_材料力学双语教学学习资料3

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1、材料力学双语教学学习资料3主讲教师：陈晓峰10第七章应力和应变分析强度理论ChapterSevenStressandStrainAnalysisStrengthTheories§7–1应力状态概述§7–1ConceptsoftheStateofStress1．一点的应力状态：过一点有无数的截面，这一点的各个截面上应力情况的集合，称为这点的应力状态。stateofstressatapoint:Therearecountlesssectionsthroughapoint.Thegatheringofstressesinallsectionsiscalledthestateofstressatt

2、hispoint.2．单元体：构件内的点的代表物，是包围被研究点的无限小的几何体，常用的是正六面体。Element:Delegateofapointinthemember.Itisaninfinitesimalgeometricbodyenvelopingthestudiedpoint.Incommonuseitisacorrectitudecubicbody.3．主单元体：各侧面上剪应力均为零的单元体。principalelement:Theelementinwhichtheshearingstressesinsideplanesareallzero.4．主平面：剪应力为零的截面。Pri

3、ncipalPlanes:Theplanesonwhichtheshearingstressesarezero.5．主应力：主平面上的正应力。principalstresses:Normalstressesactingontheprincipleplanes.6．主应力排列规定；按代数值大小Conventionoftheorderforthreeprincipalstresses:Inmagnitudeofthealgebraicvalue.7．三向应力状态：三个主应力都不为零的应力状态。stateofthetriaxialstress（threedimensionalstateofstr

4、ess）:Stateofstressthatallthethreeprincipalstressesarenotequaltozero.二向应力状态：一个主应力为零的应力状态。stateofthebiaxialstress（planestateofstress）:stateofstressthatoneprincipalstressisequaltozero.单向应力状态：一个主应力不为零的应力状态stateoftheuniaxialstress（unidirectionalstateofstress）:stateofstressthatoneprincipalstressisnotequ

5、altozero.§7–2二向应力状态分析——解析法§7–2AnalysisoftheStateofPlaneStress—AnalyticalMethod1.任意斜截面上的应力：stressesactinginarbitraryinclinedplane2.正负规定：sa截面外法线同向为正；绕研究对象顺时针转为正；逆时针为正。SignStipulate：saispositiveifitsdirectionisthesamewithoneoftheexternalnormallineofthesection；ispositiveifitmaketheelementrotateclockwi

6、se；Acounterclockwiseangleisconsideredtobepositive.§7–3二向应力状态分析——图解法§7–3AnalysisoftheStateofPlaneStress—GraphicalMethod1.应力圆：stresscircle2.单元体与应力圆的对应关系：Correspondingrelationbetweentheelementandstresscircle(1)a面上的应力(sa，ta)«应力圆上一点(sa，ta)(2)a面的法线«应力圆的半径10(3)两面夹角a«两半径夹角2a；且转向一致。(1)stress(sa，ta)inaplane

7、«apoint(sa，ta)onthestresscircumference(2)normallineofaplane«radiusofthestresscircle(3)angleabetweentwosections«angle2abetweentworadiuses；Andthedirectionofrotationisthesame.§7–10强度理论概述§7–10ConceptsofStrengthTheori