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.”

Dynamic excitation on a spacecraft

Historic measurement from 2000

This exam­ple com­bines the Vibro­grafie Sys­tem with a Piezoshak­er Mod­ule for a non-destruc­tive inspec­tion. The heat shield with C‑Si‑C (car­bon fiber-sil­i­con com­pos­ite) of the prospec­tive recov­ery vehicle/ space­craft x38 was reviewed by Shearog­ra­phy.


For eas­i­er han­dling, the Piezoshak­er mod­ule is com­pressed on the sur­face of the object via a suc­tion base.
(a) Piezoshak­er mod­ule, (b) the heat shield of the space­craft X38 © Flight of the space­craft X38.



The pic­ture shows the deter­mi­na­tion of times of the heat shield with the nat­ur­al fre­quen­cy (1400 Hz).



Local vibra­tion forms of defects at 10kHz and 18 kHz of the nose hood in the marked area of the image. Dur­ing the inspec­tions, two defects have been detect­ed in the upper area of the dog.

Vic-3D High-Speed Vibration Analysis System

Vibration1               Vibration2


The Vic-3D™ Vibra­tion Analy­sis Sys­tem by Cor­re­lat­ed Solu­tions, Inc. is a new addi­tion to the Vic-3D prod­uct line of mea­sure­ment solu­tions. Vic-3D Vibra­tion enables full-field 3D view­ing, mea­sure­ment, and analy­sis of tran­sient events. Full-field oper­a­tional deflec­tion shapes in the fre­quen­cy domain can eas­i­ly be seen and com­pared with lev­els of accu­ra­cy in the nanome­ter range.

The image above on the left is a mount­ed mod­el jet plane which has under­gone a tran­sient vibra­tion event.  To the right, the 3D vibra­tion data obtained from the event is shown as a 2D con­tour over­lay on this image.  The data over­lay enables the user to see exact­ly how much defor­ma­tion is occur­ring and where it is occur­ring.  This infor­ma­tion is avail­able at each fre­quen­cy where deflec­tion shapes occur.

The data below dis­plays one oper­a­tional deflec­tion shape obtained with the VIC-3D Vibra­tion Analy­sis Sys­tem. Three-dimen­sion­al dis­place­ments, strains, veloc­i­ties, and accel­er­a­tions can all be com­put­ed in the analy­sis soft­ware.  The result is not only visu­al, but also enables the user to export quan­ti­ta­tive data (ASCII, Mat­Lab, CSV, etc.) from the sample’s behav­ior for FEA analy­sis and val­i­da­tion.  A 3D ani­ma­tion of the mod­el jet’s oper­a­tional deflec­tion shape at 441 Hz is shown below, with only 12 microns of dis­place­ment amplitude.


Film Vibration3D_W_431Hz


What is transient vibration analysis? 

Tran­sient vibra­tion analy­sis is the process of mon­i­tor­ing, mea­sur­ing, and ana­lyz­ing the con­di­tion of sam­ples dur­ing a tran­sient event. Mate­r­i­al prop­er­ties can also be observed through the analy­sis of oper­a­tional deflec­tion shapes and mode shapes cre­at­ed by the event. These full-field 3D shapes can pro­vide use­ful infor­ma­tion which can be used to improve and cor­rect a sample’s bal­ance, dis­place­ment, flex­ure, rigid­i­ty, and over­all prod­uct per­for­mance.  Mea­sur­ing oper­a­tional deflec­tion shapes can help answer the ques­tion: “How much is this struc­ture actu­al­ly mov­ing at a par­tic­u­lar frequency?”


Why is it important to you?

Oper­a­tional deflec­tion shapes cre­at­ed from tran­sient tests show how a sam­ple can have a nonuni­form thick­ness­es, sur­face irreg­u­lar­i­ties, weak points, cracks and/or oth­er imper­fec­tions & flaws.  This infor­ma­tion can be use­ful at any point in the process of achiev­ing your over­all goal, from writ­ing a project pro­pos­al to test­ing a func­tion­al or fail­ing part in the field: The Vic-3D Vibra­tion Analy­sis Sys­tem

  • Has a jus­ti­fi­able price point when writ­ing proposals
  • Can be used: 
    • To cre­ate and val­i­date FE mod­els when design­ing parts & equipment
    • Dur­ing the research and design process
    • In the prod­uct test­ing phase
    • To pro­vide man­u­fac­tur­ing qual­i­ty assurance
    • To cer­ti­fy and assure equip­ment is oper­at­ing as expect­ed and required
    • To mea­sure and ana­lyze parts post-installation
    • To ensure prod­uct qual­i­ty and per­for­mance over time and in the field
    • When reassess­ing prod­uct func­tion­al­i­ty over time


Exam­ples of tran­sient events which can be mea­sured are the following:

▪ Door Slams ▪ Modal Ham­mer Strikes
▪ Engine Start-ups ▪ Drop Tests
▪ Explo­sive Testing ▪ Bal­lis­tic Testing


System Features 

  • View, com­pare, ani­mate, graph, extract, and export data for easy FEA comparison
  • Mea­sure 3D full-field, high fre­quen­cy mode shapes with nanome­ter resolution
  • Mea­sure extreme­ly low ampli­tudes with extreme­ly high accelerations
  • Full-field strain, defor­ma­tion, and shape vari­ables are still available
  • Easy pro­ce­dures, accu­rate results
  • User friend­ly interface
  • Only a frac­tion of the price of a laser vibrom­e­ter system


Advantages over other measurement techniques

While tra­di­tion­al vibra­tion mea­sure­ment tech­niques can be use­ful, they also have many draw­backs.  For exam­ple, accelerom­e­ters can become unglued dur­ing test­ing, can mass-load a sam­ple, and can only pro­vide point to point mea­sure­ments, often only in a sin­gle plane. Pre-test­ing and test­ing can also take days or even weeks to per­form on large struc­tures.  With the Vic-3D Vibra­tion Analy­sis sys­tem, there are no adhe­sives, wires, sig­nal ana­lyz­ers, pow­er ampli­fiers, or load cells nec­es­sary for detailed vibra­tion results.  Obtain­ing thou­sands of data points for a tiny, com­plex struc­ture or a large one is as easy as chang­ing a pair of lens­es. Sim­i­lar to dig­i­tal image cor­re­la­tion, laser vibrom­e­ters can pro­vide a non-con­tact mea­sure­ment solu­tion, but sim­i­lar to accelerom­e­ters, they are also only able pro­vide point to point mea­sure­ments.  A 3D mea­sure­ment can be achieved with mul­ti­ple scan­ning vibrom­e­ters, but these are usu­al­ly mount­ed on large robot arms which can take up valu­able lab­o­ra­to­ry space and can­not be moved eas­i­ly once installed.  Addi­tion­al­ly, these sys­tems are unrea­son­ably expen­sive for many appli­ca­tions.  The Vic-3D Vibra­tion Analy­sis sys­tem can be tak­en into the field with any com­pat­i­ble lap­top and togeth­er with the Vic-3D Work­sta­tion, the sys­tem can become mobile and secure inside your facil­i­ty.  Vic-3D Vibra­tion Analy­sis is only a frac­tion of the price of a 3D scan­ning laser vibrom­e­ter sys­tem, and since the mod­ule can be added onto any exist­ing 3D sys­tem, it’s even more affordable.