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CATEGORIES:Engineering - Mechanics Colloquia Research Seminar
 s
SUMMARY:Shock-Induced Pore Collapse in PMMA: Deformation P
 hysics and Failure Mechanics - Professor Guruswami
  Ravichandran\, Graduate Aerospace Laboratories\, 
 California Institute of Technology
DTSTART;TZID=Europe/London:20260320T140000
DTEND;TZID=Europe/London:20260320T150000
UID:TALK236110AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/236110
DESCRIPTION:Porous materials play a central role in various en
 gineering applications\, including the development
  of lightweight materials\, energy-absorbing struc
 tures\, and energetic solids. Porosity spans multi
 ple scales and arises from manufacturing defects\,
  engineered foams\, and architected metamaterials.
  Under shock loading\, rapid pore collapse induces
  intense local deformation\, often leading to fail
 ure. However\, experimental insights into this pro
 cess remain limited to continuum-level measurement
 s and post-mortem analyses. This study introduces 
 a novel technique for full-field\, internal strain
  measurements during shock compression of transpar
 ent materials\, applied to PMMA with embedded sphe
 rical pores. Using a normal plate impact setup and
  high-speed imaging at 10 million frames per secon
 d\, we visualize pore collapse and extract time-re
 solved strain fields via digital image correlation
 . Experiments reveal a critical shock stress at wh
 ich adiabatic shear bands (ASBs) initiate\, markin
 g the first in-situ observation of ASB formation d
 uring pore collapse. At higher stresses\, ASBs evo
 lve into dominant shear bands\, culminating in dyn
 amic shear fracture. We also examine wave interact
 ions between multiple pores using shadowgraphy and
  their influence on collapse and failure mechanism
 s. Complementary elasticity theory and dynamic fin
 ite element simulations provide further insight in
 to the physics governing pore collapse under extre
 me conditions.
LOCATION:Department of Engineering - LR4
CONTACT:
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