Loading Methods

Flexible and Efficient: One sensor system for dynamic, thermal and vacuum loading.


Dynamic Loading

For the dynam­ic load­ing the piezoshak­er exci­ta­tion sys­tems are designed by isi-sys. It con­sists of a Piezoshak­er, ampli­fi­er and func­tion gen­er­a­tor. For a detailed descrip­tion please refer to the report “Prod­ucts / Piezoshak­er Systems ”

The video on the right shows the lamb waves, gen­er­at­ed by the piezoshak­er, that is attached at the bot­tom of the spec­i­men. The waves trav­el across the object sur­face and excite the five local sub­sur­face defects on the top. The local defects vibrate dif­fer­ent­ly, depend­ing on their local mechan­i­cal prop­er­ties (stiff­ness). Only very lit­tle pow­er of the piezoshak­er is required, when the exci­ta­tion fre­quen­cy is close to the local defect res­o­nance fre­quen­cy. This prin­ci­ple is used in non-destruc­tive test­ing for exam­ple, espe­cial­ly to locate delam­i­na­tions in sand­wich structures.




The Piezoshak­er can be attached by vac­u­um to the object sur­face. The HVDA‑0–180 ampli­fi­er is espe­cial­ly design for isi-sys Piezoshak­ers and mobile appli­ca­tion, where high pow­er at low weight and com­pact size is a big advan­tage for mobil­i­ty and flex­i­ble han­dling. High fre­quen­cies up to 100kHz and more as well as large forces and accel­er­a­tion have been gen­er­at­ed in com­bi­na­tion with the dif­fer­ent isi-sys Piezoshak­er modules.









Thermal LoadingThermal loading

isi-sys offers timed ther­mal load­ing mod­ules to to heat-up the objects of measurement.

A auto­mat­ed pre­cise con­trol of heat load­ing and a cor­re­spond­ing timed shearo­graph­ic mea­sure­ment is required to achieve a repro­ducible test pro­ce­dure for non destruc­tive test­ing exper­i­ments and auto­mat­ed systems.

Any con­ven­tion­al halo­gen flood lights with 220V can be con­nect­ed. isi-sys rec­om­mends some flood lights used for pro­fes­sion­al pho­tog­ra­phy. Thus they can be mount­ed on stan­dard light stand of e. g. Man­frot­to etc. and eas­i­ly direct­ed to the area of inter­est inde­pen­dent of the sen­sor head. Also this lights offer some choic­es of reflec­tor combinations.

The start and dura­tion of the heat load­ing and the mea­sure­ments can be set per com­put­er con­trolled timer, which per­mits repro­ducible sequences of the test process.







Vakuum Loading

The vac­u­um is anoth­er load­ing method for non destruc­tive test­ing. The mod­u­lar sys­tem con­cept allows to com­bine the SE2 sen­sor with dif­fer­ent vac­u­um load­ing devices, which reduces sys­tem expense and keeps the equip­ment smart and mobile com­pared to oth­er solutions .

The vac­u­um meth­ods can be cat­e­go­rized depend­ing on the load­ing prin­ci­ple into vac­u­um chambers/vacuum cab­ins and vac­u­um hood/vacuum windows.


Vacuum hood and Vacuum window

Vakuum hoodThe vac­u­um hood is a mod­u­lar exten­sion acces­sories for the SE2 sen­sor. The sen­sor will be mount­ed inside of the hood and ther­fore the mea­sure­ment area is cov­ered from sun light influences.

The sys­tem has small dimen­sions and is for this rea­son very mobile and flex­i­ble, addi­tion­al­ly the low required vac­u­um pump pow­er is an advantage.





Vakuum window

If you use the vac­u­um win­dow, the sen­sor is out­side the vac­u­um vol­ume. The sys­tem is mon­i­tor­ing the object through the win­dow. The bend­ing forces are only across the field of view.

Due to the small vol­ume of the vac­u­um win­dow hood it can be used in com­bi­na­tion with the small isi-vac­u­um unit (also used for isi-piezoshak­ers with vac­u­um cup adapter). The unit includes two sep­a­rate vac­u­um pumps, where the sec­ond can be used for the vac­u­um suc­tion cup tripod.



Vacuum chamber and Vacuum cabin

Gen­er­al­ly vac­u­um cham­bers or cab­ins have the advan­tage against vac­u­um hoods and win­dows, that the forces appear uni­form from all sides on the object. This avoids super­posed fringes by glob­al defor­ma­tion such as by hood, where a bend­ing force on the object sur­face is super­posed, as usu­al­ly the pres­sure forces are applied only in one direc­tion on one side of the sur­face, where the hood is applied.

In both sys­tems the sen­sor is inside the vac­u­um vol­ume, which caus­es pres­sure load­ing also on the sen­sor. The cam­ber and the cab­in are big­ger than the object and there­fore depend­ing on object size the mobil­i­ty is restricted.

isi-sys offers the new­ly designed test­ing vac­u­um cab­in based on alu­mini­um-foam sand­wich ele­ments, which is rec­om­mend­ed e. g. for fre­quent­ly man­u­al spot tests or lab­o­ra­to­ry use.  Sam­ples with a size up to 450 x 750 mm can be mea­sured in this cabin.

Fur­ther­more isi-sys GmbH coop­er­ates with dif­fer­ent man­u­fac­tur­er for large vac­u­um chambers.