## Wolfram SystemModeler in Rotor Dynamics: Internal Damping

December 30, 2015 — Håkan Wettergren, Applications Engineer, SystemModeler (MathCore)

Explore the contents of this article with a free Wolfram SystemModeler trial.In 1869, Rankine extended Euler and Bernoulli’s century-old theory of lateral vibrations of bars to an understanding of rotating machinery that is out of balance. Classical dynamics had a new branch: rotor dynamics. Machine vibration caused by imbalance is one of the main characteristics of machinery in rotation.

All structures have natural frequencies. The critical speed of a rotating machine occurs when the rotational speed matches one of these natural frequencies, often the lowest. Until the end of the nineteenth century the primary way of improving performance, increasing the maximum speed at which a machine rotates without an unacceptable level of vibration, was to increase the lowest critical speed: rotors became stiffer and stiffer. In 1889, the famous Swedish engineer Gustaf de Laval pursued the opposite strategy: he ran a machine faster than the critical speed, finding that at speeds above the critical threshold, vibration decreased. The trick was to accelerate fast through the critical speed. Thirty years later in 1929, the American Henry Jeffcott wrote the equation for a similar system, a simple shaft supported at its ends. Such a rotor is now called the de Laval rotor or Jeffcott rotor and is the standard rotor model used in most basic equations describing various phenomena.

## Helicopter Landing on Ship: Model and Simulation

December 16, 2015 — Håkan Wettergren, Applications Engineer, SystemModeler (MathCore)

#### Background

Today, many helicopters launch from and land on ships at sea. Some are conventional helicopters, both commercial and military, and some are drones. In Wolfram SystemModeler, we now have a system for simulating helicopter landings and launches that includes waves and ships. The models have been used for the design of mechanical parts, autopilots, landing criteria, and operational limits.

#### Major components of the system

The aim has been to develop a model with an accurate depiction of the waves, ship motion, and helicopters in such a way that the results can be used not only qualitatively but also quantitatively in real industrial applications.

The first task is to calculate the motion of the landing platform mounted on the ship’s deck. There is commercially available historical wave data for different seas and oceans. Since access to this data is expensive, we will instead describe the waves mathematically. A model of the forces on the ship’s hull was developed with classical analytical theory. With the waves and ship hull forces, the motion of the ship’s landing platform can be calculated. If we assume that the helicopter landing does not influence the landing platform motion, the system is simplified. We speed up the simulation by storing the motion in a database for the different wave heights, lengths, and directions, and the ship’s speed. Typically the database will include wave heights of 1, 2, 3, and 4 m; wave directions 0, 30, 60, 90, 120, 150, and 180 degrees; wave lengths 100, 150, and 200 m; and ship speeds of 5 and 10 knots. The helicopter was modeled with the MultiBody library. It includes mechanical parts such as rotors with gyroscopic effects and landing gear with hydraulic dampers. Friction models for wheel-deck interface and flexible beams for the rotor blades have been developed. We have also developed a simple autopilot where the landing algorithm is implemented and tested. For one application, the model has been run with the actual autopilot as hardware in the loop.

## Announcing Wolfram SystemModeler 4.2

December 2, 2015 — Johan Rhodin, Kernel Developer

Explore the contents of this article with a free Wolfram SystemModeler trial.Today marks the release of Wolfram SystemModeler 4.2.

I’ll outline some of the new features and improvements we’ve done since Version 4.1. You could say that there are three main pieces to this release: usability, performance, and integration. Let’s take them one by one.

#### Usability

The first improvement you’ll notice as a user opening the product is that the diagram area is easier to understand, with crossing-line detection and joint connection points marked with solder dots:

## ‘Tis the Season to Be Coding! Wolfram Cyber Week Savings

November 30, 2015 — Wolfram Blog Team

It’s that time of year again and the holidays are upon us. Whatever your gifting traditions, Wolfram has perfect solutions for the tech lovers on your shopping list. From now until December 6, we are offering Cyber Week savings around the world, including North and South America, Australia, and parts of Asia and Africa.

