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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Prashant Srivastava February 14, 2018

Bearings, specifically rolling element bearings, are some of the most commonly used industrial components. These bearings are found in gearboxes, conveyors, motors, and rolling mills due to the low friction and low starting torque compared to hydrodynamic bearings. They can also handle changes in speed, temperature, and loads. In this blog post, we will look at different bearing types and demonstrate how to model a rotor system supported on roller bearings using the COMSOL Multiphysics® software.

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Prashant Srivastava July 12, 2017

Vibration in rotating machinery is very sensitive to the geometric, structural, and inertial properties of the various rotating and stationary components interacting with each other. These properties include the location of the mounted components and their inertial properties, bearing characteristics, and shaft properties. To understand the effects of these parameters, start with a simple model and perform various analyses to correlate the rotor response within the same model. Let’s demonstrate this process with a simply supported beam rotor example.

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Prashant Srivastava May 25, 2017

Rotating components are important elements in machines such as gas turbines, turbochargers, pumps, compressors, electric generators, and motors. Designing such a component requires studying its critical speed, which is the speed at which the amplitude of the vibration in the system becomes large — often leading to failure. Let’s explore how to find the critical speeds for a wide range of rotors via the Rotor Bearing System Simulator, created using the COMSOL Multiphysics® software.

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Bridget Cunningham March 1, 2017

To provide sufficient support for a rotating shaft or journal, it is important to choose a hydrodynamic bearing design with the right load capacity. If the applied loads are greater than a bearing design can handle, it can cause excessive wear and instability. With the Rotordynamics Module, an add-on product to the COMSOL Multiphysics® software, you can compare the load capacities for different types of hydrodynamic bearings and determine which one is best suited for your particular application.

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Bridget Cunningham January 2, 2017

When a reciprocating engine’s crankshaft is under rotation, self-excited vibrations occur. These vibrations result from the eccentricity of the crank pin and balance masses on the mechanical part. Here, we’ll accurately study the response of the rotors and the orbits of the mass balances on the shaft with the Rotordynamics Module, a new add-on product to the COMSOL Multiphysics® software and Structural Mechanics Module. From these results, you can improve a crankshaft’s design to reduce vibrations, while optimizing engine performance.

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Caty Fairclough December 6, 2016

When modeling a rotating machine, it’s important to study the vibrations influencing its behavior in order to avoid machine failure. One way to accomplish this is with the new Rotordynamics Module, an expansion to the add-on Structural Mechanics Module for the COMSOL Multiphysics® software. Today, we’ll introduce you to the Rotordynamics Module and walk you through its helpful features and functionality for improving your rotating machinery design process.

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Caty Fairclough September 8, 2016

Rotating machinery is an important element in many structures, from wind turbines to engines. The analysis of this rotating machinery — a field known as rotordynamics — is key in reducing noise and vibrations in many areas of technology. Here, we’ll take a closer look at rotordynamics and its relevance within various applications.

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