Full-field fiber trajectory motion simulation and distribution verification of complex components based on three-dimensional winding technology

Three-dimensional winding technology is an emerging composite preform manufacturing technology, which can solve the problem of large-angle fiber placement in complex core molds through robot-assisted winding, and make circular winding for core molds with arbitrary geometrical shapes within a certain length. However, the control method of 3D winding is still immature, and the winding trajectories of shaped core molds are complicated and diverse, and the resulting fiber trajectories are difficult to predict. In order to solve the above problems, the objective of this study is to establish a high-precision kinematic simulation model for the working mode and control strategy of 3D winding, which can quickly simulate the winding process by inputting the key control parameters required for 3D winding and accurately obtain the results of the full-field fiber trajectory on the surface of the core mold, so as to provide reliable process guidance for the actual 3D winding work.

Applying the mesh reconstruction method to re-grid the core molds of various complex structures is a necessary prerequisite to achieve high-precision simulation. Firstly, the core mold is sliced along the centerline direction, and the slice spacing can be selected from 0.01mm to 10mm; then the intersection points of the core mold boundary and the slices are used to reconstruct a uniform mesh; finally, the normal vector and the direction of the reference vector field are determined in each mesh, which are used as the benchmarks for the calculation of the fiber angle on the surface of the complex core mold. The helical trajectory of the 3D winding filament nozzle around the core mold can be calculated using the rigid-body rotation matrix, and the helical trajectory of the filament nozzle is also controlled by controlling the deflection angle of the helix step from the rotation plane. The kinematic simulation method is used to simulate the motion trajectory of the filament nozzle to deposit the fibers on the surface of the core mold and to predict the fiber trajectory. Through the principle of fiber deposition, the theoretical numerical calculation method is used to calculate the formula for the three-dimensional winding angle of fibers facing an arbitrary polygonal straight tube mandrel, and the quadrilateral straight tube mandrel is used as an example to compare the simulation results with the theoretical calculation results. Finally, by using KUKA-KR250 series robot with slide table and infinite rotary ring to form the 3D winding equipment, a rectangular pipe mandrel with variable cross-section and curvature of 2m in length is wound with variable step and deflection angle, and the surface density is used as the basis for comparison and verification with the simulation results.

The comparison between the before and after mesh reconstruction shows that the simulation results without mesh reconstruction of the mandrel will fluctuate greatly and have serious distortion during the small-step winding process, while the simulation results of the reconstructed mandrel are smooth and stable, and the trend of change is obvious. From the comparison of the theoretical numerical calculation and kinematic simulation of the quadrilateral straight tube mandrel winding, it can be seen that the simulation error is less than 0.2%, and the simulation calculation process takes only a few seconds to complete. In the field test, the mandrel with maximum curvature is divided into two segments, A and B, and the three-dimensional winding rotating ring wraps around the segments A and B with different deflection angles. The simulation prediction shows that in the first set of tests without deflection angle, the difference of the average surface density between the inner and outer fibers of A and B segments is , . In the third set of deflection angle of 20° conditions , . It can be seen that a uniform decrease of 20° from 90° decreases the difference between the inner and outer face densities of section A by , while a uniform increase of 70° to 90° in section B increases the difference between the inner and outer fiber densities by . Meanwhile, the accuracy of the simulation method is verified by comparing the results of the surface density measurement at selected points of the winding fibers with the simulation results.Conclusion: (1) Based on the kinematics method and the working mechanism of 3D winding technology, a simulation algorithm for 3D winding technology has been realized, and the full-field fiber trajectory can be quickly solved by the proposed control strategy with variable stepping and deflection angle as input conditions. (2) The mesh reconstruction of the core model enables the 3D winding simulation to predict the fiber trajectory for various kinds of complex structures, which is also a necessary precondition for the realization of high-precision simulation. (3) By comparing the winding angles obtained from the straight helical and oblique helical winding of a rectangular straight tube mandrel with the kinematic simulation results, the simulation error is less than 0.2%. By comparing the kinematic simulation and field test results of rectangular mandrel with variable cross-section and variable curvature, it is verified that the fiber trajectory prediction of the kinematic simulation algorithm is highly reliable for complex components. (4) The two control parameters of winding step and deflection angle of rotating ring directly affect the fiber trajectory in the whole field. The fiber surface density decreases as the step increases, and the speed of the deflection angle change is the key to change the size of the surface density. In the simulation test of the bending mandrel, the faster the deflection angle decreases, the smaller the difference between the inner and outer fiber densities, and the faster the deflection angle increases, the larger the difference between the inner and outer fiber densities.