With A Hole Laminated Composite Plate Structure Stress Analysis

The problems, related to composite plates with holes, such as stress concentration ,free-edge effect, delamination and failure checking, are of great importance for engineers to design the composite structures .It is very necessary to do further researches on such kind of problems, with the composite materials being used more and more widely in aerospace area .There is only semi analytical solution of the stresses about layered composite structure which can be provided as reference while the analytical solutions haven't been worked out yet .Nowadays Finite Element Method has been used widely in engineering area and it has been proved to be an efficient way to solve complicated problems. Therefore ANSYS is applied to do numerical simulation and analysis on mechanical properties of the composite plate with hole in this paper. According to the designable feature of the laminates, with the factors of the layer angle and the layer order taken into consideration, a new symmetrical laminate has been designed. Then calculations have been done based on the structure of the designed plate with a circular hole.Firstly, in order to check whether the parameter model established is accurate and computation method is applicable, stresses of single layer plate with hole under the in-plane uniform load are calculated .When comparing the results from ANSYS with the analytical solution figured out by the formula , they match well with small tolerance .Therefore it can be concluded that the type of the element which has been chosen and the method that has been designed both are right.Secondly, based on the analysis above, the stress concentration of the laminate with circular hole having been designed were calculated when the laminate is applied with uniform load. Then distributions of the stresses have been studied .The result can be used to estimate the reasonableness of the design.Next ,the improved laminate with softened area around the hole under the same load were calculated .Then change the dimensions of the softened area and get it calculated ,observe what the stress concentration would be like. Thus make it clear what the appropriate dimension is .Then, the interlaminar stresses of the laminate has been studied on the condition of definite error limitation. The rule of the distribution of the stresses has been obtained. The result is very useful for engineers to pre-estimate the delamination.Finally,analysis of the strength failure has been done under the two failure criterias ,maximum stress failure criteria and the Tsai-Wu failure criteria .The failure criterias take many factors into consideration and thus the results can be used to evaluate the conditions of the laminates comprehensively ,especially the safety performance.