Examination of additively manufactured auxetic components using a novel testing setup

This paper reports upon the results of an initial test cycle using a bespoke testing rig designed expressly to examine additively manufactured auxetic components. Firstly, the key problems facing practical researchers in the field of auxetics is explored with the treatment of the boundary condition identified as a key issue. The testing setup that is then introduced utilises a novel means of part mounting and facilitates optical analysis and real-time force measurements. The study analyses three different auxetic structures (re-entrant, chiral and semi-rigid), a set of samples of which were additively manufactured in TPU material. A range of parameters were varied across the three designs including interior geometry and wall thicknesses in order to demonstrate the effectiveness of the setup for the examination of different structures. Several key results were distilled from the tests that were then further analysed through numerical modelling and discussed with respect to future testing. Our investigation shows a close alignment between the physical testing results and the simulations, indicating that the testing configuration is rigorous and may be used to explore the mechanical behaviour of more complex auxetic componentry.