Generation of Random Surfaces
These examples demonstrate how to generate randomized geometric surfaces. The COMSOL Multiphysics® software provides a powerful set of built-in functions and operators, such as functions for uniform and Gaussian random distributions and a very useful sum operator. In the blog post associated with these files, "[How to Generate Random Surfaces in COMSOL Multiphysics](/blogs/how-to-generate ...
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 ...
Residual Stress in a Thin Film Resonator - 3D
Surface micromachined thin films are often subject to residual stress. This COMSOL Multiphysics example describes a thin film resonator with straight or folded cantilever beam springs. The resonance frequencies of the resonator are affected by thermal stress. Using folded springs relieves this effect. The example is made up of four models: two thin film resonators with folded cantilever beam ...
Radially Polarized Piezoelectric Transducer
This tutorial model shows how a user-defined coordinate system can be used to create any type of directional polarization of a piezoelectric material. Results are shown for the case of radial polarization of a piezoelectric disk. The piezoelectric material is PZT-5H. The example shows a static analysis. Visualization of the cylindrical coordinate system as well as the stress/strain in that ...
Piezoceramic Tube
This example involves a static 2D axisymmetric analysis of a piezoelectric actuator using the Piezoelectric Devices physics interface. It models a radially polarized piezoelectric tube, as described by S. Peelamedu and co-authors. An application area where radially polarized tubes are employed is in nozzles for fluid control in inkjet printers.
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 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 ...
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.
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 ...
MEMS Pressure Sensor Drift Due to Hygroscopic Swelling
For their integration in microelectronic circuits, MEMS devices are bonded on printed circuit boards and connected with other devices. Then, the whole circuit is often covered with an epoxy mold compound (EMC) to protect the devices and their interconnects with the board. The epoxy polymers used for such applications are subject to moisture absorption and hygroscopic swelling, which can lead to ...