# Question: Consider an NX size drill core

Consider an NX-size drill core (2-1/8 in., 5.40 cm diameter) with an L/D ratio (length to diameter) of two under an axial load of 35,466 pounds (158.89 kN). Find:

1 The state of stress within the core sample relative to a cylindrical system of coordinates (rθz)

2 The state of stress relative to an abc set of axes associated with a plane that bears due north and dips 60◦ to the east. The c-axis is normal to this plane, the b-axis is parallel to strike and the a-axis is down dip. Use the equations of transformation.

3 Show by a direct resolution of force components and calculation of area that the normal stress (σcc) on the plane in part (2) is the same as that given by the equations of transformation.

4. Is the shear stress (τac) acting on the plane in part (2) the same using forces and areas as that given by the equations of transformation? Show why or why not.

1 The state of stress within the core sample relative to a cylindrical system of coordinates (rθz)

2 The state of stress relative to an abc set of axes associated with a plane that bears due north and dips 60◦ to the east. The c-axis is normal to this plane, the b-axis is parallel to strike and the a-axis is down dip. Use the equations of transformation.

3 Show by a direct resolution of force components and calculation of area that the normal stress (σcc) on the plane in part (2) is the same as that given by the equations of transformation.

4. Is the shear stress (τac) acting on the plane in part (2) the same using forces and areas as that given by the equations of transformation? Show why or why not.

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