Automated NDT system for filament wound tubes

This sys­tem is used for auto­mat­ed, non destruc­tive test­ing of fil­a­ment wound pipes. The pipes are rotat­ed in 90° steps around their axis to mon­i­tor four cir­cum­fer­en­tial seg­ments. Two SE4 sen­sors with 2 x 4000 px are applied per seg­ment along the tube axis. For a tube length of 1m @ 8000 px this leads to 0.125 mm/px spa­tial pix­el-res­o­lu­tion for all 8 image seg­ments. After insert­ing the pipes the ends are auto­mat­i­cal­ly seal and inter­nal pres­sure is used as load­ing method. Since this cor­re­sponds to the usu­al oper­at­ing load of the tubes, the mea­sured defor­ma­tion dis­tri­b­u­tion visu­alis­es main­ly the rel­e­vant struc­tur­al defects in con­trast to oth­er load­ing meth­ods such as ther­mal load­ing.

Due to the high defor­ma­tion sen­si­tiv­i­ty of the SE4 sen­sors com­bined with the high spa­tial pix­el res­o­lu­tion even small­est defects can be detect­ed. An oper­a­tor final­ly cat­e­goris­es the object as IO / NIO. Auto­mat­ed or AI based image analy­sis is pos­si­ble, but depend­ing on the appli­ca­tion and detec­tion require­ments. At the end of the mea­sure­ment, a report is gen­er­at­ed and auto­mat­i­cal­ly stored as a PDF in a direc­to­ry spec­i­fied by the user.

The tubes are insert­ed and removed man­u­al­ly. An exten­sion with col­lab­o­ra­tive robots or the inte­gra­tion into pro­duc­tion lines are pos­si­ble. Sev­er­al thou­sand tubes have already been test­ed per year with­out prob­lems and maintenance.

Automated NDT on guide blade rings of air turbines

Here the SE4 Sen­sor is used in com­bi­na­tion with an auto­mat­ic attached Piezoshak­er for dynam­ic exci­ta­tion. The SE4 is oper­at­ed in time aver­age mode dur­ing fre­quen­cy sweep­ing for detect­ing local defect res­o­nances of the sol­der­ing of the seal­ing band. The two mea­sure­ments on the left show pre­pared defects. Upper left: hor­i­zon­tal shear­ing, time aver­age mode; Below: ver­ti­cal shear­ing and stro­bo­scop­ic mode for phase reconstruction.


Application for Optimization of Laser Beam Welding by Ultrasonic Wave Superposition

The poten­tial of ultra­son­ic wave super­po­si­tion to improve the prop­er­ties of laser beam weld­ing was inves­ti­gat­ed using sta­tion­ary and mov­ing Piezoshak­er-Sys­tem at the Depart­ment of Cut­ting and Join­ing Man­u­fac­tur­ing Process­es (tff) at the Uni­ver­si­ty of Kas­sel. An exam­ple of this is the test on the high-strength steel alloy 22MnB5, which is pre­sent­ed here. Adap­ta­tion to oth­er weld­ing process­es and mate­ri­als is possible. 

The influ­ences of the var­i­ous exci­ta­tion para­me­ters of the Piezoshak­er on the ultra­son­ic wave super­po­si­tion were inves­ti­gat­ed, e.g. the dis­tri­b­u­tion of the AlSi-coat­ing par­ti­cles with­in the join­ing zone as well as the weld seam prop­er­ties [1].

The isi-sys Piezoshak­er-Sys­tem was used for the mov­ing wave super­po­si­tion, as shown in Fig. 1 The sys­tem con­tains a 2‑channel Piezoam­pli­fier of the HPDA‑0–180-2C series and two Piezoshak­ers of the PS-W-02 series. The Piezoshak­ers are firm­ly con­nect­ed to the laser optics via a mount and are moved rel­a­tive to the com­po­nent sur­face at a defined dis­tance from the laser beam. These are pressed onto the com­po­nent sur­face with a defined force using pneu­mat­ic cylin­ders. Uneven­ness and dif­fer­ences in the thick­ness of the join­ing part­ners can be compensated.
















Fig. 1 (left): The dis­tri­b­u­tion of the AlSi-coat­ing in com­par­i­son with­out (a) and © and with (b) and (e) influ­ence of an ultra­son­ic wave super­po­si­tion by isi-sys Piezoshak­er dur­ing laser beam weld­ing with false-col­or images of EDS-analy­sis (d) and (f) [1]

Fig. 2 (right): Super­im­posed SEM-images and sec­tioned inverse pole fig­ure map­pings (IPFM) of a weld seam with­out (a) and with ultra­son­ic super­po­si­tion (b) mea­sured with elec­tron backscat­ter dif­frac­tion shown as inverse pole fig­ure in Z‑direction [1]

[1] Pub­lished in: C. Wolf, S. Völk­ers, I. Kryukov, M. Graß, N. Som­mer, S. Böhm, M. Wun­der, N. Köh­ler und P. Mäck­el, „Enhance­ment of Weld­abil­i­ty at Laser Beam Weld­ing of 22MnB5 by an Entrained Ultra­son­ic Wave Super­po­si­tion,“ In: Mate­ri­als 2022, Bd. 15, 4800.

