# Application Gallery

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.

Search for tutorials and apps relevant to your area of expertise via the Quick Search feature. To download the MPH-files, log in or create a COMSOL Access account that is associated with a valid COMSOL license. Note that many of the examples featured here can also be accessed via the Application Libraries that are built into the COMSOL Multiphysics® software and available from the File menu.

### Self-Demagnetization of a Cylindrical AlNiCo Magnet

Soft permanent magnets like AlNiCo are easily demagnetized if handled incorrectly. This is a demonstration of how to model the self-demagnetization of a cylindrical AlNiCo magnet when moved out of its associated/protective magnetic circuit. The modeling is performed in three steps: 1. The soft magnet protected by the magnetic circuit. 2. The self-demagnetization of the soft magnet when moved ...

### Kirsch Infinite Plate Problem

This model describes a static stress analysis to obtain the stress distribution in the vicinity of a small hole in an infinite plate. The model is a classic benchmark and is described in Mechanics of Material, by D. Roylance. The stress level is then compared with the theoretical values.

### 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 ...

### Lemaitre-Chaboche Viscoplastic Model

Most metals and alloys undergo viscoplastic deformation at high temperatures. In case of cyclic loading, a constitutive law with both isotropic and kinematic hardening is necessary to describe effects such as ratcheting, cyclic softening/hardening, and stress relaxation. The Lemaitre-Chaboche viscoplastic model combines isotropic hardening with nonlinear kinematic hardening to model these ...

### Thermionic Emission in a Planar Diode

When electrons are emitted from a heated cathode in a plane parallel vacuum diode, they contribute to the space charge density in the diode, which in turn affects the electric potential distribution. If the potential difference between the cathode and the anode is not sufficiently large, a potential minimum forms between them, repelling electrons of insufficient energy back toward the cathode. ...

### Rat-Race Coupler

A 180° Ring Hybrid (Rat-Race Coupler) is a four-port network with 180° phase difference between two ports. It is cheaper to manufacture this type of microstrip line component compared to a wave guide 180° hybrid junction, so called magic-T. The objective of this model is to compute the S-parameters and to observe the matching, isolation, and coupling around the operating frequency.

### Crevice Corrosion of Iron in an Acetic Acid/Sodium Acetate Solution

Mass transport limitations within thin crevices can often result in the local electrochemistry to differ significantly between the crevice opening (mouth) and end (tip), and as a result of the differences in local chemistry, corrosion may occur. This example models crevice corrosion of iron in an acetic acid/sodium acetate solution. The model reproduces the results of Walton.

### Assembly with a Hinge

In mechanical assemblies, parts are sometimes connected so that they are free to move relative to each other in one or more degrees of freedom. Examples of such connections are ball joints, hinges, and different types of bearings. If the details of the connection are not the subjects of the analysis, it is often possible to model the connection using the Rigid Connector feature in COMSOL ...

### Polynomial Hyperelastic Model

This model shows how you can implement a user defined hyperelastic material, using the strain density energy function. The model used is a general Mooney-Rivlin hyperelastic material model defined by a polynomial. In this example, you will see two material models based on the defined expression: a two-term equation and a five-term equation. The two-term Mooney-Rivlin material model ...

### Branch-Line Coupler

A Branch Line Coupler (Quadrature 90° Hybrid) is a four-port network device with a 90° phase difference between two coupled ports. The device can be used for a single antenna Transmitter/Receiver system or an I/Q signal splitter/combiner. The objective of this model is to compute the S-parameters and to observe the matching, isolation, and coupling around the operating frequency.

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