飞行器动力工程毕业论文--飞行器动力工程毕业论文含穿孔损伤复合材料层合板刚度降模型-PAGEI-基于疲劳损伤两段论的复合材料层合板刚度降模型摘要：复合材料在静态和动态载荷作用下的损伤是十分复杂的，对损伤的精确建模是关系到复合材料力学行为描述的关键问题。精确的模型能更深刻地认识复合材料的损伤机理。本文从实际工程背景出发，利用疲劳累积损伤模型，结合疲劳损伤两段理论，对复合材料层合板的寿命问题开展了较为系统深入的研究。主要内容包括：（1）在刚度降模型的基础上，根据疲劳损伤的两阶段理论，将复合材料的疲劳损伤划分为两个阶段。并且用两种不同的函数分段描述疲劳损伤的过程，建立了疲劳损伤演化两阶段模型。通过查阅相应的试验数据，运用多元函数的最小二乘法，得到了模型中的各个拟合参数。最后以75%的强度极限应力水平为例，对模型进行了验证。（2）在无孔层合板疲劳累积损伤模型的基础上，运用“点应力准则”概念，提出了带圆孔复合材料层合板的疲劳累积损伤模型，定义了应力修正因子。通过查阅相关的试验数据，获得了特征点应力修正因子，并建立了该带孔板疲劳累积损伤模型。用该模型对孔径为5mm层合板的S-N曲线进行了疲劳寿命预测与验证。关键词：复合材料刚度降疲劳损伤寿命预测S-N曲线StiffnessreductionanalysisforcompositelaminateswithcircularholeLiWeiAbstract：Nomatterlaminatedcompositeissubjectedtostaticordynamicload,damageissignificantlycomplex.Accuratemodelingforfatiguedamageisthekeyofmechanicalcharacterizationoflaminatedcomposite.Inthispaper,startingfromapracticalengineeringbackground,usingthefatigueaccumulationdamagetheory,togetherwiththetwo-stagetheoryforfatiguedamage,ain-depthstudyforthefatiguelifeofcompositelaminatesarecarriedon.Theresearchworkinthispaperisincludedfollowing:Onthebasisofthestiffnessreductionmodel,Accordingtothetwo-stagefatiguedamagetheory,adamageprocessisdividedintotwostage。Inordertoexpressthefatiguedamageaccurately,thetwo-stagemodelforfatigueaccumulationdamageispresented.Throughaccessingtothecorrespondingtestdata,usingoftheleastsquaresmethodformulti-function,theparametersinthemodelarefinallygot.Intheend,thefatiguetestsofthecompositematerialsunder75%ultimatestrengthareinvestigatedexperimentally.Basedonthestiffnessreductionmodelofimperforatecompositelaminates,usingtheconceptof“characteristicdimension”stress,afatiguemodelispresentedforthefatigueofnotchedlaminates,andtheconceptofthecorrectfactorisalsodefined.Thefatiguetestofnotchedlaminateswithdifferentdiametersisreferedtoabtainthecorrectfactorandthemodelofnotchedlaminates.TheS-Ncurveoflaminateswitha5mmholeispresented.Keywords:composites;stiffnessreduction;fatiguedamage;lifeprediction;S-Ncurve目录TOC\o