Thermal Elements Jake Blanchard Spring 2008

Thermal Elements These elements calculate temperatures in solids There are 1-D, 2-D, and 3-D elements All have just 1 DOF per node Properties are thermal conductivity (k) for steady state analysis and density (  ) and heat capacity (cp) for transient analyses Boundary conditions can be temperatures, heat fluxes, or radiation Volumetric heating is also possible

Thermal Elements in ANSYS LINK 31 – radiation link LINK 32 – 2-D conduction bar LINK 33 – 3-D conduction bar LINK 34 – convection link PLANE 35 – 6 node triangle PLANE 55 – 4 node quad PLANE 75 – 4 node axisymmetric-harmonic element PLANE 77 – 8 node quad PLANE 78 – 8 node axisymmetric-harmonic element

More Thermal Elements SOLID 70 – 8 node solid SOLID 87 – 10 node tetrahedral element SOLID 90 – 20 node hexahedral element SHELL 57 – 4 node SHELL 131 – 4 node layered element SHELL 132 – 8 node layered element

Real Constants Area, heat transfer coeff., and emissivity for links None for planar and solid elements Thickness for shell element (not layered) Use “Sections” for layered elements

In-Class Problems k 1 =1 W/m-K k 2 =20 W/m-K cm 1 cm T=100 C T=0 C

In-Class Problems k 1 =1 W/m-K k 2 =20 W/m-K cm 1 cm q=10 4 W/m 2 T=0 C

In-Class Problems k 1 =1 W/m-K k 2 =20 W/m-K cm 1 cm q=10 4 W/m 2 h=1000 W/m 2 -K T b =50 C

In-Class Problems k 1 =1 W/m-K k 2 =20 W/m-K Channels are 3 cm in diameter cm 1 cm q=10 4 W/m 2 T=50 C 15 cm 2 cm

In-Class Problems k 1 =1 W/m-K k 2 =20 W/m-K Channels are 3 cm in diameter cm 1 cm q=10 4 W/m 2 15 cm 2 cm h=1000 W/m 2 -K T b =50 C