Study On The Effect Of Holes On The Crack Propagation Path Of CFRP

With the continuous advancement of China’s lightweight process,the application of CFRP materials in engineering structures is becoming more and more extensive.Therefore,studying the effect of holes on the crack propagation path of CFRP can provide better solutions for the design optimization of the connection structure,thus improving the overall bearing capacity and avoiding damage.In this paper,based on the improved orthotropic BEAM-PD model,the C++ program is used to simulate the progressive damage of the CFRP unidirectional plate with holes to explore the effect of the size and position of holes on the crack propagation path of CFRP.Firstly,an improved orthotropic BEAM-PD model was proposed based on the BBPD theory and Timoshenko BEAM theory,which can remove the limitation of Poisson’s ratio and improve the accuracy of numerical simulation.Secondly,the C++ language was used to write PD program,and the progressive damage simulation was conducted on the unidirectional plate with central holes with fiber directions of 0°,45° and 90° respectively.By comparing with the experimental results in the existing literature,the feasibility and accuracy of the model were verified in simulating crack propagation problems.Finally,the effect of holes on the crack propagation path of CFRP was investigated by changing the size and position of the round holes under the same fiber direction of the unidirectional plate.The results show that the simulation results of PD are in good agreement with the experimental results in the existing literature,which reflects the ability of the model to simulate the damage and fracture of CFRP.Because the performance of the fiber is better than that of the matrix,when the CFRP unidirectional plate with holes is subjected to velocity loads on both sides,the matrix damage occurs first,and then part of the load is transferred to the fiber bond,resulting in the fiber damage.For CFRP unidirectional plates with a fiber direction of 0 °,the matrix damage on the right side of the round hole becomes more and more serious when the offset distance is the same and the radius of the round hole increases gradually.The matrix bond on the right side of the round hole is broken first when the radius of the round hole is the same and the offset distance increases gradually.For a CFRP unidirectional plate with a fiber direction of 45 °,the matrix damage at the upper and lower points of the hole will branch and will no longer expand along the fiber direction after the round hole is offset to a certain distance.Some matrix damage merges directly with the matrix damage at the edge of the unidirectional plate to form cracks.As the offset distance increases gradually,the matrix damage on the upper and lower edges of the CFRP unidirectional plate with a fiber direction of 90 ° begins to branch and connects with the matrix damage generated at the upper and lower points of the round hole.When the offset distance is too large,the matrix damage generated at the round hole spreads to the edge of the unidirectional plate at the earliest,forming a crack.