Dynamic loading on a large yacht hull

Marine NDE (Spain) used the technical advantages of our Shearography-System for non-destructive examination (NDE) of large areas. The Combination of the SE sensor with the Piezoshaker system for dynamic loading helped the crew to inspect the large yacht hull (see image below). The hull with a lenghts of 30,5m was a advanced-composite and part of high performance sailing yacht in build. Because of the full-field method (100% of the inspected area is examined) testing the entire hull required only 240 shots, in three workdays.

Marine NDE

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

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 piezo-shaker (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.