WO2025019001A1

WO2025019001A1 - 3d printed tie rod

Info

Publication number: WO2025019001A1
Application number: PCT/US2023/028296
Authority: WO
Inventors: Tyler Smithson
Original assignee: Safran Cabin Inc
Current assignee: Safran Cabin Inc
Priority date: 2023-07-20
Filing date: 2023-07-20
Publication date: 2025-01-23
Anticipated expiration: 2026-01-20

Abstract

A tie rod can include an elongated shaft, and one or more eyes, where continuous fibers extend from the shaft to the one or more eyes. The shaft can include a set of continuous fibers, made of a first material, extending continuously along a length of the elongated shaft, and a variable density infill disposed in at least a portion of the elongate shaft. The variable density infill formed of a second material, the variable density infill having a variable density at least along the length of the elongated shaft. An eye can extend from a first end portion of the elongated shaft and include a curved portion. One or more continuous fibers of the set of continuous fibers extend continuously along the curved portion of the eye.

Description

3D PRINTED TIE ROD

BACKGROUND

[0001] Tie rods are commonly used to couple two parts and is primarily subjected to tensile forces. These tie rods are used in various application including, but not limited to, automobiles, aircrafts, bridges, or systems subjected to tensile load. As an example, aircrafts can include several monuments such as overhead storage bins or other compartments for storing luggage, clothing and other passenger belongings. Monuments can also include sleeping quarters for the airline crew, work stations, lavatories, and galleys.

[0002] Tie rods are often used in systems for securing the monuments to the aircraft floor or from above. The tie rods and securement systems may need to be adjustable as aircraft are repurposed or reconfigured on occasion, and the monuments may be relocated. Hence, the tie rods are designed to withstand certain static and dynamic loads to securely position the monuments while in service and in flight.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Various embodiments in accordance with the present disclosure will be described with reference to the drawings, in which:

[0004] FIG. 1 is an example of an existing tie rod.

[0005] FIG. 2 (a) illustrate a top view of a first part of an adjustable length tie rod, (b) illustrates a cross-section of the first part of the adjustable length tie rod, (c) illustrates a second part of the adjustable length tie rod, (d) illustrates a cross-section of the second part of the adjustable length tie rod, according to various embodiments.

[0006] FIG. 3 (a) illustrate a plan view of the fixed length tie rod, (b) illustrates an elevation view of the fixed length tie rod, (c) illustrates a cross-section of the fixed length tie rod, according to various embodiments.

SUMMARY

[0007] According to some embodiments tie rods include structures that provide high tensile strength and light weight compared to existing tie rods. Specific embodiments relate to tie rods manufactured using additive manufacturing or three dimensionally (3D) printed. The tie rods herein can be substantially lighter and stronger compared to existing metal and composite shaft tie rods (e.g., typically used in aircraft, automotive or other applications). This provides substantial weight benefits in a number of applications (e.g., aircraft).

[0008] According to an aspect of the present disclosure, a tie rod includes an elongated shaft, and a first eye, wherein in fibers extend continuously along a geometric shape of the elongated shaft and as the eye. The elongated shaft has a first end portion and a second end portion opposite the first end portion. The elongated shaft includes a set of continuous fibers extending continuously along a length of the elongated shaft, and a variable density infill disposed in at least a portion of the elongate shaft. The set of continuous fibers being formed of a first material. The variable density infill formed of a second material. The variable density infill has a variable density at least along the length of the elongated shaft. The first eye extends from the first end portion of the elongated shaft and comprising a curved portion. One or more continuous fibers of the set of continuous fibers extend continuously along the curved portion of the first eye.

