TY - JOUR T1 - Thermo-diffusive Coupling Effect on the Damping Ratio Based on Modified Couple Stress Theory in Micro-beam Resonators TT - اثر کوپلینگ دمایی-انتشاری بر روی ضریب میرایی بر اساس تئوری کوپل تنش اصلاح شده درمیکرو رزوناتورها JF - mdrsjrns JO - mdrsjrns VL - 15 IS - 9 UR - http://mme.modares.ac.ir/article-15-8585-en.html Y1 - 2015 SP - 116 EP - 124 KW - MEMS KW - Mass diffusion KW - Non-‎Fourier heat conduction KW - Non-Fickian mass diffusion KW - Modified couple stress theory N2 - In this work effect of mass diffusion on the damping ratio in micro-beam resonators is investigated based on modified couple stress theory and the Euler-Bernoulli beam assumptions. The couple stress theory is a non-classical elasticity theory which is capable to capture size effects in small-scale structures. The governing equation of a micro-beam deflection is obtained using Hamilton’s principle and also the governing equations of thermo-diffusive elastic damping are established using two dimensional non-Fourier heat conduction and non-Fickian mass diffusion models. Free vibration of the micro-beam resonators is analyzed using Galerkin reduced order model formulation for the first mode of vibration. A clamped-clamped micro-beam with isothermal boundary conditions at both ends is studied. The obtained results are compared with the results of a model in which the mass diffusion effect is ignored. Furthermore the mass diffusion effects on the damping ratio are studied for the various micro-beam thicknesses, ambient temperature and length scales parameters. The results show that in the valid region based on Euler-Bernoulli beam theory and before the critical thickness there is no difference between the results of mass diffusion and thermo-elastic damping and also the results indicate that by increasing the length scale parameter damping ratio decreases. M3 ER -