Three-dimensional Finite Element Analysis And Experimental Study On Macro-micro Mechanism Of CFRP Cutting

Carbon fiber reinforced plastic(CFRP)are advanced composites.They are widely used in aerospace and other fields because of their light weight,high specific strength and high specific modulus.CFRP is a kind of difficult-to-process material.It is easy to produce defects such as matrix cracking,matrix ablation,fiber breakage,fiber pullout,fiber matrix debonding and delamination during processing,and the formation of these defects is difficult to observe in actual processing.In order to explore the cutting mechanism of macro and micro CFRP,the three-dimensional modeling of macro and micro CFRP structure is carried out by using finite element technology.Four typical fiber orientations(0,45,90,135 degrees)are simulated and analyzed by using Abaqus/Explicit simulation software.The mechanism of fiber breakage and matrix breakage,chip formation and the effect of fiber orientation on cutting force and processing quality were studied by experiments.The specific contents of this paper are as follows:A three-dimensional micro-CFRP simulation model including fibers,matrix and interface phases was established.Fibers were cylindrical and randomly distributed in the matrix.Zero-thickness cohesion element was used to simulate the interface phases.Considering the constitutive,failure and evolution criteria of each material,the micro-CFRP model was simulated by using Abaqus/Explicit simulation software.The simulation results of cutting at different orientations focus on the breaking process of CFRP fibers,debonding of fibers and matrix,failure of interface phase and so on.A three-dimensional macro-CFRP simulation model based on equivalent mean method is established.Zero-thickness cohesion element is used to simulate the interface layer,and three-dimensional Hashin failure and damage evolution criterion is used to define material constitutive model based on VUMAT subroutine.In summary,the macro-CFRP model is used to simulate the right-angle cutting at different fiber orientations,and the formation process of CFRP chips at different orientations is elaborated in detail in connection with the macro-and micro-cutting failure process.At the same time,the influence of tool rake angle on chip,cutting force and machined surface was explored by using the macro CFRP model and single factor method.On the basis of macro and micro CFRP simulation,one-way CFRP cutting experiment is carried out.In order to ensure the comparability of the research results,the experiment adopts the same experimental parameters as the simulation.Cutting forces at different fiber orientations were collected during the experiment.After the experiment,the machined surface morphology and surface roughness were observed and compared with the simulation results of macro and micro CFRP.The results show that the surface of 0 CFRP is a mixture of fibers and matrix.At the micro-angle,the fibers matrix is distinct,and the fibers are broken at many places.Matrix coating phenomenon exists on the surface of 45 and 90 CFRP.The number of fiber fracture is more than that of 0 CFRP.The pits and matrix coating phenomenon on the surface of 135 CFRP.