Injected Pultrusion IP

Injected pultrusion is a process in which fiber preforms are pulled through a mold where the liquid resin is injected into the fibers and then heated until the desired degree of cure in the 

The reinforcement phase is not stationary in IP hence, when performing conservation of mass, momentum, and energy this point has to be taken into consideration. In the IP process, the resin has a relatively constant density (i.e., it does not reach gel point until the end of the 

Since the fiber phase is not stationary, the surface integral cannot be set to zero without further considerations. As shown earlier, dBr/dt = 1/V js Ur hids (see Eq. 5.10). Because der/dt = 0 in the IP process, the contribution of the surface integral to the overall mass balance is negligible. Based on this observation Equation 5.50 can be simplified mid the appropriate equation for a conservation of mass in this process can be obtained (i.e., V Ur) = 0). Using this, Equation 5.18 can be simplified and the appropriate species balance equation for the IP process can be obtained. This equation is similar to the equation obtained for the RTM process. 

The movement of the fiber phase has to be specifically taken into consideration in the momentum transfer equation. Hence, in absence of significant inertial forces (i.e., Rep l)3 Equation 5.28 must be modified to account for the movement of the fiber phase, 

If one assumes that the resin has a constant density and thermal conductivity, an energy equation for the IP process can be obtained by simplifying Equation 5.41. First by using the mass balance equation (i.e., V (Ur) — 0) one of the convective heat transfer terms in the resin phase can be neglected. Another term can be neglected by setting V (Uf ) = 0. This assumption is justified since in the IP process der/dt = 0. 

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