On the basis of the elastic constants under different pressures, the phase transitions of LiFeAs and NaFeAs are researched by the

elastic stability criteria under isotropic pressure.

The

elastic stability coefficients decrease while the elastic-plastic stability coefficients increase.

Bolotin, Nonconservative Problems of the Theory of

Elastic Stability, Corrected and authorized edition.

Teory of

Elastic Stability, New York: Mc Graw- Hill, 541 p.

DISCUSSION: The use of elastic stable intramedullary nailing for the treatment of pediatric femoral shaft fractures is based on the principles of

elastic stability and balanced forces (achieved by using the nails of the same diameter).

Atay and Coskun investigated the

elastic stability of a homogenous and nonhomogenous Euler beam [33-39].

Studies of

elastic stability of uniform vertical and longitudinally stiffened girder plates subjected to bending moment and live loads are presented in [9-12].

Beaufait and Hoadley [8], Massalas [9], Lakshmanan [10], and Hui [11] proposed the static, dynamic, and

elastic stability analysis of a beam resting on a nonlinear elastic foundation.

The text is divided into 13 chapters dealing with various subjects, including beam analysis theory, plate analysis theory,

elastic stability and buckling, and fatigue.

Elastic stability of elastically supported columns under the effect of distributed forces was studied by Lee and Kuo in 1991 [5].

By the

elastic stability criteria under isotropic pressure, it is predicted that Y[Ni.sub.2][B.sub.2]C with tetragonal structure is mechanically stable in the pressure range of 0-5 GPa.

The analysis based on the physical and mathematical model enables exact identification of mechanism of

elastic stability.