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 yacht mast

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.

NDT Yacht   NDT Yacht2


SE1 with Pie­zos­ha­ker for dyna­mic loading


Defect detec­ted by Vibro­gra­phy / dyna­mic loading


Dynamic loading on rudder blade

 

NDTRuder

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

NDTRuder2

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.

 

NDTRuder3   NDTRuder5  NDTRuder4

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.