【讨论】给大家一个柔体的实例。还有几个问题请教。

paor815

Overview   
This example presents a four-bar mechanism that will fail on simulation due to misalignment in one of the joints. The example discusses the how to replace a rigid link with a flexible link allowing the simulation of the mechanism. Hints on model creation are given but not step-by-step instructions. Model consists of three moving parts, one imposed motion, and one flexible part.  
  
Problem:  
We will use ADAMS to create a four-bar model with a flexible link. This lab will demonstrate how to perform a Modal FEA Integration by importing a Modal Neutral File and Matrix files into ADAMS models.   
  
Procedure   
  
Start ADAMS:  
1、Start ADAMS.  
2、Create a new model. (Units = mmks, Gravity = earth normal)  
  
Create Four-Bar:  
1、Create a marker at each of the following coordinates:  
O (-300, 0, 0); A (-250, 250, 0); B (250, 250, 0); C (250, 100, 0)  
2、Create links OA, AB, and BC, using the markers as end points.  
3、Make revolute joints between two links at points A and B, and between link and ground at O and C.  
4、Now rotate the revolute joint at point B one degree in the XZ plane.  
5、Add a motion to the joint at point C. (F(time) = 30.0d*time)  
6、If a simulation is run with the model as is, it will fail, since one joint is out of alignment.  
  
Add Flexible Link:  
1、Under the Build menu, follow the pull down menu for Flexible Bodies, and select Modal FEA Integration.  
The Flexible Body dialog box will open.  
2、Download the Modal Neutral File to be used: link.mnf and the Matrix files: Adams_FLX_1.mtx and model_1_FLX_1.mtx .  
In the text field for Modal Neutral File Name, enter link.mnf  
3、The flexible link will be created at the origin. Move the link so its endpoints are at points A and B, overlapping link 2.  
4、Modify the revolute joints at points A and B by replacing .model_1.PART_2 with the flexible link .model_1.FLX_1.  
5、Delete the old rigid link 2 .model_1.PART_2.  
6、Now run a simulation. This time, it will compute since the link is flexible and will deflect to account for the misaligned joint.   
  
Solution:   
  
The ADAMS command file for the rigid model: rigid.cmd  
The ADAMS command file for the flexible model: flex.cmd

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