# meshless

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## interpolation/approximation method for accurate evaluation of higher order derivatives of shape functions

Hello,

I  want to solve some problem from solid mechanics by means of meshless methods. Do you know some interpolation/approximation method which is able to accurate evaluate 3rd and 4th derivations of the shape functions and is not difficult to implement? MLS or PIM have problem with accuracy in these derivatives, as is known.
Thank you very much for your advices.

## Questions about RPIM shapefunction

I am solving a simple solid mechanics problem by meshless method.  use RPIM to  calculate shape function.

when i calculate the derivatives of shape function, i found the derivative is not close to zero at the compute point, when the point is on the boundry of problem domain. and good derivative result can be got if the compute point is in problem domain.

is there anybody has experience in working with RPIM shape function help me to fix the problem?

## Question about how to determine support radius..

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Hi, everyone.

I'm going to employ the meshfree method to analyze composite model.

But, I can't understand how to determine the support radius although I have read some references.

I will use the circular support domain.

Please explain how to determine the support radius.

## Problems with MLPG and collocation

I fight with my models... Maybe can somebody of us help me...

I model the three dimensional body, those two sizes length and width are much larger then the thickness. For solving PDE i use MLPG Method. After defining my hexahedral support domain with MLS and hexahedral test doman with Heaviside function, i make the nodal integration. For that i divide the hole problem in hexahedrals, in the centers of those the particles are placed. Then i compute the surface of the hexahedrals in test domain through gauss quadratur to assemble the stiffness matrix

## second derivative of MLS function

Can somebody help me with the second derivative of MLS function for three dimentional problems?