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Hydraulic turbine components that define the water flow, generally have a complex geometry. In the design of these components a major role is played by model tests. The complex geometry of runner’s blades and wicked gates determines high manufacturing times and high fabrication cost if they are made by classical manufacturing technologies (casting, machining on numerically controlled machines). The use of high resolution 3D printing reduces the production time, simplifies the manufacturing technology and generate high dimensional accuracy. The paper presents the design and the manufacturing process of the components from a new solution of axial hydroturbine, equipped with a permanent magnet generator and an immersed runner. The manufacturing of the main parts of the turbine (runner and wicked gates) it was made by Rapid Prototyping.

The explosive effect and high velocity penetration of the ballistic projectiles of various sizes, design and compositions, on impact with different targets (armors composed of a combination of different metals) are complex. Both practical experiments and mathematical modeling of the phenomena associated to the interaction projectile-target are required to estimate their effect or to design more efficient projectiles and armor. In this study, the basic element of the simulation model is an incendiary projectile of caliber 7.62 mm with medium piercing power, launched with a maximum speed of 750 ms-1 on the multi-material target, which contains 4 different layers assembled into a ballistic cassette made of aluminum. The purpose of this ballistic cassette is to ensure a better contact and handling of multi-layer materials. The proposed model was calculated using mathematical modeling and empirical material constants to describe the nonlinear transitory impact process. Mathematical simulation of the impact between the projectile and target during impact shows that the projectile moves sequentially through the ballistic package, causing perforation, plastic deformation and heating, the resulting fragments being then expelled into the space around the target. The model indicates that the projectile will penetrate the front aluminum plate, as well as the AlCrFeCoNi and steel plates, but will be stopped by the aluminum backing plate. The real impact tests carried out using the ballistic cassette at dynamic impact with the 7.62mm incendiary projectile confirm the model assumptions, which prove the capacity of the composite model to safely stop the projectile.

The automotive industry is one of the largest consumer of flexible hoses for fluids such as fuel or cooling. In order to limit the post production costs, every aspect of a vehicle must be tested in advance, including the lifespan, durability or failure of hoses. Throughout this paper summary results are presented for 4 types of fuel line hoses tested under controlled displacement loads at various pressures in order to validate the Finite Element Method simulations.

The purpose of our study was to analyze the influence of Ti-6Al-4V and Ti-15Zr dental implants, with complex implant designs, on the cortical and trabecular mandibular bone in regards to the stress value and its distribution using finite element analysis. A total of four 3D implant assemblies were modeled, each consisting of implant, abutment, abutment screw, cement layer, and ceramic crown. Implants were modeled with different macrostructure designs with focus on the main thread and microthread design as well as complex geometry details. All implants were inserted in the second molar position in the mandible bone section, consisting of two macro-structures, a 2 mm thick cortical bone and an internal cancellous bone. Results revealed that small variations in the implant design led to a great difference in the stress values and distribution in both cortical and cancellous bone. Our results suggest no major difference between Ti-6Al-4V and Ti-15Zr in regards to the material’s ability to decrease stress in the periimplant bone. However, within the same material, results revealed important differences between thread design and implant geometry concerning the stress values and stress concentration in cortical and cancellous bone in the mandibular model.

In this paper, we examine two types of Dammar-based bio resins. In the first type, Dammar alone is used as natural resin, while in the second type a mixture of 70% Dammar and 30% Sandarac is used. Three sample sets were made of each of these resins with a bio resin volume proportion of 55, 65 and 75% respectively, the rest being epoxy resin (used, together with the associated reinforcing material, to generate a quick polymerization process). A SEM analysis is carried out and the surface roughness of each of the studied materials. A series of mechanical properties, determined by tensile testing, are presented. We have determined the characteristic curves, tensile strength and modulus of elasticity and the influence of the epoxy resin volume proportion on the mechanical behaviour of bio resins.

