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Unexpectedly high thermal stress
Posted 2026年2月24日 GMT+8 21:35 MEMS & Piezoelectric Devices, Heat Transfer, Structural Mechanics 1 Reply
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When temperature is increased from 293.15 K to 294.15 K, thermal stress increases by more than an 10 times magnitude. I have taken materials whose CTE values are reasonably close, but the stress is still extremely sensitive to temperature. I have also defined the temperature dependent properties of materials. Side walls and bottom surface of the sensor is taken as fixed constraint while cavity & diaphragm surface is taken as free constraint.
Any suggestions on debugging this kind of thermal-stress explosion would be greatly appreciated.
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From the picture, it looks like you have a singularity along the upper edge, so that the stresses can become arbitrarily large.
Without a singularity, a quick estimate of the stress increase for one degree temperature increase in a constrained structure is Young's modulus multiplied with the CTE. For a steel, for example, that number is of the order of 2-4 MPa / degree.
-------------------Henrik Sönnerlind
COMSOL
