Abstract:
For continuous monitoring of dynamic loads, including stresses and strains in large hull structures for vessels (5), a strain measurement system (2) is employed with fibre optic cables which connect optical strain sensors (7; 16) at different points in the hull structure. Optical signals for detection of stresses and strains are distributed to the strain sensors (7; 16) from an optical transmitter (11). The strain measurement system (2) is connected via a central monitoring unit (10) to a computer-implemented control system (1) which in turn is connected to a display and data presentation unit (4) and possibly other measurement systems (3). In a first operating mode in this method strain values during loading and unloading of the vessel (5) are detected by means of the strain sensors (7; 16). By means of the control system (1) a curve is generated which shows an average strain, and an alarm signal if the average strain exceeds a predetermined threshold which indicates an unacceptable level of strain. In a second operating mode when the vessel (5) is underway, strains are continuously detected by means of the strain sensors (7; 16). An alarm signal is generated if the average strain exceeds a predetermined threshold which indicates an unacceptable level of strain. A strain measurement system and a fibre optic strain sensor (16) for use with this method are also described.
Abstract:
A fiber optic load sensor (12) and method of forming the same are disclosed for sensing the load applied to a structural surface (18). The sensor (12) comprises a length of fiber optic material (14) disposed adjacent to the surface (18). The fiber optic material is connectable to a light source (22) and to a light detector (26). The fiber optic material (14) includes at least one curved portion deformable in response to the applied load. The curved portion is dimensioned such that the light passing through the fiber optic material (14) is attenuated in linear relation to the deformation of the curved portion in response to the load applied to the surface.