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1
Soares, CarlosJ, VeridianaR Novais, PauloS Quagliatto, AlvaroDella Bona, and Lourenço Correr-Sobrinho. "Flexural modulus, flexural strength, and stiffness of fiber-reinforced posts." Indian Journal of Dental Research 20, no. 3 (2009): 277. http://dx.doi.org/10.4103/0970-9290.57357.
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Chiaraputt, S., S. Mai, B. P. Huffman, R. Kapur, K. A. Agee, C. K. Y. Yiu, D. C. N. Chan, et al. "Changes in Resin-infiltrated Dentin Stiffness after Water Storage." Journal of Dental Research 87, no. 7 (July 2008): 655–60. http://dx.doi.org/10.1177/154405910808700704.
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Plasticization of polymers by water sorption lowers their mechanical properties in a manner that is predictable by the polarity of their component resins. This study tested the hypothesis that when adhesive resins were used to create resin-infiltrated dentin, the reductions in their flexural moduli after water storage would be lowered proportional to their hydrophilic characteristics. Three increasingly hydrophilic resin blends were used to fabricate polymer beams and macro-hybrid layer models of resin-infiltrated dentin for testing with a miniature three-point flexure device, before and after 1–4 weeks of water storage. Flexural modulus reductions in macro-hybrid layers were related to, and more extensive than, reductions in the corresponding polymer beams. Macro-hybrid layers that were more hydrophilic exhibited higher percent reductions in flexural modulus, with the rate of reduction proportional to the Hoy’s solubility parameters for total intermolecular attraction forces (δt) and polar forces (δp) of the macro-hybrid layers.
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Marchenko, Aleksey, Eugene Morozov, and Sergey Muzylev. "Measurements of sea-ice flexural stiffness by pressure characteristics of flexural-gravity waves." Annals of Glaciology 54, no. 64 (2013): 51–60. http://dx.doi.org/10.3189/2013aog64a075.
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Abstract A method to estimate the flexural stiffness and effective elastic modulus of floating ice is described and analysed. The method is based on the analysis of water pressure records at two or three locations below the bottom of floating ice when flexural-gravity waves propagate through the ice. The relative errors in the calculations of the ice flexural stiffness and the water depth are analysed. The method is tested using data from field measurements in Tempelfjorden, Svalbard, where flexural-gravity waves were excited by an icefall at the front of the outflow glacier Tunabreen in February 2011.
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Kazemi, M., and G. Verchery. "A Methodology for Optimal Design of Composite Laminates Using Polar Formalism." Journal of Mechanics 32, no. 3 (January 18, 2016): 255–66. http://dx.doi.org/10.1017/jmech.2015.98.
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AbstractAn innovative optimization technique is presented for the design of composite laminated plates subjected to in-plane loads. A list of quasi-homogeneous laminates that can be used as angle-ply materials is proposed as a comprehensive solution for optimum lay-up. Two optimization procedures are performed: Dimensioning of the flexural stiffness and the elastic modulus, which provides the optimal orientations for the layers and offer highest in-plane resistance to composite laminated structures. The polar formalism for plane anisotropy is used to represent the flexural stiffness and elastic modulus tensors. Numerical examples are resolved for two materials with different elastic moduli.
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Virgin, Lawrence. "On the flexural stiffness of 3D printer thermoplastic." International Journal of Mechanical Engineering Education 45, no. 1 (December 1, 2016): 59–75. http://dx.doi.org/10.1177/0306419016674140.
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This paper describes the process of estimating Young’s modulus for the thermoplastic material commonly used in a type of 3D printer. Its twin goals are to compare and contrast a number of simple techniques from elementary structural analysis and to assess the influence of the printer density settings and print orientation (effective material anisotropy). Since components printed using additive manufacturing are used extensively for student projects, often involving load-bearing components, this contribution seeks to shed some light on fundamental modeling issues
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Agrawal, Ashutosh, and Tanmay P. Lele. "Geometry of the nuclear envelope determines its flexural stiffness." Molecular Biology of the Cell 31, no. 16 (July 21, 2020): 1815–21. http://dx.doi.org/10.1091/mbc.e20-02-0163.
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We performed computational analysis of the bending of the nuclear envelope under applied force using a model that accounts for envelope geometry. Our calculations show that the effective bending modulus of the nuclear envelope is an order of magnitude larger than a single membrane and approximately five times greater than the nuclear lamina.
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Molnar, T., V. Baranyai, S. Kemény, Gy Bánhegyi, and József Szabó. "Adjusting the Flexibility of Fabric Reinforced Composite Laminates Using Experimental Design." Materials Science Forum 812 (February 2015): 181–87. http://dx.doi.org/10.4028/www.scientific.net/msf.812.181.
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The objective of our work is to improve the mechanical stiffness of fiber reinforced laminates. The stiffness can be characterized by flexural and tensile moduli or their derivation. We applied design of experiments (DOE) to achieve our goals, because to solve the existing analytical and numerical models is complicated.We examined the effects of the following parameters: a) composition of reinforce materials (solely carbon, or carbon and glass combination), b) modulus of resin, c) mass ratio of resin-reinforcement, d) order of layers.The samples manufactured on the basis of DOE were investigated mechanically (flexural and tensile moduli measurements) and morphologically (scanning electron microscopy). We compared the measured modulus results to calculated values.
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Clinch, Robert W. "Structural characteristics of wood composite I-beams." Canadian Journal of Civil Engineering 20, no. 4 (August 1, 1993): 574–81. http://dx.doi.org/10.1139/l93-074.
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In this study, wood composite I-beams consisting of F11 slash pine flanges and either hardboard or particleboard webs were fabricated and evaluated for flexural stiffness. Prior to fabrication, both the web and flange materials were evaluated for flexural stiffness. The mean modulus of elasticity of the flange material was 16 900 MPa, while that for the particleboard and hardboard was 4250 and 4450 MPa respectively. The mean effective modulus of elasticity for the particleboard-webbed beams was 16 300 MPa and for the hardboard-webbed beams was 16 400 MPa. The implications of the findings are discussed. Key words: wood composites, I-beams, characterization.
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Bonser, R., and P. Purslow. "The Young's modulus of feather keratin." Journal of Experimental Biology 198, no. 4 (April 1, 1995): 1029–33. http://dx.doi.org/10.1242/jeb.198.4.1029.
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The flexural stiffness of the rachis varies along the length of a primary feather, between primaries and between species; the possible contribution of variations in the longitudinal Young's modulus of feather keratin to this was assessed. Tensile tests on compact keratin from eight species of birds belonging to different orders showed similar moduli (mean E=2.50 GPa) in all species apart from the grey heron (E=1.78 GPa). No significant differences were seen in the modulus of keratin from primaries 7­10 in any species. There was a systematic increase in the modulus distally along the length of the rachis from swan primary feathers. Dynamic bending tests on swan primary feather rachises also showed that the longitudinal elastic modulus increases with increasing frequency of bending over the range 0.1­10 Hz and decreases monotonically with increasing temperature over the range -50 to +50 °C. The position-, frequency- and temperature-dependent variations in the modulus are, however, relatively small. It is concluded that, in the species studied, the flexural stiffness of the whole rachis is principally controlled by its cross-sectional morphology rather than by the material properties of the keratin.
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Xiao, Tong Liang, and Hong Xing Qiu. "Theoretical Analysis on Flexural Behavior of Concrete Members Reinforced by Steel-Basalt FRP Composite Bars." Applied Mechanics and Materials 578-579 (July 2014): 236–39. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.236.
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Steel-Basalt FRP Composite Bar (S-BFCB) is a new kind of substitute material for longitudinal reinforcement, with high elastic modulus, stable post-yield stiffness and excellent corrosive resistance. It is made up of steel wrapped by basalt FRP in longitudinal direction. Based on mechanical properties of S-BFCB and the plane cross-section assumption, the moment-curvature relationship and stiffness on flexural members at different stages have been analyzed and verified by experiment. Flexural member reinforced by S-BFCB can make full use of the strength of FRP. By the principle of equivalent bar stiffness, the results show that the curvature and stiffness are almost the same results at pre-yield stage. While after yield, flexural member reinforced by S-BFCB has stable secondary stiffness and high bearing capacity. With the increase of fiber, the ultimate bearing capacity is improved.
