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.



Contractions of a Muscle

Bio­me­chan­ic researchers were study­ing the con­trac­tions of a rat Tib­ialis Ante­ri­or mus­cle.  It was desir­able to quick­ly and accu­rate­ly quan­ti­fy the over­all move­ments, as well as local­ized variations.


Because the exper­i­ments involved live tis­sues, con­ven­tion­al gauges were dif­fi­cult to apply and tend­ed to inter­fere with the motion under study.  It was impor­tant to cap­ture data quick­ly, and for as many points as pos­si­ble.  Mark­er track­ing had been used, but pro­vid­ed only gross aver­ages.  It was also time-con­sum­ing and tedious for the researchers to process this type of  information.


The Vic-3D sys­tem was used to rapid­ly cap­ture con­trac­tion data over the entire mus­cle sur­face.  Due to the system’s speed and sim­plic­i­ty, it was pos­si­ble to make numer­ous mea­sure­ments at pre­cise­ly timed inter­vals.  There was no inter­ac­tion with the spec­i­men, and no need to guess which areas would be of great­est interest.

The result­ing mea­sure­ments pro­vid­ed high spa­tial res­o­lu­tion and made it pos­si­ble to iden­ti­fy numer­ous areas where “bunch­ing” of the mus­cle tis­sue caused sig­nif­i­cant vari­a­tions in mus­cle con­trac­tion.  These areas had not been pre­vi­ous­ly iden­ti­fied with con­ven­tion­al meth­ods.  Final­ly, all cal­cu­la­tions were done auto­mat­i­cal­ly.  This saved con­sid­er­able time and avoid­ed the pos­si­bil­i­ty of human error in the data processing.


Deformation Measurement

Aerospace Application Example

aerospace_1_notitle-300x247Air­bus has built a rep­u­ta­tion for inno­v­a­tive air­craft, rec­og­nized around  the world for their safe­ty and effi­cien­cy. All of these attrib­ut­es are dri­ven by a top-notch test­ing pro­gram, whose inno­v­a­tive prac­tice are evi­denced by their use of the Vic-3D mea­sure­ment system.

One of the goals of the Air­bus test­ing pro­gram is to char­ac­ter­ize the struc­tur­al dam­age caused by col­li­sions between the air­craft and small pro­jec­tiles such as birds and oth­er ground based debris, and to ensure that the struc­tur­al integri­ty of the air­craft is maintained.

This type of event can be repro­duced by fir­ing a vari­ety of dif­fer­ent types of pro­jec­tile at a piece of air­craft struc­ture at a high veloc­i­ty. The results obtained can be used to com­pare with com­put­er mod­els of the struc­ture under impact loads, lead­ing to more high­ly opti­mized and safer designs.


aerospace_2_notitle-300x224Dr. Richard Bur­guete, exper­i­men­tal mechan­ics spe­cial­ist at Air­bus UK since 1997, explains the ben­e­fits of this approach as fol­lows: “The VIC-3D sys­tem allows us to be sure we have cap­tured all of the rel­e­vant data, some of which might have oth­er­wise been unobtainable.”

Vibration Analysis of a Brake Disc

Bremsen1 Bremsen2
Auto­mo­biles are sub­ject to many forces using oper­a­tion. Vibra­tions from the engine or the road-sur­face trans­mit through the vehicle’s chas­sis and sus­pen­sion to the most essen­tial mechan­i­cal com­po­nent of the vehi­cle, the brake system.


In this exam­ple, a 14” diam­e­ter brake disc from a heavy­du­ty truck was excit­ed using a small ham­mer to mea­sure the vibra­tion shapes of the rotor. The three-dimen­sion­al oper­a­tional deflec­tion shapes were eas­i­ly iden­ti­fied and mea­sured using the Vic-3D™ HS Vibra­tion Analy­sis Sys­tem. Ampli­tudes as small as 40 nanome­ters were mea­sured at a fre­quen­cy of approx­i­mate­ly 2,000 Hz.


Strain Measurement on a Gearwheel


Assem­bled com­po­nents typ­i­cal­ly have com­plex inter­ac­tions with one anoth­er. Con­tact points can vary dur­ing oper­a­tional cycles due to part move­ment. This means that the loca­tions of peak strains can be hard to pre­dict, and they are often not sta­tion­ary. The move­ment of parts can also make it imprac­ti­cal to main­tain elec­tri­cal con­nec­tions with gauges. Even when they are sta­tion­ary and easy to locate, the high­est strains can be con­cen­trat­ed in very small areas or have high gra­di­ents. Peak val­ues may be lost to the aver­ag­ing effect pro­duced by gauges.



Vic-3D pro­vid­ed a means for mak­ing strain mea­sure­ments across the entire pro­file of the gear tooth. Because it pro­vides full-field mea­sure­ments, it was not nec­es­sary to choose a par­tic­u­lar point at which mea­sure­ments would be made. This allowed the peak strains to be clear­ly visu­al­ized and accu­rate­ly mea­sured at var­i­ous stages of the oper­a­tional cycle. Vic-3D also mea­sured dis­place­ment in three dimen­sions. This fea­ture allowed our cus­tomer to rec­og­nize and quan­ti­fy twist­ing of the gear tooth under load.

Exhaust pipe

Exhaust1The engi­neers at Cum­mins design and test their engines to with­stand real-world con­di­tions, rang­ing from mil­i­tary deploy­ments to heavy-duty indus­tri­al sites. Cum­mins engi­neers want to know exact­ly how their parts are deform­ing under the com­bi­na­tion of ther­mal and mechan­i­cal loads. This means they’ve got to per­form their tests with the engines run­ning – and hot.

Because of the com­plex strain fields pro­duced under these con­di­tions, con­ven­tion­al gauges can­not sat­is­fy Cum­mins’ require­ments. FEA sim­u­la­tions are also lim­it­ed, due to the uncer­tain bound­ary con­di­tions. With the Vic-3D sys­tem, Cum­mins engi­neers are able to obtain detailed three-dimen­sion­al strain mea­sure­ments. These mea­sure­ments are made under real load­ing con­di­tions while the engine is run­ning. In addi­tion, the Vic-3D sys­tem is easy to set up and can mea­sure both small parts and large assemblies.




Paul Gloeck­n­er, senior research engi­neer at Cum­mins, explains the use­ful­ness of the Vic-3D sys­tem as fol­lows: “This tool allows us to make mea­sure­ments that were pre­vi­ous­ly not pos­si­ble. It has also allowed us to con­sid­er­ably reduce the time required for these tests.”

Microscopic Strain Measurement

Combination of a special stereomicroscope with Vic-3D digital image correlation on electronic components.


Uni Wien Mikroskop

Mea­sure­ment set up: Stereo micro­scope mounted

on x‑y-z-microtable (back­side) and ten­sile machine (right).


Uni Wien Mikroskop2

Uni Wien Mikroskop3

Servered ceram­ic capac­i­tor chip under bend­ing load (image width approx. 4mm):
Strain in x‑direction (upper image) and y- direc­tion (low­er image).


Uni Wien Mikroskop4

Uni Wien Mikroskop5

Stan­dard deriva­tion (upper) under load : An increased val­ue occurs on the mid­dle against the reference
state by the local­ly small bulge at the con­tact between chip and board (see 3D con­ture below). This might be caused
by mate­r­i­al , which is pressed togeth­er between the two parts (includ­ing the colour lay­er). In the upper area the
increased val­ues of the stan­dard deriva­tion is caused by the reduced speck­le density.