Dynamic Young’s modulus

The dynamic viscoelastic properties of acetylated wood have been determined and compared with other wood treatments in a number of studies. Both the specific dynamic Young s modulus (E /j) and tan S are lower in acetylated wood compared with unmodified wood (Akitsu etal., 1991, 1992, 1993a,b Korai and Suzuki, 1995 Chang etal., 2000). Acetylation also reduces mechanosorptive creep deformation of the modified wood (Norimoto etal., 1992 Yano etal, 1993). In a study of the dynamic mechanical properties of acetylated wood under conditions of varying humidity, it was concluded that the rate of diffusion of moisture into the wood samples was not affected by acetylation (Ebrahimzadeh, 1998). 

Kohara,J., Okamoto.H. Dynamic Young s modulus and piezoelectric... 

Dynamic mechanical properties of PO- or BO-treated wood were recently investigated in relation to their structure at both the cellular and the molecular level [43]. The chemical treatment reduced the specific dynamic Young s modulus E /y. 

Yano et al. [53] studied acoustic properties of acetylated Sitka spruce by specific dynamic Young s modulus and by logarithmic decrement. For oven-dried specimens, both the modulus and the decrement have been found to increase. Meanwhile, mechanical properties are generally unchanged and adhesive strength is reduced by acetylation [2]. Furthermore, creep deformation of wood under humidity change is remarkably reduced by acetylation [54]. 

Dynamic specific modulus E /y, the ratio of dynamic Young s modulus to specific gravity, and loss tangent tan 8 can be used to study the viscoelastic nature of wood. E /y is related to sound velocity and tan 8 to sound absorption or damping within the wood. A large E /y and small tan 8 characterize the acoustic quality of soundboard wood [3]. 

BENDING OF A BEAM. The complex dynamic Young s modulus can be determined from the forced, non-resonant oscillations of a single or double cantilever beam. The apparatus considered in this paper is the Dynamic Mechanical Thermal Analyzer (DMTA) (6), manufactured by Polymer Laboratories, Inc. Figure 3 shows the experimental setup for the single cantilever measurement. A thin sample is clamped at both ends. One end is attached to a calibrated shaker through a drive shaft. 

A transfer function technique for the determination of the dynamic Young s modulus and loss tangent has been described. Algorithms for performing time-temperature superposition have been discussed. 

Figure 2. Dynamic Young s modulus E of polystyrene (PS), high impact polystyrene (HIPS), separated gel, and crosslinked poly-butadiene rubber. Data from Ref. 17.

Figure 8. Dynamic Young s modulus E and loss factor d of two ABS materials containing grafted and ungrafted latex rubber respectively (29)...

Cl 198-01 Test Method for Dynamic Young s Modulus, Shear Modulus, and Poisson s Ratio for Advanced Ceramics by Sonic... 

FIGURE 8.18 Influence of pre-strain on the dynamic Young s modulus at standard conditions (65% RH, 21 °C). (From Meredith R., Mechanical Properties of Textile Fibers, Inter-science Publishers, New York, 1956.)... 

FIGURE 15. Dynamic Young s Modulus versus temperature for MoSi2-PSi3N4 materials. MS-70 and MS-80. 

ASTM C 1259, Test method for dynamic Young s modulus, shear modulus, and Poisson s ratio for advanced ceramics by impulse excitation of vibration. Annual Book of ASTM Standards, Vol. 15.01, American Society for Testing and Materials, West Conshohocken, PA (2001). 

FIGURE 60.2. Velocity versus frequency for butyl rubber. The dynamic Young s modulus as a function of frequency for butyl rubber [3]. Reprinted with permission from R.S. Witte, B.A. Mrowca, and E. Guth, Journal of Applied Physics, 20, 481 (1949). Copyright 1949, American Institute of Physics. 

Dynamic Young s modulus (EJ of wood was also calculated using free-free vibration testing. A significant increment was obtained for the PF-Nanoclay impregnated WPNC samples. 

M.S. Islam, S. Hamdan, I. Jusoh, M.R. Rahman, and Z.A. Talib, Dimensional stability and dynamic young s modulus of tropical light hardwood chemically treated with methyl methacrylate in combination with hexamethylene diisocyanate crosslinker. Ind. Eng. Chem. Res. 50, 3900-3906 (2011). 

The development of the WPCs for load-bearing structural applications necessitates the characterization of their strain rate-dependent mechanical properties. In this regard, the effect of strain rate on flexural properties of WPG was addressed by Tamrakar and Lopez [49]. The strain at failure was not significantly influenced by the strain rate variation. A prediction model for the effects on strain rate on the modulus of elasticity (MOE) of WPG material was demonstrated based on the viscoelastic standard solid model. Yu et al. [50] analyzed the variability of the dynamic young s modulus of WPG, which was measured by different non-destructive test (NDT) methods. They also estimated the correlativity between the dynamic Young s modulus and the static MOE of WPG. 

Table II, Dynamic Young s Modulus and Internal Friction of Several Fibrous Composites at Room Temperature... 

ASTM C-1259 Dynamic Young s modulus, shear modulus, and Poisson ratio for advanced ceramics by impulse excitation of vibration... 

Dynamic viscoelastic characteristics of CPE fibers (dynamic Young s modulus E and mechanical loss tangent tan 8) as a function of temperature were studied by examining low-frequency acoustic properties of the fibers with a resonance techniques that uses longitudinal vibrations of vertically suspended fiber. This method and its advantages, as well as... 

FIG. 7-4. Apparatus of Ballou and Smith for measurement of dynamic Young s modulus of fibers by free vibrations. 

FIG. 7-5. Apparatus of Fujino, Kawai, and Horino for measurement of dynamic Young s modulus of fibers by free vibrations. (A. A ) Chucks (B) sample fibers (C) clamps (D) inertial disc (E) idler pulleys (F) piano wire (C) mirror to reflect light beam (H) weight to adjust static tension. 

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