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Adi Kristiawan, Stefanus, and Ageng Bekti Prakoso. "Flexural Behaviour of Patch-Repair Material Made from Unsaturated Polyester Resin (UPR)-Mortar." Materials Science Forum 857 (May 2016): 426–30. http://dx.doi.org/10.4028/www.scientific.net/msf.857.426.
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Repair materials have been produced using an unsaturated polyester resin (UPR) as a matrix of a binder. Other ingredients are sand, cement and fly ash. No water is added to the mixture, so both the cement and fly ash only act as fillers. The UPR content is in the range of 50-60% by weight of total filler (cement plus fly ash). Their flexural performance has been characterized in term of the load-deflection behaviour, modulus of rupture, flexural modulus and stiffness. The results show that the flexural capacity of these materials at early age is at least 20 MPa, but they tend to have a lower elastic modulus. At early age, the higher amount of UPR content tends to gain a higher flexural characteristic. However, at later age there is a little influence of UPR content.
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Katz, S., and J. Gosline. "SCALING MODULUS AS A DEGREE OF FREEDOM IN THE DESIGN OF LOCUST LEGS." Journal of Experimental Biology 187, no. 1 (February 1, 1994): 207–23. http://dx.doi.org/10.1242/jeb.187.1.207.
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Previous work has shown that the scaling of mechanical behaviour in bending of the metathoracic tibiae of the African desert locust (Schistocerca gregaria) is not predicted by the scaling of external dimensions. The flexural stiffness of the tibia scales to (body mass)1.53, which is similar to the predictions of the elastic similarity model of scaling. The external dimensions, however, scale in a manner that produces relatively more elongate limb segments ­ an observation that differs from the predictions of any existing scaling model. In this paper, we examined two alternative hypotheses to explain this uncoupling of morphology and mechanics: (1) that the load-bearing cuticular material is distributed in the legs in a manner that is not indicated by changes in external dimensions, or (2) that the stiffness of the cuticular material is altered to produce the observed scaling of flexural stiffness. The second moment of area (I) scaled to (body mass)1.19, which was similar to scaling I to (tibial radius)4. This indicates that the relationship between the external dimensions of the tibiae and the specific distribution of load-bearing material is conserved independently of scale. Therefore, the locust achieves the observed scaling of flexural stiffness by altering the modulus of the load-bearing cuticular material. In fact, the time-dependent modulus (E') scales to (body mass)0.311. In essence, the scaled material stiffness provides a degree of freedom in design in addition to external morphological dimensions in accommodating the changing demands placed on a skeletal structure with increases in body size.
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Wolfgang, W. J., and L. M. Riddiford. "Cuticular mechanics during larval development of the tobacco hornworm, Manduca sexta." Journal of Experimental Biology 128, no. 1 (March 1, 1987): 19–33. http://dx.doi.org/10.1242/jeb.128.1.19.
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Tensile properties of the larval cuticle of Manduca sexta were measured during the fifth instar. It was found that as the larvae grew and the cuticle thickened, the tangent modulus (intrinsic stiffness) for the cuticle declined rapidly. The extensibility of the cuticle during the growth period remained relatively high and fairly constant, while the flexural stiffness remained low. Subsequently, during the wandering and burrowing stage the extensibility decreased dramatically. Finally, in the prepupal stage extensibility remained low while flexural stiffness was highest. Using the cuticle deposition inhibitor diflubenzuron we demonstrated that the increase in larval cuticular flexural stiffness was required for normal pupation to proceed. Thus, during larval growth the cuticle remains flexible and extensible. Once growth is completed, the cuticle becomes much less extensible and more rigid, converting the previously hydrostatic skeleton into a self-supporting skeleton. This conversion was associated with changes in cuticular structure, hydration and protein composition.
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Khalid, Muhamad Faris Syafiq, and Abdul Hakim Abdullah. "Storage Modulus Capacity of Untreated Aged Arenga pinnata Fibre-Reinforced Epoxy Composite." Applied Mechanics and Materials 393 (September 2013): 171–76. http://dx.doi.org/10.4028/www.scientific.net/amm.393.171.
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Research on natural fibre is keeps on going due to their high strength and stiffness, natural availability, and environmental friendliness. In addition, they are also recyclable, renewable and low in raw material cost. This study was done to determine the performance of aging Arenga Pinnata fibre-reinforced epoxy composite (APFREC) on varying temperature. The specimens were aged from 0 to 90 days by using accelerated aging process and were subjected to dynamic mechanical analysis (DMA) and flexural modulus evaluation. The results have shown that specimens with lower aging days have higher storage modulus initially, that is at below 70 °C but as the temperature increase, its storage modulus drastically decrease in comparison to a more aged specimen. Result of storage modulus at low temperature is similar flexure modulus evaluation. The research indicates that aging APFREC specimens has better thermal resistance.
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Cui, Hai Xing, Ming Jie Guan, Yi Xin Zhu, and Zhen Zhen Zhang. "The Flexural Characteristics of Prestressed Bamboo Slivers Reinforced Parallel Strand Lumber (PSL)." Key Engineering Materials 517 (June 2012): 96–100. http://dx.doi.org/10.4028/www.scientific.net/kem.517.96.
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A novel kind of parallel strand lumber (PSL) was produced, in which bamboo slivers with viscoelastic deformation were mixed with poplar veneer strands at a weight ratio of 1:4 as raw materials, then the flexural characteristics of PSL were investigated. The results showed that stretching treatment was an effective method to generate viscoelastic deformation of bamboo slivers, which would induce prestress in the bamboo slivers, reinforced PSL. The modulus of rupture (MOR) and modulus of elasticity (MOE) of prestressed bamboo slivers reinforced PSL were 7.84% and 11.76% higher than that of control PSL respectively. The flexural toughness index of prestressed bamboo slivers reinforced PSL was increased by 27.55% compared with control PSL. The presence of prestress in bamboo slivers reinforced PSL significantly enhanced its flexural stiffness and toughness, while it had no obvious effect on its flexural strength.
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Wei, Yang, Shen Xue Jiang, Qing Fang Lv, Qi Sheng Zhang, Li Bin Wang, and Zhi Tao Lv. "Flexural Performance of Glued Laminated Bamboo Beams." Advanced Materials Research 168-170 (December 2010): 1700–1703. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1700.
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Bamboo structures have a good performance like wooden structures. The flexural performance of glued laminated bamboo beams for bamboo structures were studied through ten large-scale beams tested. The study investigated the failure modes of bamboo beams, flexural capacity, cross-sectional stiffness and strain distribution. In test, four kinds of typical failure modes of bamboo beams include brittle fracture of the bottom fiber, compressive buckling failure at the top of the bamboo strips layers, stratified fracture and oblique tear of the bottom fiber. The control condition of the design load was the cross-sectional stiffness rather than the flexural strength according to the experimental results. The flexural elastic modulus of 10GPa is suggested to check deformation of bamboo beams in the design. The plane-section assumption of cross-sectional strain distribution along the height is verified for bamboo beams.
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Son, Dong-Hee, Baek-Il Bae, Moon-Sung Lee, Moon-Seok Lee, and Chang-Sik Choi. "Flexural Strength of Composite Deck Slab with Macro Synthetic Fiber Reinforced Concrete." Applied Sciences 11, no. 4 (February 12, 2021): 1662. http://dx.doi.org/10.3390/app11041662.
