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那位帮帮忙,模态分析怎么是这样的结果?

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发表于 2006-6-3 20:40 | 显示全部楼层 |阅读模式

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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。
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发表于 2006-6-3 21:15 | 显示全部楼层

那位帮帮忙,模态分析怎么是这样的结果?


<TABLE border=1 cellPadding=0 cellSpacing=0 class=MsoTableGrid style="BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; BORDER-LEFT: medium none; BORDER-RIGHT: medium none; BORDER-TOP: medium none; mso-border-alt: solid windowtext .5pt; mso-yfti-tbllook: 480; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext">

<TR 0; mso-yfti-firstrow: yes">
<TD windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 58.45pt; mso-border-alt: solid windowtext .5pt" vAlign=top width=78>
<H2 2">mm<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 50.55pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=67>
<H2 2">kN<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 58.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=78>
<H2 2">Ton<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 98.2pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=131>
<H2 2">Ton/mm^3<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 58.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=78>
<H2 2">Mpa<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 90.25pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=120>
<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>
<TR 1; mso-yfti-lastrow: yes">
<TD windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 58.45pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=78>
<H2 2">mm<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 50.55pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=67>
<H2 2">mN<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 58.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=78>
<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>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 98.2pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=131>
<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>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 58.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=78>
<H2 2">Mpa<p></p></H2></TD>
<TD windowtext 1pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 1pt solid; BORDER-TOP: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; WIDTH: 90.25pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=120>
<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。
发表于 2006-6-4 06:18 | 显示全部楼层

回复:(Emily39050)那位帮帮忙,模态分析怎么是这样...

<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>
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