Marine composite riser for structural health monitoring using piezoelectricity

A structural health monitoring system for a riser string, the system comprising:

• a marine riser pipe string comprising a plurality of riser pipe sections, each of the plurality of riser pipe sections comprising:
• a cylindrical form having an axis, the cylindrical form having an inner layer and an outer layer of a carbon epoxy matrix;
• and
• a cylindrical laminate sensor sheet of a PolyVinyliDene Fluoride material circumscribing the riser pipe section, the sheet having an electrically conductive coating on an inner side and on an outer side, defining an inner electrode and an outer electrode, the sheet constructed to generate electricity at the electrodes responsive to mechanical stresses and strains of the riser pipe section, wherein the sheet surrounds the inner layer and is embedded between the inner and outer layers of the carbon epoxy matrix of the riser pipe section;
• and
• a digital signal analyzer to analyze electrical signals responsive to the generated electricity at the electrodes of sensors for the plurality of riser pipe sections and to provide health monitoring for the marine riser pipe string.

A method of detecting a crack in a composite riser, the method comprising:

• assembling a marine riser pipe string utilizing a plurality of riser pipe sections, each of the plurality of riser pipe sections comprising a cylindrical form having an axis, at least one riser pipe section of the plurality of riser pipe sections comprising inner and outer layers of carbon epoxy matrix;
• providing at least one cylindrical sheet with the at least one riser pipe section, the at least one sensor sheet circumscribing the at least one riser pipe section, the at least one sensor sheet comprising a PolyVinyliDene Fluoride laminate, wherein the at least one sensor is encircles the inner layer and is embedded between the inner and outer layers of the carbon epoxy matrix of the riser pipe section;
• an electrically conductive coating on an inner side of the sheet, and an electrically conductive coating on an outer side of the sheet, defining inner and outer electrodes;
• generating electricity at the electrodes of the at least one sensor sheet responsive to mechanical stresses and strains of the at least one riser pipe section;
• and
• analyzing an electrical signal, the electrical signal responsive to the generated electricity at the electrodes of the at least one sensor sheet, to thereby detect a crack in the at least one riser pipe section.