【题目】cosmos/works题目2

很多人都使用默认的求解方式进行求解，对于一些选项的理解不够，请针对我的贴出的图，进行说明（有些需要举例说明），每个知识点加一分，为了对更多的人公平，每个知识点可以对三个人加分
（请加密50分，否则扣掉一分）。
  
加分完毕后我会调回不加密状态开始讨论
图1

thanks!I like you all.

如何提高积分啊？9楼的内容看不到啊！

游客，本帖隐藏的内容需要积分高于 50 才可浏览，您当前积分为 0

[quote]hubeiyiejian wrote:
帮助里有的!  
   
1）能否用中文解释一下，很多网友的E文水平还是很一般的喔！
2）能否有自己的理解！

帮助里有的!
  
1.On the Options tab, change the settings listed below and click OK to accept the changes. Click Cancel to discard the changes and exit the dialog box.
  
1)Gap/Contact. Lets you set options related to Gap/Contact.
  
Include global friction:
  Lets you include or ignore the effect of friction for global contact conditions. This flag does not control local contact conditions. COSMOSWorks calculates static friction forces by multiplying the normal forces generated at the contacting locations by the specified coefficient of friction. The direction of the friction force at a location is opposite to the direction of motion at that location.
  
Friction coefficient:
  Sets the coefficient of static friction for global contact conditions. For local contact conditions, a friction coefficient is specified in the Contact Pair PropertyManager for each condition.   
  
Ignore clearance for surface contact:
  When this option is checked, the program considers contact conditions regardless of the initial distance between user-defined face pairs.
  
Large displacement contact:
  When this option is checked, the program applies the loads gradually and uniformly in steps up to their full values performing contact iterations at every step. The number of steps is internally decided by the program.
  
2)Solver. Lets you specify the solver to be used to perform static analysis.
  
  Direct Sparse.:
Check this option to use the Direct sparse solver.
  
  FFE:
  Use the FFE solver to run the study.
  
  FFEPlus.:
Use the FFEPlus solver to run the study. This solver uses advanced matrix reordering techniques that makes it more efficient for large problems.
  
The following options are available with the Direct sparse and the FFEPlus solvers only:
  
Use inplane effect:
  Check this option to consider the effect of in-plane loading.
  
Use soft spring to stabilize model:
  Check this option to instruct the program to add soft springs attached to the ground to prevent instability. If you apply loads to an unstable design, it will translate and/or rotate as a rigid body. You should apply adequate restraints to prevent rigid body motion. In general, you should not activate this flag unless:
  
you ran the analysis and the program tells you that the design is not stable, or
  
you know that you have not specified adequate restraints.
  
Use inertial relief.:
     When this option is checked, the program automatically applies inertial forces to counteract unbalanced external loading. This option is particularly useful when you import loads from a motion package (COSMOSMotion) where external loads can be slightly unbalanced. When you check this option, you can solve structural problems without having to apply restraints or activate the soft spring option to stabilize the model against rigid body motions.
  
2.On the Adaptive tab, check Use p-Adaptive for solution.
  
Change the settings listed below and click OK to accept the changes. Click Cancel to discard the changes and exit the dialog box.
  
Stop when. Sets the global criterion to be used for indicating convergence and termination of the loops. Choose the desired option from the drop-down menu. You can choose:
  
Total strain energy. The strain energy of the model calculated by summing the strain energy of all elements.
  
RMS von Misses Stress. The Root Mean Square value of the nodal von Misses stresses.
  
RMS Res. Displacement. The Root Mean Square value of the nodal resultant displacements.
  
Change is xx% or more. Sets the maximum allowable relative change in the selected global criterion.
  
Update elements with relative Strain Energy error xx% or more. Sets the maximum allowable relative error in the strain energy of each element. If none of the other two stopping criteria are met, the program will increase the polynomial order of the elements with strain energy of xx% or more.
  
Starting p-order. Sets the order to be used for the first loop. The lowest order is 2 and the highest order is 5.
  
Maximum p-order. Sets the highest p-order to be used in this analysis. The highest possible order is 5.
  
Maximum no. of loops. Sets the maximum number of loops allowed in this analysis. The maximum possible number of loops is 4.
  
NOTES:
  
The p-method does not change the mesh. It changes the order of the polynomials used to approximate the displacement field. Using a unified polynomial order for all elements is not efficient. COSMOSWorks tries to increase the order of the polynomial where it is needed. This approach is called the selective adaptive p-method.
  
It is recommended to select the At Nodes option (from the Jacobian Check menu in the mesh preferences) before meshing a model when using the p-method to solve static problems.
  
Limitation: In this release, the p-method does not work when variable pressure, variable forces, or multiple pressures are defined on a face.
  
   
  
   
3.On the Flow/Thermal Effects tab, you can set the following options:
  
Include Thermal Effects. Considers thermal loading for the analysis. Select one of the following thermal options:  
  
Input Temperature. Considers the prescribed temperatures defined for the model.
  
NOTE: When using this option, make sure to specify temperatures on components or shells. Specifying temperatures on the boundary only may not be practical. You may need to create and solve a thermal study first to compute temperatures at all nodes.  
  
Temperatures from thermal study. Reads the temperature values from a thermal study. Select a Thermal study and the Time step number (for a transient thermal study).
  
Uniform temperature. Considers a uniform temperature at all nodes in the part. Specify the uniform temperature value.
  
