## Applying and Interpreting Saint-Venant’s Principle

##### Henrik Sönnerlind January 22, 2018

All structural engineers use Saint-Venant’s principle, whether actively or subconsciously. You can find various formulations of this principle in most structural mechanics textbooks, but its exact meaning is not obvious. Saint-Venant’s principle tells us that the exact distribution of a load is not important far away from the loaded region, as long as the resultants of the load are correct. In this blog post, we will explore Saint-Venant’s principle, particularly in the context of finite element (FE) analysis.

Read More##### Edmund Dickinson January 17, 2018

As two of the greatest mathematicians to have ever lived, Leonhard Euler and Joseph-Louis Lagrange made numerous contributions to continuum mechanics. Combining their individual descriptions of the subject inspired the arbitrary Lagrangian-Eulerian (ALE) method, a technique that can be used for a multitude of simulation applications. Find out how the work of Euler and Lagrange helped create the ALE method and how it aids your simulations in the COMSOL Multiphysics® software.

Read More##### Brianne Costa November 24, 2017

Magnetic flow meters are a noninvasive option for measuring blood flow. However, when patients move, displaced blood vessels can affect the sensitivity of the flow meter. Researchers from ABB Corporate Research used multiphysics modeling to study how the displacement of blood vessels in a moving patient impacts the performance of a magnetic flow meter.

Read More##### Bridget Paulus November 6, 2017

Optimizing fuel for nuclear reactors can increase the amount of power they generate, improve their safety, and lower greenhouse gas emissions. However, studying nuclear fuel can be complex, as it involves interactions between multiple physical phenomena. In his keynote talk from the COMSOL Conference 2017 Boston, Andrew Prudil of Canadian Nuclear Laboratories (CNL) discussed using multiphysics models to gain insight into nuclear fuel. If you missed his presentation, find a video recording and summary below.

Read More##### Mats Danielsson November 2, 2017

In structural mechanics, there may be situations when you want to implement your own material model. The COMSOL Multiphysics® software gives you the option to program your own material model in C code. The compiled code can then be called from the program using the External Material feature. Here, we demonstrate how to implement an external material model and then use it in an example analysis.

Read More##### Mats Danielsson October 11, 2017

The trebuchet is a large siege weapon that you might recognize from movies set in the Middle Ages or fantasy worlds. This weapon is built on the idea of converting potential energy into kinetic energy to hurl a projectile over a large distance. Simple as it seems, the trebuchet is a complicated dynamical system. In this blog post, we will build a simplified model of a counterweight trebuchet using the Multibody Dynamics Module and examine some of its design features.

Read More##### Caty Fairclough August 7, 2017

Metamaterials are artificial materials with properties that rely on a particular structural design rather than chemistry. Their structure is often complicated, making these materials challenging to fabricate. Here, we present numerical research that investigates one such material — a poroelastic metamaterial (made from a single material with voids) with the ability to expand under hydrostatic pressure.

Read More##### Peter Yakubenko July 26, 2017

Many elongated structures can be modeled effectively using 2D representations of their cross sections. A typical assumption is the plane strain approximation, which implies that all out-of-plane strain components are zero. This assumption is valid when the out-of-plane deformation is restrained; for example, when the ends of the structure are fixed. However, in many cases, the structure is free to expand in the out-of-plane direction. Let’s discuss how to model this case, which is sometimes called generalized plane strain.

Read More##### 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.

Read More##### Bridget Cunningham June 12, 2017

In the last seven years, the output of the manufacturing industry has increased by a total of around 10–20%. This growth is partly thanks to technologies and processes that save on time and costs, such as 3D printing and, as is described here, powder compaction. To model this process, we can use the new porous plasticity models in the latest version of the COMSOL Multiphysics® software.

Read More##### Bridget Cunningham May 30, 2017

Every year, over 40 million fire sprinkler systems are fitted worldwide. These systems are effective due to their piping designs, which are resistant to high heat and mechanical damage. A popular choice for such designs is threaded steel pipe. But analyzing a complex pipe design is challenging because of the detailed geometry. What approach can we take to efficiently combine accurate geometrical designs with reliable stress analyses? Version 5.3 of the COMSOL® software offers functionality for this purpose.

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