Area strain

Eyring pre-exponential factor Effective cross-sectional area of specimen Total cross-sectional area of specimen Area strain... 

Hooke s law. When a load is applied to any elastic body so that the body is deformed or strained, then the resulting stress (the tendency of the body to resume its normal condition) is proportional to the strain. Stress is measured in units of force per unit area, strain is the extent of the deformation. For example, when a bar of metal is subjected to a stretching load, the extent of the increase in length of the bar is directly proportional to the force per unit area, i.e., to the stretching load or stress. In general Hooke s law applies only up to a certain stress called the yield strength. 

General machine efficiency—delivery and location of product in pocket, extension of pocket area, strain on seal area, etc. 

THERAPEUTIC USES Proguanil as a single agent is not available in the U.S. but is prescribed in Europe for nonimmune travelers to malarious areas. Strains of P. falciparum resistant to proguanil emerge rapidly in areas where the drug is used exclusively, but breakthrough infections also may result from deficient conversion of this compound to its active antimalarial metabolite. 

Polymer (specific type) Prestrain (x, y%) Energy density (MJ Actuation pressure (MPa) Thickness strain (-%) Area strain (%) Young s modulus (MPa) Electic field (MV m ) Dielectric constant Dielectric loss factor Mechanical loss factor Coupling efficiency (%) Efficiency (%) Ref. 

When tested on VHB 4905 films prestrained biaxially by 300 x 300%, the electrodes provided an maximum area strain of 97% at 3 kV and demonstrated self-clearing with a preserved strain of 91% after the first clearing event. 

Ha SM, Yuan W, Pei Q, Pelrine R, Stanford S (2007) Interpenetrating networks of elastomers exhibiting 300% electrically-induced area strain. Smart Mater Struct 16 S280... 

The relative strain equals the absolute strain if there is zero prestrain in the film. The relative area strain is defined similarly, with the active planar area replacing length in the above expression. 

As indicated by the values, the VHB 4910 acrylic elastomer gave the highest performance in terms of strain and actuation pressure. Extensive lifetime tests have not been made, but acrylic films have been operated continuously for several hours at the 100% relative area strain level with no apparent degradation in relative strain performance. However, the acrylic elastomer has relatively high viscoelastic losses that limit its half-strain bandwidth (the frequency at which the strain is one-half of the 1-Hz response) to about 30-40 Hz in the circular strain test. By comparison, HS3 silicone has been used for prototype loudspeakers at frequencies as high as 2-20 kHz [16,17]. The acmation of CF19-2186 silicone, albeit at lower strains and fields than reported here, has been measured directly via laser reflections with full... 

Material Prestrain ix, y) (%) Actuated relative thickness strain (%) Actuated relative area strain (%) Field strength (MV/m) Effective compressive stress (MPa) Estimated Mle (MJW)... 

Before proceeding, some definitions are useful. Stress is the ratio of the force on a body to the cross-sectional area of the body. The true stress refers to the infinitesimal force per (instantaneous) area, while the engineering stress is the force per initial area. Strain is a measure of the extent of the deformation. Normal strains change the dimensions, whereas shear strains change the angle between two initially perpendicular lines. In correspondence with the true stress, the Cauchy (or Euler) strain is measured with respect to the deformed state, while the Green s (or Lagrange) strain is with respect to the undeformed state. 

Metal 0.2% Offset Yield Strength (kg/mm ) Ultimate Tensile (kg/mm ) Uniform Elongation (%) Reduction in area (%) Strain Hardening Exponent Strain Rate (Sec.- ) Strain Rate Sensitivity (e) Anneal Temp.. (K) Ref. ... 

Laminate strength related to the fibers area Strain at failure of fibers e b [%] ... 

Toughness. Membrane stability as defined by the maximal area strain c = (Ac -Ao)/Aq increases with increasing molecular weight, approaching a universal limit set by the interfacial tension. The sustainable critical strain is 0.19,... 

Fig. 20. Maximum area strain for lipid and block copol3maer bilayers as function of molecular weight. This experiment demonstrates the increased toughness of block copol3maer vesicles compared to lipid vesicles. From Ref 151, with permission from the ACS Publications Division.

This device used a diaphragm stracture with multilayer polymer elastomer as flie active material. A displacement of 2-6 mm in one strike was enough to deform flie elastomer films to more than 50 % area strain. This device produced an electrical energy output of 0.8 J/step or about 1 W. The output specific energy density of fliis device was 0.4 J/g (Kombluh et al. 2012 Pelrine et al. 2001). 

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