Lorena Deleanu

Lorena Deleanu
Universitatea Dunarea de Jos Galati | UGAL · Department of Mechanical Engineering

Professor PhD Department of Mechanical Engineering "Dunarea de Jos" University of Galati Romania
research in tribology, polymer blend and composites, lubricants, ballistic protection, standardization

About

86
Publications
15,684
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200
Citations
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January 2013 - October 2015
Universitatea Dunarea de Jos Galati
Position
  • professor, head of department

Publications

Publications (86)
Article
Full-text available
This paper presents an analysis of an isothermal model for an impact simulation in order to use the results for virtually optimizing the thickness of the panel for the same threat. The target has a stratified structure; the connection between layers is "bonded", with "breakable" detachment when there is exceeded a value for tensile stress and shear...
Article
Full-text available
Results on mechanical properties of Tensylon� composites at room temperature are presented. Single-ply and two-ply samples, obtained from the ply-precursor sheet (of two orthogonal layers) have been subjected to: load till failure in traction, at different strain rates (below 10-1 s-1) and cycles of successive loading and unloading and 5 min stress...
Article
Full-text available
Particularities of impact simulation result from applying the load only once. The designed protection system is requested not to fail once or for a small number of hits. Tests for evaluating impact protection are expensive and numerous. In the literature, there are models at the meso level (multi-fiber yarns, layers of yarns, as is the case with th...
Article
Full-text available
This paper presents characteristics of severe regime, tested on four ball machines for rapeseed oil and new formulated lubricant based on rapeseed oil and additivated with nano ZnO (average particle size 14 nm), in different concentrations (0.25% wt, 0.50 %wt and 1.0 %wt, respectively). Tests were done taking into account the procedure in SR EN ISO...
Article
The present paper aims to analyze the influence of certain parameters specific to the distribution systems on a truck engine performance. The research is focused on how the change in the shape of lobes of a camshaft can influence the vehicle functional parameters. It was considered a non-variable fuel distribution system which represents by itself...
Article
The present paper aims to analyse the possibility to prevent machine failure due to bearing faults, with the use of frequency analysis. The experimental research consisted in mounting a simple mechanical transmission, integrating an electric motor, a rigid coupling, a driven shaft, two pillow block bearings and a uniaxial accelerometer (connected t...
Article
Purpose This paper aims to present an analysis of several 3 D texture parameters for the entire wear scars obtained in severe regime, on a four-ball tester. The aim of this analysis is to correlate the tribological parameter as wear scar diameter to texture parameters. Design/methodology/approach Tested lubricants were rapeseed oil, rapeseed oil a...
Article
Full-text available
This paper presents the results of mechanical and tribological characteristics for two composites: PA6 as matrix and 5% aramid whiskers as additive material and PA6 + 10% aramid whiskers, comparing them to those made of PA6 (polyamide 6). To improve the mechanical and thermal properties of polyamide (PA6), the composites were prepared via the Brabe...
Article
Full-text available
This paper presents a characterization of PA6 and the blend PA6+EPDM (60/40) by tensile tests in order to evaluate several mechanical properties for impact resistance applications. Results were found to be dependend on test rate (10 mm/min, 250 mm/min and 1000 mm/mm). SEM investigation point out a homogenous structure. The blend has better value of...
Article
Full-text available
This paper presents an isothermal model of Storz coupling used in fire hose coupling. The model has the actual geometry of the coupling Fire and Rescue NSW for the nominal diameter of 65 mm (NEN 3374). The simulation was done for a load interval on the coupling (from F=2 kN for an actual value of water pressure, to extreme conditions with F=3 kN an...
Article
Full-text available
This paper presents the influence of taking into account friction when a cylindrical projectile hits a perfectly rigid target. Friction could change the behavior of both projectile and target, especially when target also generates friction among its components, as it occurs among layers, yarns and fibers, at different dimensional levels of body arm...
Article
Full-text available
This paper analyzes the influence of composition on the energy at break of blends PP+PA6. There were formulated 4 blends having a mass concentration of 20%, 40%, 60 and 80% PA6, respectively and the same quantities of compatibilizing additives (5% LDPE, 7% CaCO 3 and 3% Polybond 3200). Fig. 1 presents the result data of load and absorbed energy ver...
Article
Full-text available
The main objective of this study focuses on designing and testing body protection systems using advanced materials based on aramid fibers, for high impact speeds of up to 420 ± 10 m/s. Ballistic applications of aramid fiber-based composites mostly include soft body armors. The investigation of the failure mechanisms identifies issues of protective...
