## How to Model the Compression of a Hyperelastic Foam

##### Chandan Kumar September 5, 2018

To characterize hyperelastic materials, we need experimental data from a variety of tests, including subjection to uniaxial tension and compression, biaxial tension and compression, and torsion. Here, we show how to model the compression of a sphere made of an elastic foam using tension and compression test data obtained via uniaxial and equibiaxial tests. We demonstrate the use of the compressible Storakers hyperelastic material model for computation as well as how force-versus-stretch relationships are calculated for uniaxial and equibiaxial tests.

Read More##### Chandan Kumar January 4, 2018

A sphere slightly lighter than water is dropped into a small liquid-filled beaker. How do you model the resulting shape of the water surface and the motion of the sphere as it floats on the surface? In this blog post, we demonstrate how to model this system in the COMSOL Multiphysics® software. Although we are considering the case of a small sphere, the technique discussed here can be applied to other larger shapes as well.

Read More##### Chandan Kumar October 8, 2015

MEMS resonators are microelectromechanical systems primarily used as sensor elements, filters, and frequency elements. Two common actuation methods for MEMS resonators are piezoelectric actuation and electrostatic actuation. In this blog post, we will discuss the modeling of electrostatically actuated MEMS resonators. When modeling such resonators, you will often come across terms such as equilibrium point, pull-in, pull-in voltage, and time harmonic response of a biased resonator. We will explain these phenomena using a simple representation of an actuator.

Read More##### Chandan Kumar June 24, 2015

Previously on the blog, we have discussed the need for appropriate measured data to fit the material parameters that correspond to a material model. We have also looked at typical experimental tests, considerations for operating conditions when choosing a material model, and an example of how to use your measured data directly in a nonlinear elastic model. Our focus today will be on how to fit your experimental data to different hyperelastic material models.

Read More##### Chandan Kumar January 28, 2014

Here is an interesting question: How can we easily probe the solution at a point that is moving in time, but associated with a stationary geometry? One option is to use the General Extrusion coupling operator. In this blog post, we will take a look at how to use the General Extrusion coupling operator to probe a solution at a point in your geometry, and illustrate how to implement a dynamic probe using an example model.

Read More##### Chandan Kumar April 3, 2013

Some structural applications involve thin or high aspect ratio structures sandwiched between other relatively low aspect ratio structures. For example, if a piezoelectric transducer is glued on the surface of a mechanical system, the thickness of the adhesive layer is very small in comparison to the two structures it glues together. Numerical modeling of such a thin layer in two or three dimensions requires resolving it with an appropriate finite element mesh. This can result in a large concentration of […]

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