[0009] In some embodiments, the tie rod is an adjustable length tie rod. The adjustable length tie rod can include a shank comprising a threaded portion, and a second eye with a curved portion extending from an end opposite the threaded portion. The second end portion of the elongate shaft can be configured to receive the threaded portion of the shank along the length such that a total length of the tie rod is adjustable, the total length being a distance between the first eye and the second eye. The shank and the second eye can include a second set of continuous fibers extending continuously along a length of the shank and continuously along the curved portion of the first eye. The second set of continuous fibers can be formed of a first material. In some embodiments, the threaded portion can include a set of projections arranged in a staggered formation. The second set of continuous fibers can include one or more continuous fibers extending continuously through the set of projections. The second set of continuous fibers can be successively trimmed along a length of the threaded portion. The projections of the threaded portion of the shank can be radially spaced to facilitate a twist and turn engagement with the second end portion of the elongated shaft. The second end portion of the elongated shaft can include internal threads comparable with the projections of the threaded portion of the shank. The internal threads of the elongated shaft can have a first orientation and the projections have a second orientation when the shank is inserted in the second end portion of the elongated shaft and the internal threads are disengaged from the projections. Upon inserting the shank in the second end portion of the elongated shaft, the shank is twistable to engage the internal threads with the projections. The threaded portion of the shank can include a variable density infill made of the second material. The variable density infill can have a variable density along a length of the threaded portion. The elongated shaft can further include a set of discontinuous fibers formed in an empty space between the set of continuous set of fibers located at the first eye. The set of discontinuous fibers being laid in a circuitous path to enhance compressive strength in at least a portion of the elongated shaft.

[0010] In some embodiments, the tie rod is a fixed length tie rod. The fixed length tie rod can include the elongated shaft, the first eye at a first end, and a second eye located at a second end opposite the first end. The second eye can include a curved portion extending from the second end portion of the elongate shaft, where a fixed length of the tie rod is a distance between the first eye and the second eye. The one or more continuous fibers of the set of continuous fibers can extend continuously along the curved portion of the second eye. The one or more continuous fibers of the set of continuous fibers can form a closed loop extending from the first eye, along the length of the elongated shaft, to the second eye. The elongated shaft can further include a first set of discontinuous fibers formed in an empty space between the set of continuous set of fibers located at the first eye, and a second set of discontinuous fibers formed in an empty space between the set of continuous set of fibers located at the second eye. The first and the second set of discontinuous fibers can be laid in a circuitous path to enhance compressive strength in respective portions of the elongated shaft.

[0011] According to another aspect of the present disclosure, a method of manufacturing (e.g., three-dimension (3D) printing) of a tie rod is disclosed. The method includes receiving a set of instructions including a layout of a set of continuous fibers, and a variable density infill. The layout can include geometric information of the tie rod, the geometric information comprising a length of an elongated shaft and a shape of an eye of the tie rod. The method further includes configuring a first set of parameters of a 3D printer to print the set of continuous fibers such that the set of continuous fibers extend continuously along the length of the elongated shaft and the shape of the eye of the tie rod. The method can further include configuring a second set of parameters of the 3D printer to print the variable density infill subsequent to printing of the set of continuous fibers, the variable density infill having a variable density at least along the length of the elongated shaft. [0012] In some embodiments, the first set of parameters can include a first material, a geometry of the continuous fibers to form the tie rod. The second set of parameters can include a second material, and location information along a length of the tie rod. The geometric information of the tie rod can include specification (e.g., geometry, shape, size) of a set of internal threads of the elongated shaft. The configuring of the first set of parameters of the 3D printer can include printing the internal threads such that the set of continuous fibers are successively trimmed at the internal threads.

DETAILED DESCRIPTION

[0013] In the following description, various embodiments will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described.

[0014] Tie rods are slender structural elements typically designed to connect two parts and carry tensile load. These tie rods can be used in aircrafts in overhead bins, fuselage for mounting purposes, an upper monument attachment for retaining aircraft monuments, wings, or other locations and primarily subjected to tensile load. These tie rods are typically made of metal and composite material such as carbon composite, steel, aluminum, metal alloys, or other material. In an aircraft, hundreds of such tie rods may be used at various locations within the aircraft. This can add to the weight of the aircraft. Tie rods made of lighter metal alloys or carbon composites to reduce weight can be expensive and cost prohibitive.

