A nonlinear control method for resin transfer molding

Abstract In performing permeability measurements on the fiber reinforced preforms typically used in the resin transfer molding (RTM) process, two types of fluid injection are commonly utilized: constant fluid pressure and constant fluid flow rate. The constant pressure condition is often enforced by placing the test fluid within a pressure pot and supplying a constant gas pressure, thereby forcing the fluid into the mold under a constant pressure. In the case of constant fluid flow rate, the fluid is often supplied by forcing a piston through a fluid‐filled cylinder at a constant rate of displacement through the use of a press or Instron machine. This paper presents a nonlinear control method for providing constant flow rate RTM processes with a pressure pot solely through the use of a regulator. Computer simulations of the control examined the effect of various parameters on the ability to maintain constant flow rate. Rectilinear flow experiments were carried out to evaluate the theoretical development. Experimental results are in good agreement with the computer simulations. Both computer simulations and experiments show significant promise for the proposed control methodology.