Predicting the Stability of Rotor Systems with the COMSOL® Software

Ravi Ranjan July 20, 2018

While working with rotating components, stability analysis is critical, as instability can lead to catastrophic failure. Rotating systems can lead to unstable responses due to asymmetrical inertia of the disk, asymmetrical stiffness of the shaft, or cross-coupling effects due to bearings. From the designer’s point of view, it’s important to ensure that the potentially unstable modes lie outside the operating range of the machine. Let’s explore how to predict the instability in rotor systems using the COMSOL Multiphysics® software.

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Brianne Costa July 11, 2018

The word “turbocharged” is often used colloquially to describe increased speed, such as “turbocharged” coffee that energizes you faster than a regular cup of joe. Actual turbochargers also increase speed, but in combustion engines instead of your morning mug. Turbochargers operate via turbine-driven forced induction and often rely on hydrodynamic bearings for support. However, these bearings naturally include cross-bearing forces that cause negative damping and system failure. Using rotordynamics modeling, you can analyze how these forces affect turbocharger designs.

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Guest Bojan Jokanović July 5, 2018

Guest blogger Bojan Jokanović of SGL Carbon GmbH, one of the world’s leading manufacturers of carbon-based products, discusses the optimization of thermal processes in the carbon industry. Carbon products are used in many industries, including semiconductors, car manufacturing, ceramics, and metallurgy. Properties of graphite including high-temperature stability, good thermal and electric conducting behavior, and high chemical stability make this material unique. However, carbon manufacturing is an energy-intensive industry. We must build digital process chains to optimize processes and minimize costs.

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Kateryna Vyshenska June 28, 2018

Say you want to compute thermal expansion and stresses in an object. You provide the heat fluxes and temperature constraints on the boundaries, compute, and get a convergence error. Often, this result comes from a lack of displacement constraints. However, it is not trivial to provide constraints that do not induce artificial stresses. Today, we showcase the Rigid Motion Suppression feature in the COMSOL Multiphysics® software, which you can use to automatically figure out the constraints you need.

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Kirill Shaposhnikov June 18, 2018

A thorough analysis of a loudspeaker driver is not limited to a frequency-domain study. Some desirable and undesirable (but nonetheless exciting) effects can only be caught by a nonlinear time-domain study. Here, we will discuss how system nonlinearities affect the generated sound and how to use the COMSOL Multiphysics® software to perform a nonlinear distortion analysis of a loudspeaker driver.

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Brianne Costa May 29, 2018

The Doppler effect, or Doppler shift, occurs when the movement of an observer relative to a source (or vice versa) causes a change in wavelength or frequency. Discovered by Austrian physicist Christian Doppler in 1803, this phenomenon is experienced in many different ways, such as when an ambulance passes you by and you hear an audible change in pitch. Using the COMSOL Multiphysics® software, you can model the Doppler effect for acoustics applications.

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Brianne Costa May 11, 2018

Shape memory alloys (SMAs) are alloys with “memory”: They can return to their original shape after being deformed via a change in pressure or temperature. SMAs are used in a wide variety of applications — including metallurgy, manufacturing, biomedicine, and children’s arts and crafts — and their uses are always expanding…

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Caty Fairclough April 27, 2018

Picture a classroom filled with students. At the front, a teacher discusses room acoustics, including the underlying theories and acoustics phenomena involved. To help students visualize these concepts, the teacher has created a simulation app. This app, which is accessible through a web browser, enables students to dynamically alter parameters and see the results, creating a vivid learning experience. At the Technical University of Munich (TUM), several such apps are already being used, providing benefits to teachers and students alike…

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Ravi Ranjan April 18, 2018

When working with multibody systems, you may need to model a mechanism that transfers motion from one component to another. The mechanism used to implement this behavior, known as a cam-follower mechanism, plays an important role in many applications, including internal combustion engines, printing control mechanisms, textile weaving machines, and valves. You can easily model this type of mechanism with the Cam-Follower feature in the COMSOL® software. Let’s take a look at this feature in detail.

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Walter Frei April 17, 2018

In applications such as power transfer and consumer electronics, it may be critical to model electromagnetic heating of materials that are nonlinear in temperature; that is, the material’s electrical conductivity and thermal conductivity vary with temperature. When modeling these nonlinearities, even an experienced analyst can sometimes get quite unexpected results due to the combination of the nonlinear material properties, boundary conditions, and geometry. Let’s find out why this is in terms of a very simple example.

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Henrik Sönnerlind April 13, 2018

When a tuning fork is struck, and held against a tabletop, the peak frequency of the emitted sound doubles — a mysterious behavior that has left many people baffled. In this blog post, we explain the tuning fork mystery using simulation and provide some fun facts about tuning forks along the way.

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