Thermal Expansion type

General Questions
1

I am trying to model the thermal shrinkage of a tube diameter from 300K to 8K. I have temperature dependent CTE. Should I be entering secant or tangent (instantaneous) CTE data? I’m guessing secant since PrePoMax asks for a “zero temperature”?

My understanding is that tangent CTE is the traditional, thermodynamic definition of CTE, where each temperature has an instantaneous CTE value. Whereas secant CTE essentially is the integrated or averaged tangent CTE value from the reference/“zero” temperature to the datapoint temperature. Is this correct?

2

Secant. From the manual:

For isotropic material the thermal strain tensor amounts to α∆T I, where α is the (secant) expansion coefficient, ∆T is the temperature change since the initial state and I is the second order identity tensor.

Abaqus also supports tangent definition: *EXPANSION, DEFINITION=TANGENT. It can be used when modeling curing or other irreversible transformations where the thermal expansion coefficient depends on the degree of transformation.

1 Like