What Are the Applications of Threaded Rods, Threaded Bars, and Double-End Studs in the Aerospace Field?
A threaded rod is a fully threaded rod-shaped component, typically a long, thin rod with threads at both ends or along its entire length. It has no head and must be used with nuts, washers, and other accessories.
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Used for lightweight connection of large structural components such as aircraft fuselages and wings. For example, composite material parts are fixed to metal frames using multiple sets of nuts, facilitating adjustment of installation positions and preload.
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Example: In the engine nacelle, threaded rods can connect brackets to nacelle walls, withstanding vibration and loads.
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When installing on-board equipment (e.g., electronic instruments, hydraulic components), they serve as basic supporting and fixing elements. Nuts are used for locking to ensure the equipment remains stable in high-vibration environments.
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Fix fuel pipelines, cooling pipelines, etc. The long-distance adjustability of threaded rods allows them to adapt to complex spatial layouts.
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During aircraft final assembly or maintenance, they act as temporary positioning or adjustment components, enabling quick disassembly and position calibration.
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Material: High-strength corrosion-resistant alloys (e.g., titanium alloys, aerospace-grade stainless steel) are usually used to meet lightweight and anti-fatigue requirements.
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Precision: High thread precision (e.g., ISO metric fine threads or American UNF threads) ensures tight fitting and prevents loosening.
Similar to threaded rods, a threaded bar generally refers to a long, fully threaded rod. However, in the aerospace field, it may emphasize its characteristic of serving as a load-bearing main body, and in some scenarios, it can be regarded as another term for threaded rods.
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Used in key parts that need to transmit axial loads, such as the internal threaded rods of landing gear shock struts, which withstand landing impact loads.
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In satellite brackets or rocket interstage connections, they act as main load-bearing rods, and high-strength connections are achieved by matching with flanges or adapters.
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Installed in aircraft control systems (e.g., the transmission mechanisms of flaps and ailerons), the length of the rod can be adjusted by rotating nuts to achieve precise control of the mechanism stroke.
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In the deployment mechanism of spacecraft solar wings, threaded bars can serve as drive screws. The motor drives the nuts to realize the deployment and locking of the wing surfaces.
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Surface Treatment: Coating (e.g., cadmium plating, nickel-phosphorus plating) or passivation treatment may be applied to enhance corrosion resistance and wear resistance.
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Anti-Vibration Design: Anti-loosening nuts (e.g., nylon insert lock nuts) or thread-locking adhesives are used to prevent loosening caused by high-frequency vibration.
A double-end stud is a rod with threads at both ends and a smooth shaft or partial threads in the middle. One end is screwed into the threaded hole (often a blind hole) of the connected part, and the other end fixes another part with a nut, eliminating the need to penetrate the entire structure.
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Used for connecting aircraft engine cylinder blocks and cylinder heads (e.g., combustion chambers, turbine components). One end is screwed into the threaded hole of the cylinder block, and the other end fastens the cylinder head with a nut, withstanding high temperatures, high pressures, and alternating loads.
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Example: Double-end stud connections between the compressor casing and bearing seat of a gas turbine engine.
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In composite material wing or fuselage structures, double-end studs connect metal embedded parts (e.g., titanium alloy bushings) to composite laminates, avoiding stress concentration caused by directly machining threads in composite materials.
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For parts that require frequent disassembly, such as aircraft cabin doors and inspection covers, double-end studs can protect the base threaded holes and prevent thread wear due to repeated disassembly and assembly.
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Used for equipment installation in spacecraft instrument cabins, facilitating quick disassembly and maintenance without damaging the main structure.
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Strength Grade: High-strength grades (e.g., Grade 12.9 and above) are usually used, and high-temperature resistant alloys (e.g., Inconel, Incoloy) are selected as materials.
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Fitting Precision: The threaded end for screwing into the base adopts an interference fit or transition fit (e.g., H7/m6) to ensure connection reliability.
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Choose double-end studs when frequent disassembly is required or the base needs to be protected.
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Choose threaded rods for long-distance adjustment or lightweight connections.
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Choose threaded bars when high static or dynamic loads need to be borne.
In aerospace design, the application of these three types must be comprehensively evaluated based on specific working conditions (e.g., temperature, load type, environmental corrosion level) and airworthiness standards (e.g., FAA, EASA certifications).
