1
|
Deleanu L, Totolici Rusu V, Ojoc GG, Cristea GC, Boțan M, Vasiliu AV, Popescu C. The Behaviour of Stratified Fabrics of Aramid Fibres under Stabbing Conditions. Polymers (Basel) 2024; 16:882. [PMID: 38611140 PMCID: PMC11013810 DOI: 10.3390/polym16070882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/08/2024] [Accepted: 03/14/2024] [Indexed: 04/14/2024] Open
Abstract
This paper presents research on several factors influencing the stabbing behaviour of stratified panels made of aramid fabric Twaron® SRM509 Teijin Aramid BV (Arnhem, The Netherlands). The inputs in the test campaign were the number of layers, the impact energy, and the sample size. Tests were performed on small samples (130 mm × 130 mm) on an Instron® CEAST 9350 drop-tower impact system (Norwood, MA, USA) and on larger samples (400 mm × 400 mm) using a test installation with the same values of the impact energy. Knife type S1 was used, with the geometry recommended in NIJ Standard 0115.00 Stab Resistance of Body Armor SEM, and macro photography investigations revealed the failure mechanisms of panel, layers and fibres. A very important conclusion of this study regarding the stabbing performance of fabric Twaron® SRM 509 in particular, but also in general for panels for body protection is that a research study could start on small size samples, with an accurately instrumented machine, in order to establish the influence of significant factors of stab resistance (energy level, number of layers in a panel, etc.), as these samples are less expensive and less time consuming, but the study should be continued to examine larger size samples. The obtained data are useful for the prototype.
Collapse
Affiliation(s)
- Lorena Deleanu
- Department of Mechanical Engineering, Faculty of Engineering, “Dunarea de Jos” University, 800201 Galati, Romania; (V.T.R.); (A.V.V.)
| | - Viorel Totolici Rusu
- Department of Mechanical Engineering, Faculty of Engineering, “Dunarea de Jos” University, 800201 Galati, Romania; (V.T.R.); (A.V.V.)
| | - George Ghiocel Ojoc
- Department of Mechanical Engineering, Faculty of Engineering, “Dunarea de Jos” University, 800201 Galati, Romania; (V.T.R.); (A.V.V.)
| | - George Catalin Cristea
- National Institute for Aero-Space Research (INCAS) “Elie Carafoli”, 061126 Bucharest, Romania; (G.C.C.); (M.B.)
| | - Mihail Boțan
- National Institute for Aero-Space Research (INCAS) “Elie Carafoli”, 061126 Bucharest, Romania; (G.C.C.); (M.B.)
| | - Alexandru Viorel Vasiliu
- Department of Mechanical Engineering, Faculty of Engineering, “Dunarea de Jos” University, 800201 Galati, Romania; (V.T.R.); (A.V.V.)
| | - Christian Popescu
- Center for Research and Innovation for CBRN Defense and Ecology (CRICBRNDE), 041309 Bucharest, Romania;
| |
Collapse
|
2
|
Păduraru I, Ojoc GG, Petrescu H, Graur I, Pîrvu C, Deleanu L. The Behavior of Glass Fiber Composites under Low Velocity Impacts. Polymers (Basel) 2023; 15:4549. [PMID: 38232001 PMCID: PMC10708034 DOI: 10.3390/polym15234549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/20/2023] [Accepted: 11/24/2023] [Indexed: 01/19/2024] Open
Abstract
This paper presents experimental results on the behavior of a class of glass fiber composites under low velocity impacts, in order to analyze their usage in designing low velocity impact-resistant components in car and marine industries. Also, a finite element model at the meso level (considering yarn as a compact, homogenous and isotropic material) was run with the help of Ansys Explicit Dynamics in order to point out the stages of the failure and the equivalent stress distribution on the main yarns in different layers of the composite. The composites were manufactured at laboratory scale via the laying-up and pressing method, using a quadriaxial glass fiber fabric (0°/+45°/90°/-45°) supplied by Castro Composites (Pontevedra, Spain) and an epoxy resin. The resin was a two-component resin (Biresin® CR82 and hardener CH80-2) supplied by Sika Group (Bludenz, Austria). The mass ratio for the fabric and panel was kept in the range of 0.70-0.77. The variables for this research were as follows: the number of layers of glass fiber fabric, the impact velocity (2-4 m/s, corresponding to an impact energy of 11-45 J, respectively) and the diameter of the hemispherical impactor (Φ10 mm and Φ20 mm) made of hardened steel. The tests were performed on an Instron CEAST 9340 test machine, and at least three tests with close results are presented. We investigated the influence of the test parameters on the maximum force (Fmax) measured during impact, the time to Fmax and the duration of impact, tf, all considered when the force is falling to zero again. Scanning electron microscopy and photography were used for discussing the failure processes at the fiber (micro) and panel (macro) level. At a velocity impact of 2 m/s (corresponding to an impact energy of 11 J), even the thinner panels (with two layers of quadriaxial glass fiber fabric, 1.64 mm thickness and a surface density of 3.51 kg/m2) had only partial penetration (damages on the panel face, without damage on panel back), but at a velocity impact of 4 m/s (corresponding to an impact energy of 45 J), only composite panels with six layers of quadriaxial fabric (5.25 mm thickness and a surface density of 9.89 kg/m2) presented back faces with only micro-exfoliated spots of the matrix for tests with both impactors. These results encourage the continuation of research on actual components for car and naval industries subjected to low velocity impacts.