[0015] FIG. 1 illustrates an example of existing tie rod 100. The tie rod 100 can include a shaft 110, and two eye bolts 120, 130. The eye bolts 120, 130 can be attached to the end portions of the shaft 110. In the illustrated embodiment, the eye bolts 120, 130 can be threadingly engaged with the shaft 110. For example, the shaft 110 can include internal thread configured to engage with external threads 122, 132 of the eye bolts 120, 130. The tie rod can have a length L defined as a distance between centers of the eye bolts 120, 130. The length L of the tie rod can be adjustable by varying an amount of insertion of one or both the eye bolts 120, 130 into the end portions of the shaft 110. The eye bolts 120, 130 can include bushings 124, 134. The shaft 110 can have a diameter DI and the eye bolts 120, 130 can have a diameter D2. As can be seen, the tie rod 100 is slender where the length L is substantially larger than the diameter DI and D2. The tie rod 100 is typically manufactured using known machining processes and made of metal or metal alloys.

[0016] The present disclosure provides significantly lighter tie rods with high tensile strength. For example, the present disclosure provides tie rods that can be three dimensional (3D) printed components based on stress analysis and force flow paths. The stress analysis can be performed on a 3D CAD model of a tie rod to determine 3D printing information including structural features of the tie rod. Based on the 3D printing information, a 3D printer can be configured to print the tie rod. For example, tie rods can be 3D printed to include continuous fibers extending along a shaft as well as around an eye of the tie rod. Additionally, one or more portions or gaps can be filled with variable density infill to provide some compression strength. Such tie rod with composite material can be light weight without being limited by manufacturing costs. On the contrary, existing tie rods and its manufacturing methods may not be able to manufacture such lightweight tie rod structures, or may be cost prohibitive.

[0017] The present disclosure provides 3D printed tie rods that can be lighter and structurally strong. For example, the tie rod herein can include continuous long fibers (e.g., made of glass, hemp, basalt or carbon or other 3D printing material configured to withstand tensile stress. Each fiber of the continuous long fibers can extend continuously along a straight line as well as along curved portions (e.g., at an eye) of the tie rod. Additionally, the tie rod can include variable density infill to provide additional structural support under compression and buckling. The variable density infill can be made of different material than the continuous long fibers. The present disclosure illustrates an adjustable length tie rod (discussed with respect to FIG. 2) and a fixed length tie rod (discussed with respect to FIG. 3). However, the present disclosure is not limited to the illustrated tie rods and other structural components subjected to tensile stresses that can be manufactured in a similar manner.

[0018] In many embodiments, the tie rods can include continuous long fiber in combination with short fiber infused polymers made by an additive manufacturing (e.g., 3D printing) process. From a strength of materials perspective, continuous long fibers can allow for high-strength tension (e.g., higher than the best alloy metals). Short fibers can provide much higher shear and compression than the polymer and/or polymer and long fiber combinations. Short fibers may also provide cross-linking between individual filament laydown lines and also between deposition layers.

[0019] From a manufacturing perspective, the continuous long fibers can be formed as flat layers (e.g., each layer being in a plane) parallel to a build plate which can be aligned in many cases with load resistors like a tie rod. Short fibers in a filament stiffen the material so that support structures are minimal, and relaxation is very low. Accordingly, precise and fast prints with little post-processing is possible. By optimizing the parameters available in additive manufacturing or 3D print systems, the tie rod can be both lighter (e.g., up to 75% weight reduction compared to existing tie rods) and less expensive. Furthermore, the proposed concepts herein enable custom manufacturing of components.

