Learning Forum

[Shubham96]

I am currently working on validating the results obtained from manufacturing of honeycomb sandwich structure with its honeycomb core made of Kevlar, using FEM. While the defining of Isotropic material properties requires the input of combination of any 2 characteristic properties of the material, say, Poisson ratio and Young Modulus or Shear Modulus or Young Modulus, what has been received from the manufacturer's end is a data sheet which lists its Compressive Strength, Shear Strength and Shear Modulus (Requisite file attached), which does not seem to be sufficient enough for defining the material in ANSYS. Is there anything I am missing out or it can be done with the given data ? How to go about it ? (Note- The material code is PK2-1/8-3.0, the nomenclature can be understood by the attached file links)https://www.plascore.com/download/datasheets/honeycomb_data_sheets/Plascore_PK2.pdfhttps://www.plascore.com/download/datasheets/honeycomb_data_sheets/Plascore_Terminology.pdf

[Prashank]

Hey , did you get the values.....
I am looking for the same thing

[peteroznewman]

I explain how to use values from the honeycomb datasheet in this Discussion.

Here is a working link to the Aramid core.

https://www.plascore.com/download/datasheets/honeycomb_data_sheets/PLA_PK2_2019.pdf

[Prashank]

hello sir, 

i have few doubts regarding your method to find out the remaining properties to define the new orthotropic material(poisson ratios, young's modulus).

i read a research paper in which there were formulas to find out the poisson ratios in different direction. According to it the poisson ratios cant be same in different directions. so can you please share the methods adopted by you to find out these.

i am considering to use the 2nd one. But i dont even have the young's modulus value in z direction.

so how should i define this material in ansys library.

[peteroznewman]

 In my case, the table included the Compressive Modulus.  You will have to contact the manufacturer and request that data.

[Prashank]

Okey....
In even your case the Young's modulus(in X & y direction) is not given...so how did you find out that...?

[peteroznewman]

Under Bare Compressive, where it says Modulus, that is Young's Modulus.

Under Plate Shear, where it says Modulus, that is Shear Modulus.

[Prashank]

hi , thanks for replying . i understand what are you trying  to say.

In the previous ans which you mentioned the datasheet was:-

note: Here shear modulus is given in two directions(YZ,XZ) & young's modulus in one direction(Z direction)

but what i wanted to know this

1.how did you find out the values of young's modulus in X and Y direction?

2. poisson ratios in all the three direction? And how does the poisson's ratios  values are same in every direction if the material is orthotropic?

3.shear modulus in XY direction.

[peteroznewman]

The three numbers highlighted dominate the results. All the other numbers have only a small effect on the results. Use 1% of the average of Shear YZ and Shear XZ as an estimate for Shear XY.  Use 1% of Young's Modulus in Z for the X and Y.   You can use zero for the Poisson's ratio. 

Since you don't have the Young's Modulus in Z (yet) you could estimate it from a source such as this.  It lists the modulus for an aramid fiber of 85 GPa and lists the density as 1.39 g per cubic cm. The density of the honeycomb core is only 3.5% of that, so you could take that fraction of the modulus of the fiber and say the honeycomb compressive modulus is 2.9 GPa.  You can replace this with the value the manufacturer provides if and when they do.

Do some experiments to convince yourself that these values you are making up can vary widely and have little effect on the result of bending of a honeycomb core sandwich composite structure.

[MichaelDelle]

 Shouldnt the poisson's ratio be 0.33 ? instead of 0.033