Research On The Influence Of Geodesic Curvature Of Trajectory On The Tensile/Flexural Strength Of Composite Component

With the gradual development of automatic placement technology,the existing placement equipment has been able to achieve variable angle placement of fiber tows,making the placement angle continuously change in the same layer.Compared with the traditional laying mode of fixed angle,the variable angle laying of fibers can not only increase the flexibility of design,but also make full use of the directional characteristics of composites,making it possible to improve the performance of components or reduce the weight of components.Focusing on the variable stiffness laminates manufactured by AFP,this paper is aiming to study the influence of geodesic curvature of placement trajectory on the tensile and flexural properties of composite members.The main research contents are as follows:Firstly,the first part of this paper focus path trajectory of fiber curve laying.Based on the general requirements of trajectory design for AFP,the layability of trajectory is emphatically analyzed,and the factors affecting the trajectory layability are put forward.On the basis of previous studies,a new fiber placement curve path is proposed and its function is deduced.The expression of variable-angle curve layer structure is determined.Advantages and disadvantages of shifted method and parallel method for constructing variable stiffness laminates were discussed.Finally,shifted method is selected to construct variable-angle layers in this paper.Secondly,based on the classical laminate theory,the constitutive relation of the fiber angle-changing laminate is obtained.It is found that the internal force of the structure will change with the change of the fiber angle,which makes it possible to improve the mechanical properties of the laminate.Aiming at the problem that the analysis model of fiber curve lamination can not be created directly in ABAQUS,a variable angle laminate curve lamination analysis model is established by using discrete idea of MATLAB software,and the tensile and bending properties of traditional and variable angle laminates are simulated and analyzed by using ABAQUS finite element software.Then,based on the technology of automatic fiber placement,the geodesic curvature of the fiber laying track is analyzed,the technological parameters window of the experiment is determined,and the trajectory planning of the curve laying is carried out by using the idea of equal distance method.The design principles of three curve laying are put forward,and the actual laying experiment is carried out by means of the corresponding automatic laying equipment.And solidify the laminate.Finally,the relevant specimens were prepared,and the tensile and bending properties were tested on the mechanical testing machine.The experimental results show that:when the radius of geodesic curvature is 1000mm and the ratio of curvilinear ply is 50%,that is to say,the laminate samples with[<±12|0>/0/0]_scan obtain better comprehensive mechanical properties of tension and bending.At this time,the tensile strength is 1989MPa,and the bending strength is 1383MPa.Compared with the traditional laminates with 0 degree straight-line ply,the tensile strength decreases only 9.882%,while the bending strength increases 22.82%.Its guiding significance is that for some components with low tensile strength requirements,some tensile properties can be reduced appropriately to make the bending properties more greatly improved,so as to obtain components that satisfy the stress requirements.