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Critical Strains

Gic Mode I plane strain critical strain energy release rate (J m-2)... [Pg.76]

The fracture behaviour of polymers, usually under conditions of mode I opening, considered the severest test of a material s resistance to crack initiation and propagation, is widely characterised using linear elastic fracture mechanics (LEFM) parameters, such as the plane strain critical stress intensity factor, Kic, or the critical strain energy release rate, Gic, for crack initiation (determined using standard geometries such as those in Fig. 1). LEFM... [Pg.80]

Fig. 2. Critical-current degradation in a multifilamentary NbTi Cu composite as a function of stress and strain. Critical current, /c, is expressed as a fraction of the initial unstrained critical current, Icq. Data points are indicated by the solid circles, x s mark the maximum load point for the two fatigue tests shown in Fig. 3. Fig. 2. Critical-current degradation in a multifilamentary NbTi Cu composite as a function of stress and strain. Critical current, /c, is expressed as a fraction of the initial unstrained critical current, Icq. Data points are indicated by the solid circles, x s mark the maximum load point for the two fatigue tests shown in Fig. 3.
Electroporation. When bacteria are exposed to an electric field a number of physical and biochemical changes occur. The bacterial membrane becomes polarized at low electric field. When the membrane potential reaches a critical value of 200—300 mV, areas of reversible local disorganization and transient breakdown occur resulting in a permeable membrane. This results in both molecular influx and efflux. The nature of the membrane disturbance is not clearly understood but bacteria, yeast, and fungi are capable of DNA uptake (see Yeasts). This method, called electroporation, has been used to transform a variety of bacterial and yeast strains that are recalcitrant to other methods (2). Apparatus for electroporation is commercially available, and constant improvements in the design are being made. [Pg.247]

One of the most important appHcations of LEFM is to estimate the critical crack or defect size which causes fast fracture to occur. This occurs when the value of iCin a stmcture becomes equal to the plain strain fracture toughness, of the material the critical crack size, for a given stress and fracture toughness, is then given by equation 31. [Pg.90]

An even wider range of wavelength, toward the infrared, can be covered with quantum well lasers. In the Al Ga As system, compressively strained wells of Ga In As are used. This ternary system is indicated in Figure 6 by the line joining GaAs and In As. In most cases the A1 fraction is quite small, X < 0.2. Such wells are under compressive strain and their thickness must be carefully controlled in order not to exceed the critical layer thickness. Lasers prepared in this way are characterized by unusually low threshold current density, as low as ca 50 A/cm (l )-... [Pg.131]

The strength of laminates is usually predicted from a combination of laminated plate theory and a failure criterion for the individual larnina. A general treatment of composite failure criteria is beyond the scope of the present discussion. Broadly, however, composite failure criteria are of two types noninteractive, such as maximum stress or maximum strain, in which the lamina is taken to fail when a critical value of stress or strain is reached parallel or transverse to the fibers in tension, compression, or shear or interactive, such as the Tsai-Hill or Tsai-Wu (1,7) type, in which failure is taken to be when some combination of stresses occurs. Generally, the ply materials do not have the same strengths in tension and compression, so that five-ply strengths must be deterrnined ... [Pg.14]

Forming Limit Analysis. The ductihty of sheet and strip can be predicted from an analysis that produces a forming limit diagram (ELD), which defines critical plastic strains at fracture over a range of forming conditions. The ELD encompasses the simpler, but limited measures of ductihty represented by the percentage elongation from tensile tests and the minimum bend radius from bend tests. [Pg.223]

Expansion strains may be taken up in three ways by bending, by torsion, or by axial compression. In the first two cases maximum stress occurs at the extreme fibers of the cross section at the critical location. In the third case the entire cross-sectional area over the entire length is for practical purposes equally stressed. [Pg.987]

B/ Fragmentation rate g/s Ib/s (AL/Ll Critical agglomerate deformation strain ... [Pg.1821]

G. Critical strain energy release rate J/m J/m U Fluidization gas velocity cm/s ft/s... [Pg.1821]

FIG. 20-70 The influence of moisture as a percentage of sample saturation S on granule deformabihty. Here, deformation strain (AL/L) is measured as a function of applied stress, with the peak stress and strain denoted by tensile strength and critical strain (AL/L) of the material. Dicalcium phosphate with a 15 wt % binding solution of PVP/PVA Kolhdon VAG4. [Holm et al., Powder Tech., 43, 213 (1.9S.5J,] With land permission from Elsevier Science SA, Lausanne, Switzerland. [Pg.1883]

The critical strain energy release rate is the energy equivalent to fracture toughness, first proposed by Griffith [Phil. Trans. Royal Soc., A22I, 163 (1920)]. They are related by... [Pg.1887]


See other pages where Critical Strains is mentioned: [Pg.549]    [Pg.549]    [Pg.266]    [Pg.168]    [Pg.465]    [Pg.72]    [Pg.516]    [Pg.562]    [Pg.496]    [Pg.50]    [Pg.234]    [Pg.549]    [Pg.549]    [Pg.266]    [Pg.168]    [Pg.465]    [Pg.72]    [Pg.516]    [Pg.562]    [Pg.496]    [Pg.50]    [Pg.234]    [Pg.102]    [Pg.102]    [Pg.252]    [Pg.203]    [Pg.311]    [Pg.541]    [Pg.542]    [Pg.542]    [Pg.544]    [Pg.548]    [Pg.324]    [Pg.116]    [Pg.130]    [Pg.150]    [Pg.248]    [Pg.299]    [Pg.494]    [Pg.366]    [Pg.461]    [Pg.138]    [Pg.403]    [Pg.52]    [Pg.1443]    [Pg.1882]    [Pg.1887]   
See also in sourсe #XX -- [ Pg.12 , Pg.17 , Pg.18 , Pg.32 , Pg.73 , Pg.90 , Pg.93 , Pg.96 , Pg.103 ]

See also in sourсe #XX -- [ Pg.435 , Pg.463 ]




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