OPTIMIZATION OF DIAMOND ANVIL CELL PERFORMANCE BY FINITE-ELEMENT ANALYSIS

Many diamonds used as anvils in diamond anvil cells fail at the base due to a concentration of tensile stress in this region. We have calculated the maximum principal tensile stresses in the lower half of the anvil and in the support for simulated anvil plus support finite element meshes. The Young's modulus E and Poisson's ratio nu for both components were varied systematically. Geometrical parameters determining the shape of the light port in the support and the shape of the anvil were also varied. The basal tension in the anvil appears to be minimized when the anvil has large E, small nu and the support has similar E and large nu. The effect of geometry in minimizing or enhancing basal tension is profound. There is a well defined tension minimum for a conical light port of semi-angle 25-30-degrees. Simulations were also calculated for a diamond on a flat B4C plate. Such supports often fail at low pressure (around 3.5 GPa). The tension in the support decreased rapidly for a small increase in plate thickness.