标题: 【讨论】给大家一个柔体的实例。还有几个问题请教。 [打印本页] 作者: paor815 时间: 2004-6-28 13:22 标题: 【讨论】给大家一个柔体的实例。还有几个问题请教。 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 作者: paor815 时间: 2004-6-28 13:23
这是整个详细说明和cmd和mnf和mtx文件作者: paor815 时间: 2004-6-28 13:43
有几个问题不明白，还请高手赐教：
1、Adams_FLX_1.mtx 和model_1_FLX_1.mtx 这两个文件有什么作用？是不是生成mnf文件时自动生成的？倒入时是不是得和mnf文件同一个目录？
3、我创建模型是用的自己的名字，可是仿真出错，不明白，研究发现，是不是给的名字和官方给的名字不一样？于是我修改名字，model的name是model_1，mnf时给的名字是FLX_1，可是还是出错。不明白为什么？
错误如下：
WARNING: The corrector has not converged after 1 attempts. No. of iterations = 10.
WARNING: The corrector has not converged after 2 attempts. No. of iterations = 10.
WARNING: The corrector has not converged after 2 attempts. No. of iterations = 10.
WARNING: The corrector has not converged after 2 attempts. No. of iterations = 20.
ERROR: The simulation stopped at time = 7.57546E-02 . ADAMS cannot solve
the equations of motion.
The greatest error in an equation is 4.46925E-02 in the
equation for FLEX_BODY model_1.FLX_1 .
The greatest change in a variable is 4.28903E-17 in the
variable for PART model_1.PART_4 .
Try the following in this order:
1. Use the MAXIT argument on the EQUILIBRIUM, IC, KINEMATICS,
or INTEGRATOR command to increase the maximum number of
iterations.
2. Temporarily change the value of the PATTERN argument on the
EQUILIBRIUM, IC, KINEMATICS, or INTEGRATOR command to
PATTERN = T.
3. Temporarily increase the value of the ERROR argument on the
EQUILIBRIUM, IC, KINEMATICS, or INTEGRATOR command at
time = 7.57546E-02 .
4. If one or more forces change rapidly or sharply near
time = 7.57546E-02, modify the force or forces.