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SUMMARY:Mechanical performance of wall structures in 3D printing processes
 : theory\, design tools and experiments - Prof Akke Suiker\, Eindhoven Uni
 versity of Technology 
DTSTART:20180302T140000Z
DTEND:20180302T150000Z
UID:TALK99886@talks.cam.ac.uk
CONTACT:Hilde Hambro
DESCRIPTION:A mechanistic model is presented that can be used for analysin
 g and optimising the mechanical performance of straight wall structures in
  3D printing processes. The two failure mechanisms considered are elastic 
 buckling and plastic collapse. The model incorporates the most relevant pr
 ocess parameters\, which are the printing velocity\, the curing characteri
 stics of the printing material\, the geometrical features of the printed o
 bject\, the heterogeneous strength and stiffness properties\, the presence
  of imperfections\, and the non- uniform dead weight loading. The sensitiv
 ity to elastic buckling and plastic collapse is first explored for three b
 asic configurations\, namely i) a free wall\, ii) a simply-supported wall 
 and iii) a fully-clamped wall\, which are printed under linear or exponent
 ially- decaying curing processes. As demonstrated for the specific case of
  a rectangular wall lay-out\, the design graphs and failure mechanism maps
  constructed for these basic configurations provide a convenient practical
  tool for analysing arbitrary wall structures under a broad range of possi
 ble printing process parameters. Here\, the simply-supported wall results 
 in a lower bound for the wall buckling length\, corresponding to global bu
 ckling of the complete wall structure\, while the fully-clamped wall gives
  an upper bound\, reflecting local buckling of an individual wall. The ran
 ge of critical buckling lengths defined by these bounds may be further nar
 rowed by the critical wall length for plastic collapse. For an arbitrary w
 all configuration the critical buckling length and corresponding buckling 
 mode can be accurately predicted by deriving an expression for the non-uni
 form rotational stiffness provided by the support structure of a buckling 
 wall. This has been elaborated for the specific case of a wall structure c
 haracterised by a rectangular lay-out. It is further shown that under the 
 presence of imperfections the buckling response at growing deflection corr
 ectly asymptotes towards the bifurcation buckling length of an ideally str
 aight wall. The buckling responses computed for a free wall and a wall str
 ucture with a rectangular lay-out turn out to be in good agreement with ex
 perimental results of 3D printed concrete wall structures. Hence\, the mod
 el can be applied to systematically explore the influence of individual pr
 inting process parameters on the mechanical performance of particular wall
  structures\, which should lead to clear directions for the optimisation o
 n printing time and material usage. The model may be further utilised as a
  validation tool for finite element models of wall structures printed unde
 r specific process conditions.
LOCATION:Oatley Seminar Room\, Department of Engineering
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