# hw5 - 2 What principle would you use Please explain in...

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BE 110 CONTINUUM MECHANICS Fall 2009 Homework Assignment #5 Due Thursday 10/29/09, 3:30 PM before class No late submissions will be accepted. 1. Reading Assignment . Study the stress components in cylindrical coordinates . Please note that there are many biomechanics problems for which cylindrical coordinates are useful. See Section 3.6. 2. Practice Problems . Show that the maximum shear stress at any point is equal to ½ ( τ MAX τ MIN ), where τ MAX is the maximum principal stress and τ MIN is the minimum principal stress. It is acting on a plane that makes a 45 o angle to the axes pointing in the principal directions of τ MAX and τ MIN . (For solution see Problem 4.1). One of the most famous solutions in mechanics is the force acting on a sphere in a viscous solution moving slowly, also known as Stokes formula. See problem 4.3 on page 104. It has numerous applications and plays a major role in molecular mechanics. 3. *Design Problem . Shear Stress Transducer Design a device that serves to measure shear stress in the range up to about 1000 dyn/cm
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Unformatted text preview: 2 . What principle would you use? Please explain in detail. What applications would you foresee for such a device in medicine? 4. * Design Problem . Blood clot obstruction The vessels in the microcirculation may be obstructed by a blood clot. Such clots can arise by binding and polymerization of the plasma protein fibrinogen on a specific receptor on the surface of the endothelial cell. The yield stress (a shear stress at which the material will start to deform and move) in a blood clot is of the order of magnitude of 2000 dyn/cm 2 . - Find the pressure drop necessary to push out a blood clot from a capillary with diameter of 10 μm and length 200 μm. - How large is this pressure drop compared to the pressure drop across the entire circulation (see any text in Cardiovascular Physiology)?- What technique would you design to remove such blood clot? * The problem needs to be turned in for grading. 1...
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## This note was uploaded on 04/30/2010 for the course BENG 112A taught by Professor Mcculloch during the Winter '09 term at UCSD.

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