本帖最后由 mxlzhenzhu 于 2016-5-4 23:10 编辑
发动机悬置可以简化为一个刚度阻尼单元(CBUSH单元),在VL中可以定义类似这种减振垫依赖于频率的动刚度属性,此贴简要介绍如此功能,有兴趣的可以研究一下。
建模过程和模型文件打包了【可能这儿说复杂了,你先摸索下吧;】,请参考;
软件版本为VL12.0的
http://pan.baidu.com/s/1eQ3TOfo
Mark:2015-1-8
今天对比了一下,用hypermesh前处理,完成不含动刚度,以及含有动刚度的计算,分别用VL和Nastran直接积分法(SOL108)求解,并完成了对比;
可以确认的是Nastran属性卡片PBUSHT,是在VL中是识别的;用HM的人应该感到Happy喽!:P
【截图有点多,用附件形式贴上来吧】
可以看到,不含动刚度的时候,两个软件计算差不多;
http://pan.baidu.com/s/1c0nM1Yo
而含有动刚度的时候,两个软件还是有点差别;
http://pan.baidu.com/s/1dD6bvJr
所有文件,截图,打包如下:
http://pan.baidu.com/s/1nt4zen3
《《《《《《《《《《《《《=============我是分隔符==============》》》》》》》》》》》》》》》》
手册里面关于CBUSH单元的介绍:
1,它是一个广义弹簧阻尼单元,支持6个自由度刚度、阻尼和附加质量输入功能;还支持一些非线性刚度阻尼属性,大变形分析;
2,它的自由度定义在BUSH Location位置,它的单元刚度可以在局部坐标系定义,也可以在指定坐标系定义,它的各阻抗定义项会分配到GA、GB的自由度上去,处理起来有点类似梁单元;
3,CBUSH单元能够消除一些普通弹簧单元可能会遇到的内部约束问题(internal constraint);因此比这些普通弹簧单元要好用;它的移动自由度和转动自由度之间存在耦合。
其他说明:
Hello!,
Since I know well the CBUSH element this is the only spring element I use in FEMAP & NX NASTRAN, is great!.
The CBUSH element is a generalized spring-damper structural scalar element connecting two noncoincident grid points, or two coincident grid points, or one grid point with an associated PBUSH entry. This combination is valid for any structural solution sequence. To make frequency dependent the PBUSH need only have an associated PBUSHT Bulk Data entry. The PBUSHT entry for frequency dependency is only used in SOL 108 and SOL 111. You can also use the PBUSHT entry to define load-displacement dependency in SOL 106.
The use of CBUSH element is all advantages over CELASi elements. For example, if you use CELASi elements and the geometry isn’t aligned properly, internal constraints may be induced. The CBUSH element contains all the features of the CELASi elements plus it avoids the internal constraint problem. The CBUSH element as a replacement for scalar element for static analysis. The analysis joins any two grid points by user-specified spring rates, in a convenient manner without regard to the location or the displacement coordinate systems of the connected grid points. This method eliminates the need to avoid internal constraints when modeling, OK?.
In dynamic analysis, the CBUSH elements can be used as vibration control devices that have impedance values (stiffness and dampling) that are frequency dependent.
Best regards,
Blas.
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Blas Molero Hidalgo
Ingeniero Industrial
Director
其他介绍:
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