[0020] In many embodiments, a process of manufacturing 3D printed tie rods herein includes specific configuration of a 3D printer (e.g., Mark II printer). For example, a layout of the continuous fibers can be determined based on stress analysis of a tie rod, and force flow lines. Based on the layout of the continuous fibers, one or more printing parameters of a 3D printer can be determined. For example, one or more parameters can be print path and directions, a fiber thickness, a speed of printing, a print length, temperature, number of repetitions of the continuous fibers, density of infill and fiber placement, temperature and humidity of the storage environment and printing environment, Post-processing finishes, and support structure parameters.

[0021] FIG. 2 illustrates an example of an adjustable length tie rod 200. The tie rod 200 can include a first part 210 and a second part 230. In FIG. 2, (a) illustrate a top view of the first part 210 and (b) illustrates a cross-section of the first part 210. A top view of the second part 230 is illustrated in FIG. 2(c) and a cross-section of the second part 230 in FIG. 2 (c). As discussed herein each portion 210, 230 of the tie rod 200 can include continuous long fibers (e.g., 251 , 252) that extend along an entire length of a shaft portion on one side, curve around curved portions of an eye, and further extend along the shaft portion on the other side. The tie rod 200 structure and different fiber alignments are further discussed in detail below.

[0022] In many embodiments, the first part 210 of the tie rod 200 can include an elongated shaft 212 with a first end portion 213 and a second end portion 214 opposite the first end portion 213. The elongated shaft 212 can include a set of continuous fibers 251 extending continuously along a length L2 of the elongated shaft 212. The set of continuous fibers 251 can be manufactured by additive manufacturing, where layers of such continuous fibers 251 can be stacked on top of each other to form the tie rod herein. [0023] For example, in a first layer, a first continuous fiber of 251 can be laid at the periphery, a second continuous fiber 251 can be laid inwardly adjacent to or in contact with the first continuous fiber, the third fiber 251 can be laid inwardly adjacent to or in contact with the second fiber and so on. Similarly, a second layer can be formed and stacked on top of the first layer. This way, the continuous fiber 251 in each layer can extend along a y- direction and another set of similar continuous fibers can extend along a z-direction (e.g., out- of-the plane of the paper) to form the 3D structure. The present disclosure is not limited to a particular stacking direction and other variations are possible. For example, the fibers 251 can be stacked outwardly, vertically (in z-direction), or a combination thereof.

[0024] In many embodiments, a first eye 220 can extend from or formed within the first end portion 213 of the elongated shaft 212. In some embodiments, the first eye 220 can include a bushing to receive a hook or other attachments of joining components (not shown). The first eye 220 can include a curved portion 221. The one or more continuous fibers of the set of continuous fibers 251 can extend continuously along the curved portion 221 of the first eye 220. Accordingly, the one or more continuous fibers of the set of fibers 251 can be curved. Hence, tensile strength can be enhanced as the tensile stress can be shared by an entire length of the continuous fiber including the straight portion of the shaft 212, and the curved portion 221 of the eye 220.

[0025] In some embodiments, the second end portion 214 can include a threaded portion 214a including threads 216. The threads 216 can rectangular, square, helical, or other teeth shapes. In the illustrated embodiment, the threaded end portion 214a can include a hollow interior with the threads 216 formed on an inner surface. As illustrated, a cross section of the threads 216 show square teeth. The threads 216 (e.g., square teeth) can be spaced from each other along a length (e.g., x-direction). In the illustrated embodiment, in FIG. 2(b), the threads 216 may be formed on diametrically opposite ends of the hollow portion of the shaft 212. As illustrated, the threads 216 have a first orientation (e.g., 90°/270° with respect to a longitudinal axis i.e., along the length L2). In some embodiments, at least a portion of the second end portion 214 or the threaded portion 214a of the shaft 212 may be externally tapered. One or more of the continuous fibers 251 may be successively trimmed along a length of the threaded portion 214a. The present disclosure is not limited to the illustrated thread configuration, and other threads are possible. For example, the threads 216 may be continuous (e.g., helical shaped) or discrete projections/grooves (e.g., rectangular, square, triangular, etc.). [0026] In some embodiments, the shaft 212 can include a set of discontinuous fibers (e.g., not illustrated in FIG. 2(a), but similar to a reference character 263 in FIG. 2 (c) or a reference character 362 in FIG. 3(a)) formed in an empty space between the set of continuous set of fibers located at the first eye, the set of discontinuous fibers being laid in a circuitous path to enhance compressive strength in at least a portion of the elongated shaft.

