Detection & Analysis of Barely Visible Impact Damage & its Progression on a Composite Overwrapped Pressure Vessel

To ensure structural integrity and reduce repair and maintenance cost, in-service health and usage monitoring techniques are employed in many engineering areas.

In this context this dissertation, developed in Thales Alenia Space, has the purpose to create and test an automatic procedure to detect and monitor the damage occurred on a COPV (Composite Overwrapped Pressure Vessel) obtained by filament winding.

After a first theoretical introduction, the analytical examples Es. 3.20, 3.21, 3.22 from Abrate's work 'Impact on Composite Structures' are reproduced with the commercial software Radioss. These three models deal with low speed velocities coherently with the intent to cause a BVID (Barely Visible Impact Damage). During the consequent analysis of the result, displacements and contact forces are compared with the analytical results. Relative errors stay under 8%.
On the latter part of the thesis the tested procedure is applied to the COPV.

Once the model is prepared, a first pressure analysis of the integer structure is made. The tank is than impacted by a low-velocity steel sphere. The damage is detected and the structure is again subjected to the same pressure load so we can see the lower strength capability and the reduction of the mechanical properties of the material.

 

The Author

Valentina Dolci
Thales Alenia Space/Politecnico di Torino