Abstract
Compliant mechanisms are designed to allow great flexibility in motion in order to reduce the number of mechanical parts needed, and are especially useful for micro-mechanical devices. The problem described here is the design of a two-dimensional liquid nozzle aiming to be used as the injection nozzle of an ink-jet printer. A flexible wall controls the injection, which is assumed to be linearly elastic even with large deformation. The analysis is performed with the spring-segment model. The fluid is assumed to be in ideal flow and analyzed using the finite element method. We first present the formulation of the coupled fluid-structure interaction analysis, and subsequently derive the sensitivity of the outlet width with respect to the design parameters. The relationship between the outlet width and the design parameters is then first-order approximated. The values of the design parameter changes are determined by means of the Moore-Penrose generalized inverse so as to realized the objective value of the outlet width for a certain inlet velocity and pressure. The structural renewal is then iterated to correct the error of the first-order approximation. A Numerical example validating the proposed design methodology is finally presented.
