Progressive Accumulated Damage Analysis Of Composite Laminates With Hole Strengthening Structures

With the extensive application of composite materials, composite laminates are paid more and more attention for their excellent integrated properties. However, many holes are drilled on these laminated plates for assembly or functional requirements, which will cause stress concentration around these holes and lead to further structural damages of varied degrees under external loadings. Meanwhile, because of the free edge effect of interlaminar stress which is unique for composite laminates, damage modes will be increased and the damage process around holes will become more complicated. This phenomenon will not only weaken the structure strength, but also makes the strength prediction more difficult. Therefore, it is significant to research the damage process and damage mechanism for the application of composite laminates. In addition, finding ways to improve the strength of laminated plate with holes has become one of the urgent problems to be solved.Extra layers, which are called as strengthening layers, can be glued around these holes to improve laminates’loading capacity and increase ultimate strength.Based on three-dimensional progressive damage theory and stiffness degradation theory, using ANSYS parametric design language (APDL), the finite element model of composite laminated plate with hole-strengthening layers is established, to research the damage mechanism and the influence of hole-strengthening layers’parameters to ultimate strength of laminated plate. The detail contents are as follows:Firstly, the accuracy of interlaminar stress analysis with the ANSYS software was verified. And then the hole-edge stress singularity of laminated plate was analyzed to offer theoretical support for progressive accumulated damage analysis.Secondly, accumulated damage model of composite laminates is created. Under tensile load, the damage process and damage mechanism are analyzed. After comparison between the simulation results and experimental results cited from references, the rationality and correctness of the model was verify.Thirdly, accumulated damage model of composite laminates with hole-edge strengthening layers is established. After that, the influence of strengthening layers’ parameter to damage process and ultimate strength is discussed and summarized.Finally, the paper summarizes overall failure modes of laminated plate with hole-edge strengthening layers, analyzes the cause of these modes and presents necessity of rational design of strengthening layers.