Research On The Process Parameters Optimization And The Influence Of The Defects On The Mechanical Properties For Automatic Fiber Placement

Automated fiber placement, which integrated the technology of CAD/CAM, numerical control, heating, heating, combined the advantages of Automated Tape Laying and Filament Winding, is one of the most important forming technology of the advanced composite materials. Manufacturability of prepreg directly affects the quality of Automatic fiber placement, which is the guarantee of smooth during the Automatic fiber placement process, determining the quality of the product performance. This paper takes large composite component using domestic prepreg for automated placement as background. Then process carried out in straight and cured trajectory, using the Automated fiber placement equipment which self-developed by Nanjing University of Aeronautics & Astronautics. The author analyzed the influences of related parameters on the quality of Automatic fiber placement process to optimize these parameters. On the basis of the study above, the influence of the transverse gap and overlap on the mechanical properties was studied. Lay the foundation for the development of the technology in the future, and provide important reference for the specification of the production process.Considering the different laying surface during the process, the author discusses a new means to evaluation the quality of the process. The influences of these parameters(heating temperature, fiber compaction force and laying head speed).on the Automatic fiber placement process were analyzed by this means. Meanwhile, the author use response surface method to optimize the parameters of the prepreg.The author analyzed the common defects and initiation mechanism of towpreg during the process of curve Automated fiber placement on the plane. The author used the minimum turning radius to reflect the capacity of lateral deformation of prepreg, which characterized by effective bonding length ratio. Under a certain condition, the greater the effective bonding length ratio, the smaller the minimum turning radius, the stronger the capacity of lateral deformation of prepreg, the better the result of Automated fiber placement. The influences of these parameters on the Automatic fiber placement process were analyzed by this means. The results showed, with the increase of temperature, minimum turning radius is reducing until achieve minimum value. With the increase of pressure, minimum turning radius is insignificantly. With the increase of pressure velocity, minimum turning radius is increasing until achieve maximum value.Based on the unidirectional laminate, the authors designed transverse gap, overlap and defect free laminates by the variety of central distance of the prepreg during the transverse process using the automated fiber placement equipment. Then, the effects of the mechanical properties of the cured products were studied(on the containing defect layer, adjacent tow lateral clearance and overlap were 1mm). The result shows: a. the transverse gap makes the transverse tensile strength of the part decreased by 12.62% and the bending strength is 17.82%; but it has little effect on the longitudinal tensile strength, the part thickness and elastic modulus. b. Transverse overlap makes the transverse tensile strength increased by 3.35%, bending strength increased by 9.06%, and the thickness increased by 23.65%, while the tensile strength and elastic modulus of the parts was not affected obviously.