NOPR Collection:

Steel fibers with non-circular cross-section used as reinforcement in self-compacting concrete

2017-08-01T00:00:00Z

Title: Steel fibers with non-circular cross-section used as reinforcement in self-compacting concrete Authors: Pająk, Małgorzata; Ponikiewski, Tomasz Abstract: The paper evaluates the methods of consideration of a non-circular shape of the cross-section of a steel fiber in determination of the aspect ratio of the fiber as well as the influence of these fibers on mechanical properties of the matrix. The analysis has been performed on the example of a composite made from self-compacting concrete and two types and three volume ratios (0.5%, 1.0% and 1.5%) of steel fibers with rectangular and part-of-a-circle cross-sections. Compressive and flexural tests have been performed. The influence of the above mentioned steel fibers on the mechanical properties of SCC has been analyzed in the view of the latest investigations performed on cement-based materials reinforced with fibers with non-circular cross-sections. Based on the research it is found that the compressive strength is slightly affected by the fibers. The flexural behavior of the SCC reinforced with non-circular fibers is comparable to that with the circular ones only in case of long corrugated fibers. In case of these fibers pronounced improvement of the flexural parameters has been observed proportional to the amount of fibers. The influence of short hooked fibers on the flexural behavior of SCC is less predictable and also different from the one observed for circular fibers. It has been shown that the differences in definition of the aspect ratio of the fiber without consideration of its cross-sectional shape can lead to underestimation of the aspect ratio. The real aspect ratio was used in the formula to describe the flexural tensile strength of SFR-SCC, however, it seems not to be crucial as other factors are unknown. Page(s): 251-260

Texture and morphology based conductivity analysis of fuel cell - bipolar plate using scanning electron microscopic images

2017-08-01T00:00:00Z

Title: Texture and morphology based conductivity analysis of fuel cell - bipolar plate using scanning electron microscopic images Authors: Pravin, M C; Karthikeyan, S; Sathyabama, B; Vinothini, D Synthiya Abstract: The main objective of this work is to analyze strength and conductivity of the fuel cell bipolar plate using microstructural analysis. This paper focuses on the structural characterization of fuel cell by texture and morphological analysis of its composite bipolar plate which is the major component of the proton exchange membrane (PEM) fuel cell stack. The composite plates were prepared with compression molding technique using activated charcoals and epoxy (araldite) at various temperatures ranging between 170°C and 190°C with the pressure of 20 bar. Texture and morphological structures of a composite are directly related with the strength and conductivity of the material. The internal structures of the composite bipolar plate are acquired using scanning electron microscope (SEM) which provides microstructural information of the specimen. In this paper, nature of bonding in SEM image is detected using texture and morphological features. Texture features derived from Gray level co-occurrence matrix (GLCM) and Tamura is used to characterize the arrangement of molecules and nature of bonding. Gray level co-occurrence matrix (GLCM) and Tamura based approach is used to calculate texture features. These textural features analyze the internal textures of each samples prepared. Morphological operations are used to find the area covered by each discontinuous region where the discontinuity affects the bonding and thus the strength and conduction. The image processing approach analyses the internal structure of the prepared samples and validates its flexural strength and electrical conductivity performed experimentally. The sample prepared at 190^oC and pressure 20 bar has met the target value defined by the US, Department of Energy (DOE) and has homogeneous internal structure with less discontinuities and better bonding among the prepared samples. Page(s): 261-269

Effect of rock dust, cenosphere and E-waste glass addition on mechanical, wear and machinability behaviour of Al 6061 hybrid composites

2017-08-01T00:00:00Z

Title: Effect of rock dust, cenosphere and E-waste glass addition on mechanical, wear and machinability behaviour of Al 6061 hybrid composites Authors: Prakash, K Soorya; Gopal, P M; Kavimani, V Abstract: This paper has a propensity to identify low cost and ordinarily available reinforcements besides comparatively reviewing fly ash, bagasse ash, rice husk ash reinforced aluminium composites. This has led to microstructure, mechanical and wear characteristic investigation of newer composite developed through stir casting with cenosphere, rock dust and e-waste cathode ray tube (CRT) panel glass powder. Comparison over experimental results with available reported data of said reinforcements clarifies that newer reinforcements have also yielded equivalent properties. Addition of these newer reinforcements up to 10% increases the tensile strength whereas maximum of 65.12% hardness raise is attained for cenosphere and 63.04% for CRT addition to that of Al 6061 T6. Tensile strength increases up to 9.84% for 15% cenosphere reinforcement, 9.02% for 10% CRT addition. Addition of cenosphere and rock dust up to 15% increases the wear resistance but in the case of CRT powder, wear resistance is high up to 10% and then decreases due to formation of glass globes for further CRT addition. In perspective of the research an admissible increment in wear resistance and machinability of the developed novel hybrid composites is evidenced through scanning electron microscope (SEM) micrographs besides indicating better surface finish while turning. Page(s): 270-282

Tensile and compressive properties of epoxy syntactic foams reinforced by short glass fiber

2017-08-01T00:00:00Z

Title: Tensile and compressive properties of epoxy syntactic foams reinforced by short glass fiber Authors: Yu, Wei; Xue, Hailong; Qian, Meng Abstract: The hollow glass microsphere/epoxy resin syntactic foams reinforced by short glass fibers are fabricated. The microsphere is constant 5% weight ratio to the epoxy resin matrix and the fibers with weight ratio to the resin matrix are 5%, 10%, 20% and 30%. Their mechanical properties are studied by uniaxial compression test and tension test. The compressive deformation morphology and tensile fracture surfaces of syntactic foams are investigated. It is obtained that the compressive and tensile strength of syntactic foams are enhanced by adding fibers, and the 10% fiber weight ratio is found to be much more efficient, which shows 70% and 49% higher compressive strength and tensile strength respectively than that of syntactic foams without fiber content. However, the strength decreases with further addition of glass fiber beyond 10% weight ratio. The reason of strength enhancements is discussed. The compressive and tensile moduli are also enhanced by adding fibers. The ductility of composites is found to decrease with larger fiber filling. Page(s): 283-289