological graph and optimization criteria. In the second step, determine for each technological operation the optimal orientation and fixation scheme of the analyzed part, combining elements of the set theory and the global utility method, with a method of simultaneous optimization of the orientation and fixation fundamentals for two different transformation areas with distinct quotas and conditions that need to be achieved. In the third step, is identified and analyzed several construction variants of structures for the equipment. By formulating a technologically adapted graph to describe structures of orientations, but also other structures, is obtained an associated mathematical model and optimization criteria for the optimum design variant of the orientation and fixation at the analyzed operation. When is desired a complete appreciation of all the technological operations, the fourth step of system optimization is proposed, which is also based on a technology graph and an associated mathematical model adapted to the evaluation of the analyzed types of equipment.
Microstructure characterization of HfNbTaTiZr High Entropy Alloy Processed in Solid State
Authors: Manea C A , Geambazu L E , Bololoi R V , Mateş I , Miculescu F , Sohaciu M G , Csaki I 
Published: September 2020

Abstract
This work investigates the alloying degree of HfNbTaTiZr high entropy alloy in equimolar percentages from raw, high purity powder, using solid state processing, for further uses in coating work components in harsh environments like marine, geothermal or oil and gas industry. The combination of elements was chosen according their properties, tailoring the composition for the final purpose. The alloying has been performed in a planetary ball mill with stainless steel vial and balls in a protective argon atmosphere to prevent oxidation, contamination or ignition and N-heptane as a process control agent to improve the material’s behavior during welding and re-welding in mechanical alloying process. Samples were taken at regular periods of time and analyzed to check the alloying degree evolution and to establish the optimum parameters for milling, best results being obtained at a speed of 300 rpm for 180 min (effective time) providing an alloying degree over 50% was achieved.