# Thermal stress analysis of polymeric photo-thermal microactuator¶

## Overview¶

The aim of this test case is to validate the following functions:

- thermomechanical solvers

The simulation results of SimScale were compared to the analytical results presented in [Elbuken]. The meshes used were created using second order tetrahedral automatic meshing algorithm on the SimScale platform.

## Geometry¶

The radius (*R*) and thickness of the microactuator was set to 130 μm and 100 μm respectively and remained constant for all the cases. For cases from A1 to A5 the length (*L*) and width (*W*) of the microactuator arm was remained constant at 1000 μm and 50 μm respectively whereas the bending angle (*θ*) was changed from 6° to 14°. For cases from B1 to B8 the length (*L*) and bending angle (*θ*) of the microactuator arm was remained constant at 700 μm and 6° respectively whereas the width (*W*) was changed from 30 μm to 100 μm. Due to symmetry, only half of the model was taken for the analysis. The skeleton of the geometry used for the analysis is shown in the figure below:

## Analysis type and Domain¶

**Tool Type** : CalculiX, Code_Aster

**Analysis Type** : Thermomechanical

**Mesh and Element types** :

Case | Arm length (μm) | Width (μm) | Bending angle (°) | Mesh algorithm | No. of nodes | No. of 3D elements | Solver |
---|---|---|---|---|---|---|---|

A1-1/2 | 1000 | 50 | 6 | Tetrahedral automatic | 23652 | 14408 | CalculiX/Code_Aster |

A2-1/2 | 1000 | 50 | 8 | Tetrahedral automatic | 23147 | 14046 | CalculiX/Code_Aster |

A3-1/2 | 1000 | 50 | 10 | Tetrahedral automatic | 23713 | 14330 | CalculiX/Code_Aster |

A4-1/2 | 1000 | 50 | 12 | Tetrahedral automatic | 22525 | 13586 | CalculiX/Code_Aster |

A5-1/2 | 1000 | 50 | 14 | Tetrahedral automatic | 22724 | 13670 | CalculiX/Code_Aster |

B1-1/2 | 700 | 30 | 6 | Tetrahedral automatic | 29407 | 18758 | CalculiX/Code_Aster |

B2-1/2 | 700 | 40 | 6 | Tetrahedral automatic | 31521 | 20498 | CalculiX/Code_Aster |

B3-1/2 | 700 | 50 | 6 | Tetrahedral automatic | 30997 | 20243 | CalculiX/Code_Aster |

B4-1/2 | 700 | 60 | 6 | Tetrahedral automatic | 33551 | 22158 | CalculiX/Code_Aster |

B5-1/2 | 700 | 70 | 6 | Tetrahedral automatic | 26071 | 16664 | CalculiX/Code_Aster |

B6-1/2 | 700 | 80 | 6 | Tetrahedral automatic | 28881 | 18754 | CalculiX/Code_Aster |

B7-1/2 | 700 | 90 | 6 | Tetrahedral automatic | 21715 | 13479 | CalculiX/Code_Aster |

B8-1/2 | 700 | 100 | 6 | Tetrahedral automatic | 22347 | 22347 | CalculiX/Code_Aster |

Mesh used for case A1 and B1 are shown in the figures below.

## Simulation Setup¶

Material:

- SU-8: isotropic: \(E\) = 4 GPa, \(\mu\) = 0.22, \(\rho\) = 1200 kg/m³, \(\kappa\) = 0.2 W/(mK), Expansion coefficient = 52 e-6 1/K, Reference temperature = 300 K, Specific heat = 1500 J/(kg K)

Initial Condition:

- Temperature = 300 K

Constraints:

- Face ABCD constrained in all directions
- Face IJKL constrained in x-direction only

Temperature Loads:

- Constant temperature of 300 K on face ABCD

Heat Flux Loads:

- Laser surface heat flux of 9433.96 W/m² (0.5 mW) on face IGMOK
- Convective heat flux with \(h\) = 10 W/(m²K) and Reference temperature = 300 K on faces AEIKOMGC, GHMN, MNPO, KLOP, CGHD, BFJLPNHD, AEFB, EIJF