vertical difference between eroded profile and underlayer multiplied by the cosine of the 

 structure slope angle or 



d^{t) = rmn[z^{x,t)-z^(x,t=0)]cosQ (4.12) 



where min indicates the minimum value with respect to x, Za(x,t) is the damaged profile 

 elevation at location x and time t, and Zu{x,t=0) is the underlayer elevation at x before 

 testing began. The numerical interpolation technique used to compute the eroded depth 

 was not required for the depth of cover as the underlayer was smooth relative to the 

 profiler probe size in comparison to the undamaged armor profile. 



80 



