A study of mechanical configuration optimisation in micro-systems

This paper shows that there are three main categories of factors that make the optimum mechanical design of micro-systems different from macro-systems: scale effects, a limited range of materials, and a limited range of production processes. The combined effect of these factors can make the optimum configuration of a micro-system potentially very different from that of the same system on a macro-scale. In particular, the use of flexible elements for hinges is much more feasible and desirable on a micro-scale.Notation a acceleration (m/s²) - A cross-sectional area (m²) - B magnetic flux wb/m²] - b width m] - C constant - d depth m] - D drag N] - E Young's modulus N/m²] - E*= - f resonant frequency Hz] - F _D drive force N] - F _E electrostatic pulling force N] - F emmisivity function - F _G geometric view factor - g gravitational constant m/s²] - h _c convention heat transfer coefficient W/m²K] - h height m] - i current A] - I _A second moment of area m⁴] - I _I moment of inertia kg m²] - J polar second moment of area m⁴] - k stiffness N/m] - K thermal conductivity W/m K] - l length m] - m mass kg] - M moment N m] - P load N] - P _H Hertz contact pressure N/m²] - P _C cylinder pressure N/m²] - q heat transfer rate W] - R, r radius m] - Re Reynolds number - T, t temperature K] - T _A atomic friction torque N m] - T _D drive torque N m] - T _F Coulomb friction torque N m] - T _I inertial resistive torque N m] - u velocity m/s] - mean velocity m/s] - V volume m³] - V _e voltage V] - x distance between electrodes m] - y maximum distance to neutral axis m] - angular acceleration rad/s²] - _d thermal diffusivity 1/K] - rolling friction factor - P pressure difference N/m²] - ₀ dialectric constant F/m] - strain - dynamic viscosity Pa s] - scale factor - _S coefficient of sliding friction - _R coefficient of rolling friction - _{1, 2} Poisson's ratio - density (kg/m³) - temperature rise °C] - _B bending stress N/m²] - _y yield strength N/m²] - shear stress N/m²] - reliability constant