Study on the Deformation Measurement of the Cast-In-Place Large-Diameter Pile Using Fiber Bragg Grating Sensors

This paper presents the preparation and execution of on-ground static and engine load tests for the composite unmanned aerial vehicle (UAV). The test was conducted for pre-flight structural strength verification of the remotely piloted aerial target named HORNET, after introducing some structural modifications. The ground tests were performed before the flight test campaign, to ensure the strength and operational safety of the modified structure. The panel method and Computer Aided Design (CAD) modelling were adopted for numerical evaluation of aerodynamic and inertial forces’ distribution to simulate loading scenarios for launch, flight and parachute deploying conditions during the static test. Then, the multi-stage airframe static test was prepared and executed with the use of a designed modular test rig, artificial masses, as well as a wireless strain measurement system to perform structure verification. The UAV was investigated with 150% of the typical load spectrum. Furthermore, an engine test was also conducted on a ground test stand to verify strain and vibration levels in correspondence to engine speed, as well as the reliability of data link and the lack of its interferences with wireless control and telemetry. In the article, data achieved from the numerical and experimental parts of the test are discussed, as well as post-test remarks are given.

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental UAV Structure Investigation by Pre-Flight Load Test

Kurnyta

Zieliński

Reymer

et al. 2020

“…FBG sensing technology can monitor pile deformation in the process of pile foundation static load and drawing tests. FBG sensors have been embedded in the pile to reveal the stress mechanism of the pile [ 17 , 18 , 19 ]. For the strain test of the pile body in the pile jacking process, it is very important to overcome the serious disturbance caused by soil particle movement to the pile end and pile body and to protect the sensor from damage during the test.…”

Section: Introductionmentioning

confidence: 99%

Fiber Bragg Grating Sensors for Pile Jacking Monitoring in Clay Soil

Wang

Liu

Zhang

et al. 2020

The small deformation of the model pile in a pile jacking test makes its accurate measurement very difficult. Based on the installation method of clamping at both ends, a sensitized miniature fiber Bragg grating (FBG) strain sensor was developed to measure the pile strain of small-size model piles. This study investigated the working principle of the sensitized miniature FBG sensor and analyzed the strain transfer characteristics of the sensor by calibration test. The lateral resistance and the earth plug resistance of the model pile were measured accurately by the grooves embedded in the outer tube of the double-wall opening model pile and the sensors directly pasted on the surface of the inner tube. The results of this study show that the sensitized miniature FBG strain sensor has the advantages of high sensitivity, strong interference resistance, and high test accuracy. The FBG strain sensor was completely fixed on the pile by clamping supports at both ends, and the strain measured using the FBG strain sensor was found to be consistent with the pile deformation.

“…The applicability of the fiber grating sensor in monitoring the strain distribution of the pile during jacking had been demonstrated. Gao et al [21] monitored the deformation of PCC (Large diameter pipe pile by using cast-in-place concrete) piles based on a new quasi-distributed fiber sensing technology while the strain of PCC model piles based on FBG sensors was monitored. However, the traditional monitoring technology used during the pile jacking process of indoor model pipe piles is primarily a strain gauge [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Test and Study of Pipe Pile Penetration in Cohesive Soil Using FBG Sensing Technology

Wang

Liu

Zhang

et al. 2020

In order to examine the applicability of Fiber Bragg Grating (FBG) sensing technology in the static penetration of pipe piles, static penetration tests in clay were conducted using double-wall open and closed model pipe piles. The strain was measured using FBG sensors, and the plug height was measured using a cable displacement sensor. Using one open pile and two closed piles, the difference in pipe pile penetration was compared and analyzed. Based on FBG sensing technology and the strain data, the penetration characteristics of the pipe pile, such as axial force, lateral friction, and driving resistance were examined. Results showed that FBG sensing technology has superior testing performance for the pipe pile penetration process, can accurately reflect the strain time history of pipe piles, and can clearly reflect the penetration process of pipe piles with increasing penetration depth. In addition, the variation law of the characteristics of the jacked pile pile–soil interface was obtained. This test has significance for model tests and the engineering design of pipe piles.