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).

 

 

 

 

 

 

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.

 

The exam­ple shows an appli­ca­tion of NDT on a 30m CFK yacht mast (low­er left). The time aver­age result of the SE1 mea­sure­ment and dynam­ic load­ing by our Piezoshak­er (low­er right) is indi­cat­ing a larg­er delim­i­ta­tion below the sur­face start­ing from a small vis­i­ble crack. Usu­al­ly, small cracks are often seen on the sur­face, but not all are relat­ed to delam­i­na­tion, which needs any repair.

  

 

Detec­tion and mea­sure­ment of defects on a rud­der blade by the SE-Sen­sor and dynam­ic load­ing.

Set­up for mea­sure­ment on a rud­der by dynam­ic loading.

The direct rigid mount­ing of the sen­sor on the rud­der by the suc­tion cups allows out­door mea­sure­ment even at strong winds with high flex­i­bil­i­ty. The high qual­i­ty inter­fer­ence fil­ters of the sen­sor per­mits mea­sure­ment under day light conditions.

 

    

A: 9,3 kHz                                            B: 7,5 kHz                                           C: 5,5 kHz

Mea­sure­ment results (time aver­age) show­ing local vibra­tion modes of defects due to reduced or inho­mo­ge­neous stiff­ness of the mate­r­i­al. Even if a big field of view is select­ed, it is pos­si­ble to detect small defects. Defect size and type as well as the depth of the defect (delam­i­na­tion) deter­mine the nor­mal modes (res­o­nance fre­quen­cy) of the local defect area.