Paweł Gąsior

Optical fiber sensors integrated with composite material based constructions

In the present work we demonstrate measurements obtained using optical fiber head sensors for high pressure composite vessel, composite strengthened concrete beam and the high-voltage composite insulator.

Application of Optical Fibre Sensors to Measuring the Mechanical Properties of Composite Materials and Structures

The role of polymer composites in mechanical structures has been steadily increasing. The key factor here is the coefficient of specific strength, i.e. a ratio of tensile strength to specific gravity. As compared with metals, this coefficient assumes a high value for composites, including the polymer ones. Other major factors determining the choice of materials are: the product price, mass manufacturability, high strength and durability, corrosion resistance, material production and machining energy consumption and a few more. Also the latter criteria increasingly favour composites. Materials engineering as applied to composites offers the possibility of creating entirely new materials and modifying the traditional materials, which in both cases better meet designers’ expectations. The ever increasing popularity of composite structures is first of all due to the considerable reduction in weight in comparison with metal structures, at a sufficiently high mechanical durability. Nevertheless, the safety requirements require that the stress-strain state of composite structure be monitored. Standard NDE methods such as radiography, interferometric holography, ultrasonic scanning or visual inspection are usually not effective in on-line monitoring. Even if they were used for periodic checks, they would not be able to detect promptly defects critical to the condition of the monitored structure. Moreover, conventional measurement devices, such as electrical resistance strain gauges, often get damaged in adverse environmental conditions. State-of-the-art measuring methods based on optical fibre technology are increasingly often used to monitor the structural health of industrial objects. Optical fibre sensors have many advantages over the conventional devices. The obvious one is that they can work at high levels of electromagnetic interference and in other adverse conditions (high dust concentration, high temperature, high pressure, significant deformations). Moreover, such sensors are characterized by high (deformation and temperature) measuring sensitivity in a wide measuring range. Owing to their small geometric dimensions and a relatively small weight they can be installed inside a structure (e.g. by embedding them in the composite material) or on its surface. Thanks to their high potential for multiplexing it is possible to create a nervous system of the object being monitored, enabling health and damage assessment. In addition, optical fibre based sensors ensure spark-proof safety which is an important consideration for inflammable applications.

Magnetomechanical Properties of Terfenol-D Powder Composites

In this work the methodology of determining mechanical and magnetomechanical properties (mainly magnetostriction) of original composite material on epoxy resin matrix and powdered Giant Magnetostrictive Material (Terfenol-D) has been presented. Researches were carried out in order to differentiate properties of the GMM composite with two different volume fraction of Terfenol-D powder (35% and 45%) in comparison with bulk Terfenol-D. Results show that composites magnetostriction highly depends on volume fraction of Terfenol-D powder, and it is few times lower than in monolithic material. Moreover a possible ways of application were indicated.

Optical fiber sensors in health monitoring of composite high-pressure vessels for hydrogen

In the present work we present the results of our latest research into an implementation of optical fiber sensors for flaw tolerance test application on high pressure composite hydrogen vessels. For monitoring influence of flaws on composite parameters, as point measurement heads permanently installed on tanks surface, fiber Bragg gratings (FBG) were used. The aim of our experiments was to examine structural behavior of the composite hydrogen vessels and test appropriate topologies of sensors to detect the damages.