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In this research, flexural performance was evaluated using macro-synthetic fiber-reinforced concrete (MFRC) in structural deck plates. Material tests were performed to evaluate the mechanical properties of the MFRC, and the flexural strength evaluation was conducted in two experiments, positive and negative moment tests. In the material test results, compressive strength and modulus of elasticity of the MFRC were increased compared with normal concrete. Flexural tensile tests showed that, after achieving maximum strength, the deck plates had sufficient residual strength until fracture. Structural tests showed that flexural strength and cracking load of all specimens increased according to macro synthetic fiber dosage. According to the experimental results, we proposed a flexural strength model of a steel deck plate containing macro synthetic fiber. The model showed greater accuracy than the current standard compared with the experimental results. In addition, since it was confirmed that the MFRC steel decks had greater flexural stiffness until yielding, it will be necessary to quantitatively evaluate the effect of MFRC on the effective flexural stiffness of steel decking in future studies.
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Wu, Shao Peng, Guo Jun Zhu, Ling Pang, and Cong Hui Liu. "Influences of Aging History on Low Temperature Performance of Asphalt Concrete." Key Engineering Materials 385-387 (July 2008): 493–96. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.493.
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According to three-point bending test, this paper explores the influence of low temperature on the flexural strength, the tensile strain and bending stiffness modulus of the aged Stone Mastic Asphalt (SMA-13) concrete. The asphalt mixtures are aged according to the short-term aging (at 135°C, 4 hours), and long-term aging (asphalt concrete at 85°C, 120 hours) and natural aging (3 months, 6 months and 9 months). The result shows that, with the same loading rate, the tensile strain of specimens at -30°C are smaller than those at -10°C; but when temperature is certain, the tensile strain of specimens lager than those of aged specimens. The longer the aging time lasts, the more flexural strength differences between high and low temperatures can be found. A pretty well index variation can be found between the tensile strain and temperature. The same trend also appears between the bending stiffness modulus and temperature of SMA-13 asphalt concrete.
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Lee-Sullivan, P., and L. T. Seng. "Effects of Stitching on Composite Impact Behaviour and Stiffness." Advanced Composites Letters 2, no. 2 (March 1993): 096369359300200. http://dx.doi.org/10.1177/096369359300200201.
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The influence of stitching technique on the damage pattern of impacted glass/epoxy composite laminates was investigated. Two different techniques were evaluated; running-stitching (RS) and cross-stitching (CS) respectively. CS was found to be better than RS in suppressing delamination growth. Even so, the RS laminate was less susceptible to delamination than the unstitched equivalent. Although stitching is beneficial, it causes significant reduction in tensile stiffness but has minimal effects on the flexural modulus.
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Birkinshaw, C., C. J. McCarthy, N. Regan, M. D. C. Hale, D. Cahill, and M. McCourt. "The Thermomechanical Behaviour of Wood Subject to Fungal Decay." Holzforschung 53, no. 5 (September 10, 1999): 459–64. http://dx.doi.org/10.1515/hf.1999.076.
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Summary Specimens of Pinus sylvestris have been subject to decay by the brown rot fungus Coniophora puteana, the white rot fungus Phanerochaete chrysosporium, and to doses of γ irradiation sufficiently high to cause significant molecular damage. Specimens of Picea abies have been subject to decay by the brown rot fungus Postia placenta. The dynamic mechanical properties of the decayed and degraded materials have been assessed between −100 °C and 120 °C using in some cases a natural frequency instrument and in other cases a driven frequency instrument. The results obtained have allowed calculation of the temperature coefficients of modulus for the materials at various stages of decay or degradation, and these are relatively constant regardless of the history of the specimen. Such changes as do occur can be explained by modulus dependent frequency effects. The static mechanical properties of some specimens were also assessed by three point bending at 20 °C. Measured changes in dynamic stiffness and flexural modulus have been compared with the weight changes and the proportionality constant relating strength and stiffness loss to weight loss obtained for each situation. These show that in the case of fungal attack the dynamic stiffness falls more quickly than flexural strength, and that, as would be expected, the brown rot fungi are the more effective at reducing mechanical properties.
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Király, Anett, and Ferenc Ronkay. "Development of Electrically Conductive Polymers." Materials Science Forum 729 (November 2012): 397–402. http://dx.doi.org/10.4028/www.scientific.net/msf.729.397.
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Conducting composites based on graphite, carbon black and polypropylene have been prepared and the effect of composition on the flexural modulus and electrical conductivity has been studied. The conductivity of polymers containing only one kind of filler did not increase significantly, their modulus of elasticity was the highest for graphite filling, and the lowest for nanotube filling. The conductivity of dual filler hybrids increased significantly due to the synergetic interaction between the two fillers. At lower graphite contents, because of the better dispersion of graphite, the material became more flexible, but at higher carbon black contents the stiffness increased significantly. In the case of triple filler hybrids, if keeping the graphite content at a certain level and varying only the carbon black/nanotube ratio, the conductivity and the flexural modulus varied according to exponential and linear rules respectively.
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Alasmari, Hasan Aied, B. H. Abu Bakar, and A. T. Noaman. "A Comparative Study on the Flexural Behaviour of Rubberized and Hybrid Rubberized Reinforced Concrete Beams." Civil Engineering Journal 5, no. 5 (May 22, 2019): 1052–67. http://dx.doi.org/10.28991/cej-2019-03091311.
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This paper aims to investigate the flexural behaviour of the rubberized and hybrid rubberized reinforced concrete beams. A total of fourteen beams, 150×200 mm in cross-section with 1000 mm in length, were subject to a laboratory test over an effective span of 900 mm. The sand river aggregate was replaced by 10%, 12.5%, and 15% of crumb rubber (volume). The hybrid structure contained two double layers: 1) rubberized reinforcement concrete at the top layer of the beam and 2) reinforcement concrete at the bottom layer of the concrete beam. The static responses by the flexural test of all the beams were evaluated in terms of their fresh properties, failure patterns, total energy, flexural strength, stiffness, and ultimate deflection, modulus of rupture, strain capacity, and ductility index. The results showed that there were improvements when the hybrid beams were used in most cases such as failure pattern, ultimate load, stiffness, modulus of rupture, and stress. The rubberized concrete beams showed improvements in the strain capacity as illustrated in strain gauges and stress-strain curves, toughness, ultimate deflection, and ductility index. The findings of the study revealed an improved performance with the use of the hybrid beams. This has resulted in the implementation of innovative civil engineering applications in the engineering sustainable structures.
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Annamalai, Saravanan, Suresh Periyakgoundar, Kumaravel Paramasivam, and Aravindha Balaji Selvaraj. "Investigation of Bending, Sound Absorption, and Damping Properties of AZ91D-Swivel Plate." Advances in Materials Science and Engineering 2020 (May 22, 2020): 1–13. http://dx.doi.org/10.1155/2020/9621921.
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A comparison was made between Mg alloy and A3 steel on weight, bending, sound absorption, and vibration conditions. In this study, a swivel plate, which is used in rotating car seats, is to be taken into consideration for finding bending, natural frequency, and frequency under static loading conditions. The swivel plate is generally made up of A3 steel plate; instead, we have replaced that with Mg alloy (AZ91D) plate. Stiffness, flexural strength, natural frequency, frequency under different static loading conditions, and sound absorption capacity were obtained through experimental methods. Finally, it was concluded that the damping capacity of Mg alloy of swivel plate is higher, has better stiffness, and incurred weight reduction by 26.58% less than that of the A3 steel. Also, the Mg alloy material exhibits better specific flexural strength, and specific flexural modulus and sound absorption coefficient are 11.76% and 25% higher than those of A3 steel at higher frequency level (2000 Hz) and at lower frequency level (100 Hz).
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Zhou, Z., D. Li, J. Zeng, and Z. Zhang. "Rapid fabrication of metal-coated composite stereolithography parts." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 221, no. 9 (September 1, 2007): 1431–40. http://dx.doi.org/10.1243/09544054jem827.
