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support@mecway.com
Mecway
FEA
Contact Conductance/Resistance
I have been using MECWAY with CCX to model contact conductance in thermal analyses using the bonded contact feature. This appears to use it in a contact coefficient (W/m²/K) manner. In space applications, one often will use the total conductance as this has typical ranges you can look up based on bolt size which is G = h*A.
Is there anyway to enforce this directly? My typical method right now is to calculate the h value required via h = G/A where A is the application area which is tedious since it is dependent on the elements. Is there any way to have h calculated based on dividing a total conductance value by the element applied areas (perhaps from master or from slave group)? Perhaps a way to use a formula I am missing?
Additionally, similar to materials, since the bolted contact is a property of the bolt size, I'd like to have parameters defining them in the model that can be re-used based on number of bolts across applied elements. For example I might have G_4_40 = 0.21 W/K and then if there area 3 bolts across one bonded contact, G = 3*G_4_40 and h = G/A_elements.
Sorry if this is trivial but I couldn't find an immediate way to do this.
Is there anyway to enforce this directly? My typical method right now is to calculate the h value required via h = G/A where A is the application area which is tedious since it is dependent on the elements. Is there any way to have h calculated based on dividing a total conductance value by the element applied areas (perhaps from master or from slave group)? Perhaps a way to use a formula I am missing?
Additionally, similar to materials, since the bolted contact is a property of the bolt size, I'd like to have parameters defining them in the model that can be re-used based on number of bolts across applied elements. For example I might have G_4_40 = 0.21 W/K and then if there area 3 bolts across one bonded contact, G = 3*G_4_40 and h = G/A_elements.
Sorry if this is trivial but I couldn't find an immediate way to do this.
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Comments
If you could use the internal solver, you might make point connections with line2 fin elements instead of contact. You'd still have to convert the conductivity but it would depend on the easier fin element geometry (cross section area and length).
That's OK, sounds like I'll need to just convert those G-values to h-values based on expected bolt contact area and then explicitly model the bolted contact regions on each component. Little extra effort but should work the same. Maybe I can write some Python script to help.
Since the h-values will be standard parameters, is there a way to define those as a parameter that can be re-used across different connections or am I at the mercy of copy paste?
If there's a way to turn the command into a CCX custom input, you can make it a *include to manipulate an external text file.
If you have python chops, look into the XML reader. We have had people here write readers for checking the database or manipulating terms inside, not just through the API, but externally as an XML file. Once you get the basic idea down, this opens up a lot of possibilities.