10. Material matrix summary

Questions and discussion for this lecture live here. Fire away by hitting Reply below :fire:

Are these equations only for materials that are homogenous? Would this apply to something that is anisotropic?

Yes, homogeneous isotropic material is assumed.

Is it a bit of a stretch to apply this to say carbon fiber polymers, if I knew the layup (or directions of fibers)?

I have to be honest I don’t have any experience with this material. The analysis methods in this course will give you a first approximation of how forces are distributed through your structure, provided it can be approximated as a pin-jointed structure.

But how the material responds to the forces that are developed is not something I could advise on - my hunch would be that for low stress levels, the approximation would be reasonable but as you start to push the material further, you may introduce additional behaviours not captured within our isotropic homogeneous material assumption.

I guess, you can boil the question down to…

How closely does your CFP material agree with the behaviour of a steel bar in uniaxial tension and compression?

If the agreement is good - by extension, the analysis procedure from the course may be a good approximation.

I like how you explained this. It gives me a better understanding of the analysis limits at these beginning stages of learning.

This is my first dive at FEA, I just completed ‘Structural Analysis’ at the undergrade level. We reached up to Moment Distribution in class.

For some context, I am also in an undergraduate research program where I am making a 2 ft CFRP (Carbon Fiber Reinforced Polymer) Beam and subjecting it to 3 point loading.

My professor/mentor has explained to me that currently there is no complete set of failure theories for CFRP’s because of their engineered nature.

However, we clearly model this material’s behavior with FEA at the aerospace level. Therefore, after completing your courses with FEA/Python, I’ll be trying to understand how to apply this to CFRP.

Sounds like fascinating work - material science is one big area where there are still many gains to be made for Civil and Structural engineers. Good luck with your work and don’t hesitate to get in touch with any further questions :+1:

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