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In this paper, the rapid fabrication method based on stereolithography (SL) and electrochemical deposition is described in detail and mechanical test results of composite nickel-coated SL parts are presented. Coatings of electrodeposited nickel on SL prototypes result in increases in Young's modulus, UTS, flexural modulus, and strength. Electrodeposited nickel coating has dramatically improved the overall strength and stiffness of SL parts. The adhesive strength of the roughened SL resin-nickel interface is higher than the original. In particular, the influence of the surface roughness on adhesive strength between SL and metal is investigated. Moreover, this paper has presented an application of a structural electrodeposited nickel coating over SL parts to make a functional airfoil model with a complex internal structure and sufficient mechanical strength and stiffness.
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Ravi Sankar, H., P. Vamsi Krishna, V. Bhujanga Rao, and P. Bangaru Babu. "The effect of natural rubber particle inclusions on the mechanical and damping properties of epoxy-filled glass fibre composites." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 224, no. 2 (April 1, 2010): 63–70. http://dx.doi.org/10.1243/14644207jmda282.
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Vibration damping is proving important for improved vibration and noise control, dynamic stability, fatigue, and impact resistance in advanced engineering systems. In the present work, the effect of natural rubber particle inclusions on the mechanical and damping properties of epoxy-filled glass fibre composites is investigated. Test specimens are fabricated with inclusion of natural rubber particles of different sizes and tested for tensile strength, tensile modulus, flexural strength, and flexural modulus. These mechanical properties are influenced by the size of the rubber particle inclusions. Vibration tests are carried out and damping ratio is calculated. It is observed that damping ratio varies with inclusion of natural rubber particles and that 0.25mm particle inclusions improve damping better than other selected particle sizes without greatly affecting the stiffness in the case of cantilever beams and fixed free plates.
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Christoforo, André L., Túlio H. Panzera, Fabiano B. Batista, Paulo H. R. Borges, Francisco A. R. Lahr, and Claudenir F. Franco. "The position effect of structural Eucalyptus round timber on the flexural modulus of elasticity." Engenharia Agrícola 31, no. 6 (December 2011): 1219–25. http://dx.doi.org/10.1590/s0100-69162011000600019.
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Round timber has great use in civil construction, performing the function of beams, columns, foundations, poles for power distribution among others, with the advantage of not being processed, such as lumber. The structural design of round timber requires determining the elastic properties, mainly the modulus of elasticity. The Brazilian standards responsible for the stiffness and strength determination of round timber are in effect for over twenty years with no technical review. Round timber, for generally present an axis with non-zero curvature according to the position of the element in the bending test, may exhibit different values of modulus of elasticity. This study aims to analyze the position effect of Eucalyptus grandis round timber on the flexural modulus of elasticity. The three-point bending test was evaluated in two different positions based on the longitudinal rotation of the round timber element. The results revealed that at least two different positions of the round timber element are desired to obtain significant modulus of elasticity.
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Ardiyanto, Pramaditya, Putu Suwarta, Sutikno, Indra Sidharta, and Wahyu Wijanarko. "Thickness Effect of Polyurethane Foam Core on the Flexural Behaviour of Composite Sandwich Materials." Applied Mechanics and Materials 758 (April 2015): 1–6. http://dx.doi.org/10.4028/www.scientific.net/amm.758.1.
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This study explored the feasibility of flexural performance of composite sandwich material composed of various low density polyurethane foam core thickness sandwiched between GFRP skins. The mechanical behaviour of this material was assessed by carrying out a flexural testing. Each spesimen had a nominal dimensions of 110 mm x 30 mm x (c + 4 mm). These spesimens with various core thickness (c) of 2 mm. 5 mm. and 8 mm were then tested in three point bending according to ASTM C 393-00. This study revealed that. by incorporating the thickest core ( 8 mm ) . the bending strength decreases by 42.3 % compared to 5 mm core and it further decreases by 72.6 % compared to 2 mm core. The material stiffness showed positive trend for the thickest core (8 mm). it increases by 53.1 % and 78.1 % compared to 5 mm core and 2 mm core respectively. Low shear modulus of polyurethane foam core contributed to the low bending strength of composite sandwich material with 8 mm core. This was further confirmed by failure analysis under optical microscope which revealed that core shear failure was the dominant failure mechanism for 8 mm core. Meanwhile the dominant failure mechanism for 2 mm core and 5 mm core was microbuckling which confirm the high modulus of GFRP skin. The material stiffness was affected by the high modulus of GFRP skin and the core thickness.
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Sadeghian, Pedram, Dimo Hristozov, and Laura Wroblewski. "Experimental and analytical behavior of sandwich composite beams: Comparison of natural and synthetic materials." Journal of Sandwich Structures & Materials 20, no. 3 (May 31, 2016): 287–307. http://dx.doi.org/10.1177/1099636216649891.
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In this study, the flexural behavior of sandwich composite beams made of fiber-reinforced polymer (FRP) skins and light-weight cores are studied. The focus is on the comparison of natural and synthetic fiber and core materials. Two types of fiber materials, namely glass and flax fibers, as well as two types of core materials, namely polypropylene honeycomb and cork, are considered. A total of 105 small-scale sandwich beam specimens (50 mm wide) were prepared and tested under four-point bending. Test parameters were fiber types (flax and glass fibers), core materials (cork ad honeycomb), skin layers (0, 1, and 2 layers), core thicknesses (6–25 mm), and beam spans (150 and 300 mm). The load–deflection behavior, peak load, initial stiffness, and failure mode of the specimens are evaluated. Moreover, the flexural stiffness, shear rigidity, and core shear modulus of the sandwich composites are computed based on the test results of the two spans. An analytical model is also implemented to compute the flexural stiffness, core shear strength, and skin normal stress of the sandwich composites. Overall, the natural fiber and cork materials showed a promising and comparable structural performance with their synthetic counterparts.
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Adjrad, Arezki, Youcef Bouafia, Mohand Said Kachi, and Hélène Dumontet. "Modeling of Externally Prestressed Beams until Fracture in Non Linear Elasticity." Applied Mechanics and Materials 749 (April 2015): 379–85. http://dx.doi.org/10.4028/www.scientific.net/amm.749.379.
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In this paper, we present an analytical model to analyze reinforced and prestressed concrete beams loaded in combined bending, axial load and shear, in the frame of non linear elasticity. In this model, the equilibrium of the beam is expressed by solving a system of equations, governing beams equilibrium, based on the stiffness matrix of the beam, which connects the load vector to the node displacements vector of the beam. It is built from the stiffness matrix of the section which takes into account a variation of the shearing modulus (depending on the shear variation) instead of assuming a constant shearing modulus as in linear elasticity. For the internal tendons, the stiffness matrix is completed by the terms due to the prestress effect in flexural equilibrium and by the balancing of one part of the shear by the transverse component of the force in the inclined cables.
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Kelly, D. A. "Expansion of the tunica albuginea during penile inflation in the nine-banded armadillo (Dasypus novemcinctus)." Journal of Experimental Biology 202, no. 3 (February 1, 1999): 253–65. http://dx.doi.org/10.1242/jeb.202.3.253.
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Artificial inflation of corpora cavernosa from the nine-banded armadillo (Dasypus novemcinctus) showed that the expansion of the tunica albuginea during erection increases both components of flexural stiffness: the second moment of area and Young's modulus of elasticity. Folded tissue and crimped collagen fibers in the tunica albuginea permit its expansion during erection. As the tunica albuginea's radii increase in size, its second moment of area also increases. The crimped collagen fibers permit the flaccid tunica albuginea to expand to strains of 25 % longitudinally and 15 % circumferentially, after which tissue stiffness increases by 3–4 orders of magnitude. Radial expansion of the corpus cavernosum is limited by collagenous trabeculae. The trabeculae maintain the non-circular cross section of the corpus cavernosum during erection. Restricting expansion appears to protect the corpus spongiosum and urethra from occlusion, but has the side effect of reducing the potential flexural stiffness of the corpus cavernosum by reducing the second moment of area of the tunica albuginea.
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Behera, D., and A. K. Banthia. "Thermal, Mechanical and Morphological Performance of BisGMA/TiO2 Nanocomposite." Advanced Materials Research 29-30 (November 2007): 241–44. http://dx.doi.org/10.4028/www.scientific.net/amr.29-30.241.