[0027] In some embodiments, the elongated shaft 212 can include a variable density infill 261 disposed in at least a portion of the elongate shaft 212. The variable density infill 261 can be formed of a second material. The variable density infill 261 has a variable density at least along the length the elongated shaft 212. Additionally, the density may vary along a diameter D3. In some embodiments, the variable density infill 261 can be short fiber infused polymers. [0028] For example, as illustrated in FIG. 2(a), the variable density infill 261 structure can include a mesh like structure having a first set of short fibers in first orientation and a second set of fibers in a second orientation interlinking the first set of fibers. In some embodiments, the spacing between each of the short fibers can be varied to form a mesh structure of varying density. For example, a center portion of the elongated shaft 212 can include a dense mesh structure compared to other portions of the elongated shaft 212. In some embodiments, the elongated shaft portion 212 can have a uniform mesh structure, wirile a second part (e.g., 230) can have variable density infill (e.g., 262) with varying density (e.g., resulting from a tapering mesh structure) along a length, as illustrated in FIG. 2(c).

[0029] In many embodiments, the elongate shaft 212 can be adjustable coupled to the second part 230 of the adjustable length tie rod 200. The second part 230 can include a shank with a second eye. In the illustrated embodiment, a shank 231 can include a threaded portion 234, and a second eye 232. The second eye 232 can include a curved portion extending from an end opposite the threaded portion 234. A bushing 224 may be provided in the second eye 232. The second part 230 can have a length of L3. The length L3 in combination with the length L2 enables adjusting a total length of the tie rod 200. The total length being a distance between the first eye 220 and the second eye 232. For example, the total length can be a sum of L2 and a portion (e.g., 10%, 20%, 20%, 40%, etc. of the length L3) of the shank 231 projecting from the second end portion 214.

[0030] In many embodiments, the shank 231 and the second eye 232 can include a second set of continuous fibers 252 extending continuously along the length L3 of the shank and continuously along the curved portion of the second eye 232. The second set of continuous fibers 252 can be formed of the first material (e.g., same as the first set of fibers 251). The continuous fibers 252 can be formed in the same way as the first set of fibers 251 . In some embodiments, another set of continuous or discrete fibers 263 made of second material can be included to fill gaps between the long continuous fibers 252. The gaps may be caused due to geometric shape of the tie rod.

[0031] In many embodiments, the threaded portion 234 of the shank 231 can be received within the second end portion 214 of the elongate shaft 212 along the length such that a total length of the tie rod 200 is adjustable. The threaded portion 234 can include a set of projections 236 arranged in a staggered formation. In some embodiments, the projections 236 can be referred as teeth. In some embodiments, the projections 236 can be spaced from each other along the length L3, where at least some of projection 236 on one side can be offset from the projection 236 on an opposite side.

[0032] In many embodiments, the second part 230 can include the second set of continuous fibers 252, wherein one or more continuous fibers extending continuously through the set of projections 236. The second set of continuous fibers 252 can be successively trimmed along a length of the threaded portion 234. The threaded portion 214a of the shank 231 can include a variable density infill 262 made of the second material. The variable density infill 262 having a variable density along a length of the threaded portion.

[0033] In many embodiments, the projections 236 of the threaded portion 234 of the shank 231 can be radially spaced to facilitate a twist and turn engagement with the threaded portion 214a of the elongated shaft 212. The second end portion 214 of the elongated shaft 212 can include internal threads 216 compatible with the projections 236 of the threaded portion 234 of the shank 231.