Strain Gauge Comparison

In this exam­ple a Vic-3D mea­sure­ment with 5MP CMOS Cam­era was per­formed. The acryl spec­i­men is fixed in a ten­sile test­ing machine. A strain gauge is attached at the back in com­bi­na­tion with a SCAD 500 strain gauge ampli­fi­er. The out­put of the SCAD 500 was con­nect­ed to the DAQ of the DIC sys­tem. The strain results are record­ed par­al­lel with the Vic-3D mea­sure­ment and plot­ted in a dia­gram. The cam­era type is equipped with Sony 5Mpx Pregius sen­sor, 75 fps.

Strain Gauge Comparison-1  Strain Gauge Comparison-1a

Image 1: Vic-3D mea­sure­ment of the acryl specimen


Strain Gauge Comparison-2









Image 2: Com­par­i­son of strain gauge data (red curve) and DIC Strain data (black curve)


The Vic-3D data match near­ly per­fect with the strain gauge data. Even at low strains the dif­fer­ence is less than 25 micro strain.

NDT of Carbon-NOMEX (honeycomb core) composite: Dynamic loading on a large yacht hull

Marine NDE (Spain) used the tech­ni­cal advan­tages of our Shearog­ra­phy-Sys­tem espe­cial­ly in com­bi­na­tion with the dynam­ic exci­ta­tion for non-destruc­tive exam­i­na­tion (NDE) of large areas such as com­plete yacht hulls (see image below). The hull with a lenghts of 30,5m was a car­bon-fir­ber-com­pos­ite and part of high per­for­mance sail­ing yacht in build. Because of the full-field method (100% of the inspect­ed area is exam­ined), the test­ing of the entire hull required only 240 shots, in three workdays.


The yacht hull con­sists of a sand­wich con­struc­tion, where are in par­tic­u­lar used hon­ey­comb cores (NOMEX).

Marine NDT1Marine NDT2







On the left — A shearo­gram of a detect­ed bond­ing defect (in red oval). The yel­low X marks the loca­tion of the core sam­ple shown at the right. The destruc­tive test con­firms the shearo­gram’s indi­ca­tion that there is a sig­nif­i­cant nev­er-bond between the hon­ey­comb core mate­r­i­al and the film adhe­sive in this area.


Dynamic loading on a wind turbine blade and resin bridges

Analysis of a wind turbine blade

The test pan­el was an orig­i­nal sec­tion of a wind tur­bine blade with a defect (a foam block with bridges). Pre­vi­ous­ly the defect was locat­ed by infil­tra­tion of col­or through small drilled holes. The sam­ple is exam­ined non-destruc­tive­ly by the SE-Sen­sor.


Section RotorBlade-a  Section RotorBlade2

left: Set-up

right: Time aver­age result at fre­quen­cy of 2569Hz show­ing the debond­ing area.





Section RotorBlade3Section RotorBlade4left: Live view of sur­face includ­ing shearing.

right: Time aver­age mea­sure­ment from the marked area in the live image.




De-bonding of resin bridges

A GFRP sand­wich with foam blocks and resin bridges should be exam­ined. The detec­tion of the defect type und struc­ture is very quick and reli­able in this case, because the defects are vis­i­ble, not only at their local nat­ur­al fre­quen­cies, but also due to their forced deflec­tion shapes over a wide fre­quen­cy bandwidth.

Section2 RotorBlade


The exci­ta­tion fre­quen­cies of the select­ed mea­sure­ments are 1398 Hz (1), 3133 Hz (2), 2442 Hz (3) and 4906 Hz (4) — num­ber­ing in fol­low­ing images:

Section2 RotorBlade2

Vakuum loading on battery packs

Air inclu­sion or air pock­ets in mod­ern Li-bat­tery packs is a seri­ous and dan­ger­ous prob­lem. The isi-sys SE2 sen­sor is able to detect tiny and large defects such as air bub­bles, air pock­ets, cracks and oth­er with­in a sec­ond. The defects can be far below or near to the sur­face. An exam­ple of a bat­tery pack (test sam­ple from Uni­ver­si­ty of Munich, IWB) and the mea­sure­ment result is shown below.

Test set­up:

The test has been done by SE2 sen­sor in com­bi­na­tion with a glass vac­u­um cham­ber for a sim­ple man­u­al test. This is an eco­nom­ic solu­tion for spot NDT by man­u­al ser­vice. For auto­mat­ed series test in pro­duc­tion dif­fer­ent setups are required.

Test poce­dure:

The bat­tery packs are test­ed by small pres­sure dif­fer­ences of some mbar, which can be applied in sec­onds or below in small cham­bers. The sen­sor is mon­i­tor­ing the sur­face of the bat­tery pack while the pres­sure is changed, mea­sur­ing the dif­fer­en­tial defor­ma­tion of the sur­face. Due to the expan­sion of the air bub­bles and air pock­ets, the air inclu­sions can be locat­ed such as shown in the fol­low­ing images.

The first image shows the live view of the bat­tery pack from the sen­sor. The sec­ond shows the recon­truct­ed phase, which is cor­re­spond­ing to the local defor­ma­tion gradient.

battery pack3
















battery pack2

Gen­er­al­ly the required pres­sure dif­fer­ence depends on the defect depth, defect size an the mechan­i­cal stiff­ness of the test­ed struc­ture, but in gen­er­al the load is small due to the high sen­si­tiv­i­ty of the sen­sor detect­ing dif­fer­en­tial defor­ma­tions of the surface.

Operation mode analysis on a mobile phone during vibration alert



Ref­er­ence coor­di­nates and con­tour of the mobile phone.






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.


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.



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.