Thermal Expansion in a MEMS Device
This model analyzes the thermal expansion in a MEMS device, such as a microgyroscope, where thermal expansion should be minimized. The device is made from the copper-beryllium alloy UNS C17500 and uses temperature-dependent material properties from the Material Library. The purpose of this model is to exemplify the use of the Material Library in COMSOL Multiphysics. This library contains more ...
Electromagnetic Force Calculation Using Virtual Work and Maxwell Stress Tensor
The model compare the electromagnetic force calculated by *virtual work* and *maxwell stress tensor* methods on the axial magntic bearing. The forces is evaluated by studying the effect of a small displacement on the electromagnetic energy of the system. This is done by using the *Magnetic Fields*, *Deformed Geometry* and *Sensitivity* physics interfaces.
Piezoelectric Rate Gyroscope
This model shows how to analyze a tuning fork based piezoelectric rate gyroscope. The direct piezoelectric effect is used to drive an in-plane tuning fork mode. This mode is coupled to an out of plane mode by the Coriolis force and the resulting out of plane motion is sensed by the reverse piezoelectric effect. The geometry of the tuning forks is designed so that the eigenfrequencies of the ...
Adhesion and Decohesion of Indenting Ball
A steel ball is pressed down against a rubber membrane. When the contact pressure exceeds a certain value, the two parts start sticking together. When the ball is retracted, the membrane is pulled upwards in the bonded region. During the retraction, the bond is partially broken. This happens when the stresses exceed the limits specified in the decohesion law.
Piezoelectric Valve
Piezoelectric valves are frequently employed in medical and laboratory applications due to their fast response times and quiet operation. Their energy efficient operation, also dissipates little heat, which is often important for these applications. This model shows how to model a piezoelectric valve in COMSOL. The valve is actuated by a stacked piezoelectric actuator. A hyper-elastic seal is ...
Pull-in Voltage for a Biased Resonator-2D
Silicon micromechanical resonators have long been used for designing sensors and are now becoming increasingly important as oscillators in the consumer electronics market. In this series of models, a surface micromachined MEMS resonator, designed as part of a micromechanical filter, is analyzed in detail. The Stationary Analysis of a Biased Resonator model performs a stationary analysis of ...
Microresistor Beam
Microresistors allow for quick and accurate actuation or structural movement directly related to the electricity that is applied to them. Microresistors can be used in many applications where small perturbations or deflections are required to be applied to devices, almost instantaneously. The Microresistor Beam app illustrates the importance of fully coupled, multiphysics simulations. An ...
Prestressed Micromirror
One method of creating spring-like structures or inducing curvature in thin structures is to plate them to substrates that are under the influence of residual stresses. The plating process can control this stress even for similar materials. One such device is the electrostatically controlled micromirror. It is typically quite small, and arrays of such devices can be implemented in projectors. ...
Thermoelastic Damping in a MEMS Resonator
Thermoelastic damping, which arises when you subject a material to cyclic stress, is an important factor when designing MEMS resonators. The stress brings about deformation, where materials heat under compressive stress and cool under tensile stress. Thus, due to the resulting heat flux, energy is lost to bring about this damping. The magnitude of the energy loss depends on the vibrational ...
Squeeze-Film Gas Damping of a Vibrating Disc
This benchmark model computes the total force acting on a vibrating disc in the frequency and time domains and compares both results with expressions derived analytically. When the vibration amplitude is small enough that the system is linear the frequency and time domain results agree well with theory. Larger amplitude vibrations, which result in a non-linear response that cannot be modeled in ...