[0034] During an assembling process of the shank 231 with the elongate shaft 212, the internal threads 216 of the elongated shaft 212 can be in a first orientation (e.g., 90° or 270° with respect to x-axis) and the projections 236 can be in a second orientation (e.g., 0° or 180° with respect to x-axis). When the shank 231 is inserted in the second end portion 214 of the elongated shaft 212 and the internal threads 216 are disengaged from the projections 236. By adjusting an amount of insertion of the shank 231 within the second end portion 214, the length of the tie rod 200 can be adjusted. Upon inserting the shank 231 in the second end portion 214 of the elongated shaft 212, the shank 231 is twistablc to engage the internal threads 216 with the projections 236 and lock the shank 231 with the elongated shaft 212. [0035] FIG. 3 illustrate (a) a plan view, (b) an elevation view, and (c) a cross-section of a fixed length tie rod 300, according to various embodiments. As discussed herein, a tie rod can include continuous long fibers that extend along an entire length of a shaft portion on one side, curve around curved portions of the eyes. The continuous long fiber can further extend along the shaft portion on the other side. In some embodiments, the continuous long fibers form a closed loop along the length of the tie rod. The closed loop extending from around a first eye to a shaft portion, around a second eye, and back to the first eye. These long continuous fibers significantly enhance a tensile load carrying capacity of the tie rod compared to existing tie rods. A tie rod 300 comprising such long continuous fibers and other structural enhancement features is further discussed in detail below.

[0036] In the illustrated embodiment, the tie rod 300 is a fixed length tie rod having a fixed length L4. The tie rod 300 can include an elongated shaft 310 and two eyes 320, 330 fixed to or integrally formed with the elongated shaft. Accordingly, the fixed length can be a distance between center of the two eyes 320, 330 or ends of the eyes 320, 330. The eyes 320 and 330 can include bushings 324 and 334, respectively.

[0020] The elongated shaft 310 can include a first end portion 301 and a second end portion 302 opposite the first end portion 301. The first eye 320 can extend from or formed as a part of the first end portion 301 . The second eye 330 can extend from or formed at the second end portion 302. Each of the first eye 320 and the second eye 330 can include a curved portion. The eyes 320, 330 can have substantially circular, elliptical, oval, or other shapes. Each eye can include a bushing (e.g., 324, 334).

[0037] As illustrated in FIG. 3(a) and (b), the tie rod 300 can include a set of continuous fibers 351 can extend continuously along the length of the elongated shaft 310, as well as around curved portions of the eyes 320, 330. The continuous fibers 351 can start at an end portion (e.g., 302), extend towards an opposite end (e.g., 301) along the shaft portion 310, curve around the eye 320, extend toward the second eye 330, and extend/curve back to the starting point in a continuous manner (e.g., without any breaks or discontinuous portions in the fibers). The continuous fibers 351 can be formed of a first material. In some embodiments, the continuous fibers 351 can include a fiber portion 363 made of a second material. As illustrated, the continuous long fibers 351 form a closed loop along the entire length L4 of the tie rod 300. The closed loop extending from around a first eye to a shaft portion, around a second eye, and back to the first eye. These long continuous fibers significantly enhance a tensile load carrying capacity of the tie rod compared to existing tie rods. In some embodiments, all or only a few of the continuous fibers 251 can extend continuously along both the first eye 320 and the second eye 330 including their curved portions.

[0038] Furthermore, the tie rod 300 can include a variable density infill (e.g., 361, 362) disposed in at least a portion of the elongate shaft 310. The variable density infill (e.g., 361, 362) can be formed of a second material. As discussed herein, the variable density infill (e.g., 361, 362) has a variable density at least along the length of the elongated shaft 310. The variable density infills can include a mesh structure with short fibers laid in inclined manner and interconnected to each other. The variable density infill 361, 362 can be similar to the variable density infill 261, 263 of the tie rod 200 discussed herein.

