| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | ALL; |
| Area: | |
| Date Logged & Current Version | Jan 2020 12.02.00.14 |
Problem:
Calculate SAM stress values and Expansion stress values independently, and then add these two stress values in the SECONDARY user defined code combination
Solution:
It is important to understand that the category selected for a combination determines which equations will be used to calculate the stress value from the forces and moment values for that combination.
In this example case, the Combination method was set to SRSS, and the Category for SAM combination was set to Expansion. Note the M/S column setting, this would mean that the Forces and Moments from S1, S2, and S3 will be summated using SRSS (see AutoPIPE help for details on this M/S setting).
The equations for thermal stress calculations (see help> code compliance calculations) will then be used on the summated forces and moments values to generate the stress value for the SAM user code combination
if the intent to calculate the SAM stress values is through Occasional category, then the stress values from SAM combination and Maximum Thermal Combination can be added together simply by using a user defined SECONDARY combination. Using Sum or Abs Sum will be up the user, the results for SECONDARY combinations will be added at stress level (note the M/S column setting = S).
In case the intent is to calculate the SAM stress values using Expansion category, then the following example can help setup SECONDARY combination:
a. Consider a model with three thermal cases T1, T2, and T3. The model also has three SAM cases S1, S2, and S3
b. SAM is required to be calculated in the expansion category using SRSS method: We will simply create a User Defined Code Combination say SAM, set the Combination method to “3 SRSS”, and category to Expansion. This combination should give us the SAM Stress Value.
As we cannot use the Max Range combination because the SAM user Defined Combination also belongs to Expansion category, we would want to generate all thermal ranges and find the maximum out of these
c. Go to Result Model Options and set the “No. of thermal ranges” to 3.
d. Open the Code Comb. Tab of Load Combinations dialog and note that the program has added the possible thermal load ranges “T1 to T2”, “T1 to T3”, and “T2 to T3” in addition to the existing thermal combinations “Amb to T1”, “Amb to T2”, and “Amb to T3”. Now we have all the thermal ranges for this model.
e. Create a new User defined code combination named “MAX_THER”, with the Combination Method set to “10 Max Stress”, and category set to Expansion. Add all the six thermal combinations “Amb to T1”, “Amb to T2”, “Amb to T3”, “T1 to T2”, “T1 to T3”, and “T2 to T3” to that combination at Stress level with a factor of 1.0 (again, note the value of M/S column).
The MAX_THER combination will calculate the thermal combination which results in the maximum stress value.
f. Now, create a new User Defined Code Combination “SECONDARY”, set the Combination Method to Sum or Abs. Sum (whichever is required), and add the two User Defined Combinations SAM and MAX_THER to that combination. The SECONDAY combination should be able to give a stress value which is the sum of Maximum Thermal Range Stress and SAM stress.