The Application Gallery features COMSOL Multiphysics® tutorial and demo app files pertinent to the electrical, structural, acoustics, fluid, heat, and chemical disciplines. You can use these examples as a starting point for your own simulation work by downloading the tutorial model or demo app file and its accompanying instructions.

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Eigenfrequency Shifts Caused by Temperature Changes

This example explores the shift in natural frequencies caused by changing the temperature. One study investigates a doubly clamped beam where both ends are fixed, while the other study looks at a cantilever beam where only one end is fixed. The following effects are studied: * Stress stiffening * Change in size * Constraint effects * Temperature-dependent Young's modulus Results show that the ...

Vibrations of a Disk Backed by an Air-Filled Cylinder

The vibration modes of a thin or thick circular disc are well known, and it is possible to compute the corresponding eigenfrequencies to arbitrary precision from a series solution. The same is true for the acoustic modes of an air-filled cylinder with perfectly rigid walls. A more interesting question to ask is: What happens if the cylinder is sealed in one end not by a rigid wall but by a thin ...

Viscoelastic Structural Damper

Viscoelastic dampers are frequently used to protect tall structures against vibration. The Viscoelastic Structural Damper application can perform the time-domain and frequency-domain analyses for a typical viscoelastic damper. The purpose of the app is to compute and analyze the important parameters of the damper such as the hysteresis loop and loss and storage moduli for a prescribed material ...

Truss Bridge Designer

The Truss Bridge Designer app is an example of how to design a simulation tool for a class of civil engineering structures, in this case a Pratt truss bridge. Such a bridge is characterized by the diagonal beams on each side of the bridge, which all slant down and in toward the center of the span. Because of this design, the diagonal beams are subjected only to tension, while the vertical beams, ...

MEMS Pressure Sensor Drift due to Hygroscopic Swelling

Modern integrated circuits are available as plastic encapsulated microcircuits (PEM). These devices are molded out of polymeric materials and epoxy resins in order to protect the internal semiconductors. Unfortunately, polymeric mold compounds absorb moisture when exposed to a humid environment, thus swelling and causing undesired strains, which can be as high as thermal strains. This ...

Modeling Rigid Bodies

In many structural dynamics applications, some components are stiff compared to the supporting structure. Such a stiff part will only contribute to the dynamic properties of the structure through its mass and moment of inertia. It is then possible to reduce the model size significantly by treating it as a rigid body. In this example the eigenfrequency of an assembly is computed where one of the ...

Contact Analysis of a Snap Hook Using a Penalty Formulation

This example simulates the insertion of a snap hook in its groove. Here, the purpose of the contact modeling is only to transmit correct contact forces in a global sense into the model, which is a situation well suited for using the penalty method. This contact algorithm is based on the penalty factor formulation related to the penetration of the solid parts in contact. In some cases, this ...

Vibrating Micromirror with Viscous and Thermal Damping: Transient Behavior

Micromirrors are used in certain MEMS devices to control optic elements. This example model illustrates a mirror that is initially actuated for a short time and then exhibits damped vibrations. It simulates a vibrating micromirror surrounded by air and uses the *Thermoviscous Acoustics, Transient*, the *Shell*, and the *Pressure Acoustics, Transient* interfaces to model the fluid-solid ...

Linear Buckling Analysis of a Truss Tower

Trusses are commonly used to create light structures that can support heavy loads. When designing such a structure, it is important to ensure its safety. For a tower made of bars, buckling can cause the structure to collapse. This model shows how to compute the critical buckling load using a linear buckling analysis. The solution is compared with an analytical expression for critical load ...

Stress Relaxation of a Viscoelastic Tube

This model studies the temperature effects on the viscoelastic stress relaxation in a long thick-walled cylinder. In particular, decay of the stresses under the influence of the temperature field during a period of two hours is studied. A four-term generalized Maxwell model represents the material.