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Publication Date: 2016-Nov-01
Document File: 3 page(s) / 234K

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During laparoscopic surgery, devices whose jaws are closed via an I‐Beam member, can be subjected to high forces when firing on excessively thick tissue. Specifically, the I‐Beam member can experience tensile forces perpendicular to the cutting direction which create excessive tensile stresses. Surface imperfections and small fillet radii also give rise to stress concentrations. Upon yield and fracture of the I‐Beam member, the crack propagation direction of current technology can cause the top flange to break off the I‐Beam and fall into the patient during surgery. In this work, three geometric features are proposed which control the location and crack propagation direction of I‐Beam fractures during excessive loading in an attempt to minimize the risk of this failure to the patient.

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During laparoscopic surgery, devices whose jaws are closed via an I‐Beam member, can be subjected to  high  forces  when  firing  on  excessively  thick  tissue.  Specifically,  the  I‐Beam  member  can  experience  tensile  forces  perpendicular  to  the  cutting  direction  which  create  excessive  tensile  stresses.  Surface  imperfections and small fillet radii also give rise to stress concentrations. Upon yield and fracture of the  I‐Beam  member,  the  crack  propagation  direction  of  current  technology  can  cause  the  top  flange  to  break off the I‐Beam and fall into the patient during surgery.   In this work, three geometric features are  proposed  which  control  the  location  and  crack  propagation  direction  of  I‐Beam  fractures  during  excessive loading in an attempt to minimize the risk of this failure to the patient.  


Three knife‐edge geometric features are proposed to control the location and propagation directions of  fracture  cracks  experienced  during  firing  on  excessively  thick  tissue.  The  geometric  features  aim  to  create stress concentrations in desired locations. When loaded, the geometric features allow the I‐Beam  member  to  fail  at  prescribed  locations.  Figure  1  shows  the  stress  distribution  of  a  loaded  I‐Beam,  (simulated via Finite Element Analysis), and Figure 2 shows an I‐Beam which as failed during firing on  thick tissue. 


Figure 1: Stress Distribution Under Typical Load 


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Figure 2: Fractured I‐Beam After Firing on Excessively Thic...