Collapse
Affiliation(s)
- Iulian Păduraru
- “Dunărea de Jos” University of Galati, Faculty of Engineering, Department of Mechanical Engineering, 800008 Galati, Romania;
| | - George Ghiocel Ojoc
- “Dunărea de Jos” University of Galati, Faculty of Engineering, Department of Mechanical Engineering, 800008 Galati, Romania;
| | - Horia Petrescu
- National University of Science and Technology “Politehnica”, Faculty of Industrial Engineering and Robotics, 060042 Bucharest, Romania;
| | - Iulia Graur
- “Dunărea de Jos” University of Galati, Transfrontier Faculty, Department of Applied Sciences, 800008 Galati, Romania;
| | - Cătălin Pîrvu
- National Institute for Aerospace Research “Elie Carafoli”, 061126 Bucharest, Romania;
| | - Lorena Deleanu
- “Dunărea de Jos” University of Galati, Faculty of Engineering, Department of Mechanical Engineering, 800008 Galati, Romania;
| |
Collapse
|
3
|
Georgescu C, Deleanu L, Chiper Titire L, Ceoromila AC. Tribology of Polymer Blends PBT + PTFE. Materials (Basel) 2021; 14:ma14040997. [PMID: 33672560 PMCID: PMC7924065 DOI: 10.3390/ma14040997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 11/30/2022]
Abstract
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 regime, the variables being the PTFE concentration (0%, 5%, 10% and 15% wt) and the sliding regime parameters (load: 1, 2.5 and 5 N, the sliding speed: 0.25, 0.5 and 0.75 m/s, and the sliding distance: 2500, 5000 and 7500 m). Results are encouraging as PBT as neat polymer has very good tribological characteristics in terms of friction coefficient and wear rate. SEM investigation reveals a quite uniform dispersion of PTFE drops in the PBT matrix. Either considered a composite or a blend, the mixture PBT + 15% PTFE exhibits a very good tribological behavior, the resulting material gathering both stable and low friction coefficient and a linear wear rate lower than each component when tested under the same conditions.
Collapse
Affiliation(s)
- Constantin Georgescu
- Department of Mechanical Engineering, Faculty of Engineering, “Dunarea de Jos” University of Galati, 800008 Galati, Romania;
- Correspondence: (C.G.); (L.D.); Tel.: +40-743-105-835 (L.D.)
| | - Lorena Deleanu
- Department of Mechanical Engineering, Faculty of Engineering, “Dunarea de Jos” University of Galati, 800008 Galati, Romania;
- Correspondence: (C.G.); (L.D.); Tel.: +40-743-105-835 (L.D.)