Preprint
Full-text available
The main objective of this study focuses on designing and testing body protection systems using advanced materials based on aramid fibers, for high impact speeds of up to 410...430 m/s. The investigation of the failure mechanisms identifies issues of protective materials, major challenges and technological problems for efficient development of thes...
Article
The objective of this study was to determine the lowest temperature at which hemp seed oil ignited (505°C) and also the highest temperature at which hemp seed oil did not ignite in at least three tests performed (500°C). The oil was tested on a cylindrical surface heated to various temperatures. A total of 16 tests were carried out to determine the...
Article
This paper presents the influence of load and sliding velocity on several tribological parameters like friction coefficient and wear rate of the wear scar diameter of the balls used in a four-ball test, when using rapeseed oil as lubricants. The test parameters for were: loading force - 100 N, 200 N and 300 N (± 5%), sliding speed of 0.38 m/s, 0.53...
Article
Full-text available
This paper presents results on tribological characteristics for polymer blends made of polybutylene terephthalate (PBT) and polytetrafluoroethylene (PTFE). This blend is relatively new in research as PBT has restricted processability because of its processing temperature near the degradation one. Tests were done block-on-ring tribotester, in dry re...
Article
Full-text available
For this paper, the authors studied the behavior of castor oil, when it accidentally reaches a hot surface. Thus, the lowest temperature at which castor oil ignited at least once in three tests and the highest temperature at which castor oil did not ignite in three tests were determined. To determine as accurately as possible these two temperatures...
Preprint
Full-text available
This paper presents results on tribological characteristics for polymer blends made of polybutylene terephthalate (PBT) and polytetrafluoroethylene (PTFE). This blend is relatively new in research as PBT has restricted processability because of its processing temperature near the degradation one. Tests were done block-on-ring tribotester, in dry re...
Article
Full-text available
Present paper aims to present the steps of developing a prototype used for the display of several functional parameters which does not normally appear on the dashboard of an automobile. Data is collected from the vehicle CAN bus, follow-up processed with a MCP2515 microcontroller and a ATMEGA328P and finally displayed on a color touchscreen. The pr...
Chapter
Full-text available
This chapter means to explain the tribological behavior of polymer-based materials, to support a beneficial introducing of those materials in actual applications based on test campaigns and their results. Generally, the designers have to take into consideration a set of tribological parameters, not only one, including friction coefficient, wear, te...
Article
Full-text available
This paper presents an analysis of two cases, simulating the impact of a cylindical projectile on a perfectly rigid plate. One case is run without friction, the second one is run taking into account a friction coeficient between the plate and the projectile. The authors used for the projectile the same material constitutive model for both cases, ba...
Preprint
This paper presents the influence of taking into account friction when a cylindrical projectile hits a perfectly rigid target. Friction could change the behavior of both projectile and target, especially when target also generates friction among its components, as it occurs among layers, yarns and fibers, at different dimensional levels of a body a...
Preprint
Full-text available
Particularities of impact simulation result from applying the impact load only once and the designed system is requested not to fail once or for a small number of hits. Tests for evaluating of the impact protection are expensive and numerous. In the literature, there are models at the meso level (multi-fiber yarns, layers of yarns, as is the case w...
Preprint
Full-text available
This paper presents results from numerical and experimental investigation on Charpy tests in order to point out failure mechanisms and to evaluate new polymeric blends PP+PA6+EPDM. Charpy tests were done for initial velocity of the impactor of 0.96 m/s and its mass of 3.219 kg and these data were also introduced in the finite element model. The pro...
Article
Full-text available
This paper presents the influence of hexagonal boron nitride (hBN) as additive in refined rapeseed oil in different mass concentration of 0.25%wt, 0.5%wt and 1%wt on the tribological parameters, obtained on a four-ball machine. The test parameters were load: 100 N, 200 N and 300 N and the rotational speed 1000 rpm, 1400 rpm and 1800 rpm, correspond...
Article
Full-text available
The issue of impact simulation results from the fact that the impact load is unique and the designed system or element is requested not to fail only once or a small number of loadings. Tests for assessments of the degree of impact protection are expensive and numerous because they require a high probability of impact resistence. In the literature,...
Article
Full-text available
This paper presents an analysis of data resulting from the same material constitutive model, based on experimental data and model developed by Johnson and Cook. The same case of impacting a cylindrical body on a perfectly rigid target was run with four different mesh size (2 mm, 1 mm, 0.5 mm and 0.25 mm). Here, the comparing criterion was the maxim...
