Papers by Keyword: Fiber

Abstract: The paper was written in the framework of research in mechanisms of the increased mobility on the basis of parallel kinematic structures, for which a fibre control instead of rigid elements is designed. The experiment is focused on the verification of the fibre properties in simplified mechanical systems such as motion on an inclined plane, vibration of a moving weight hanging on a fibre and fibre interaction with two types of pulley. The arrangement and instrumentation of the experimental stand and of the system for the measurement of position and axial forces in a fibre are described. The results should serve for tuning the computational model, the results of which are also presented in the framework of specific experiments.

Abstract: This paper describes the projectile impact resistance of cement based composite slabs. The resistance is evaluated on the basis of the presented experimental program. In the experiment, local damage was inflicted by impact of defined projectiles on specimens made from normal strength concrete (NSC), steel fiber-reinforced concrete (FRC), ultra-high performance concrete (UHPC) and ultra-high performance fiber-reinforced concrete (UHPFRC) with different fiber content. Deformable ogive-nose projectiles with diameter of 7.92 mm and mass of 8.04 g with impact velocity about 700 m/s were in the experiment hitting center of the specimens. Data from the measured and visual evaluation of specimen damage were used for comparison of specimen projectile impact resistance in relation to the used material.

Abstract: The mechanical strengths of self-compacting concrete (SCC) with different strengths and different fibers were investigated. By mechanics performance testing on concrete samples, it shows that the fiber can significantly reduce strength of the self-compacting concrete during curing period. The 28d tensile strength of self-compacting concrete can be improved when steel fiber, polypropylene fiber, or polyethylene fiber were used. Moreover, steel fiber can improve the 28d compressive strength; contrarily, polypropylene fiber and polyethylene fiber can reduce the 28d compressive strength.

Abstract: Polypropylene Fibre (PF) as reinforcement has contributed to the intensity of Foamed Concrete (FC) slab when subjected to impact loading. The presence of PF in the admixture reduces the micro-porosity that generates the micro-crack of the slab. However, the fibrillation of PF in the admixture enhances the bonding mechanism system between PF and the FC matrix. The impact test conducted uses an instrumented drop-weight impact tower. Results show that FC without PF produces a distinct radial crack and clear fragments within the crater field unlike FC with PF. However, both slab materials did not generate spalling nor scabbing upon impact and the influence of porosity produces only local damage due to the mechanism of brittle crushing effect of porous walls. In this study, the energy absorption between FC with and without PF was investigated and from observation produces only minor differences. Results also verify that FC with PF did not loss its ability to absorb energy upon impact.

Abstract: A new class of Epoxy Emulsion modified Engineered Cementitious Composite (EM-ECC) has been developed for enhanced pipeline protection. The performance of typical ECC materials, such as flexural strength, anti-corrosion and early strength, has been improved by the addition of epoxy emulsion and rapid hardening cement. Our results indicated that the flexural strength of as-made EM-ECC increases with the increase of the EM/cement ratio after curing for 28 days. The retention rate of flexural strength of specimens remains analogical after immersed in water, 5 wt% Na₂SO₄ and 5 wt% NaCl solutions, respectively. The flexural strength reached ca. 16 MPa at 60 wt% replacement rate of rapid hardening cement after curing for 3 days. This new class of EM-ECC will shed light to the design of new applications for the oil and gas industry.

Abstract: This paper is focused on behavior of fiber reinforced cement composites (FRC) and ultrahigh-performance fiber reinforced cement composites (UHPFRC) in dependence on the direction of casting. Twelve prismatic samples of size of 400 x 100 x 100 mm were cast into moulds; six of these were FRC and the other six were UHPFRC. Three samples of both series were cast in the common horizontal direction and the other three in the vertical way. It was found that fracture energy of horizontally cast prisms was approximately three times higher in both cases than the vertically cast ones. The peak loads of FRC were very similar for both ways of casting. On the other hand the UHPFRC behaved differently, the peak load of horizontally cast prisms was approximately 2,5 times higher than the vertically cast ones. It was demonstrated that these differences are caused by the way of casting and vibration.

