Dynamic Compression of Metals

Dynamic compression

Study­ing the behav­ior of met­als dur­ing a high-speed dynam­ic com­pres­sion event has always been chal­leng­ing due to the com­plex test set up and fast data cap­ture rates required. Cur­rent­ly, very lit­tle lit­er­a­ture is avail­able regard­ing defor­ma­tion behav­ior at strain rates of  10 to 500s-1. Uti­liz­ing high-speed cam­eras, the Vic-3D HS sys­tem can be used to quan­ti­fy the sur­face dis­place­ments and strains in three dimen­sions over the entire field with great pre­ci­sion. Dig­i­tal Image Cor­re­la­tion (DIC) has gained wide­spread pop­u­lar­i­ty over recent years in such high-speed appli­ca­tions due to its high accu­ra­cy, flex­i­bil­i­ty and ease of use.




Dynamic compression2In this exam­ple, a 6mm diam­e­ter cylin­dri­cal spec­i­men was com­pressed at a strain rate of 50s-1. The Vic-3D HS sys­tem was used to cap­ture the  sur­face dis­place­ments and  strains on  the  spec­i­men dur­ing the event. A ran­dom speck­le pat­tern is applied to the spec­i­men that allows the analy­sis soft­ware to eas­i­ly track the defor­ma­tion to sub-pix­el accu­ra­cy. Although the high- speed cam­eras are capa­ble of much high­er cap­ture rates, for this test they were set to an appro­pri­ate frame rate of 14,400fps to max­i­mize spa­tial res­o­lu­tion while acquir­ing an ade­quate num­ber of images dur­ing the event. The cam­eras were post-trig­ger at a res­o­lu­tion of 1024 x 400 pix­els. After the event, the images are trans­ferred to the computer’s  hard  dri­ve, and  then  post-processed using Vic-3D analy­sis software.

Images cour­tesy of Amos Gilat & Jere­my Sei­dt at Ohio State University.