A transient thermal analysis is performed to determine the temperature distribution and a linear static analysis is run to determine the residual stress.
Thermal Analysis Solution
The analysis type is defined as a transient thermal analysis (ANTYPE,TRANS).
The following example input obtains the solution for the thermal analysis:
ANTYPE,TRANS ! Perform a transient analysis TRNOPT,FULL ! Specifies transient analysis options TIME,600 ! Final time for solution OUTRES,ALL,-10 ! Saved results at every 60 seconds
Structural Analysis Solution
A linear static analysis (ANTYPE,STATIC) is performed. For the stress analysis, SOLID87 elements are converted to SOLID187 elements.
The Tool-Narayanaswamy (TN) shift function with fictive temperature is used with the viscoelastic constitutive model. As with other time-temperature superposition models, the shift function is accessible via the TB,SHIFT command, as shown in the following input example:
TB,SHIFT,1,1,4,FICT ! Specify Tool-Narayanaswamy shift function TBDATA, 1,700,46400,0.3 ! TN constants - Reference temperature, H/R and X TBDATA, 4, 750, 0.25, 1.58E-5 ! Fictive T, weight, relaxation time .... TBDATA, 16, 10.7510E-6, -2.4208E-8, 5.7267E-11 ! glass CTE coefficients ! Time-dependent behavior of shear and bulk modulus can be ! represented via Prony series. Prony series for deviatoric ! Maxwell elements is defined as follows: TB,PRONY,1,1,4,SHEAR TBDATA,1, 0.48844 , 1.58E-5 ! Prony pairs ....
According to the reference results, volume relaxation for glass occurs much less rapidly than the shear relaxation.[1] The Prony series input for volume decay is therefore not considered in this problem.
A full simulation based on the time stepping from the reference input file requires approximately 3.5 hours (using eight processors). You can adjust the time-step increment according to your needs:
A larger increment accelerates the simulation but is less accurate.
A small increment is more computationally intensive, requiring a longer analysis time, but offers greater accuracy.
Important: The structural portion of the analysis requires 10 solve operations. The first solution (time = 1 - 60) requires more time to converge than the remaining nine; however, it is not good practice to increase the time increment for the first solution.