Assigning Properties and Materials |
  
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Assigning Properties and Materials |
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When modeling in the 2D Frame Analysis module, it is important to understand that the program is set to assign a "Default" section to members and a "Default" material to that section. This is done to ensure that at least some value of area, moment of inertia, and Young's modulus are established for each and every member in the model, as these are prerequisites for performing an analysis by the stiffness method.
While these values do serve the purpose of providing a real numerical value for these necessary parameters, they are not meant to be realistic values for design. In fact, they are intentionally set to represent extremely small members of an extremely soft material, specifically so they will lead to enormous deflections and stresses that will jump right out to an engineer and clearly indicate that something is not yet correct in the model. These default values should only be regarded as placeholders so the program can immediately start producing results without reporting errors such as "division by zero". But the results are not meaningful in any way until the user applies engineering judgment and establishes realistic values for these parameters.
The following is a proposed workflow process that will make very efficient use of the 2D Frame Analysis module:
Start on the Sections & Materials tab, Material Data subtab, and create a material with a meaningful name like “No.2D-F” or "Aluminum". Then define the properties of that material. Repeat this process for each distinct material that will be required for the model.
Next, move to the Sections & Materials tab, Section Data subtab, and add all of the sections that will be required for the model. As each new section is added to the Section Data list, use the Material column to relate the section to one of the materials that was defined in the previous step.
Finally, move to the Members & Loads tab, Member Data subtab, and add all of the members that will be required for the model. As each new member is added to the Member Data list, use the Section Name column to relate the member to one of the sections that was defined in the previous step.
Think of this modeling process as a cascading series of relationships. Each member refers to a certain section. Each section refers to a certain set of material properties. When thought of in this way, the steps above will provide a very logical workflow process that will aid in producing a functional and meaningful model in an efficient manner.
