Multi-point fiber optic laser-ultrasonic transducer based on long-period fiber grating.

For ultrasonic non-destructive testing, the development of miniaturized, embeddable, and distributed ultrasonic transducers has always been a hot research topic. In light of this, a novel fiber optic laser-ultrasonic transducer, employing the long-period fiber grating (LPFG), was introduced in this study to facilitate the implementation of embedded and distributed applications. LPFG couples the light transmitted in the optical fiber into the photoacoustic conversion material.

Understanding the Toughening Mechanism of Silane Coupling Agents in the Interfacial Bonding in Steel Fiber-Reinforced Cementitious Composites.

Interfacial bonding between a fiber and a matrix plays an essential role in composites, especially in fiber-reinforced cementitious composites that are superior forms for bearing flexural and tension load in construction applications. Yet, despite the importance, effective and economic approaches to improve the interfacial bonding between a steel fiber and a cementitious matrix remain unfeasible. Herein, we report a pathway adopting a silane coupling agent (SCA) to modify an interfacial transition zone (ITZ) and enhance interfacial bonding.

Experimental Investigation on Interfacial Defect Criticality of FRP-Confined Concrete Columns.

Defects between fiber reinforced polymer (FRP) and repaired concrete components may easily come out due to misoperation during manufacturing, environmental deterioration, or impact from external load during service life. The defects may cause a degraded structure performance and even the unexpected structural failure. Different non-destructive techniques (NDTs) and sensors have been developed to assess the defects in FRP bonded system.

Effect of Stress Amplitude on the Damping of Recycled Aggregate Concrete.

Damping characterizes the energy dissipation capacity of materials and structures, and it is affected by several external factors such as vibrating frequency, stress history, temperature, and stress amplitude. This study investigates the relationship between the damping and the stress amplitude of environment-friendly recycled aggregate concrete (RAC). First, a function model of a member's loss factor and stress amplitude was derived based on Lazan's damping-stress function.

Influence of Wind Pressure on the Carbonation of Concrete.

Carbonation is one of the major deteriorations that accelerate steel corrosion in reinforced concrete structures. Many mathematical/numerical models of the carbonation process, primarily diffusion-reaction models, have been established to predict the carbonation depth. However, the mass transfer of carbon dioxide in porous concrete includes molecular diffusion and convection mass transfer.