Mechanical properties static

Fibres do little to enhance the static compressive strength of concrete (e.g. [42-46]), with increases in strength ranging from essentially nil to perhaps 25% 

For very high volume steel fibre concretes, the effect of the fibres on the flexural strength can be quite dramatic. For some reactive powder concretes (RPC), flexural strengths can reach 60 MPa with about 2.4% fibres by volume, and 102 MPa with 8% fibres [60]. Ductal , another RPC, can achieve a flexural strength of about 45 MPa, with 2% by volume of 13-15 mm long fibres with diameters of 0.2 mm [61] similarly. Sun etal. [62] obtained strengths of about 60 MPa with 4% by volume of 13 mm long by 0.175 mm diameter fibres. 

As has been stated previously, fibres are added to concrete primarily to improve the toughness, or energy absorption capacity any improvements in strength are 

Steei fibres are widely recommended for use in conjunction with conventional steel reinforcement, in order to improve the shear resistance of structural elements (as discussed in some detail in Chapter 14). The fibres bridge across the cracks that form in the concrete matrix, and help to maintain the integrity of the material. This improvement in the residual strength of the matrix leads to an increase in the shear capacity (e.g. [64]). 

The data are similarly scattered for torsion, with different studies showing anything from no increase in torsional strength [68] to a 100% increase [69], with other studies showing intermediate values. 

The tensile, flexural and impact properties of PP, PET, neat blend and MFCs are given in Table 15.3. 

Sample Tensile strength (MPa) Tensile modulus (MPa) Elongation at break (%) Flexural strength (MPa) Flexural modulus (MPa) Impact strength (J/m) 

Several studies on the dynamic mechanical analysis of synthetic and natural fiber reinforced PP composites [74-77] were reported in the literature. Lopez et al [78] reported that the incorporation of the PET fibrils separately into the PP matrix increased the storage modulus (stiffness). They also reported a decrease in the tan values of the resultant composite in comparison with PP. Li et al [73] studied the d5mamic mechanical properties of a composite where in situ generated PA6 fibrils reinforced the PP matrix. The glass transition temperature of PP was found to be higher in the case of PP/PA6 in situ composite than in a neat PP/PA6 blend. 

The conspicuous feature of the current study is that storage and loss moduli, and mechanical loss factor of the MFCs prepared at different draw ratios are compared with those of neat PP and neat blend. To the best of our knowledge, no reports have been published pertaining to the effect of draw ratio on the dynamic mechanical properties of the MFCs. 

Normalized storage modulus can be defined as the ratio of the storage modulus of the composite to the storage modulus of the matrix at the same temperature. It is evident from the plot that as the draw ratio increases the normalized storage modulus increases, reaches a maximum value and then decreases. Also at a particular draw ratio, the normalized storage modulus increases with increase in temperature. This indicates the restriction of the mobility of the PP molecules due to the presence of the PET microfibrils at elevated temperatures. 

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Given the existence of interphases and the multiplicity of components and reactions that interact to form it, a predictive model for a priori prediction of composition, size, structure or behavior is not possible at this time except for the simplest of systems. An in-situ probe that can interogate the interphase and provide spatial chemical and morphological information does not exist. Interfacial static mechanical properties, fracture properties and environmental resistance have been shown to be grealy affected by the interphase. Careful analytical interfacial investigations will be required to quantify the interphase structure. With the proper amount of information, progress may be made to advance the ability to design composite materials in which the interphase can be considered as a material variable so that the proper relationship between composite components will be modified to include the interphase as well as the fiber and matrix (Fig. 26). 

Static mechanical properties of aerogels have been measured mainly by the three-point flexure test [54] or by direct longitudinal compression [55]. The... 

LOU 97b] Lourdin D., Bizot H., Colonna P., Correlation between static mechanical properties of starch-glycerol materials and low-temperature relaxation , Macromolecular Symposia, vol. 114, pp. 179-185,1997. 

Static mechanical properties in the vicinity of the nematic-isotropic transition in liquid single crystal elastomers (LSCEs) have been investigated [10, 11]. In Fig. 5 the deformation L/Lq (mon) is plotted as a function of the reduced temperature red- Here Lo(mon) denotes the length of the LSCE at the phase transition temperature of the nematic-isotropic phase transition and... 

Table 7.8 Examples of static mechanical properties of unidirectional fiber/epoxy RPs... 

Ducheyne, P. and Hench, L.L. (1982) The processing and static mechanical properties of metal fibre reinforced bioglass , J. Mater. Sci. 17, 595. Diffusion across a bioglass-metal interface. 

