Summary of my seminor of Material test for CFRP product design


I opened my seminar of a topic as a material test of CFRP and a way of thinking of a material test and a seminar as the way indispensable to a CFRP product design the other day.


I had 20 participates in this seminar relatively from a distant place.



Some have been felt through this seminar.

Because that could think there was also a part where I provide the person who sees this blog with useful information, too.

I think I'll excerpt and tell to you.


"Diremption" about recognition of a material test

This seminar remained by other seminars as a material test of CFRP and was the one specialized in the theme from which you assume that I don't have that of being taken up.


Therefore the persons who participated are;

– CFRP product manufacturer

– CFRP designer

– CFRP component test conductor

– CFRP CAE analysis conductor


For all of them, necessity of a material test could be felt to some degree, and I found to participate with strong sense of purpose.

Though sense of purpose of the person who participated is this high, my impressions for them are;.


"There is diremption in a recognized material test and the material test which should be performed actually."


This is the fact that I face it by many situations as well as a seminar like this time (ex. meetings at an advisor destination).


A medium as "diremption" above-mentioned has diremption of various points of view (for example, test quality, test item, test method and processing of data, etc.), and diremption is felt more or less about each.


The cause of diremption


Then, what is the cause diremption like the above causes?

Several reasons are assumed.


The first of it is;

"Too hurry to make the shape."


This column is being described several times, it's fact to feel like making the shape for principle proof as expected.

I often say and hears that that is necessary as a way of thinking of an enterprise.


There is a necessary phase as well as making the shape and doing principle proof.


Even if principle proof is done, the people are surely facing the status that;


"Then it becomes stable, and can I keep making the product which could do the principle proof?"




The question which says so and the one I face anxiously.


In this situation, many people would think the things from the view point of the process.


"Quality control and management of the pressure and the temperature during the molding process."


Such as, isn't the one by which thought is called off general in the direction?


Of course, such point of view is also necessary.


The one which shouldn't be forgot?


"CFRP material contains the property variations by every batch."


The obvious fact that I say so.


This material variation can be evaluated only by material tests.

It's because property variation by a process has been contained by the value by the sampler.

And another reason that diremption forms is;


"Strong anisotropy the material possesses"


Something as this anisotropy is also the cause which can raise importance of the material test and also disturb the designer who deals with it.


For example when one of strength of UD, it's different from a fibrous direction tens of times at 90 deg direction.


The elastic modulus which is one of the physical properties according to that also changes.


Further, existence of a mode as "shearing".

Moreover an idea as "in plane" and "interlaminar" is making the value more complicated.

The material, called fiber reinforced plastic as well as CFRP is;


"The material changes into the different material by the load direction and mode."


Steady evaluation, based on such fact, becomes indispensable to a material test to each loading mode.


It'll be directly connected with the worst situation that a product destroys this at an unexpected place when it isn't done.


What is necessary to overcome diremption?


They're honest with a thing necessary to the purpose in which this diremption is buried, I think it's quite difficult that time gets a clear solution.


Because a technical part, not to mention.

"Design concept" is the important weight about the way of thinking.



There is an additional point, need to consider, to understand diremption. That it;

"The material standard doesn't exist in CFRP except for a part exception of the agate material."

When the fact that I say so is re-recognized, there is something to say.


Please assume metal.


When trying to produce metal items, people would use SUS304 public material material standards?


There isn't a person who uses the alloy which doesn't also know which who made compared with what kind of constitution for a product suddenly.


When even that would like to use the alloy, how would it be done?


You would start the discussion with material supplier to get the basic material property data, for sure.


The case is same even if the material is FRP.


The starting point is to prepare the temporary material requirement value after the material tests are conducted.


It's the data indicated on the material standard, so I can't make the test suitable and acquire data.

Therefore material, when it's tested, for, it's necessary also to do a quality request about each process such as doing the test into which the test fragment for which the material makes a flat board with its own safekeeping important matter actually is processed and get formal data.


A way of thinking like the above may be the some help in which one factor for overcoming the diremption.


It applies because the situation is different depending on each person, but you can image the process briefly. The story, mentioned above, shows the very limited aspect of the whole area. But this column would be one of the reference information for persons who would need to conduct material testing.

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