فهرست نشریات علمی دسترسی آزاد ایران

We discuss the asymptotic behaviour of solutions for the nonlocal quasilinear hyperbolic problem of Kirchhoff Type \[ u_{tt}-\phi (x)||\nabla u(t)||^{2}\Delta u+\delta u_{t}=|u|^{a}u,\, x \in \mathbb{R}^{N} ,\,t\geq 0\;,\]with initial conditions $u(x,0) = u_0 (x)$ and $u_t(x,0) = u_1 (x)$, in the case where $N \geq 3, \; \delta \geq 0$ and $(\phi (x))^{-1} =g (x)$  is a positive function lying in $L^{N/2}(\mathbb{R}^{N})\cap L^{\infty}(\mathbb{R}^{N})$. It is proved that, when the initial energy \ $ E(u_{0},u_{1})$, which corresponds to the problem, is non-negative and small, there exists a unique global solution in time in the space \ ${\cal{X}}_{0}=:D(A) \times {\cal{D}}^{1,2}(\mathbb{R}^{N})$. When the initial energy $E(u_{0},u_{1})$ is negative, the solution blows-up in finite time. For the proofs, a combination of the modified potential well method and the concavity method is used. Also, the existence of an absorbing set in the space ${\cal{X}}_{1}=:{\cal{D}}^{1,2}(\mathbb{R}^{N}) \times L^{2}_{g}(\mathbb{R}^{N})$ is proved and that the dynamical system generated by the problem possess an invariant compact set ${\cal {A}}$ in the same space.Finally, for the generalized dissipative Kirchhoff's String problem\[ u_{tt}=-||A^{1/2}u||^{2}_{H} Au-\delta Au_{t}+f(u) ,\; \; x \in \mathbb{R}^{N}, \;\; t \geq 0\;,\]with the same hypotheses as above, we study the stability of the trivial solution $u\equiv 0$. It is proved that if $f'(0)>0$, then the solution is unstable for the initial Kirchhoff's system, while if $f'(0)<0$ the solution is asymptotically stable. In the critical case, where $f'(0)=0$, the stability is studied by means of the central manifold theory. To do this study we go through a transformation of variables similar to the one introduced by R. Pego.