Method for preparing a fiber-reinforced composite article by using computer-aided engineering

A method for forming an injection-molded fiber-reinforced thermoplastic composite article using a molding machine controlled by a control system connected to the molding machine, comprising steps of:

• forming a trial composite article made of a fiber-reinforced composite molding resin including a polymeric material having a plurality of fibers by injection molding using the molding machine under a trial molding condition, wherein the trial composite article has a trial fiber orientation distribution that indicates distribution of the fibers of the polymeric material in the trial composite article resulted from a flow of the fiber-reinforced composite molding resin during the injection molding, the injection molding being performed by injecting the fiber-reinforced composite molding resin into a metal mold through a molding nozzle by pressing the fiber-reinforced composite molding resin by a driving device;
• analyzing the trail fiber orientation distribution of the trial composite article formed under the trial molding condition and measuring physical yield stress parameters on a shear viscosity of the trial molding article and physical fiber orientation parameters of the trial composite article from the trial fiber orientation distribution of the trial composite article by performing a first molding simulation executed on the control system;
• by using the measured physical yield stress parameters on the shear viscosity of the trial composite article and the physical fiber orientation parameters of the trial composite article, generating a predicted fiber orientation distribution fitting with the trial fiber orientation distribution of the trial composite article;
• determining a real molding condition for the molding machine for forming a real composite article of the fiber-reinforced composite molding resin from the measured physical yield stress parameters on the shear viscosity of the trial composite article and the predicted fiber orientation parameters by using a second molding simulation executed on the control system, so as to adjust a fiber orientation distribution of the read composite article;
• and
• controlling the mold machine by the control system to injection-mold the real composite article under the real molding condition using the fiber-reinforced composite molding resin,
• wherein the physical yield stress parameters on the shear viscosity of the fiber-reinforced composite molding resin is represented using an expression:
• η
• ⁡
• (
• γ
• .
• ,
• T
• ,
• P
• )
• =
• τ
• y
• γ
• .
• +
• η
• 0
• ⁡
• (
• T
• ,
• P
• )
• 1
• +
• (
• η
• 0
• ⁢
• γ
• .
• τ
• *
• )
• 1
• -
• n
• τ
• y
• =
• τ
• y
• ⁢
• ⁢
• 0
• ⁢
• exp
• ⁡
• (
• E
• Y
• RT
• )
• where η represents a shear viscosity, {dot over (γ)} represents a shear rate, T represents a molding temperature, n and τ* represent constants, η0 represents a zero-shear-rate viscosity, τy0 represents a reference yield stress, Ey represents an activation energy of yield flow, T represents an absolute temperature, and R represents a gas constant.