Kristoffer Sjolund, a junior in Mechanical Engineering, was one of five student awardees and was recognized for his presentation, Mechanical Properties of Interlocking Assemblies on a Rhombille Tiling.

Andrew Williams, a graduate student in Mechanical Engineering, was one of the five recognized graduate student mentors.

Both students work with professor Thomas Siegmund in his Microstructure Testing and Analysis Lab.

Every year, SURF enables Purdue undergraduate students in STEM fields to conduct hands-on research, including professional development and symposiums during the summer months.  Read more about SURF: https://engineering.purdue.edu/Engr/Research/SURF

Kristoffer's abstract:

The  use  of  glue-less  assembly  methods  has  permitted  the  construction  of  rigid  structures  for  centuries.  Japanese  interlocking  wood  joints  and  stereotomic  structures  by  repetitious  stacking  of  unit  blocks  are classical  examples.  The  implementation  of  interlocking  structures  occurs  when  materials  such  as  mortar and  nails  are  unavailable  or  undesired.  There  has  been  a  recent  revival  of  interest  in  these  construction  methods as modern manufacturing tools enable new form and function. As humanity continues to innovate, materials possessing mechanical properties such as heightened flexibility without compromising strength or increased resistance to fracture will be needed. As one such example, this work examines interlocking assemblies  emerging  from  a  rhombille  tiling.  Rhombille  tilings  are  formed  by  using  three  rhombuses  to  create a regular hexagon, then tessellating those hexagons. The resulting assembly is one of disphenoids and has either triangular or hexagonal symmetry. The elements are arranged such that the assembly forms a hexagonal plate with two thirds the density of a solid plate of equal thickness. Rotation free and restricted states are realized. The mechanical properties of this interlocked assembly are examined in finite element analysis  and  experiments  performed  on  physical  models  realized  by  3D  printing.  Initial  results  suggest  a  chiral  response  to  loading  paths  in  the  hexagonally  symmetric  arrangement.  Triangularly  symmetric  arrangements  suggest  load  paths  based  on  concentric  or  patterned  hexagons.  These  load  patterns  are distinctly  different  from  those  in  comparable  solid  plates.  All  assemblies  have  shown  fracture  resistance  where damage is localized to few elements, leaving the remainder of the plate intact.