Transcript SlidingHardWedge.ppt

Modeling the Sliding of a Hard
Wedge on a Metal Substrate
Ernesto Gutierrez-Miravete
Rensselaer at Hartford
CCAT- Summer 2010
Problem Description
• A hard, rigid carbide wedge (semi-angle = a)
moving at constant speed V encounters a metal
block (breadth =b, hardness = H) and begins to
slide over its surface to a certain depth = d, under
plane strain conditions for a total sliding length =
L.
• Initially, a prow forms in front of the sliding
wedge and is pushed by it (plowing).
• The prow grows in size and eventually may
transform into a chip that is in turn ejected in
front of the wedge (cutting).
Plowing vs Cutting
Friction Coefficient due to Plastic
Deformation during Plowing
• Tangential Force:
Ft = H d b
• Normal Force:
Fn = H d b tan a
• Friction Coefficient:
m = Ft/Fn = cot a
• For the case herein considered a = 45 degrees so
m=1
Finite Element Model
• AdvantEdge (Third Wave Systems Inc.) is a
commercial implementation of the finite element
method designed to analyze the behavior of
metals encountered during machining operations
• The code embodies an explicit scheme capable of
modeling coupled, non-linear thermo-mechanics
at large strains and strain rates incorporating
constitutive deformation behavior, contact,
friction, fracture and adaptive meshing.
Systems Investigated
• The following alloy systems were investigated. The
material property databases included in the
software were used. The value of the friction
coefficient in the code was set to 0.
Al-6061-T6
1020 Steel
Cu-37700 Brass
Ti6Al4V
• Other parameter values were as follows:
d = 0.005 mm; V = 10 m/s; L = 0.1 mm
Results- Al6061
Results –1020 Steel
Results – Cu 37700
Results – Ti6Al4V
Summary
• In all cases considered, the computed normal forces
were larger than the tangential forces.
• Friction coefficient values calculated from the
computed forces where in all cases within 10-20% of
the expected value of 1.
• Both, tangential and normal forces obtained under
cutting conditions decreased to about ~80% of their
values exhibited during plowing conditions.
• The point of transition from plowing to cutting is
material dependent.
Modeling the Sliding of a Hard Wedge
Ernesto Gutierrez-Miravete
Rensselaer-Hartford