Article
This paper presents a review on using friction coefficient in modelling ballistic impact. The are discussed on friction introduced in modelling the impact at different levels: micro (fiber and yarns), meso (woven or unidirectional fabrics) and macro (layered or equivalent monoblock structures). Recent works simulating the impact projectile - target...
Article
Full-text available
This paper presents the influence of BN as additive in refined rapeseed oil in a mass concentration of 1%wt on the tribological parameters. Tests are done on a four-ball machine. The test parameters were load: 100 N...300 N and the the sliding speeds of 0.38 m/s, 0.53 m/s and 0.69 m/s, respectively. Particles of hexagonal BN have 500 ± 100 nm. The...
Article
Full-text available
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...
Article
Full-text available
The objective of this paper is to simulate the behavior of unidirectional fabrics, as realistic as possible, in order to be able to use the model in designing impact-resistant packages. There was discussed the influence of the number of layer and the impact velocity on several characteristics as residual velocity of the projectile, its acceleration...
Article
Full-text available
Based on studies on characterization of surface topography, the following conclusions can be drawn: surface texture analyses are statistical. There is no agreed methodology for characterizing both the texture of worn surfaces and those of new ones (unworn). The methodology depends on many factors: the shape and size of triboelements, the available...
Article
Purpose This paper aims to present the influence of glass bead concentration in a matrix of polyamide on wear and several three-dimensional (3D) parameters of the surface texture when the composite is sliding on steel in dry contact. Design/methodology/approach There were mold disks with the following concentrations in glass beads: 2.5, 5.0, 10,...
Article
Full-text available
Vegetable oil-based lubricants have several disadvantages as compared to mineral and synthetic ones, including low viscosity that not encourage the generation of a continuous film when the tribosystem runs, consequently, implying a mixt or boundary. This is why the additivation of such oils is of great interests for researchers, producers and users...
Article
Full-text available
This paper presents a macro FEM isothermal model for simulating the impact of a 9 mm FMJ bullet on a stratified packs in order to restrain the preliminary tests for actual stratified packs made of layers of Twaron LFT SB1plus (Teijin), taking into account the friction between layers and between bullet and layers, in order to obtain the number of la...
Article
. The authors experimentally determined the influence of temperature and shear rate on the dynamic viscosity of two vegetable oils (soybean oil, olive oil). The hydraulic oil ISO VG 46 was used for comparison. The behavior of these two oils was similar to the hydraulic one, for larger shear rates (30 s-1…80 s-1) and for higher temperatures (60ºC…90...
Article
The objective of the present work is to evaluate the wind potential in the nearshore of the Mediterranean Sea. Thus, a comprehensive picture of the wind conditions is provided by considering 15-year of cumulative information coming from remotely sensed data and from two numerical models. These are provided by the European Center for Medium-Range We...
Article
Full-text available
Bird strike is a major threat to both fixed and rotary wing aircraft, damaging the nose section, wings, or propulsion elements. It involves a complex material failure under dynamic, loads. The purpose of this work is to perform numerical predictions in the case of a horizontal tail plane, considering a number of span wise impact locations. Three ty...
Article
Full-text available
Purpose – The purpose of this paper is to establish the influence of oil concentration in oil-in-water emulsions on their flammability on hot surfaces and on their viscosity. The interest in fire test systematization is obviously developing due to many grades and applications of fluids and new design solutions asking for higher parameters in exploi...
Article
Full-text available
Polybutylene terephthalate (PBT) and its aramid fiber composite (10 wt.%) were investigated in order to measure their wear and frictional properties under variations of applied load (5 N, 10 N, 15N) and velocity (0.25 m/s, 0.5 m/s and 0.75 m/s), in dry regime. The tribological properties of the composite were evaluated using a block-on-ring tribote...
Article
Full-text available
This paper presents an analysis of a composite cell at a micro level. The authors modeled the interface between a micro sphere and a polymeric matrix for two cases: an interface characterized by a strong bond between the two involved bodies and an interface with low friction between the micro sphere and the polymeric matrix. Even if these models ar...
Conference Paper
Full-text available
This work gives theoretical calculation and experimental data on the lubrication capability of rapeseed oil, as obtained by cold press technology. Tests done on the four ball machine pointed out low values of the friction coefficient as prove of a very thin lubricant film, at least for the test parameters (normal load 100...300 N and sliding speed...
