那位帮帮忙，模态分析怎么是这样的结果？

Emily39050

我做的是七联泵曲轴的第一曲轴，建模的时候是用毫米建立的模型，在弹性模量为2.06E11怕，密度为7.85克/立方厘米，我在做的时候弹性模量输入的2.06E5,密度是7.85E-6，在曲轴的两端轴承左端选择三个点，XYZ三个方向约束，右端XY两个方向，最终求出的频率是5.36，34.521，39.614，42.551，51.676，这个结果应该不正确，可是我又不止为什么？难道必须对七个曲轴放在一起才能做？还是我单位有问题。还有，怎么看振形，谢谢各位了。

usefully

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<H2 2">mm<p></p></H2></TD>
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<H2 2">kN<p></p></H2></TD>
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<H2 2">Ton<p></p></H2></TD>
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<H2 2">Ton/mm^3<p></p></H2></TD>
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<H2 2">Mpa<p></p></H2></TD>
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<H2 2"><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="9800" UnitName="m">9800m</st1:chmetcnv>/s^2<p></p></H2></TD></TR>
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<H2 2">mm<p></p></H2></TD>
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<H2 2">mN<p></p></H2></TD>
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<H2 2">10^<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="6" UnitName="kg">6kg</st1:chmetcnv><p></p></H2></TD>
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<H2 2">10^<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="6" UnitName="kg">6kg</st1:chmetcnv>/mm^3<p></p></H2></TD>
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<H2 2">Mpa<p></p></H2></TD>
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<H2 2"><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="9800" UnitName="m">9800m</st1:chmetcnv>/s^2<p></p></H2></TD></TR></TABLE>建模使用毫米，所以你的输入参数都必须按毫米来计算，在转换时要注意应该首先将所有单位转换为量纲的基本单位，比如力的单位N，如果要转换到以毫米为基准的单位制，必须现将N转换为：kg*m/s^2,然后将M转换为mm，所以N转换前后数值扩大了1000倍。再如弹性模量Pa,现将其转换为N/m^2=kg*(m/s^2)/(m^2)=kg/(m*s^2),可见转换为以毫米为基准后，数值缩小了1000倍。

AaronSpark

<DIV class=quote><B>以下是引用<I>Emily39050</I>在2006-6-3 20:40:12的发言：</B><BR>我做的是七联泵曲轴的第一曲轴，建模的时候是用毫米建立的模型，在弹性模量为2.06E11怕，密度为7.85克/立方厘米，我在做的时候弹性模量输入的2.06E5,密度是7.85E-6，在曲轴的两端轴承左端选择三个点，XYZ三个方向约束，右端XY两个方向，最终求出的频率是5.36，34.521，39.614，42.551，51.676，这个结果应该不正确，可是我又不止为什么？难道必须对七个曲轴放在一起才能做？还是我单位有问题。还有，怎么看振形，谢谢各位了。</DIV>
<P>单位明显不统一</P>