[0039] In some embodiments, the elongated shaft 310 can include different structural features to enchance compression strength and/or to lighten the weight of the tie rod 300. For example, as shown in FIG. 2 (b) and (c), the tie rod 300 can include hollow portions 312, 313 and/or a brace protion 314. The brace portion 314 can provide strutural support (e.g., against bending or buckling) to the elongated shaft 310. In some embodiments, the brace portion 314 can stiffen or support the hollow elongated shaft 310 or fixes another member in position. The brace portion 314 can serve as a connecting element that provides stability to the elongated shaft 310. The brace portion 314 can redistribute a load (e.g., tensile or compressive) to adjacent member (not shown). In many embodiments, the brace portion 314 can be include variable density infill made of a second material.

[0040] In some embodiments, the elongated shaft 310 can further include a first set of discontinuous fibers 362 formed in an empty space between the set of continuous set of fibers 251. In some embodiments, a discontinuous fiber (e.g., 363) can be a small portion extending from a continuous fiber (e.g., 351). For example, the discontinuous fiber 363 can extend only around the curved portion of the eye 330 and may be truncated before extending along the shaft 310. Empty spaces may arise due the geometric shape of different portions of the tie rod 300. For example, empty portions may be located at the first eye 320 and the second eye 330, and a second set of discontinuous fibers 362 can be formed in such empty space. In an illustrated example, the first and the second set of discontinuous fibers 362 can be laid in a circuitous path to enhance compressive strength in respective portions of the elongated shaft. The discontinuous set of fibers 362 can be made of the first material (e.g., of 351) or a second material (e.g., of variable density infill). Accordingly, tie rods can be made of composite materials with customized structures to enhance the strength and lighten a tie rod. Such advantages can be highly appreciated in applications such as aircrafts. [0041] FIG. 4 is a flow chart of an example method of manufacturing a tie rod using additive manufacturing. An example implementation can involve three-dimension (3D) printing of a tie rod, however other methods are possible. The method 400 can involve operations 401, 403, and 405. The operations herein can be used to manufacture components (e.g., tie rods 200, 300) of different geometric shapes and structures therein without limiting the method to a particular tie rod.

[0042] Operation 401 can involve receiving a set of instructions including a layout of a set of continuous fibers, and a variable density infill. The layout can include geometric information of the tie rod. The geometric information can be a length of an elongated shaft and a shape of an eye of the tie rod. For example, a layout of the set of continuous fibers 251, 351, shown in in FIGS. 2, 3, can be prepared based on stress analysis of tie rods under different loading conditions. Similarly, the variable density infill (e.g., 261, 262, 361, 362 in FIGS. 2, 3) and their locations in a tie rod can be prepared based on the stress analysis. The stress analysis can provide insights into a length, curvature, and other geometric information that are favorable under the loading conditions. Furthermore, depending on the material used for 3D printing or other additive manufacturing process, thickness and lengths of the continuous fibers can be determined to sustain the tensile stress exerted by the loading conditions of the stress analysis. In some embodiments, the stress analysis can be performed via simulations done using computer aided design (CAD) software implemented on a computer or via a cloud-based system.

[0043] Operation 403 can involve configuring a first set of parameters of a 3D printer to print the set of continuous fibers such that the set of continuous fibers extend continuously along the length of the elongated shaft and the shape of the eye of the tie rod. In some embodiments, the first set of parameters can include a first material, a geometry of the continuous fibers to form the tie rod.

[0044] In some embodiments, referring to FIG. 2, the geometric information of the tie rod (e.g., 200) can include a set of internal threads of the elongated shaft. Accordingly, the configuring of the first set of parameters of the 3D printer can include printing the internal threads (e.g., 216) such that the set of continuous fibers are successively trimmed at the internal threads. Similarly, geometric information related to a component (e.g., a second part 230 in FIG. 2(c)) can be configured to print external threads (e.g., 236), and the set of continuous fibers can be formed continuously within each tooth of the external thread (e.g., 236). [0045] Operation 405 can involve configuring a second set of parameters of the 3D printer to print the variable density infill subsequent to printing of the set of continuous fibers, the variable density infill having a variable density at least along the length of the elongated shaft. The second set of parameters can include a second material, and location information along a length of the tie rod. As an example, referring to FIGS. 2 and 3, the variable density infills (e.g., 261, 262, 361, 362) can be formed of discrete short length fibers interconnected to each other to form a mesh. The mesh structure can have a variable cross-section (e.g., along a length). The mesh structure can extend along the empty spaces, braces, or other hollow portions to improve compression strength of the tie rods.

