Dependence of flexural strength and

Carbon-Fiber Composites. Cured laminates of phenoHc resins and carbon-fiber reinforcement provide superior flammabiHty resistance and thermal resistance compared to unsaturated polyester and epoxy. Table 15 shows the dependence of flexural strength and modulus on phenoHc—carbon-fiber composites at 30—40% phenoHc resin (91). These composites also exhibit long-term elevated temperature stabiHty up to 230°C. 

Fig. 15. Microstructural dependence of flexural strength and fracture toughness of silicon nitride ceramics. The composition of these specimens was 90 wt % Si3N4-10 wt % Y3A15Op (27).

Waku, Y, Sakata, S. 1., Mitani, A., Shimizu, K., Hasebe, M. (2002). Temperature dependence of flexural strength and microstructure of Al Oj/YjAljOj /ZrO ternary melt growth composites. Journal of Materials Science, 37(14), 2975-2982. doi 10.1023/A 1016073115264. 

Figure 2. Dependence of flexural strength on polymer content of wood treated with GMA ( , TBTMA-MAnh (O), and TBTMA-GMA (A). The specimens had fibers parallel to their width.

Fig. 2.76 Temperature dependence of flexural strength of partially and fully stabilized zirconia single crystals, polycrystalline PSZ, and hot-pressed Si3N4 (HPSN). PSZ is partially stabilized Zr02 with Y2O3 [24], With kind permission of Wiley and Sons...

Those stmctural variables most important to the tensile properties are polymer composition, density, and cell shape. Variation with use temperature has also been characterized (157). Flexural strength and modulus of rigid foams both increase with increasing density in the same manner as the compressive and tensile properties. More specific data on particular foams are available from manufacturers Hterature and in References 22,59,60,131 and 156. Shear strength and modulus of rigid foams depend on the polymer composition and state, density, and cell shape. The shear properties increase with increasing density and with decreasing temperature (157). 

For the materials data given in Table 3-1 a GRP panel having 2.4 times the thickness of a steel panel has the same flexural stiffness but 3.6 times its flexural strength and only half its weight. The tensile strength of the GRP panel would be 50% greater than that of the steel panel, but its tensile stiffness is only 17% that of the steel panel. The designer s interest in this GRP panel would then depend in this context on whether tensile stiffness was what was required. 

Figures 10 and 11 show the weight change and the retention of strength for iso-phthalic unsaturated polyester resin (iso-UP). These behaviors show almost the same tendency as MTHPA-EP, however, as shown in Figure 12 the concentration influences flexural strength and the strength becomes minimum at the concentration of 30wt%. This behavior is thought to depend on contradictory tendency of the wetability and the reactivity with the concentration.

Glasses are purely elastic bodies at room temperature with elastic moduli between ca. 50 and 90 kN/mm. The flexural strength and tensile strength values (between 10 and 100 N/mm ) depend upon the quality of the surface. 

In Fig. 2 and Fig. 3, flexural strength and flexural modulus of the cured resin depending on the PET content are shown. It is observed that flexural modulus of the cured resin made from glycolyses product using PG is higher than... 

The fracture resistance of a material depends on all of the properties which have been discussed including tensile strength, yield stress, elastic modulus, flexural strength, and impact resistance, all of which depend, in part, on fillers. Fillers, consequently, are important determinants of fracture resis-Only those phenomena which are related... 

Minerals generally improve both flexural strength and flexural modulus of filled plastics and WPCs (Table 4.3), however, the extent of improvement is different for flex strength and flex modulus. Effect on flex strength is often not more than 10-20%. Effect on flex modulus can reach 200-400%, and it often depends on particle size of the filler and its aspect ratio. The higher the filler amount and the aspect ratio, the larger the effect of filler on flexural modulus (though not always, particularly that related to the filler amount). 

As it will be shown later in this chapter, flexural strength and modulus, and the ultimate load (load at break, or load at failure) are all proportionally dependent on the moment of inertia. Thus, it can be concluded right away that a break load of a GeoDeck board, whatever its length would be, for Heavy Duty board will be 240% (140% higher) of that for Traditional board or Tongue and Groove board (on a deck). 

Figure 2.16 Dependence of (a) flexural strength and (b) modulus on heat treatment for pitch C/BN.

Continuous carbon fiber reinforced SiC composites were prepared by Xu and Zhang [211] using CVI, in which the preforms were fabricated by the three dimensional braid method. For the composites with no interfadal layer, flexural strength and fracture toughness increased with the density of the composites and the maximum values were 520 MPa and 16.5 MPam , respectively. The fracture behavior was dependent on the interfacial bonding between fiber /matrix and fiber bundle/bundle, which was determined by the density of the composites. Heat treatment had a significant influence on the mechanical properties and fracture behavior. The composites with pyrolysis interfacial layers exhibited characteristic fracture and relatively low strength (300 MPa). 

Under three point bend loading of a composite (beam), cracks may be developed due to tensile stresses at the lower stratus of the specimen as well as compression stresses at the upper one, or due to interlaminar shear. The type of failure depends on the ratio of span to depth (L/D). Short beam specimens usually fail in shear and long ones by tensile or compression stresses. For interlaminar shear strength (ILSS) tests, a L/D = 5 was chosen (ASTM-D-2344-76). In case of flexural strength tests, this ratio was fixed to 40 (DIN 29971). 

In summary, the mechanical properties are presented in Figures 18.19 and 18.20. Both, the flexural strength and stiffness were remarkably improved, depending on the way of processing and the particular material composition chosen. Compared to the isotropic matrix materials or blends, the stretched and isotropized blend shows values which are clearly high-... 

Plastics are viscoelastic. Their behavior is partly elastic and partly that of a very viscous fluid. Properties of strength and rigidity vary with amount of stress, the rate of loading, and the temperature at which the stress is applied. Viscoelastic behavior requires performance tests to measure time dependence. The viscoelasticity of plastics also severely limits the usefulness of many short-time tests such as impact, tensile, and flexural strengths and modulus. Unfortunately, such test data are very widespread because they are easier and cheaper to obtain than time- and temperature-dependent information. These data can cause much confusion and disappointment when used for plastics. Short-time data are useful for quality control and specification purposes, and if properly interpreted, can shed some light on plastic performance. However, they cannot be used in design and are more often than not misleading because they do not account for the viscoelastic behavior of plastics. 

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