Learning Forum

[Connor Kosowski]

Hello,

I am currently simulating a heat sink with a fluid structure interaction. I am comparing an aluminum nitride heat sink to a copper heat sink. Essentially, I have simulated a fluent case and linked it to a tranisent structural case. Water flows between the heat sink microchannels, and the heat sink itself is subjected to fluctuating heat fluxes over time. That being said, I am not certain as to whether many creep life models are applicable, since my simulation is not steady state. I also am unsure as to how I would go about assigning creep life constants for many of the creep life models. 

I believe it is more appropriate to consider a fatigue life model, since that pertains to fluctuating loads. However, I am also unsure about how I would go about setting up that scenario for simulations either.

Any help or insight would be greatly appreciated

[danielshaw]

Mechanical does not provide an automated method for assessing creep-fatigue.    If you have access to Ansys Sherlock or Ansys nCode DesignLife, you consider using those tools.

The general approach taken using Ansys Mechanical is to run a cyclic time transient creep analysis and monitor creep damage per loading cycle (e.g., accumulated equivalent creep strain).  For secondary creep, the damage should be linear with each loading cycle.  You can then extrapolate the number of cycles required to reach tertiary creep (which is typically the failure criteria).