Radial single point rupture solutions for a general MEMS model

TL;DR

This paper analyzes a class of nonlinear differential equations modeling MEMS devices, establishing existence, uniqueness, and qualitative properties of radial rupture solutions, and exploring their bifurcation behavior.

Contribution

It provides new results on the existence, uniqueness, and qualitative analysis of radial rupture solutions for a general MEMS model with power nonlinearities.

Findings

Existence and uniqueness of rupture solutions

Asymptotic behavior near the origin

Bifurcation diagram characterization

Abstract

We study the initial value problem $$ \begin{cases} r^{-(\gamma-1)}\left(r^{\alpha}|u'|^{\beta-1}u'\right)'=\frac{1}{f(u)} & \textrm{for}\ 0<r<r_0,\\ u(r)>0 & \textrm{for}\ 0<r<r_0,\\ u(0)=0, \end{cases} $$ for $\gamma>\alpha>\beta\geq 1$ and $f\in C[0,\bar u)\cap C^2(0,\bar u)$, $f(0)=0$, $f(u)>0$ on $(0, \bar u)$ and $f$ satisfies certain assumptions which include the standard case of pure power nonlinearities encountered in the study of Micro-Electromechanical Systems (MEMS). We obtain the existence and uniqueness of a solution $u^*$ to the above problem, the rate at which it approaches the value zero at the origin and the intersection number of points with the corresponding regular solutions $u(\,\cdot\,,a)$ (with $u(0,a)=a$) as $a\to 0$. In particular, these results yield the uniqueness of a radial single point rupture solution and other qualitative properties for MEMS models. The bifurcation diagram is also investigated.