Civil Engineers have used fiber reinforced polymer (FRP) with high axial strength as an effective and economical
alternative to steel in harsh corrosion environments. However, the practical applications of FRP are limited by the
tendency of FRP materials to fail suddenly under lateral pressure and surface injury. For example, shear stresses result
from the bonding effect between the FRP material and the structure of the anchorage system due to the lower shear
strength of FRP. This paper proposes a novel smart FRP anchorage system with embedded optical fiber Bragg grating
(FBG) sensors to monitor the axial strain state and accordingly the interfacial shear stress, as well as the interfacial
damage characteristics of FRP anchorage. One FBG sensor was embedded in an FRP rod outside the anchorage region
to evaluate the properties of the material, and seven FBG sensors were distributed along the rod in the anchor to
monitor the axial strain variations and study the interfacial mechanical behaviors of the smart FRP anchorage under a
static pulling load. The experimental results agreed well with theoretical predictions. The smart FRP anchorage system
with optical FBG sensors proves effective and practical for monitoring the long-term mechanical behavior of FRP anchorage systems.
Casing pipes in oil well constructions may suddenly buckle inward as their inside and outside hydrostatic pressure
difference increases. For the safety of construction workers and the steady development of oil industries, it is critically
important to measure the stress state of a casing pipe. This study develops a rugged, real-time monitoring, and warning
system that combines the distributed Brillouin Scattering Time Domain Reflectometry (BOTDR) and the discrete fiber
Bragg grating (FBG) measurement. The BOTDR optical fiber sensors were embedded with no optical fiber splice joints
in a fiber reinforced polymer (FRP) rebar and the FBG sensors were wrapped in epoxy resins and glass clothes, both
installed during the segmental construction of casing pipes. In-situ tests indicate that the proposed sensing system and
installation technique can survive the downhole driving process of casing pipes, withstand a harsh service environment,
and remain in tact with the casing pipes for compatible strain measurements. The relative error of the measured strains
between the distributed and discrete sensors is less than 12%. The FBG sensors successfully measured the maximum horizontal principal stress with a relative error of 6.7% in comparison with a cross multi-pole array acoustic instrument.
KEYWORDS: Chemical elements, Process control, Telecommunications, Sun, Astronomical engineering, Mechanics, Systems modeling, Computer simulations, Rectum
The rendezvous problem was analyzed by the guidance method of qualitative differential game for space vehicle while the target is maneuvering, based upon the perturbation equation of orbital elements. By taking into account of fuel assumption for rendezvous control process under radial thrust, we introduced the performance index for quantitative differential game into Hamiltonian function to resolve the guidance problems for maneuvering space vehicle for orbit approaching, and gave a set of theoretical solution, barriers and an example for simulation. From mathematically simulation it is verified that there are the barriers in the method for the target maneuvering.
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