The conductivity of insulation can't be set as zero (singular matrix)

TBE_Legend

Hello dear all,
   I have found where the problem is! The conductivity of insulation can't be set as zero or it will cause the error in solving matrix.

Arthur  

--- 09/6/16 (二)，yti1978_95 <yti1978_95@yahoo.com.tw> 寫道：

寄件者: yti1978_95 <yti1978_95@yahoo.com.tw>
主旨: [COMSOL_Users] Help! limitation of Thermal-electric-structural interaction model ?
收件者: COMSOL_Users@yahoogroups.com
日期: 2009年6月16日,二,下午9:12

Hi,
I try to simlulate the thermal stress bending and induced temperature from the Joule heating of a embedded piezoresistive layer within a cantilever structure. But I can't solve it, so I wonder if the 3D thermal-electric- structural interaction can only be applied to single layer (Just as the example of "Microresistor Beam" in the software)
My 3-D geometry is simple: one U shape conductive layer on one insulation layer. I apply dV on one end of U shape conductive layer and ground on the other end. The self heating of conductive layer should induced temperature on the whole structure and caused thermal bending.
When I solve it, the error : "singular matrix" come out. I guess the problem is in the interior boundary between the conductive layer and insulation layer. The default setting of boundary is "continuity" . But it is unreasonable because the electrical current only in conductive layer. I think it should be electrical insulation as other boundaries of U shape conductive layer. However, there are no this choice in GUI. If I change the default boundary to others, ex. electrical shielding, distributed resistance.. .The result is still the same when I solve it.
So I wonder if the 3D thermal-electric- structural interaction can only be applied to single layer.

Could anyone help me to solve this puzzle? Thank you very much!

Arthur
IMTEK, Germany