Re: RP Strength Anisotropy Question

From: Maurizio Bertoldi (
Date: Mon May 18 1998 - 22:02:47 EEST

On Mon, 18 May 1998, John Kietzman wrote:

> Does anybody know of any measurements of orientation-dependent tensile
> strengths (or other mechanical properties) for commercial RP processes?
> The obvious experiment is building tensile specimens in the plane vs.
> making specimens vertically, in the build direction.
> I am familiar with the work by Gibson and Shi (commercial SLS machine)
> and Thompson (old SLS machine), but I'd be interested in other SLS
> work as well. I'd also really like to hear about any work in FDM or SLA
> (including fresh-from-the-machine vs. post-cured parts).
> Have any of the companies released data like this, or even been known
> to collect the data internally? Are any academics investigating this?
> Any pointers appreciated,
> John Kietzman
> Stanford University
> Rapid Prototyping Laboratory

Dear John,
my name is Maurizio Bertoldi and I'm a visiting researcher at University
of Illinois at Chicago.
We are currently working on the FDM process and one of the topics we have
focused on is the thermo-mechanical charachterization of FDM parts.
We have produced and tested a number of tensile test specimens with
different orientations, in order to obtain the complete stiffness matrix
for an orthotropic material (6 by 6 - 9 indipendent constants).
Right now we are performing tests to calculate the thermal expansion
coefficients in three different directions (x-y-z, where z is the build
We have used two materials: standard ABS and ceramic (green body).

As far as I know, Stratasys has never released any data regarding this
and I don't even think they have done these tests internally.

I'm not familiar with the work you mentioned and I would greatly
appreciate if you could give me the references.

The work will be presented and published at the National SFF Symposium in
Austin, this August.
Let me know any further questions/comments.

Best regards,

Maurizio Bertoldi E-mail:

University of Illinois at Chicago
Manufacturing Processes Laboratory (room 1036)
Department of Mechanical Engineering (MC 251)
842 West Taylor Street Phone: (312) 413.7408
Chicago, IL 60607-7022 Fax: (312) 413.0447

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