Abstract: The present study aimed to characterize the agricultural residues of sugarcane bagasse {SB} and pineapple core {PC} for the use in immobilization of Lactobacillus rhamnosus NRRL 442. Using Standard Official Methods, SB and PC were found to contain approximately equal amount of nutrition content. The nutrition contents found include: 2.7-2.8 % of protein, 9.8-10 % of crude fiber, and 0.3-0.5 % of fat. On the other hand, SB demonstrated relatively higher solution holding capacity of 9.42 ± 2.3 g/g dry size sample than that of 6.04 ± 2.1 g/g dry size sample in PC. Under screening electron microscope, the fiber of SB has a flat and even surface; in contrast, the fiber of PC has a rough and overlapping surface which may promote the attachment or cell holding capacity during the immobilization process. However, the viability tests after cells immobilization have shown that SB provided higher cell survivability of 93.6 % than that of 64.1% in PC. These result highlighted the greater role of solution holding capacity of cellulose in ensuring a better cell survivability after immobilization process. As conclusion, this study showed the near future potentiality of SB and PC as immobilization carriers for Lactobacillus rhamnosus NRRL 442. It may substitutes proportionally of raw materials and be functional feed for ruminant.

Abstract: Foamed Concrete (FC) needs high strength to prevent dynamic loading, thus it is important to enhance the ductility. Usage the Polypropylene Fibre (PF) examined its contribution in strength of FC on impact resistance. Microstructures were observed that air voids in matrix of FC produce micro-porous that reduce interfacial bonding into matrix and generate micro-crack that may propagation crack growth. Presence of PF in admixture results fibrillation and reduces micro-cracks. Tensile test was investigated that PF delays crack growth in matrix. In this investigation impact test were conducted using an instrumented drop-weight impact tower. When impactor hits the target surface in free surface condition causes compressive plastic wave transform to be tensile wave. It was affected by tensile strength therefore local effect has not found spalling in crater field. In addition influence of porous in matrix FC has ability to absorb the energy and it was not found distal crack around surface area. Penetration depth results showed FC with PF subjected to impact loading was lower than without FC. Presence of PF increases FC strength and local effect results there was not impression of fragments around distal surface due to brittle crushing.

Abstract: Fibers from the culms of Bambusa arundinacea and Dendrocalamus asper were extracted mechanically and chemically treated using alkaline solution. Tensile and thermal properties of both bamboo fibers were examined. Tensile test on the bamboo fibers showed that Bambusa arundinacea fibers have higher strength and stiffness yet lower elongation than Dendrocalamus asper fibers. When the fibers were chemically treated, similar trend on tensile properties was observed but at lower magnitude compared to those shown by untreated fibers. Further characterization revealed that Bambusa arundinacea fibers are of higher fiber diameter and higher cellulose content compared to Dendrocalamus asper fibers. Thermogravimetric analysis showed that both fibers with same treatment have similar thermal stability, with chemically treated fibers are of higher thermal stability than untreated ones. The chemical treatment removed the lignin from the fiber structure, and affected tensile and thermal properties of both bamboos fibers.

Abstract: This report reviews biomimetic studies performed in China on the beetle forewing, noting that Chinese scholars studying bionics have substantially advanced various branches of biomimetic research in beetles. The report also proposes the development of branches of bionic research and establishes the foundation for corresponding experiments and theories. Then, using the A. dichotoma forewing as a an example, the cross-sectional shape, orientation of the laminated fiber layers, structure of the trabeculae, and respective mechanical properties of the forewing, as well as their biological significance, are reviewed. 1) The forewing has a lightweight border frame structure and an optimal design of variable cross-sections suitable for different positions, which achieves the specific second moment of inertia required for flight. 2) Due to the non-equiangular, laminated structure of the forewing, there are two types of tensile fracture morphologies: fiber breakage and residual bridging. This study demonstrates the anisotropy and the effectiveness of the forewings tensile strength by analyzing the orientation direction of the fibers. 3) The trabecular structure can be used to efficiently improve the peel resistance of the laminated composites. Based on the above points, possible directions for future work are also indicated in this paper.