机械工程毛明旭机械振动大作业工字梁的模态分析

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1、机械振动大作业工字梁的模态分析机械工程XXXXXXXXxxxxxxxxxxx工字梁的模态分析问题：已知梁的截面为工字型，梁的长度lOOnrni,截面尺寸如下图,材料弹性模量200Gpa,泊松比0.3,密度7.8g/cm3。试分析其振动模态如图1所示：T2Ansys分析:ANSYSDEC31201215:42:52图2Ansys建模1.选定问题所属领域命令：Preference>structural2.选择4节点的四边形单元Preference>Preprocessor>ElementType>Add/Edit/Delete>Add

2、3.选择模型材料特性（弹性模量、泊松比、密度）命令：Preference>PreprocessorMaterialProps>MaterialModels>StructuralLinear>ElastiOIsotropic选择设置其中的EX为200E9,PRXY为0.3,选择Density为7.8E31.几何建模命令：关键点Preference>Preprocessor>Modeling>Create>Keypoints>lnActiveCS线Preference>Preprocessor>Modeling>Create>Line

3、s>Lines>StraightLine面MainMenu>Preprocessor>Modeling>Create>Areas>Arbitrary>ByLines12个节点坐标依次为：1(0,0,0),2(0.01,0,0),3(0.01,0.002,0),4(0.006,0.002,0),5(0.006,0.008,0),6(0.01,0.008,0),7(0.01,0.01,0),8(0,0.01,0),9(0,0.008,0),10(0.004,0.008,0),11(0.004,0.002,0),12(0,0.002,0

4、)得到的工字梁的平面模型如下图所示：AREAANSYSDEC31201219:28:21102.划分网格命令：MainMenu>Preprocessor>Meshing>SizeCntrls>ManualSize>Lines>PickedAreas设置单元边长度为0.005m,然后点击Mesh,划分的网格具体如下图所示:DEC31201215:42:521.拉伸平面生成三维模型命令：MainMenu>Preprocessor>Modeling>Operate>Extrude>ElemExtOpts,设置Elementtypeno.

5、2,即为SOLID45单元，并设置划分段数为100.MainMenu>Preprocessor>Modeling>Operate>Extrude>Areas>ByXYZOffset,在DXDYDZOffsetforExtrusion屮输入0,0,0.1,将该平面图形向Z方向拉伸0.1m。拉仲后的三维模型如下图所示:DEC31201215:42:521.定义求解类型命令MainMenu>Solution>SolutionType>NewAnalysis选择modal,即进行模态分析。MainMenu>Solution>Solutio

6、nType>AnalysisOptions选择BlockLanczos，填写5,義示进行5阶的*莫态分析。2.加载命令Menu>Select>Entities在第一个下拉框中选择Node,第二个下拉框中选择ByLocation,第三栏坐标选择方式屮选择Zcoordinates,然后在Max,Min空格栏处填写0,然后点击OK,即完成实体设置。命令MainMenu>PreprocessorLoads>DefineLoads>Apply>StructuralDisplacement>OnNodes然后在出现的对话框中选择Pickall

7、,在新出现的对话框中选择ALLDOF,然后在VALUEDisplacementvalue空格栏中填写0。3.求解MainMenu>Solution>Solve>CurrentLS4.后处理STEF-1SU3=1FREQ=715.676DMX=9.92DEC31201219:28:21处理得到的二阶模态如下图所示:DISFLACEMENTSTEF=1FREQ=100SDMX-9.S23ANSYSDEC31201215:42:52ANSYSDEC51201219:29:12DISPLACEMENTSTEF=1SUS=3FREQ-2€2

8、1DMX=12.23:处理得到的四阶模态如卜•图所示:DISFLACEXEMTSTEP=iANSYSDEC31201215:42:52FREQ=433iDEX-9.915DEC31201219:04:17STEF-1SU3=5FREQ=5510U・