## Mechanical Engineering Landing Gear Example: Wolfram SystemModeler

November 24, 2015 — Håkan Wettergren, Applications Engineer, SystemModeler (MathCore)

#### Background

Teachers and textbook authors often need to simplify a real-world problem to pinpoint a specific area to work with—for instance, the examples in a textbook. However, even in real-world engineering, simplifying a problem can bring clarity when our understanding might otherwise drown in a sea of details. In this blog, we will design the landing gear for a helicopter. I have chosen the example of landing gear because the simplification to one degree of freedom gives accurate results and is typically how the problem is treated in textbooks. The solution is attainable through hand calculation. But a more subtle understanding of the problem can be gained using the Wolfram Language and Wolfram SystemModeler.

## Releasing the OPCClassic Library

August 26, 2015 — Patrik Ekenberg, Applications Engineer, Wolfram MathCore

Explore the contents of this article with a free Wolfram SystemModeler trial.Wouldn’t it be great if you could easily connect your simulation models to your existing infrastructure? Whether you are working in industries such as oil and gas, industrial energy, or life sciences, connecting to your processes in order to monitor and control them is vital.

The OPC (Object Linking and Embedding for Process Control) standard has been developed by industry and the OPC Foundation just for that purpose. OPC is a set of data transfer standards for multi-vendor, multi-platform, secure, and reliable interoperability in industrial automation:

## Model and Simulate Cooling Circuits with the SmartCooling Library

June 9, 2015 — Anneli Mossberg

Explore the contents of this article with a free Wolfram SystemModeler trial.The SystemModeler Library Store, launched with the release of Wolfram SystemModeler 4, is continually growing with free and purchasable libraries developed by both Wolfram and third parties. One of our commercial newcomers is SmartCooling, a Modelica library developed by the Austrian Institute of Technology (AIT) that is used for modeling and simulating cooling circuits. When I was asked to present this library on our blog, my first thought was, “Who better to demonstrate the ideas of SmartCooling than the people who actually developed it?” So I asked Thomas Bäuml, one of the creators of SmartCooling, to help answer some of my questions regarding the principles behind the library and its applications.

## Functional Mock-up Interface (FMI) Import in Wolfram SystemModeler

April 8, 2015
Johan Rhodin, Kernel Developer
Henrik Tidefelt, Software Engineer

Explore the contents of this article with a free Wolfram SystemModeler trial.An important emerging standard has been rapidly adopted by industry: the Functional Mock-up Interface (FMI). It’s an independent standard allowing model exchange between different tools. We introduced FMI export with Version 4.0 of SystemModeler. Exporting your model as a Functional Mock-up Unit (FMU) serves many purposes. First and foremost, it can be used in other tools and programming languages. It also protects your intellectual property by compiling the model code to a binary, which is useful when exchanging models with customers and collaborators. Now with Version 4.1 of SystemModeler, we are happy to announce that we also support FMI import.

## Reliability Analysis in SystemModeler 4.1

March 25, 2015
Jan Brugård, CEO, Wolfram MathCore
Johan Rhodin, Kernel Developer

Explore the contents of this article with a free Wolfram SystemModeler trial.Today we are proud to announce the release of Wolfram SystemModeler 4.1. We will present some of the news in blog posts, beginning with this one, in which we will highlight the new reliability functionality.

We will illustrate this with an example, and you can try it out by downloading a trial version of SystemModeler and this example model, and a trial of the Wolfram Hydraulic library.

Most people probably have experiences with things they bought and liked, but that then suddenly failed for some reason. During the last few years we have both experienced this problem, including a complete engine breakdown in Johan’s car (the engine had to be replaced), and Jan’s receiver, which suddenly went completely silent (the receiver had to be sent in for repair and have its network chip replaced).

In both cases it caused problems for the customers (us) as well as for the producer. These are just a couple of examples, and we’re sure you have your own.