Applied Force to Stretch Material

Applied force to stretch material is the force exerted on a material to make it stretch, deform, or change shape during drilling operations.  In drilling, the applied force is the weight and rotational power applied to the drill bit, which encounters resistance from the material it's cutting or penetrating. 

Key Points about Applied Force

Downward Force  -  The applied force to push the drill bit downward into the material, which helps to break through or cut the material.
Rotational Force (Torque)  -  This force rotates the drill bit, enabling it to cut into the material by applying shear stress along the material’s surface.
Tensile Force  -  This is any force that stretches or pulls the material being drilled.  While tensile force is usually minimized in drilling to prevent tool breakage, certain drill bits or techniques may cause the material to stretch or deform slightly.

 

Applied Force to Stretch Material Formula
\( F_a \;=\;  A_c \cdot E \cdot \dfrac{ L_a - L_b  }{ L_b } \)
Symbol	English	Metric
\( F_a \)  = Applied Force	\(lbf\)	\(N\)
\( A_c \) = Area Cross-section	\(ft^2\)	\(m_2\)
\( E \) = Young's Modulus	\(lbf\;/\;in^2\)	\(Pa\)
\( L_a \) = New Length	\(ft\)	\(m\)
\( L_b \) = Old Length	\(ft\)	\(m\)