Motion Measurement on Rear Swinging Fork

The video shows the appli­ca­tion of a stereo image cor­re­la­tion (phase syn­chro­nized) for a three-dimen­sion­al dis­place­ment mea­sure­ment or move­ment analy­sis (Vic-3D).

The used stereo cam­era sys­tem is based on two 5 Mpix­el cam­eras with a frame rate of 6Hz (at full res­o­lu­tion) in com­bi­na­tion with the isi-sys syn­chro­niza­tion and trig­ger device for stro­bo­scop­ic obser­va­tion of peri­od­ic events.

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Four mea­sure­ment areas (hydraulic cylin­der — below, wheel hub — left, swingarm — mid­dle and lin­ear unit — right above) with speck­le pat­terns were mon­i­tored for the eval­u­a­tion. The vec­tor arrows rep­re­sent the cur­rent dis­place­ment state.

 

Combination Stereomicroscope and Vic-3D digital image correlation

Appli­ca­tion exam­ples of a spe­cial stere­omi­cro­scope in com­bi­na­tion with Vic-3D dig­i­tal image cor­re­la­tion on elec­tron­ic components.

Stereomikroskop

Image 1: Mea­sure­ment setup

Mea­sure­ment set up: Stereo micro­scope mount­ed on x‑y-z-microtable (back­side) and ten­sile machine (right).

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Image 2: Strain in x‑direction

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Image 3: Strain in y‑direction

Strain dis­tri­b­u­tion of a half cut capac­i­tor-chip (left part) and its sol­der­ing area (round sec­tion). The board is under
bend­ing load. The board is ver­ti­cal on the right sight of the image. The local red area is show­ing a crack in the
sol­der­ing part. Image area approx. <2mm.

 

Lötkugel

Image 4: The main strain of mea­sur­ing a sol­der ball d=300µm under hor­i­zon­tal shear stress is shown.

 

Operation mode analysis on a mobile phone during vibration alert

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Ref­er­ence coor­di­nates and con­tour of the mobile phone.

 

 

 

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This arti­cle describes the mea­sure­ment and analy­sis of the oper­a­tion deflec­tion shapes and rigid body vibra­tion motions of a mobile phone excit­ed by its vibra­tion alert. The mearure­ment is done, using a non con­tact, 3D, full-field, high speed stereo image cor­re­la­tion sys­tem in com­bi­na­tion with the new Vic-3D FFT mod­ule ana­lyzes the record­ed defor­ma­tion data in the fre­quen­cy domain by phase-sep­a­ra­tion method.

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The mea­sured defor­ma­tions and dis­place­ments dur­ing the vibra­tion alert are eval­u­at­ed against the ref­er­ence state for each stereo image pair. In this case the record­ing time cov­ers about 5,5 sec­onds with 1000 FPS cor­re­spond­ing to about 5500 sin­gle measurements.

The fol­low­ing fig­ure show the aver­age vibra­tion ampli­tude U.

 

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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.

Challenges

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.

Solution

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

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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.

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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

Challenges

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.

 

Solution

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.