Temperatures from COSMOSFloWorks. Reads the temperature values resulting from a completed COSMOSFloWorks on the same configuration from a file. Select the desired FloWorks Result Files (*.fld) that has been generated by COSMOSFloWorks. SolidWorks model name, configuration name, and time step number associated with the specified file are displayed.
  
Reference temperature at zero strain field. Type the temperature at which no thermal strains exist in the model.
  
Include fluid pressure effects from COSMOSFloWorks. Reads the pressure results from a COSMOSFloWorks result file.
  
Fluid pressure option. Sets the file with pressure results generated by COSMOSFloWorks. SolidWorks model name, configuration name, and time step number associated with the specified file are displayed.
  
To import temperature and pressure from COSMOSFloWorks:
  
In COSMOSFloWorks, export results to COSMOSWorks for the configuration similar to the COSMOSWorks model.
  
In the COSMOSWorks Manager tree, right-click a static study icon and select Properties.
  
The Static dialog box opens.
  
Click the Flow/Thermal Effects tab.
  
Do following:
  
To import temperature, check Include Thermal Effects, select Temperatures from COSMOSFloWorks, and browse to select the desired FloWorks Result File (*.fld).
  
The SolidWorks model name, COSMOSFloWorks configuration name, and the time step associated with the temperature profile appear.
  
NOTE: Make sure that the configuration exported by COSMOSFloWorks corresponds to the COSMOSWorks model.
  
To import pressure, check Include fluid pressure effects from COSMOSFloWorks, and browse to select the desired FloWorks Result File (*.fld).
  
Click OK.
  
When you run the study, fluid pressure and/or thermal effects are imported.
  
   

查到了一些资料:
Cosmos软件是美国SRAC（Structure Research and Analysis Corporation ）公司
的产品，它具有计算速度快、解题时占用磁盘空间少、使用方便、分析功能全面、与其
他CAD/CAE软件集成性好等优点，下面简要介绍一下这些特点。
COSMOS为什么速度快？
　　要解释清楚这个问题应该考查一下有限元分析软件的算法。有限元分析软件现在基
于的算法有两种：一种是所谓的直接解法，一种是所谓的迭代解法。因为有限元软件处
理的对象大部分是高元方程组，因此直接解法总能求得解，但速度就不能保证很快，虽
然迭代法解题的速度很快，但不能保证所有的算法都是收敛的，因此传统的有限元分析
软件大都采用直接解法。1982年，前苏联的三位数学物理博士致力于研究有限元分析的
迭代算法的收敛性问题，因为，如果能保证迭代法总是收敛的，就可以大幅度提高解题
速度。他们采用穷举法，分析迭代法中所有发散的算法，最后总结出500多种导致迭代法
发散的原因并加以有效的对症下药，终于在11年后的1993年发明了举世瞩目的FFE（快速
有限元法，Fast Finite Element ）算法。FFE方法其实就是针对不同的迭代算法总能保
证其收敛的改进的迭代法，现在的Cosmos就是采用的这种FFE方法。这是Cosmos解题速度
快的一个重要的原因。
Cosmos解题时为什么占用的磁盘空间那么少？
　　Cosmos采用的算法是FFE技术，而FFE技术是1993年才发明的，要想把这种快速有限
元技术应用到Cosmos软件中，必须重新编写Cosmos的源代码，1993年世界上比较先进的
C++语言技术已经成熟，面向对象技术、内存优化管理技术、磁盘管理技术也已上了一个
新台阶。正是因为在Cosmos的新的源代码中利用了这些新技术，所以Cosmos才具有用少
的磁盘空间解决复杂的分析问题的能力。虽然SRAC在重新编写Cosmos源码上付出了代价
，但却换回了其他CAE软件不能比拟的功能。

我是刚学COSMOS,就把我知道的说说吧,请指正:
三中求解器中第一个为直接法,就是求解载荷边界条件和刚度矩阵形成的稀疏矩阵方程,采用的是分离变量的传统的方程组求解方法,所得解精确,但是速度很慢,而且要占用很多空间,ANSYS所采用的就主要是这种办法.
第2个和第3个采用的是俄罗斯科学家发现的一种新的求解方法,他把所有可能导致解发散的情况进行了穷举,并分别采用对应措施(详细的我记不大清楚了,改天查查看),从而使得求解很迅速,而且因为它采用的是比较先进的语言(好象是C或C++吧)来编程,所以对空间的使用很有效率,计算时需要的空间就比较小了.其中第3个是第2个的改进.我自己的经验和理解,不大和不复杂的问题2种(我没用过第2种求解器)求解结果差别不大,速度第3种快,但是也快不了多少,对复杂的问题第一种很慢,有时还会不收敛,但收敛的话结果比较可信,第3种求解快,收敛好,但有时结果明显不可信.
后面的三个选项我就用过"使用软弹簧使模型稳定",意思是在计算时可以不对模型施加约束或约束可以施加的不足够,即模型存在刚体位移,计算时程序会对在模型四周施加弹簧使模型稳定不出现刚体位移,但不影响模型的受力情况,这种情况所得的应力分布结果对某些情况来说比较精确(免除施加约束造成的应力集中),但是没有位移和变形的结果.
  
不对之处,请多指点!

没有人愿意讨论吗？我举一个例子，比如关于解算器的选择，这三种有啥区别，每种的适用范围等等，因为这些都可以在帮助里查到，而且这些对理解有些问题的分析很有好处的！

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