This report discusses the use of COMSOL Multiphysics to simulate the behaviour of piezoelectrically actuated MEMS resonators called trampolines. After building the proper geometry and optimising the mesh, a series of simulations will be done to study the mode shapes of the trampoline’s membrane in order to find the best one suited for potential applications. Their frequencies will be computed along with the effect of residual stress in the silicon nitride on those frequencies. The highest actuation voltage will be determined next and the geometrical optimisation of the actuation and detection electrode will take place through various stationary studies in which no residual stress is introduced and a the measurement of charges in a piezoelectric material in COMSOL will be discussed. Finally, the optimisation of the same geometrical parameters will be repeated, this time adding the residual stress in the simulation in order to determine if those optimal parameters are affected by the stress.