More economical management of bridges can be achieved through early problem detection and mitigation. The paper describes development and implementation of two fully automated (robotic) systems for nondestructive evaluation (NDE) and minimally invasive rehabilitation of concrete bridge decks. The NDE system named RABIT was developed with the support from Federal Highway Administration (FHWA). It implements multiple NDE technologies, namely: electrical resistivity (ER), impact echo (IE), ground-penetrating radar (GPR), and ultrasonic surface waves (USW). In addition, the system utilizes advanced vision to substitute traditional visual inspection. The RABIT system collects data at significantly higher speeds than it is done using traditional NDE equipment. The associated platform for the enhanced interpretation of condition assessment in concrete bridge decks utilizes data integration, fusion, and deterioration and defect visualization. The interpretation and visualization platform specifically addresses data integration and fusion from the four NDE technologies. The data visualization platform facilitates an intuitive presentation of the main deterioration due to: corrosion, delamination, and concrete degradation, by integrating NDE survey results and high resolution deck surface imaging. The rehabilitation robotic system was developed with the support from National Institute of Standards and Technology-Technology Innovation Program (NIST-TIP). The system utilizes advanced robotics and novel materials to repair problems in concrete decks, primarily early stage delamination and internal cracking, using a minimally invasive approach. Since both systems use global positioning systems for navigation, some of the current efforts concentrate on their coordination for the most effective joint evaluation and rehabilitation.
Robotic drilling is the basic process for the non-destructive rehabilitation (NDR) system in the Automated Non-destructive
Evaluation and Rehabilitation System (ANDERS) for bridge decks. In this paper, we present a study
and testing of a concrete drilling process that is used for robotic drilling process for bridge decks repair. We first
review the ANDERS and NDR design. Then we present the experimental setup for the drilling process study.
A set of testing experiments are performed considering drilling process parameters such as drill bit size, drill
rotating speed, drill thrust force and types of concrete composites. Based on the experiments and analysis, we
identify and find that the optimal set of drilling process parameters for the ANDERS application is 1/4-inch bit
size, drill rotational speed of 1500 rpm and thrust force around 35 lbs. We also demonstrate that the monitoring
of drill feeding displacement and thrust force cannot be used to detect and identify the cracks in bridge decks.
Improving the energy conversion efficiency is one critical factor for practical usage of vibrational energy harvesting
devices. In this paper, we design and prototype a vibration-based energy harvester with a high output
energy density. The proposed harvester is based on a composite cantilever beam-mass design. The cantilever
beam is made of a high piezoelectric constant, lead magnesium niobate-lead titanate (PMN-PT) material. A
polydimethylsiloxane (PDMS) coating is applied to the cantilevers to decrease stress concentration of the thin
PMN-PT and therefore increase the strength of the cantilever. A PDMS proof mass is also added to decrease
the natural frequency of the cantilever system and to increase displacement and the voltage output. It is found
that a 7.4 mm PMN-PT cantilever with a PDMS coating and proof mass produces a sustained 0.7 mW of RMS
power (16.8 V, 58 μA) at an acceleration of 55 m/s2.
We investigate effects of bending stress on piezoelectric properties of polyvinylidene fluoride (PVDF) as a polymer
sensor. The sensor was designed and fabricated into a special size and shape so that it can be attached to small
insects, such as the American cockroach (Periplaneta Americana) to measure the insects' locomotion. The
performance of the sensor is studied using a controlled linear stage to buckle the sensor mimicking the bending of
the sensor due to the leg movements of cockroaches. For comparison, a roach robot was used for multi-leg study.
Results indicate that buckling motion of the sensor produce an output that is different from regular stretching effect.
The sensor-generated charge depends on the localized stress distribution and dipole alignment. This paper discusses
the methods of characterization of piezoelectricity useful for insect applications.
Pneumatic tires are critical components in mobile systems that are widely used in our lives for passenger and
goods transportation. Wheel/ground interactions in these systems play an extremely important role for not only
system design and efficiency but also safe operation. However, fully understanding wheel/ground interactions
is challenging because of high complexity of such interactions and the lack of in situ sensors. In this paper, we
present the development of a tire tread deformation sensor and energy harvester for real-time tire monitoring and
control. Polyvinylidene fluoride (PVDF) based micro-sensor is designed and fabricated to embed inside the tire
tread and to measure the tread deformation. We also present a cantilever array based energy harvester that takes
advantages of the mechanical bandpass filter concept. The harvester design is able to have a natural frequency
band that can be used to harvest energy from varying-frequency vibrational sources. The energy harvester
is also built using with new single crystal relaxor ferroelectric material (1 - &Vkgr;)Pb(Mg1/3Nb2/3)O3-&Vkgr;PbTiO3 (PMN-PT) and interdigited (IDT) electrodes that can perform the energy conversion more efficiently. Some
preliminary experiment results show that the performance of the sensor and the energy harvester is promising.
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