| | - Larisa Chiper Titire
- Department of Mechanical Engineering, Faculty of Engineering, “Dunarea de Jos” University of Galati, 800008 Galati, Romania;
| | - Alina Cantaragiu Ceoromila
- Department of Applied Sciences, Cross-Border Faculty, “Dunarea de Jos” University of Galati, 800008 Galati, Romania;
| |
Collapse
|
4
|
Pîrvu C, Musteată AE, Ojoc GG, Deleanu L. Numerical and Experimental Results on Charpy Tests for Blends Polypropylene + Polyamide + Ethylene Propylene Diene Monomer (PP + PA + EPDM). Materials (Basel) 2020; 13:E5837. [PMID: 33371408 PMCID: PMC7767435 DOI: 10.3390/ma13245837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/10/2020] [Accepted: 12/14/2020] [Indexed: 11/16/2022]
Abstract
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 proposed model takes into account the system of four balls, including support and the ring of fixing the three balls and it has a finer discretization of the impact area to highlight the mechanisms of failure and their development in time. The constitutive models for four materials (polypropylene with 1% Kritilen, two blends PP + PA6 + EPDM and a blend PA6 + EPDM) were derived from tensile tests. Running simulations for each constitutive model of material makes possible to differentiate the destruction mechanisms according to the material introduced in the simulation, including the initiation and the development of the crack(s), based on equivalent plastic strain at break (EPS) for each material. The validation of the model and the simulation results were done qualitatively, analyzing the shape of broken surfaces and comparing them to SEM images and quantitatively by comparing the impact duration, energy absorbed by the sample, the value of maximum force during impact. The duration of the destruction of the specimen is longer than the actual one, explainable by the fact that the material model does not take into account the influence of the material deformation speed in Charpy test, the model being designed with the help of tests done at 0.016 m/s (1000 mm/min) (maximum strain rate for the tensile tests). Experimental results are encouraging for recommending the blends 20% PP + 42% PA6 + 28% EPDM and 60% PA6 + 40% EPDM as materials for impact protection at low velocity (1 m/s). Simulation results are closer to the experimental ones for the more brittle tested materials (with less content of PA6 and EPDM) and more distanced for the more ductile materials (with higher content of PA6 and EPDM).
Collapse
Affiliation(s)
- Cătălin Pîrvu
- National Institute of Aerospace Research “Elie Carafoli” INCAS, 061126 Bucharest, Romania
| | - Andreea Elena Musteată
- Faculty of Engineering, “Dunărea de Jos” University of Galati, 800008 Galati, Romania; (A.E.M.); (G.G.O.)
| | - George Ghiocel Ojoc
- Faculty of Engineering, “Dunărea de Jos” University of Galati, 800008 Galati, Romania; (A.E.M.); (G.G.O.)
| | - Lorena Deleanu
- Faculty of Engineering, “Dunărea de Jos” University of Galati, 800008 Galati, Romania; (A.E.M.); (G.G.O.)
| |
Collapse
|
5
|
Abstract
Vegetal oils could be a solution to replace mineral oils, but their atypical behavior constrains users to test them. Tests on hot surface were done with the help of an original test equipment. The method is designed to imitate the worst scenario that could happen when fluid leakage reaches hot surfaces. The ignition temperature on hot surface for the tested vegetal oils is in a narrow range (495...510oC), higher than most mineral oils, this being due to the similar composition in fat acids.
Collapse
|
6
|
Totescu E, Deleanu L, Mihail A, Petrescu A, Teodosiu O. Study of an influenza outbreak recorded in the town C during the epidemic period February--March 1979. Virologie (Montrouge) 1982; 33:251-3. [PMID: 7147706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
7
|
Drăgănescu N, Duca M, Gîrjabu E, Popescu-Pretor I, Răducanu S, Deleanu L, Totescu E. Epidemic outbreak caused by West Nile virus in the crew of a Romanian cargo ship passing the Suez Canal and the Red Sea on route to Yokohama. Virologie (Montrouge) 1977; 28:259-62. [PMID: 602018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
8
|
Steiner N, Babeş VT, Berca C, Birt E, Bodor S, Constantinescu N, Companeţ V, Deleanu L, Haşaş T, Gazibar L, Lupşaiu O, Makai M, Mureşan I, Pop O, Zaharia AC, Surianu G, Zilinschi G. Incidence of hepatitis B surface antigen (HBsAg) in some areas of Romania. Virologie (Montrouge) 1977; 28:141-6. [PMID: 867805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The incidence of HBsAg in several areas of Romania was studied by 253,460 routine determinations performed from 1973 to 1975. HBsAg incidence was of 1.5% in blood donors and reached the highest value in acute viral hepatitis patients undifferentiated according to the clinical form. The values obtained were in agreement with the results of other studies covering more limited zones of the country. Considerable differences in HBsAg incidence depending on geographic area were observed.
Collapse
|
9
|
Cristea A, Copelovici Y, Cajal N, Niculescu R, Telegută L, Strulovici D, Dincă A, Bădescu F, Pucă D, Roman V, Cretco T, Zubac I, Căpuşan I, Surianu G, Suciu D, Bente O, Companet L, Siminonescu D, Brebenel C, Diaconu E, Totescu C, Popescu-Pretor I, Deleanu L, Cuteanu I, Vlad G, Alexandrescu N, Dragomir O, Vasilovici R. [Analysis of the evolution of morbidity caused by viral hepatitis in the S.R. of Rumania using a mathematical model]. Virologie (Montrouge) 1977; 28:23-40. [PMID: 850998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|