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.