3 Replies Latest reply on Dec 12, 2017 6:07 AM by Jean Gardy Jeune

# How do I simulate muscle properties?

Hi! I'm a beginner in the Solidworks world. I'm trying to simulate the strains suffered by the rectus femoris muscle. I already created the morphological model which contains the muscle itself and the two tendons. I have come across some doubts/problems when trying to figure out which material and properties should I use. My doubts are the following:

1. I have read a lot of information on the internet and several papers, trying to find out which kind of material (and its properties) should I use to fit the muscle properties. That is quite hard since most of the studies are not done with Solidworks (I know that maybe it is not the best software available for this purpose) but I have to use it and I have to figure out how to do it as soon as possible. But going back to the question, since the muscle is non-linear. anisotropic, almost incompressible and viscoelastic; I have come to the idea that the best way to simulate it is using a non-linear study and an hyperelastic material with a Mooney-Rivlin model for the muscle. The problem is that I am not really sure about that, and in case that I am right, I am quite lost about the parameters I need to use for defining it. So I hope you can give me advice about if it is correct and if it is, about the parameters that I need to use.

2. This muscle is bipennate, which means that on one side its fibres are oriented with 10 degrees of pennation angle and the other side is oriented with -10 degrees of pennation angle. The pennation angle is the angle formed by the fibres and the line of action of the muscle (You can get a better idea of what I am trying to explain with the following image).

This means that the muscle is very resistant to the strains in both angles. Is there any way to specify this? I mean, to tell that the material resists the strains along an axis with 10 degrees and not along its longitudinal axis? I thought about an orthotropic material, but I think it does not really fit my needs. So I would appreciate it if you could help me to find out how to specify this if there is any way of doing it.

Thank you so much in advance!

• ###### Re: How do I simulate muscle properties?

This may not be very helpful, but years ago I worked on a paper dealing with determining and simulating articular cartilage. We ended up running many, many mechanical tests on sampled tissue (creep, stress, strain, etc.) and editing the material properties to match the empirical data. We had a very VERY hard time finding any truly reliable material properties for simulation in the literature for soft tissue.

• ###### Re: How do I simulate muscle properties?

Hi, Grant! First of all, thank you for your answer. Is there any way for me to take a look at the resources you used for your paper, in order to get an idea of the material properties for the muscle? It would be really interesting to use them as references for my study. Thank you again!

• ###### Re: How do I simulate muscle properties?

Hi Sofia,

You do not need to know which material to use. You only need to know the elastic behavior of the muscle. I am not very sure if you can operate on a real muscle but you could try and find a material that deforms the same way. For example apply a force to it and note the deformation. You will have a Stress-Strain curve. Some softwares like Marc-Mentat will give you the Mooney coefficients you need once you have the curve. If you can have the curve (preferably in the form of table) post it down below i will get them for you.

I hope that helps.

Regards