Method for monitoring axial loads in structures by identifying natural frequencies

A method of monitoring axial loads in structures through the identification of natural frequencies, the method comprising the steps of:

• arranging measurement sensors (201) on a test mooring comprising at least three links;
• connecting said sensors (201) to a signal acquisition, conditioning, and processing unit (202);
• tensioning and exciting the test mooring;
• collecting vibration data from the test mooring by means of said sensors (201);
• identifying natural frequencies of the test mooring based on the collected data;
• developing a load monitoring model based on mechanical characteristics of the test mooring;
• performing modal analysis of the load monitoring model to determine the natural frequencies of the model;
• comparing the natural frequencies of the test mooring calculated based on the collected data with the natural frequencies obtained by the load monitoring model;
• adjusting the load monitoring model until said natural frequencies obtained by the load monitoring model are equal to the natural frequencies of the test mooring;
• extrapolating the load monitoring model by increasing the number of links in the test mooring;
• generating a calibration chart via modal analysis for different loads;
• placing vibration measurement sensors (201) along an actual mooring (105);
• exciting the actual mooring (105);
• conditioning the data obtained by said measurement sensors (201) by means of a signal acquisition, conditioning, and processing unit (202);
• transforming data obtained by said measurement sensors from the time domain to the frequency domain for determining the natural frequencies of the mooring;
• analyzing the natural frequencies and determining the vibrational profile achieved by the load monitoring model that is most similar to the vibrational profile of the mooring and its equivalent load;
• and
• displaying the equivalent load value on a monitor (203).