Kar Karger-Kocsis, J., Erdelyi, S., Nagy, G. Polyurea/vinylester hybrid thermoset resins with in situ produced silicate filler Preparation and static mechanical properties. J. Appl. Polym. Sci. 103 (2007) 853-859. 

This model proposes a functional differentiation of chromosomal and interpolar spindle fibers in good accord with the cytological features of prometaphase congression and separate poleward motion and spindle elongation in anaphase, with the static mechanical properties, and with the slight evidence for differences in chromosomal and interpolar fibers from their differing responses to colchicine and chloral hydrate (p. 245). Any more extended discussion is unwarranted until the motions of granules and displaced chromosomes have been fully described in a variety of forms specific predictions are readily formulated. 

The relationships between the static mechanical properties of trabecular bone and apparent density vary for the different types of trabecular bone because of the anatomic site-, age-, and disease-related variations in trabecular architecture. Both linear and power-law relationships can be used to describe the dependence of modulus and compressive strength on apparent density (Tables A2.2, A2.3), with typical coefficients of determination (r values) in the range 0.5-0.9. Differences in the predictive... 

B6.6 MECHANICAL PROPERTIES OF VEINS B6.6.1 Static mechanical properties of veins... 

Greenwald, S.E. and Berry, C.L. (1978) Static mechanical properties and chemical composition of the aorta of spontaneously hypertensive rats, a comparison with the effects of induced hypertension. Cardiovas. Res., 12, 364-372. 

Wolinsky H and Glagov S, Structural basis for the static mechanical properties of the aortic media , Circ. Res., 1964 14 400-413. 

Tencer AF, Ahmed AM, Burke DL (1982) Some static mechanical properties of the lumbar intervertebral joint, intact and injured. J Biomech Eng 104 193-201... 

Recall the HP relation, which summarizes the effect of grain size on some static mechanical properties. Experimental results indicate that the resistance of materials to fatigue-crack initiation and propagation is significantly influenced by grain size. This applies to ceramics as well. It is widely recognized that, when all the other structural factors are kept approximately fixed, an increase in grain size will... 

Various sophisticated techniques have been developed over the past decade or so, such that certain nanoceramics can now be produced with some measure of superplasticity. The present discussion will begin with static mechanical properties, such as the stress-strain relation and hardness. 

While TMA refers to a measurement of a static mechanical property, there are also techniques that employ dynamic measurement. In the torsional braid analysis (TEA), a sample is subjected to free torsional oscillation. The natural frequency and the decay of oscillations are measured. This provides information about the viscoelastic behavior of materials. However, these measurements are elaborate and time consuming. In dynamic mechanical analysis (DMA), a sample is exposed to forced oscillations. A large number of useful properties can be measured by this technique see also Section 6.2.6.5. 

Static Mechanical Properties Properties at Low Temperatures and Low Strain Rates. The flow stress of the transition metals Mo, W, Nb, and Ta is strongly dependent on temperature and a strain rate below a characteristic transition temperature 7k (corresponding to 0.1 to 0.2 of the absolute melting temperature) and plastic strain rates below lxl0 s [1.165]. As an example, experimental data on the temperature dependence of the flow stress of recrystallized Ta are shown in Fig. 3.1-157. This dependence has... 

Amundson, K.. and Helfand, E., Quasi-static mechanical properties of lamellar block copolymer microstructure. Macromolecules, 26, 1324-1332 (1993). 

Table 18-3. Static mechanical properties of cellulose film elastic modulus (E ), plastic modulus (E, yield strength (aj, ultimate strength (MPa)...

Natural rubber/cw-1,4-polybutadiene (NR/BR) blends (70/30 mass ratio) have been widely used in the tire industry. Many nanocomposites based on organo-montmorillonite (OMMT)/rubber blends have been investigated. However, relatively little attention had been paid to binary rubber hybrids/ montmorillonite nanocomposites, and according to Zheng Gu et ah, no studies existed dealing with OMMT/NR/BR nanocomposites. So, the authors described the preparation of OMMT/NR/BR nanocomposites by direct mechanical blending and determined the cure characteristics, static mechanical properties, dynamic mechanical properties, and thermal stability of the nanocomposites. OMMT/NR/BR nanocomposites had exactly the same onset decomposition temperature and lower thermal degradation rate as the NR/BR blends. 

The viscoelastic properties of polymers can be determined using H(r) or L(t), and the static mechanical properties can then be calculated from those spectra [1]-... 

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