Key Issues In Automatic Fiber Placement For Compound Surfaces

With the continuous update of automatic placement equipment and the rapid promotion of automatic placement technology,automatic fiber placement has been widely used in the aerospace field.Placement path planning is an important part of automatic composite material placement.The quality of the planned placement path directly relates to the performance of the final component.Existing placement path planning methods are generally implemented on parametric surfaces or continuous surfaces,which have high requirements on the continuity and integrity of the surface.However,in the actual production process,the compound surfaces with poor continuity are often encountered.The geometric discontinuity between the individual patches makes the existing placement path planning method cannot be directly applied to the compound surface.Therefore,how to plan the placement path on the compound surface is an urgent problem to be solved.This paper improves the existing placement path planning method so that it can be applied to compound surfaces with poor geometric continuity.And through the CATIA CAA secondary development technology to write the corresponding software function module,verified the feasibility of the method.The core of the method includes the following two aspects: constructing a compound surface topology relationship table and quickly retrieving it;extending the path to adjacent patches while ensuring the continuity of the path.The B-rep structure is used to interact with CATIA CAA to obtain the topological relationship between the top surface of the compound surface and the boundary line,and to generate a topological structure table for quick retrieval.The existing placement path planning method is invoked on each individual patch.When the placement path is generated to the patch boundary,the topology table is used to quickly determine the adjacent surface,and the adjacent patch is determined under the constraints of path continuity and placement direction The starting point of the path allows the placement path to continue to be generated until the compound surface boundary.The specific research results of this article are as follows:(1)Investigated the development history and current situation of automatic fiber placement and placement path planning technology at home and abroad,and introduced commonly used placement path planning methods.The existing problems on the compound surface are analyzed.(2)A method for constructing the topological relationship of compound surfaces is proposed.Aiming at the compound surface in CATIA,a method for establishing the topological relationship of the compound surface based on the B-rep structure is proposed,and CAA is used for secondary development to obtain the topological relationship between the points,lines and surfaces in the compound surface,and to establish the topological structure table to facilitate Quick search.(3)A method for generating the initial placement path on the compound surface is proposed.The initial placement path is generated on the single-sided patch based on the discrete point information,and the termination condition for generating the path on the single-sided patch is determined.The topology table is used to quickly search the adjacent patches to determine the termination condition of the placement path on the compound surface.Consider the path continuity and placement direction constraints to determine the starting point of the placement path on the adjacent patch.(4)A placement path densification method on the combined surface is proposed.The topological structure table of the compound surface is used to retrieve the surface patches that the densified path passes through,and the boundary position is continuously processed.Finally,fitting and smoothing the equidistant path points to realize the equidistant densification of the fiber placement path on the compound surface.(5)Compose the compound surface placement path planning software.The secondary development of CATIA CAA was used to realize the placement path planning on the compound surface,and the effectiveness of the above placement path planning method was verified.