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SUMMARY:Puncture mechanics of soft solids: A theoretical perspective - Pro
 fessor Mattia Bacca\, University of British Columbia
DTSTART:20241108T140000Z
DTEND:20241108T150000Z
UID:TALK222373@talks.cam.ac.uk
CONTACT:46601
DESCRIPTION:Abstract: The determination of the critical puncture force req
 uired to pierce a soft material is key to improve surgical technology (e.g
 . robotic surgery)\, manufacturing (e.g. food processing) and in-situ mate
 rial characterization. This seminar discusses a mechanical theory able to 
 calculate the critical depth 𝑑𝑐 and force 𝐹𝑐 required to inser
 t a cylindrical needle with a spherical tip into a hyper elastic material.
  Needle insertion occurs as a mechanical instability\, by which the needle
 -specimen system snaps between the ‘indentation’ configuration and the
  ‘penetration’ one\, which then becomes energetically favoured. The mo
 del considers quasi-static indentation\, thus neglects rate-dependent beha
 viour in the material. It also considers frictionless contact\, and the cu
 t material is assumed to be incompressible. Both 𝑑𝑐 and 𝐹𝑐 are
  functions of the toughness and shear modulus of the cut material\, and of
  the radius of the needle. The scaling relations obtained from the model a
 re then compared against experiments\, giving good agreement. To account f
 or frictional and adhesive contact between needle and specimen\, the model
  is extended to correlate interfacial properties with the evolution of the
  puncture force with penetration depth. The extended model is again compar
 ed against experiments to provide validation\, and shows that the penetrat
 ion of tough and soft materials is controlled by friction\, while for brit
 tle and stiff materials adhesion prevails. Finally\, we analyse the role o
 f volumetric compressibility in puncture\, and discover that tough and sof
 t materials develop higher puncture resistance when compressible (lower bu
 lk modulus).\n\nMattia Bacca obtained a PhD in Structural Engineering in 2
 013\, at the at the University of Trento\, which awarded his thesis as ‘
 Best PhD Thesis’ that year. Continuing his studies\, he joined the Unive
 rsity of California\, Santa Barbara (USA) as a Postdoctoral Fellow\, prior
  to joining the University of British Columbia (Canada)\, in 2017\, as a f
 aculty member. He is Assistant Professor in Mechanical Engineering\, and m
 ember of the Biomedical School\, and the Institute of Applied Mathematics.
  During his career as a faculty\, he received the Early Career Award from 
 the Human Frontiers in Science Program\, who is funding part of his resear
 ch. His research is devoted to understanding the biological world through 
 the use of mechanics via the development of mathematical and computational
  models.
LOCATION:Oatley 1 Meeting Room\, Department of Engineering
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