Progressive Damage Failure Analysis Of Fiber Reinforced Composite Turbine Shaft Structure

In the design of a new generation of turbofan engine with high thrust-weight ratio,failure mode analysis and bearing capacity prediction of composite shaft structure are important parts of the structural integrity analysis of low-pressure turbine shafts,which provide a basis for the design and application of low-pressure turbine shaft.In view of the failure mode analysis and bearing capacity prediction of composite turbine shaft,three aspects of work were carried out:composite material transverse strength analysis,failure mode analysis of composite materials at non-ideal interfaces,and progressive failure analysis of composite turbine shaft:Based on the micromechanics theory of composite materials,the calculation method of stress concentration factor and strength of composite materials under transverse tensile,compression and shear loads was proposed,and SiC/TC4 laminate test was carried out to verify the effectiveness of the calculation method.The analysis shows that choosing a component material with a fiber volume fraction between 35%and 45%,and the elastic modulus difference between the fiber and the matrix is small,which is beneficial to improve the bearing capacity of the composite material.Based on the bilinear cohesive force model,a representative volume element model containing the interface was established,combined with the maximum stress criterion and the maximum displacement criterion to analyze the interface damage evolution process and its influencing factors.The calculation method of the transverse strength of the composite material,the interface cracking angle and the transverse tensile critical cracking load of the interface considering the interface cracking was proposed,and its effectiveness was verified by experiments.The analysis shows that the interface cracking significantly reduces the transverse tensile strength of the composite material.Taking a certain type of aero-engine low-pressure turbine shaft as a prototype,a progressive failure analysis model of composite turbine shaft structure based on Hashin failure criterion was established to simulate the damage evolution process and failure mode of the shaft structure under tensile and torsional loads,and to predict the tensile and torsional strength of the shaft.The results show,the higher the temperature,the smaller the tensile load and torsional load that the shaft can withstand;the maximum tensile strength is at 0°and the maximum torsional strength at 45°.When the tensile strength and torsional strength are considered comprehensively,±30° symmetrical layup is the optimal layup plan.