# Vegas Part 3: The talks

**Posted:**August 5, 2006

**Filed under:**Applied Mechanics, Conferences, Manufacturing 2 Comments

**I.S. Jawahir’s talk:**

The talk presented a synthesis of the existing slip-line models in metal cutting theory with emphasis on the work done by their group based on the universal slip-line model. Though most of these metal-cutting models cannot be extended to composite machining due to the inherent differences between metals and composites, it was interesting to see their approach. The most surprising part was the definition of friction coefficient on the tool-chip interface. Instead of the friction coefficient, they have defined a tau/k equivalent term. Due to the excessive temperatures at this interface, this quantity is estimated using regression analysis. This difficulty in establishing a valid friction coefficient is hightened due to the inability to correctly evaluate the temperatures at this interface. Dr. Fang, a previous student of Dr. Jawahir elaborated on this in a subsequent session. He suggested taking the “optimal” coefficient that would yield the best solutions which surely doesnt seem accurate to say the least! Consequently, further research in this field was conferred quintessential. 🙂

Dr. Jawahir’s talk reminded me in many ways of Dr. Ramulu’s lecture, bubbling with energy and enthusiasm, even the jokes! 🙂 For once I was grateful for the absent speakers, he spoke for a good 40 minutes.

Hmmmm, in other words, we are trying to find a friction coefficient. We can’t measure a repeatable friction coeffecient, and we can’t measure the temperature it’s dependent on. Our results will not be accurate. We need more funding.

Sounds sort of like my thesis!

yes, the ambiguity arises from trying to find the “optimal” friction coefficient that would yield the best solution! Its sort of like forcing your FEA program to spit out the right solution. 🙂

But to be fair, Dr. Fang’s group is trying to find the temperature distributions around that zone using infrared sensors etc (they do have NSF funding for that) , but its still a long way to go!