Researcher:
Samur, Evren

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Master Student

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Evren

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Samur

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Samur, Evren

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2005 - 20074

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Researcher Of Publications: search.filters.isAuthorOfPublication.6e1607db-7793-403f-b1d1-8521465dfa06

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Now showing 1 - 4 of 4
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    A robotic indenter for minimally invasive characterization of soft tissues
    (Elsevier Science Bv, 2005) Avtan, Levent; Düzgün, Oktay; N/A; N/A; Department of Mechanical Engineering; Samur, Evren; Sedef, Mert; Başdoğan, Çağatay; Master Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering College of Engineering; 192890; N/A; 125489
    We have developed a robotic indenter for minimally invasive measurement of tissue properties during a laparoscopic surgery. Using the indenter, we conducted animal experiments in situ and successfully measured the force versus displacement response of pig liver under static and dynamic loading conditions. Using the small deformation assumption, we estimated the effective Young's modulus of pig liver around 15 kPa from the force-displacement data of static indentations. We also obtained the relaxation function, describing the variation of force response with respect to time, from the data of stress relaxation experiments. We observed that pig liver shows linear viscoelastic behavior.
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    A robotic indenter for minimally invasive measurement and characterization of soft tissue response
    (Elsevier, 2007) Avtan, Levent; Düzgün, Oktay; N/A; N/A; Department of Mechanical Engineering; Samur, Evren; Sedef, Mert; Başdoğan, Çağatay; Master Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering College of Engineering; 192890; N/A; 125489
    The lack of experimental data in current literature on material properties of soft tissues in living condition has been a significant obstacle in the development of realistic soft tissue models for virtual reality based surgical simulators used in medical training. A robotic indenter was developed for minimally invasive measurement of soft tissue properties in abdominal region during a laparoscopic surgery. Using the robotic indenter, force versus displacement and force versus time responses of pig liver under static and dynamic loading conditions were successfully measured to characterize its material properties in three consecutive steps. First, the effective elastic modulus of pig liver was estimated as 10-15 kPa from the force versus displacement data of static indentations based on the small deformation assumption. Then, the stress relaxation function, relating the variation of stress with respect to time, was determined from the force versus time response data via curve fitting. Finally, an inverse finite element solution was developed using ANSYS finite element package to estimate the optimum values of viscoelastic and nonlinear hyperelastic material properties of pig liver through iterations. The initial estimates of the material properties for the iterations were extracted from the experimental data for faster convergence of the solutions.
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    Visual and haptic simulation of linear viscoelastic tissue behavior based on experimental data
    (IEEE Computer Soc, 2006) N/A; N/A; Department of Mechanical Engineering; Sedef, Mert; Samur, Evren; Başdoğan, Çağatay; Master Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 192890; 125489
    We have developed a new numerical scheme for simulating linear viscoelastic tissue behavior modeled by FEM. We have integrated experimentally-measured viscoelastic tissue properties into our model for realistic force feedback to the user. A new precomputation method based on superposition principle was proposed for real-time computation of nodal displacements and interaction forces. We achieved stable haptic interactions by executing the viscoelastic model at 100Hz while the haptic loop was updated at 1KHz. The developed model and the proposed pre-computation approach have been both validated using ANSYS.
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    Real-time finite-element simulation of linear viscoelastic tissue behavior based on experimental data
    (Ieee Computer Soc, 2006) N/A; N/A; N/A; Department of Mechanical Engineering; Sedef, Mert; Samur, Evren; Başdoğan, Çağatay; Master Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 125489
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