▁ 1 9 3 3 , ▁' 3 4 , ▁and ▁' 3 5 , ▁and ▁there ▁is ▁no ▁doubt ▁that ▁the ▁experience ▁at ▁the ▁University ▁of ▁Michigan ▁served ▁to ▁confirm ▁him ▁in ▁his ▁choice ▁of ▁his ▁life ' s ▁work . ▁ ▁Career ▁For ▁his ▁doctor al ▁research ▁Mind lin ▁set ▁himself ▁a ▁fundamental ▁problem ▁in ▁theoretical ▁el astic ity : ▁determ ining ▁the ▁str esses ▁in ▁an ▁el astic ▁half - space ▁subject ed ▁to ▁a ▁sub - sur face ▁point ▁load . ▁The ▁results , ▁now ad ays ▁referred ▁to ▁as ▁" M ind lin ' s ▁problem ", ▁represent ▁a ▁general ization ▁of ▁the ▁two ▁classical ▁ 1 9 th ▁century ▁solutions ▁respectively ▁associated ▁with ▁the ▁names ▁of ▁Kel vin ▁and ▁B ouss ines q , ▁and ▁have ▁become ▁the ▁basis ▁for ▁analyt ical ▁form ulations ▁widely ▁employed ▁in ▁ge ote chn ical ▁engineering . ▁His ▁paper ▁was ▁published ▁in ▁Physics ▁( now ▁the ▁Journal ▁of ▁App lied ▁Physics ) ▁in ▁ 1 9 3 6 , ▁the ▁year ▁Mind lin ▁received ▁his ▁Ph . D . ▁degree . ▁ ▁Mind lin ▁remained ▁an ▁assistant ▁for ▁another ▁two ▁years , ▁at ▁which ▁point ▁he ▁was ▁elev ated ▁to ▁instruct or ▁in ▁civil ▁engineering , ▁and ▁only ▁in ▁ 1 9 4 0 ▁did ▁he ▁receive ▁promotion ▁to ▁assistant ▁professor . ▁ ▁In ▁ 1 9 4 2 ▁Mind lin ▁was ▁co - opt ed ▁by ▁the ▁App lied ▁Physics ▁Labor atory ▁in ▁Silver ▁Spring , ▁Maryland , ▁an ▁institution