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Vinyl ester BisGMA [Bisphenol-A-glycidyldimethacrylate] resin has been modified by incorporating Titanium dioxide(TiO2)nanoparticles (0.5%-2% by weight). An ultrasonic mixing process was employed to disperse the particles into the resin system prior to casting and curing test specimens. From TEM investigation, it is found that the particles are nano size (5-60nm) and dispersed throughout the entire volume of the resin. Dynamic mechanical analysis was conducted for both the neat resin and nanocomposite. In dynamic mechanical analysis, nanocomposite shows increase in storage modulus (6%), and glass transition temperature (5.8%) from neat resin system. Thermogravimetric analysis shows 7.5% better thermal stability. In addition, the nanocomposite shows enhance in the stiffness by 5% in flexural loading. The Tg and flexural modulus of the nanocomposites were enhanced as the particle volume fraction was enhanced and than decreased.
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Akbari, Hassan. "Effects of Soil Modulus and Flexural Rigidity on Structural Analysis of Water Intake Basins." Civil Engineering Journal 3, no. 3 (March 30, 2017): 172–79. http://dx.doi.org/10.28991/cej-2017-00000083.
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A water intake basin is a buried box that functions as a water reservoir near shorelines. Number of these structures has been increased in the recent years and for a safe design, it is necessary to know their behaviour under applied loads. In addition to common dead, live and seismic loads, the bottom of such a basin is usually located below sea water level and endures uplift pressure as well as reaction of supporting soils. Uncertainty of these special loads complicates the structural response of this buried basin to the applied loads. Therefore, the unreliability in the soil parameter and in the rigidity of the basin structure is studied in this research by calculating the generated internal bending moments. Different loads and load combinations have been taken into account and finite element analysis is carried out for modelling nonlinear behaviour of different types of supporting soils. It is concluded that the geometry and flexural stiffness of the basin affects the analysis more than the soil parameters because the contribution of the soil modulus in the total stiffness of the system is negligible than the structural rigidity of the basin structure. In addition, inner walls and geometry of the basin should be modelled in detail to obtain acceptable results.
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Ahmed, Mansur, Md Saiful Islam, Qumrul Ahsan, and Md Mainul Islam. "Fabrication and Characterization of Unidirectional Silk Fibre Composites." Key Engineering Materials 471-472 (February 2011): 20–25. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.20.
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Natural fibres offer a number of benefits as reinforcement for synthetic polymers since they have high specific strength and stiffness, high impact strength, biodegradability etc. The aim of this study is to fabricate and determine the performance of unidirectional silk fibre reinforced polymer composites. In the present initial study, alkali treated silk fibres were incorporated as reinforcing agent, while a mixture of 20% maleic anhydride grafted polypropylene (MAPP) and commercial grade polypropylene (PP) was used as matrix element. The unidirectional composites were fabricated by using hot compression machine under specific pressure, temperature and varying fibre loading. Tensile, flexural, impact and hardness tests were carried out by varying silk fibre volume fraction. Composites containing 45% fibre volume fraction had higher tensile and flexural strength, Young’s modulus and flexural modulus compared to other fabricated composites including those with untreated silk fibres. SEM micrographs were taken to examine composite fracture surface and interfacial adhesion between silk fibre and the matrix. These micrographs suggested less fibre pull out and better interfacial bonding for 40% fibre reinforced composites.
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Valašková, Veronika, and Jozef Vlček. "Laboratory and In situ Investigation of Modulus of Elasticity of Foam Concrete." E3S Web of Conferences 157 (2020): 06013. http://dx.doi.org/10.1051/e3sconf/202015706013.
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Foam concrete (FC) is a building material which consists of a combination of cement, water additives and technical foam. This material has some useful advantages such as low density, high stiffness and compression and flexural strength in comparison to the granular fill materials, good thermal resistance or damping potential. It’s currently used as a levelling layer for floors or as a sub-base layer of the new pavements or industrial floors or at the road reconstructions and excavations. Because of utilization of the foam concrete is aimed at the horizontal slab-like structures, deformation characteristics such as modulus of elasticity are important for the design of such a layer. High porosity of the final material reaching almost 70% of the volume complicates the determination of the stiffness parameters. Its stiffness is higher in comparison with the conventional granular fill materials but when thin layer is proposed, membrane like behavior influenced by the local imperfections of the material and the geometry can affect the overall stiffness of the compound. This paper presents the firsts attempts to estimate the modulus of elasticity of foam concrete of dry bulk density of 400 kg·m-3 in laboratory and as a derived value from in situ load tests using SOJUZDORNII theory.
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Bristogianni, Telesilla, Faidra Oikonomopoulou, and Fred A. Veer. "On the flexural strength and stiffness of cast glass." Glass Structures & Engineering 6, no. 2 (June 2021): 147–94. http://dx.doi.org/10.1007/s40940-021-00151-z.
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AbstractCast glass has great potential for diverse load-bearing, architectural applications; through casting, volumetric glass components can be made that take full advantage of glass’s stated compressive strength. However, the lack of engineering, production and quality control standards for cast glass and the intertwined ambiguities over its mechanical properties-particularly due to the variety in chemical compositions and the lack of understanding of the influence of flaws occurring in the glass bulk-act as an impediment to its wide-spread application. Addressing the above uncertainties, this work studies a total of 64 silicate-based glass specimens, prepared in 20 * 30 * 350 mm beam size, either by kiln-casting at relatively low forming temperatures (970–1120 $$^{\circ }$$ ∘ C), or by modification of industrially produced glass. For the kiln-casting of the specimens, pure and contaminated recycled cullet are used, either individually or in combination (composite glasses). The defects introduced in the glass specimens during the casting process are identified with digital microscopy and qualitative stress analysis using cross polarized light, and are categorized as stress-inducing, strength-reducing or harmless. The Impulse Excitation Technique is employed to measure the Young’s modulus and internal friction of the different glasses. Differential Scanning Calorimetry is used on a selection of glasses, to investigate changes in the glass transition range and fictive temperature of the kiln-cast glasses due to the slower cooling and prolonged annealing. The four-point bending experiments are shedding light upon the flexural strength and stiffness of the different glasses, while the fractographic analysis pinpoints the most critical defects per glass category. The experiments show the flexural strength of cast glass ranging between 30–73 MPa, according to the level of contamination and the chemical composition. The measured E moduli by both methods are in close agreement, ranging between 60–79 GPa. The comparison of the flexural strength with prior testing of cast glass involving shorter span fixtures showed a decreasing strength with increasing size for the contaminated specimens, but similar strengths for pure compositions. The results highlight the versatile role of defects in determining the glass strength and the complexity that arises in creating statistical prediction models and performing quality control.
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Amiri, Ali, Matthew N. Cavalli, and Chad A. Ulven. "A new approach of stiffness degradation modeling for carbon fiber-reinforced polymers under cyclic fully reversed bending." Journal of Composite Materials 51, no. 20 (January 25, 2017): 2889–97. http://dx.doi.org/10.1177/0021998317690239.
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Carbon fiber-reinforced polymers are being used in advanced structural applications such as aerospace, automotive, and naval industries. Therefore, there is a rising need for predicting their fatigue life and improving their fatigue behavior. In this study, the fatigue behavior and changes in flexural modulus of bidirectional carbon fiber-reinforced polymers due to cyclic fully reversed bending are investigated. A unique fixture is designed and manufactured to perform fully reversed four-point bending fatigue tests on (0 °/90 °)15 carbon/polyester specimens with a stress ratio of R = −1 and frequency of 5 Hz. The expected downward trend in fatigue life with increasing maximum applied stress was observed in the S–N curves of samples. Based on the decay in the flexural modulus of the specimens, a modified exponential model is proposed to predict the life of carbon fiber-reinforced polymers under fully reversed bending. The empirical constants in the model are calculated based on the results of experiments. The model is applied to predict the fatigue life of the samples that did not fail during the tests and cycle-to-failure of the specimens are found.