In this paper, the authors show a part of research works performed on the use of 3D scanners and 3D printers to execute the molds required for the cast of parts with complex surfaces. 3D scanning allows copying of certain surfaces in our environment, based on existing models. The finished parts may also be executed from metals that are relatively easy to cast (bronze, aluminum etc.). In order to execute the molds destined for the casting, various pieces may be scanned, with a volume size in the range of [150x150x200 mm3 ÷ 500x500x2000 mm3]. Plastic model printing is performed depending on the capacity of the 3D printer used. This paper shows the results achieved with general-purpose scanner and printer, valued at affordable prices.

The body of a craft is subjected to a series of complex loads, both static and dynamic. The global strength of such a body is given by the entire assembly of the hull, deck and strengthening framing system, all of these components working together [1]. Such a boat must first of all fulfill a very important requirement, namely: minimum hull resistance so that the engine power would primarily be used to achieve the highest possible speed. This can only be achieved if the hull wetted surface is as small as possible, which leads to the need to reduce the hull asembly weight. Thus, in this paper there are proposed and tested a number of nine lamination alternatives for the initial structure, designed as a sandwich system with different types of core materials. From the total nine alternatives, three of them are hybrid structures in which there are explored structural alternatives with several types of core materials. The verification of structures obtained with the proposed materials and lamination schedules was made using numerical methods both for naval hydrodynamics to determine loads and for naval structures for global body strength and analysis.

The main target of the study is to highlight, by means of numerical simulations, the advantages and possible drawbacks of using composite materials instead of the classical cast iron to equip the brake system of railway freight vehicles. The qualitative and quantitative evaluations refer mainly to the braking capacity by considering as main parameter the stopping distance, in various operational conditions. Results indicate that composite materials are more efficient in the braking process, but in the case of low speeds, the recommendation is to perform earlier and/or stronger braking actions than usual, in classical cast iron equipment on rolling stock.

This paper presents a study based on simulating the impact between a yarn (or a single fiber with greater dimensions) and a bullet, the impact velocity being 400 m/s. The characteristics of the involved materials are taken from literature. The yarn is considered isotrope, but the values of the characteristics are close to those of aramid fibers and cooper and lead alloys used for manufacturing the bullets. Analysing the yarn failure caused by a bullet, this FE model allows for identfying the stages in the failure process. First, the yarn is pushed by the bullet and the local elongation of the yarn is tacking place. The yarn rupture occurs in the “strangled” zones, caused by the stretch of the yarn directly supporting the impact. The breaking of the yarn in the thinned zone (more pronounced asymmetric breaking) and it is visible that the yarn elastic recoil starts next the bullet. The friction between the yarn and the bullet is only on the conical surface of the bullet in the tapered zone of the bullet. The yarn is detaching from the bullet (the contact zones between the bullet and the yarn in polymeric matrix become smaller, justifying a neglectable influence of the thermal effect). The yarn has no more contact with the bullet. This step is in the favor of the assumption that, in the actual multi-yarn impact, the other layers of yarns maintain the bullet and the first yarns in contact and this is why bunch of fibers (fragments of the failed yarns) are pressed against the bullet and remain on it. The simulation results were qualitatively validated by SEM investigations of fiber failure under the same conditions as the model.

Environmental problems occurring in isolated or hardly accessible inhabited areas can be adequately addressed using membranes and membrane processes.In the present paper, the recuperative separation of aluminum ion from the aluminum sulfate-treated water through permeation using capillary composite membranes, from polypropylene with ethylene propylene diene terpolymer sulfonic acid (PP / S-EPDM) inclusions is followed by the reaction of complexation with 8-hydroxy quinoline. The installation used for studying the permeation process provides a usable surface area of 1 m2, the source phase solution volume is 3 L, and the receiving phase is 300 mL. The two phases are recirculated through the outside of the membranes (SP) and respectively through membranes (RP), by means of individual peristaltic pump that can provide flow variations between 2 and 200 mL / min by varying the intensity of the power supply. The optimal operating parameters were determined: operating time, pH and receiving phase flow, thus achieving an ionic flux (IR) above 10-11 mol / cm 2. s and a recovery factor (RF) over 90%.