Replacement of the Green Bank Telescope azimuth track

Anderson, Ron; Symmes, Arthur; Egan, Dennis

doi:10.1117/12.784807

Cited by 8 publications

(6 citation statements)

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“…Following a successful installation, the track is now exhibiting satisfactory performance for all aspects of telescope operation [7]. Figure 15 Configuration of the revised GBT Azimuth Track.…”

Section: Discussionmentioning

confidence: 97%

Improving the service life of the 100-meter Green Bank Telescope azimuth track

2008

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The NRAO Green Bank Telescope (GBT), located in Green Bank, West Virginia, is supported by 16 steel wheels which rest upon a composite steel and concrete Azimuth Track, 210 feet (64 meters) in diameter. From the start of observing in February 2001, the Azimuth Track design presented an operational problem for NRAO. By the spring of 2001, slippage of the top plate on the base plate was causing hold-down bolt failures. In July 2002, wear between the top and base plates (fretting) had become evident around the entire track circumference. NRAO engineers took immediate action to reduce both the track slippage and wear problems. But in January 2003, cracks were discovered in two adjacent top plates; by 2006 the top plates were cracking at a rate of almost one a month -an alarming rate given the design service life of 20 years. This paper will summarize the engineering analysis efforts that were subsequently conducted to assess the root cause of the GBT track degradation problem. We will also discuss a trial modification section that was installed in June 2004. Finally, we will discuss the design solution that was developed to remedy the track performance problem.

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Section: Discussionmentioning

confidence: 97%

Improving the service life of the 100-meter Green Bank Telescope azimuth track

2008

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“…The final form of rolling contact fatigue of the wheel-rail is the fracture of the wheel-rail material, which can seriously affect the normal operation of the antenna. Through the research and analysis of the working damage situation of wheel-rail of large reflector antennas in various countries, the wheel-rail of large reflector antennas generally experience the following types of damage on the surface [6][7][8][9][10][11][12][13][14]:…”

Section: A Antenna Wheel-rail and Damage Formsmentioning

confidence: 99%

“…The wheel-rail damage of large reflector antenna reduces its surface accuracy and directly affects the antenna pointing performance, so it is important to study the detection of damage to the wheel-rail surface. The GBT antenna in the U.S.A. was built and operated for a few years and had problems with wear on the surface of the substrate and wear plate, Anderson R et al investigated this issue, designed and manufactured a new component system, and updated the antenna component in 2007, which greatly improved the performance and service life of the azimuth orbit of the GBT antenna [13,14]; Aiming at the mechanical behavior of the inclined joint track of GBT antenna and the fretting wear of the contact interface between wearresistant plate and substrate, Juneja G et al simulated the rolling situation of the roller by using the moving load method, and analyzed the force by using the finite element method, which provided a reference for the design and transformation of the antenna wheel-rail [15]; In order to make the antenna have good pointing performance, DR Smith et al pointed out that attention must be paid to the wheel-rail design to make it have high hardness to withstand great contact pressure [16]; Guo Hongwei et al used Hertz contact theory and finite element method to analyze the stress of a radar wheel-rail type antenna mount, and did metallurgical analysis under the condition of satisfying the strength to determine the cause of cracks on the surface of the roller [17].…”

Section: Introductionmentioning

confidence: 99%

A Method for Damage Detecting of Large Reflector Antennas Wheel-Rail Based on Electromagnetic Ultrasonic Technology

Jin,

Ban,

Feng

2024

IEEE Access

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The azimuth wheel-rail of large reflector antennas is one of the key components, it not only supports the whole weight of the antenna, but also directly affects the antennas' pointing performance by its surface accuracy. Usually, the whole weight of the large reflector antenna is thousands of tons, its azimuth frame rollers have great contact stress with the wheel-rail surface, repeated rolling can cause rolling contact fatigue on the wheel-rail surface, resulting in wear, cracks and other damage to the wheel-rail, and even lead to failure or fracture of the wheel-rail in serious cases, so it is very important to monitor the damage of the antenna wheel-rail. Current studies are based on Hertzian theory for stress analysis of rollers and wheel-rails, it cannot visually determine the damage. In order to visually detect the usage of antenna wheel-rail surfaces, this paper, for the first time, proposed the method using electromagnetic ultrasonic detection to detect the damage of antenna wheel-rail surface. Based on the principle of electromagnetic ultrasonic nondestructive testing, the simplified wheel-rail model containing wear, corrosion and crack damages are simulated. The results show that this method can effectively detect the surface damage of the antenna wheel-rail surface, and it can provide an important reference for the research of wheel-rail damage detection of large reflector antennas.

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“…During the operation of radio telescopes, a series of problems affecting the pointing accuracy of the azimuth tracks [1], such as track wear, fatigue cracks, and impact damage to track welded joints, occur in the wheel-rail contact system. A lot of design optimizations and improvements to tracks have already been conducted [2][3][4]. For the QiTai radio telescope (QTT) studied in this paper, the joints of the azimuth track are all welded.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Mechanical Characteristics and Wheel–Rail Contact Simulation of a Welded Joint for a Large Radio Telescope Azimuth Track

Chen,

Yin,

Yang

et al. 2024

Buildings

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The azimuth track is an important component of the radio telescope wheel–rail system. During operation, the azimuth track is inevitably subject to phenomena such as track wear, track fatigue cracks, and impact damage to welded joints, which can affect observation accuracy. The 110 m QiTai radio telescope (QTT) studied in this paper is the world’s largest fully steerable radio telescope at present, and its track will bear the largest load ever. Since the welded joint of an azimuth track is the weakest part, an innovative welding method (multi-layer and multi-pass weld) is adopted for the thick welding section. Therefore, it is necessary to study the contact mechanical properties between the wheel and the azimuth track in this welded joint. In this study, tensile tests based on digital image correlation technology (DIC) and Vickers hardness tests are carried out in the metal zone (BM), heat-affected zone (HAZ), modified layer, and weld zone (WZ) of the welded joint, and the measured data are used to fit the elastic–plastic constitutive model for the different zones of the welded joint in the azimuth track. Based on the constitutive model established, a nonlinear finite element model is built and used to simulate the rolling mechanical performance between the wheel and azimuth track. Through the analysis of simulated data, we obtained the stress distribution of the track under different pre-designed loads and identified the locations most susceptible to damage during ordinary working conditions, braking conditions, and start-up conditions. The result can provide a significant theoretical basis for future research and for the monitoring of large track damage.

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Replacement of the Green Bank Telescope azimuth track

Cited by 8 publications

References 0 publications

Improving the service life of the 100-meter Green Bank Telescope azimuth track

Improving the service life of the 100-meter Green Bank Telescope azimuth track

A Method for Damage Detecting of Large Reflector Antennas Wheel-Rail Based on Electromagnetic Ultrasonic Technology

A Study on the Mechanical Characteristics and Wheel–Rail Contact Simulation of a Welded Joint for a Large Radio Telescope Azimuth Track

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