Conference Paper
Full-text available
This work presents the tribological behavior of PBT (polybuthylene terephthalate) + 10% aramid fibbers and PBT, when sliding against steel in dry regime in order to point out the influence of adding fibers. Tests were done on a block-on-ring tribotester, for normal loads of 5... 30 N and sliding speeds 0.25... 0.75 m/s, for a sliding distance of 50...
Article
Full-text available
This paper presents the tribological behaviour of four polymeric materials, polybutylene terephthalate (PBT), PBT + 10% micro glass beads, PBT + 10% polytetrafluoroethylene (PTFE) and PBT + 10% aramid fibers, in order to rank them in dry sliding regime. Tests were done using a block-on-ring module. The test parameters were: the sliding speed was se...
Article
Full-text available
This paper presents a simulation of a bullet impact on a plate, all materials being assigned to a bilinear isotropic hardening model. The developed model takes into account the yield and fracture limits of both involved materials for the bullet and the plate one. The model was developed with the help of Ansys 14.5 and could be used to establish a t...
Article
This paper presents a comparative study upon tribological behavior of polybutylene terephthalate (PBT) and a blend of PBT + 10% aramid fibers, in dry regime. Some of the properties of PBT grade CRASTIN 6130 NC010®. The tested materials they were obtained by molding at ICEFS Savinesti Romania. The aramid fibers added into PBT were supplied by Teijin...
Article
Purpose – This research aims to characterize the tribological behavior of polybutylene terephthalate (PBT) and PBT composites with micro glass beads (MGB) on steel, in dry conditions and on a block-on-ring tester, pointing out the influence of sliding distance and speed. The tribology of PBT and its composites is still in an early stage because thi...
Article
Full-text available
This study presents the influence of the normal force on the surface quality of the friction couple steel – polybutylene terephthalate (PBT) + 10 % polytetrafluoroethylene (PTFE). There were calculated the average values of the amplitude and functional parameters, as obtained from investigating square areas on the wear tracks, with the help of a pr...
Conference Paper
The tested materials are PBT (Crastin 6130 NC010, Dupont) and three composites: PBT+10% glass beads, PBT+10% PTFE and a hybrid one, PBT+10% glass beads (GB)+10% PTFE (massic concentration). The test characteristics were: block-on-ring tribotester, dry sliding, sliding speed v=0.25-0.75 m/s, normal force F=1-5 N, sliding distance 7500 m. There were...
Article
Full-text available
The materials involved in this research study were produced by die moulding in order to obtain bone samples type 1A (SR EN ISO 527‐2:2003). These composites have a matrix of polybutylene terephthalate (PBT) commercial grade Crastin 6130 NC010, DuPont. The values for the glass beads concentrations were established at 10 % and 20 %(wt). Block‐on‐ring...
Article
Full-text available
The paper presents results on friction and wear, obtained from testing polybutylene terephthalate (PBT) against steel in a block-on-ring tribotester, for dry sliding. There were identified particular processes characterizing the friction couple and the test conditions. Tests were done for three sliding speeds: 0.25 m/s, 0.50 m/s and 0.75 m/s and fo...
Conference Paper
Full-text available
This work compares tribological characteristics for four materials tested on a block-on-ring tester: polybuthylene terephtalate (PBT), PBT+10% micro glass beads (GB), PBT+10% PTFE and PBT+10% GB+10% PTFE. The tests were done with blocks made of the above-mentioned polymeric materials and rings made of steel grade 100Cr6, in dry conditions, for thre...
Article
Full-text available
This paper presents the influence of adding materials (micros glass spheres) in a matrix of PBT on several mechanical properties: elasticity modulus, stress at break , elongation at break, energy at break. The mechanical properties of these composites depend on the glass beads concentration. The additivation of polybuthylen therephtalate with glass...
Article
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The paper presents some results on investigation of the superficial layers of several polymeric composites intended for tribological applications. The evaluation of the tribological behavior is done with the help of SEM images, virtual images obtained by 3D profilometry and X-ray diffractometry.
Article
Full-text available
Industrial equipment using hydraulic fluids are design to accept higher load and speed, implicitly higher temperatures, including for fluids. Leakages from enclosures like gear boxes or hydraulic systems could increase the risk of fluid reaching hot surfaces, thus producing fires hard to be controlled and isolated. The designer have to evaluate the...
Article
Full-text available
This paper presents a study on the surface quality pointing out the influence of relative sliding on the topography parameters. Traditional roughness parameters as Ra and Rq, deal only with relative high of the asperities to the mean line and they give no information on shape, slope and asperities magnitude, on their appearance frequency on the pro...