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Lu, Na. "A Study of Surface Morphology and Flexural Strength of Hemp Fiber Reinforced Composite with Recycled High Density Polyethylene Matrix." Applied Mechanics and Materials 71-78 (July 2011): 4416–20. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.4416.
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Hemp fiber has recently captured a significant interest in the science and engineering community because of its high specific strength and stiffness with an environmentally friendly feature. This paper reports a systematic study relating a specific surface treatment on hemp fiber with respect to the flexural strengths of the treated hemp fiber reinforced recycled polymeric composites. The flexural strength, strain, and modulus of rupture of the composite were tested on a constant rate of extension testing machine following ASTM standards. Surface morphologies of fiber and fracture surfaces of the composites were also observed using the Scanning Electron Microscope (SEM) and Fourier Transfer Infrared Spectroscopy (FTIR) technique.
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Lurie, Sergey, Yury Solyaev, Alexander Volkov, and Dmitriy Volkov-Bogorodskiy. "Bending problems in the theory of elastic materials with voids and surface effects." Mathematics and Mechanics of Solids 23, no. 5 (March 6, 2017): 787–804. http://dx.doi.org/10.1177/1081286517691570.
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In the present study, a comparison of pure, three-point, four-point and cantilever beam bending problems in the frame of the theory of elastic materials with voids (micro-dilatational elasticity) has been provided via analytical modelling and three-dimensional finite-element analysis. We consider the extended variant of the theory with surface effects using a variational approach. At first, we compare the known approximate semi-inverse analytical solution of the pure bending problem with a corresponding three-dimensional finite-element solution in the frame of micro-dilatational theory. It is demonstrated that in the numerical solution – unlike the analytical one – all boundary conditions are satisfied accurately, and there exist distortions of the cross-sections and lateral faces of the beam. The generalized analytical solution of the beam pure bending problem with surface effects is also established and compared with numerical simulations. The effective elastic properties of the beam with micro-dilatations are introduced by comparing its displacements and corresponding classical beam displacements. The influence of scale, coupling and surface parameters on the effective elastic moduli in different bending and simple tension tests is studied. It is shown that all considered types of bending experiments provide the determination of close values of the effective flexural modulus of the beams with different thickness. This means that it is possible to use any bending test with beams of different thickness for reliable identification of the material constants of the theory. It is also possible to use the simple analytical expression for an effective flexural modulus that follows from the analytical solution of the pure bending problem. It is also shown that stiffness of the beam with micro-dilatation in any bending tests should always be higher as compared with the stiffness of such a beam in simple tension. For thin beams, there are no scale effects, and its effective flexural modulus is equal to the material’s Young’s modulus without micro-dilatation. Possible rise of the negative size effects in the model with surface effects is also discussed.
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Roy, Sandipan, Debojyoti Panda, Niloy Khutia, and Amit Roy Chowdhury. "Pore Geometry Optimization of Titanium (Ti6Al4V) Alloy, for Its Application in the Fabrication of Customized Hip Implants." International Journal of Biomaterials 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/313975.
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The present study investigates the mechanical response of representative volume elements of porous Ti-6Al-4V alloy, to arrive at a desired range of pore geometries that would optimize the reduction in stiffness necessary for biocompatibility with the stress concentration arising around the pore periphery, under physiological loading conditions with respect to orthopedic hip implants. A comparative study of the two is performed with the aid of a newly defined optimizing parameter called pore efficiency that takes into consideration both the stiffness quantity and the stress localization around pores. To perform a detailed analysis of the response of the porous structure over the entire spectrum of loading conditions that a hip implant is subjected toin vivo, the mechanical responses of 3D finite element models of cubic and rectangular parallelepiped geometries, with porosities varying over a range of 10% to 60%, are simulated under representative compressive, flexural as well as combined loading conditions. The results that are obtained are used to suggest a range of pore diameters that lower the effective stiffness and modulus of the implant to around 60% of the stiffness and modulus of dense solid implants while keeping the stress levels within permissible limits.
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Hughes, Erik AB, Andrew Parkes, Richard L. Williams, Mike J. Jenkins, and Liam M. Grover. "Formulation of a covalently bonded hydroxyapatite and poly(ether ether ketone) composite." Journal of Tissue Engineering 9 (January 2018): 204173141881557. http://dx.doi.org/10.1177/2041731418815570.
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Spinal fusion devices can be fabricated from composites based on combining hydroxyapatite and poly(ether ether ketone) phases. These implants serve as load-bearing scaffolds for the formation of new bone tissue between adjacent vertebrae. In this work, we report a novel approach to covalently bond hydroxyapatite and poly(ether ether ketone) to produce a novel composite formulation with enhanced interfacial adhesion between phases. Compared to non-linked composites (HA_PEEK), covalently linked composites (HA_L_PEEK), loaded with 1.25 vol% hydroxyapatite, possessed a greater mean flexural strength (170 ± 5.4 vs 171.7 ± 14.8 MPa (mean ± SD)) and modulus (4.8 ± 0.2 vs 5.0 ± 0.3 GPa (mean ± SD)). Although the mechanical properties were not found to be significantly different (p > 0.05), PEEK_L_HA contained substantially larger hydroxyapatite inclusions (100–1000 µm) compared to HA_PEEK (50–200 µm), due to the inherently agglomerative nature of the covalently bonded hydroxyapatite and poly(ether ether ketone) additive. Larger inclusions would expectedly weaken the HA_L_PEEK composite; however, there is no significant difference between the flexural modulus of poly(ether ether ketone) with respect to HA_L_PEEK (p = 0.13). In addition, the flexural modulus of HA_PEEK is significantly lower compared to poly(ether ether ketone) (p = 0.03). Ultimately, covalent linking reduces hydroxyapatite particulate de-bonding from the polymeric matrix and inhibits micro-crack development, culminating in enhanced transfer of stiffness between hydroxyapatite and poly(ether ether ketone) under loading.
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Fatmawati, Dwi Warna Aju. "Composite Flowable Fabricated (CFF) Sebagai Alternatif Bahan Pasak Gigi Paska Endodontik." Majalah Kedokteran Gigi Indonesia 21, no. 2 (December 1, 2014): 159. http://dx.doi.org/10.22146/majkedgiind.8751.
