▁S utton ▁and ▁his ▁colle agues ▁advanced ▁the ▁quant itative ▁character ization ▁of ▁the ▁crack ▁tip ▁stra in ▁fields ▁in ▁highly ▁du ct ile ▁materials . ▁They ▁studied ▁the ▁theoretical ▁H utch inson - R ice - R osen gren ▁( HR R ) ▁crack ▁tip ▁stra in ▁fields . ▁They ▁measured ▁the ▁el astic - pl astic ▁stra ins ▁and ▁showed ▁that ▁the ▁crack ▁tip ▁stra in ▁fields ▁were ▁in ▁approximate ▁agreement ▁with ▁theoretical ▁predictions ▁for ▁nomin ally ▁Mode ▁I ▁loading ▁conditions . ▁The ▁work ▁received ▁the ▁SE M ▁RE ▁Pet erson ▁Award ▁in ▁ 1 9 9 6 ▁as ▁the ▁out standing ▁application ▁research ▁article ▁published ▁in ▁Ex perimental ▁Mechan ics . ▁In ▁the ▁early ▁ 1 9 9 0 s , ▁it ▁became ▁clear ▁that ▁limitations ▁inher ent ▁to ▁the ▁ 2 D - D IC ▁method ▁could ▁be ▁removed ▁by ▁modifying ▁the ▁vision ▁system . ▁ ▁S utton ▁and ▁his ▁co - work ers ▁invent ed ▁and ▁regularly ▁improved ▁the ▁new ▁measurement ▁system . ▁The ▁vision ▁system ▁nomin ally ▁emp lo ys ▁two ▁cam eras ▁to ▁view ▁a ▁single ▁region . ▁Since ▁all ▁three ▁components ▁of ▁disp lacement ▁are ▁measured , ▁the ▁method ▁was ▁initially ▁term ed ▁three - dimensional ▁digital ▁image ▁correlation ▁( 3 D - D IC ). ▁With ▁the ▁development ▁of ▁vol um et ric ▁D IC ▁methods ▁circa ▁ 2 0 0 0 , ▁the ▁term ▁S tere o D IC ▁was ▁adopted . ▁The ▁ability ▁to ▁make ▁internal ▁( vol um et ric )