Research On Design Method Of Axial Gradient Structure Annular Braid

The circular braiding technique is generally used for manufacturing a fiber-reinforced composite structural with a hollow structure,which has the characteristics that the structural component is formed once and has high integrity.Due to the fact that in the application of fiber reinforced composites,the different parts of the same component may be subjected to different forces and local damage may occur at the stress concentration,it is necessary to increase the strength in the weak parts of the components.The angle between the fiber and the axial direction,the braiding angle,is the most intuitive parameter reflecting the strength of the three-dimensional braided structural component.In this paper,the tow trajectory prediction algorithm and the take-up speed inverse algorithm are proposed for the equal-section mandrel to solve the problems above.The relevant research background of circular braiding technique and the current research status at home and abroad are introduced first.Then,from the braiding process of the circular braiding technique,the components of the circular braiding process and its motion state are introduced.In order to facilitate the analysis of the circular braiding process,the complex braiding machine's components and motion state are simplified into a mathematical model.Based on the traditional method,the tow trajectory prediction algorithm is proposed.The algorithm is based on the idea of finite element and iterative method in traditional method.It can be used to predict the tow trajectory of any equal-section mandrel.Once the braiding parameters are inputted,the tow trajectory can be calculated automatically.Meanwhile,based on the idea of finite element method and dichotomy method combined with trajectory prediction algorithm,the inverse algorithm of velocity variation curve corresponding to the change of braiding angle is obtained.Then the related experiments were carried out to study the influence of different winding speeds on the braiding angle.The conclusions were drawn as follows:for the equal-section mandrel,other process parameters,such as rotating angular velocity and guiding ring radius,are unchanged,as the take-up speed increases,the value of the specific braiding angle at the steady state is reduced.At the same time,the initial value of the braiding angle is independent of the magnitude of the take-up speed and does not change with the change of the take-up speed.Finally,the effectiveness of the inverse algorithm of the velocity curve is verified.The influence of the algorithm parameters,the number of subdivided edges,on the simulation results is discussed.The variation law of the velocity curve and its causes are analyzed.the uniform law is gained when can obtain of can be obtained with three different types of braiding angle variation curve.