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Penelitian ini bertujuan untuk menggali, menganalisis dan membandingkan pasak CCF (plastis) dengan pasak NiTi logam (rigid) sebagai alternatif pasak gigi paska perawatan endodontik yang biokompatibel. Penelitian ini menggunakan sampel elemen gigi insisif rahang atas yang telah disesuaikan dengan kriteria penelitian. Semua sampel gigi diberi perlakuan sesuai dengan kelompoknya. Prosedur kelompok pasak CCF yaitu dengan mengaplikasikan komposit flowable pada saluran akar gigi yang telah dilakukan pengambilan gutta-percha sedalam 2/3 panjang saluran akar dan menyisakan 1/3 gutta-percha di daerah apikal, sampai seluruh saluran akar dan ruang pulpa terisi penuh. Komposit flowable dilakukan penyinaran (curing LED) selama 20 detik. Perlakuan pada kelompok pasak NiTi sama seperti pada kelompok pasak CCF, bedanya pasak NiTi diinsersi menggunakan bahan luting semen ionomer kaca tipe 1. Selanjutnya semua sampel gigi baik yang prefabricated maupun fabricated dilakukan uji three bending point dengan pengaturan sesuai dengan standart ISO10477. Secara deskriptif nilai rerata kelompok pasak NiTi (stiffness = 115,30 N/mm; modulus elastisitas = 9,31 Gpa; flexural = 812 Gpa) lebih besar dari nilai rerata kelompok pasak CFF (stiffness = 35 N/mm; modulus elastisitas = 3,45 Gpa; flexural = 475,8 GPa) dan secara statistik hasil penelitian menunjukkan terdapat perbedaan yang signifikan antara pasak prefabricated (NiTi) dengan fabricated (CFF). Sehingga dapat disimpulkan bahwa walaupun secara deskriptif dan statistik ada perbedaan, namun bahan komposit flowable dapat dijadikan sebagai bahan pasak alternatif dan perlu penelitian lebih lanjut yang sesuai standar keberadaannya sebagai bahan pasak alternatif. Composite Flowable Fabricated (CFF) as Enddodontic Dental Post alternative. Composite Flowable Fabrcated (CFF). CFF is composite resin that viscous and plastic which used as material to enhance the retention and stability of post endodontic treatment and restoration materials. NiTi post is prefabricated post endodontic that the insertion needs luting material. This study was to explore, analyze, and compare CCF (plastic) and NiTi (rigid) post endodontic as alternative of post endodontic that is compatible. This study used element sample of maxillary incisive tooth. All of teeth sample was taken treatment that was appropriate with the groups. the procedure of CFF post group was to make application of flowable composite in root canal up to full that had been done taking of gutta percha as deep as 2/3 of root canal length and left 1/3 gutta percha in apical area. Flowable composite was cured by LEDfor 20 seconds. Treatment of NiTi post group was same with CCF post group, the different NiTi post was inserted using glass ionomer luting type 1. Furthermore all of tooth sample, prefabricated and fabricated, was tested by threebending point with ISO10477. The result showed that mean of NiTi post (stiffness= 115,30 N/mm; modulus elastisitas = 9,31 Gpa; flexural= 812 Gpa) was higher than CFF post (stiffness = 35 N/mm; modulus elastisitas = 3,45 Gpa; flexural= 475,8 GPa); and there was significant different between prefabricated (NiTi) dengan fabricated(CFF) post statistically. Although composite flowable can be used as alternative of post endodontic and needs further research that is suitable with standard of post materials.
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Nashed, B. S., J. M. Rice, and Yong K. Kim. "Projectile Impact Behavior of Z-Fiber Reinforced Laminar Composites." Advanced Materials Research 441 (January 2012): 717–25. http://dx.doi.org/10.4028/www.scientific.net/amr.441.717.
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The bending toughness, strength retention, resistance to damage and bending stiffness of glass fiber mat, laminar composites under high strain rate impact loading conditions was studied. One of the main disadvantages of laminar composite materials is their poor interlaminar shear strength. Recent work has demonstrated a method of Z-direction reinforcement of these composites using electrostatic flocking techniques improve delamination resistance and fracture toughness without degrading the composites tensile strength or other in-plane properties when loaded quasi-statically. The Z-direction reinforcement is accomplished by electrostatically flocking short fibers perpendicular to and between the composite ply layers. In this study, composite samples were prepared using the flocking method in two fabrication modes by the; so-called Z-Axis wet and Z-Axis dry procedures. In this work, Z-direction reinforced composite panels (including a non reinforced control) that were previously projectile impact damaged were tested using established mechanical testing procedures. Damage areas were quantified and compared using image processing techniques. Three point bending tests were also conducted on these projectile impact damaged panels to determine and compare their bending toughness, strength retention and modulus. The results show that Z-Axis reinforcement by the flocking technique improves the overall mechanical strength and stiffness properties of glass fiber mat laminar composites. For example, Z-Axis reinforced projectile damaged and not damaged glass fiber mat composite laminates are found to have flexural strengths 9% to 15% higher and a flexural modulus (stiffness) 22% to 26% higher than comparable (not Z-Axis flock reinforced) glass fiber mat samples.
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Hessami, Reza, Aliasghar Alamdar Yazdi, and Abbas Mazidi. "Investigation of tensile and flexural behavior of biaxial and rib 1 × 1 weft-knitted composite using experimental tests and multi-scale finite element modeling." Journal of Composite Materials 53, no. 23 (April 4, 2019): 3201–15. http://dx.doi.org/10.1177/0021998319839855.
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In this study, tensile and flexural behavior of biaxial and rib weft-knitted composite is obtained numerically and experimentally. Multi-scale finite element modeling is employed to simulate the tensile and flexural behavior of composite samples. In the finite element modeling, the geometry of a unit cell of each fabric is initially modeled in ABAQUS software, and then periodic boundary conditions were applied to a unit cell. The stiffness matrix for each structure was obtained by a python code via meso scale modeling and used as input data for the macro modeling. To validate the numerical model, two types of weft-knitted fabrics (rib 1 × 1 and biaxial fabrics) are produced by a flat weft knitting machine. Epoxy resin is used to construct composite by the vacuum injection process (VIP). After that, the tensile and three-point bending tests were applied to composite samples. The experimental results showed that tensile strength and tensile modulus of biaxial composites are greater than rib composites, in both wale and course directions. Moreover, in three-point bending test, biaxial composite showed more strength and more stiffness in comparison to rib composite. Finite element results were compared to experimental results in tensile and bending tests. The results showed that good agreement with experimental results in the linear section of tensile and flexural behavior of composites. Consequently, the current multi-scale modeling can be used to predict the stiffness matrix and mechanical behavior of complex composite structures such as knitted composites.
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Hossen Beg, Md Dalour, Shaharuddin Bin Kormin, Mohd Bijarimi, and Haydar U. Zaman. "Effects of different starch types on the physico-mechanical and morphological properties of low density polyethylene composites." Journal of Polymer Engineering 35, no. 8 (October 1, 2015): 793–804. http://dx.doi.org/10.1515/polyeng-2013-0276.
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Abstract The aim of this research is to investigate the effects of different thermoplastic starches and starch contents on the physico-mechanical and morphological properties of new polymeric-based composites from low density polyethylene (LDPE) and thermoplastic starches. Different compositions of thermoplastic starches (5–40 wt%) and LDPE were melt blended by extrusion and injection molding. The resultant materials were characterized with respect to the following parameters, i.e., melt flow index (MFI), mechanical properties (tensile, flexural, stiffness and impact strength) and water absorption. Scanning electron microscopy (SEM) was also used in this study for evaluating blend miscibility. MFI values of all blends decreased as the starch content increased, while the sago starch formulation showed a higher MFI value than others. The incorporation of fillers into LDPE matrix resulted in an increased in tensile modulus, flexural strength, flexural modulus and slightly decreased tensile strength and impact strength. However, sago starch filled composites exhibited better mechanical properties as compared to other starches. The SEM results revealed that the miscibility of such blends is dependent on the type of starch used. The water absorption increased with immersion time and the thermoplastic sago starch samples showed the lowest percentage of water absorption compared with other thermoplastic starches.
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Ju, Minkwan, Kyoungsoo Park, and Cheolwoo Park. "Punching Shear Behavior of Two-Way Concrete Slabs Reinforced with Glass-Fiber-Reinforced Polymer (GFRP) Bars." Polymers 10, no. 8 (August 9, 2018): 893. http://dx.doi.org/10.3390/polym10080893.
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This study investigated the punching shear behavior of full-scale, two-way concrete slabs reinforced with glass fiber reinforced polymer (GFRP) bars, which are known as noncorrosive reinforcement. The relatively low modulus of elasticity of GFRP bars affects the large deflection of flexural members, however, applying these to two-way concrete slabs can compensate the weakness of the flexural stiffness due to an arching action with supporting girders. The test results demonstrated that the two-way concrete slabs with GFRP bars satisfied the allowable deflection and crack width under the service load specified by the design specification even in the state of the minimum reinforcement ratio. Previous predicting equations and design equations largely overestimated the measured punching shear strength when the slab was supported by reinforced concrete (RC) girders. The strength difference can be explained by the fact that the flexural behavior of the supporting RC beam girders reduces the punching shear strength because of the additional deflection of RC beam girders. Therefore, for more realistic estimations of the punching shear strength of two-way concrete slabs with GFRP bars, the boundary conditions of the concrete slabs should be carefully considered. This is because the stiffness degradation of supporting RC beam girders may influence the punching shear strength.
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Phani, M. Kalyan, Anish Kumar, T. Jayakumar, Walter Arnold, and Konrad Samwer. "Mapping of elasticity and damping in an α + β titanium alloy through atomic force acoustic microscopy." Beilstein Journal of Nanotechnology 6 (March 18, 2015): 767–76. http://dx.doi.org/10.3762/bjnano.6.79.
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The distribution of elastic stiffness and damping of individual phases in an α + β titanium alloy (Ti-6Al-4V) measured by using atomic force acoustic microscopy (AFAM) is reported in the present study. The real and imaginary parts of the contact stiffness k * are obtained from the contact-resonance spectra and by using these two quantities, the maps of local elastic stiffness and the damping factor are derived. The evaluation of the data is based on the mass distribution of the cantilever with damped flexural modes. The cantilever dynamics model considering damping, which was proposed recently, has been used for mapping of indentation modulus and damping of different phases in a metallic structural material. The study indicated that in a Ti-6Al-4V alloy the metastable β phase has the minimum modulus and the maximum damping followed by α′- and α-phases. Volume fractions of the individual phases were determined by using a commercial material property evaluation software and were validated by using X-ray diffraction (XRD) and electron back-scatter diffraction (EBSD) studies on one of the heat-treated samples. The volume fractions of the phases and the modulus measured through AFAM are used to derive average modulus of the bulk sample which is correlated with the bulk elastic properties obtained by ultrasonic velocity measurements. The average modulus of the specimens estimated by AFAM technique is found to be within 5% of that obtained by ultrasonic velocity measurements. The effect of heat treatments on the ultrasonic attenuation in the bulk sample could also be understood based on the damping measurements on individual phases using AFAM.
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Likittheerakarn, Suppawat, Supawadee Kurdpradid, Nanthapon Smittipornpun, and Thtitima Sritapunya. "Comparison of Mechanical Properties of Biocomposites between Polybutylene Succinate/Corn Silk and Polybutylene Succinate/Cellulose Extracted from Corn Silk." Key Engineering Materials 737 (June 2017): 275–80. http://dx.doi.org/10.4028/www.scientific.net/kem.737.275.
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Corn silk (CS) is agricultural wastes with high cellulose content and polybutylene succinate (PBS) now is more interesting in production of plastic products due to be biopolymer and high flexibility but it is lack of stiffness and strength. Therefore, the goal of this work was to study the possibility of cellulose extraction from CS fiber which was characterized by Fourier Transform Infrared Spectrometer (FTIR) for using cellulose as a reinforcing filler in PBS. Moreover, the mechanical properties (e.g. flexural and impact testing) of PBS/cellulose biocomposite were investigated and compared with that of neat PBS and PBS biocomposite adding various amounts of sodium hydroxide (NaOH) treated CS. The FTIR results showed the contents of hydroxyl (-OH) and ketone (C=O) groups in extracted CS were lower than ones of virgin CS. It was indicated that hemicellulose and lignin were more removed during extraction process, finally obtained ‘cellulose’. For mechanical testing, both cellulose and treated CS filled in PBS affect the decreased impact strength of PBS biocomposites while flexural strength and flexural modulus were increased. Furthermore, the flexural properties were reduced with enhancing filler contents from 1-15 phr for both fillers. By comparison, the flexural properties of PBS/cellulose were slightly lower than that of PBS/treated CS whereas its impact property was quite higher, especially for 10 phr cellulose loading. Therefore, cellulose can be taken more advantage for composite production by ductile property retention of PBS compared with treated CS. In addition, both cellulose and treated CS can be use as reinforcing filler for polymer to improve stiffness and strength.
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Zhang, Liwen, Zuqian Jiang, Wenhua Zhang, Sixue Peng, and Pengfei Chen. "Flexural Properties and Microstructure Mechanisms of Renewable Coir-Fiber-Reinforced Magnesium Phosphate Cement-Based Composite Considering Curing Ages." Polymers 12, no. 11 (October 31, 2020): 2556. http://dx.doi.org/10.3390/polym12112556.
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As a renewable natural plant fiber, Coir fiber (CF) can be used to as an alternative to improve poor toughness and crack resistance of magnesium phosphate cement (MPC), replacing such artificial fibers as steel fiber and glass fiber and thereby reducing huge energy consumptions and large costs in artificial fibers’ production and waste treatment. Aiming at examining the effects of CF volume concentrations on MPC flexural properties, this study employed a typical three-point bending test, including thirty cuboid specimens, to investigate the flexural strength, load-deflection behavior, and flexural toughness of MPC with different CF volume concentrations from 0% to 4% at the curing age of seven days and 28 days. Results demonstrated that CF presented similar effects on MPC’s properties at two curing ages. At both curing ages, as CF grew, flexural strength increased first and then decreased; specimen stiffness, i.e., MPC elastic modulus, displayed a decreasing trend; and flexural toughness was improved continuously. Additionally, modern microtesting techniques, such as, scanning electron microscopy (SEM) and energy dispersive X-ray detection (EDX), were adopted to analyze the microstructure and compositions of CF and specimens for explaining the properties microscopically.
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Sultaniya, Amit, Jeffrey A. Priest, and C. R. I. Clayton. "Impact of formation and dissociation conditions on stiffness of a hydrate-bearing sand." Canadian Geotechnical Journal 55, no. 7 (July 2018): 988–98. http://dx.doi.org/10.1139/cgj-2017-0241.
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Methane gas recovery from gas hydrate–bearing sands requires dissociation of the hydrate. Understanding changes in the stiffness of the sand is essential if future production scenarios are to be modelled realistically. This paper reports the results of resonant column tests conducted to measure changes in shear and flexural Young’s modulus (stiffness) of sand specimens during the formation and dissociation of hydrate within the pore space. Factors such as hydrate saturation, effective stress, and dissociation method (thermal stimulation and depressurization) were evaluated. Results show a nonlinear relationship between stiffness and hydrate volume, with hydrate formation and dissociation giving markedly different changes in stiffness. Stiffness increases more slowly during the initial stages of hydrate formation, compared to later stages, with the eventual stiffness being independent of the effective stress applied at the start of formation. In contrast, the onset of dissociation leads to a rapid reduction in stiffness, with thermal stimulation giving a greater reduction compared to depressurization for similar changes in hydrate volume. These results highlight the impact of hydrate morphology on changes in stiffness during the hydrate formation process or its dissociation. We present and discuss a conceptual model to explain the differences observed.
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Gu, Yin, Wei Dong Zhuo, and Yu Ting Qiu. "Static Behavior of Layered Fiber Reinforced Concrete T-Shaped Beam." Advanced Materials Research 168-170 (December 2010): 2037–43. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.2037.
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This paper proposes a concept of layered fiber reinforced concrete (LFRC) beam. In the concept of a LFRC beam, low-modulus fiber and high-modulus fiber are randomly dispersed and uniformly distributed into the concrete matries of the compression and tension zones, respectively. The static behaviors of LFRC beam are investigated from both experimental and numerical aspects. Four-point bending tests are performed on two simply supported T-shaped LFRC beam specimens and an ordinary T-shaped RC beam specimen with large scales. Comparison between the testing results of LFRC and RC beam specimens shows that the initial cracking load, flexural toughness and post-yielding stiffness of a LFRC beam can be significantly improved, but the ultimate loads are nearly without change. Numerical simulations are also carried out to investigate the static behaviors of the LFRC beam specimens. It is found that the simulation results are agreed well with that of tests. Further numerical parameter analysis for the LFRC beam specimens is conducted. The effects of high-modulus fiber volume fraction on the static behaviors of LFRC beams are studied. The research results show that the additions of high-modulus fibers have little effect on the initial stiffness, yielding loads and ultimate loads of LFRC beams; both the load and displacement at the initial cracking point increase linearly with the increasing volume fraction of the high-modulus fiber, but both the yielding displacement and ultimate displacement decrease linearly with the increasing volume fraction of the high-modulus fiber.