[0046] The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the disclosure as set forth in the claims.

[0047] Other variations are within the spirit of the present disclosure. Thus, while the disclosed techniques are susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific form or forms disclosed, but on the contrary', the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the disclosure, as defined in the appended claims.

[0048] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the disclosed embodiments (especialty in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serv e as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any? and all examples, or exemplary? language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

[0049] Disjunctive language such as the phrase “at least one of X, Y, or Z,” unless specifically stated otherwise, is intended to be understood within the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present.

Claims

CLAIMS That which is claimed is:

1. A tie rod comprising: an elongated shaft having a first end portion and a second end portion opposite the first end portion, the elongated shaft comprising: a set of continuous fibers extending continuously along a length of the elongated shaft, the set of continuous fibers being formed of a first material; and a variable density infill disposed in at least a portion of the elongate shaft, the variable density infill formed of a second material, the variable density infill having a variable density at least along the length of the elongated shaft; and a first eye extending from the first end portion of the elongated shaft and comprising a curved portion, wherein one or more continuous fibers of the set of continuous fibers extend continuously along the curved portion of the first eye.

2. The tie rod of claim 1 , wherein the tie rod is an adjustable length tie rod, the adjustable length tie rod comprising: a shank comprising a threaded portion, and a second eye with a curved portion extending from an end opposite the threaded portion, wherein the second end portion of the elongate shaft is configured to receive the threaded portion of the shank along the length such that a total length of the tie rod is adjustable, the total length being a distance between the first eye and the second eye.

3. The tie rod of claim 2, the shank and the second eye comprise a second set of continuous fibers extending continuously along a length of the shank and continuously along the curved portion of the first eye, the second set of continuous fibers being formed of a first material

4. The tie rod of claim 3, wherein the threaded portion comprises a set of projections arranged in a staggered formation.

5. The tie rod of claim 4, wherein the second set of continuous fibers comprises one or more continuous fibers extending continuously through the set of projections.

6. The tie rod of claim 4, wherein the second set of continuous fibers are successively trimmed along a length of the threaded portion.

7. The tie rod of claim 4, wherein the projections of the threaded portion of the shank are radially spaced to facilitate a twist and turn engagement with the second end portion of the elongated shaft.

8. The tie rod of claim 7, wherein the second end portion of the elongated shaft comprises internal threads comparable with the projections of the threaded portion of the shank.

9. The tie rod of claim 8, wherein the internal threads of the elongated shaft have a first orientation and the projections have a second orientation when the shank is inserted in the second end portion of the elongated shaft and the internal threads are disengaged from the projections.

10. The tie rod of claim 9, wherein upon inserting the shank in the second end portion of the elongated shaft, the shank is twistable to engage the internal threads with the projections.

11. The tie rod of claim 2, wherein the threaded portion of the shank comprises a variable density infill made of the second material, the variable density infill having a variable density along a length of the threaded portion.

12. The tie rod of claim 1, wherein the elongated shaft further comprises a set of discontinuous fibers formed in an empty space between the set of continuous set of fibers located at the first eye, the set of discontinuous fibers being laid in a circuitous path to enhance compressive strength in at least a portion of the elongated shaft.

13. The tie rod of claim 1, wherein the tie rod is a fixed length tie rod, the fixed length tie rod comprising: a second eye with a curved portion extending from the second end portion of the elongate shaft, wherein a fixed length of the tie rod is a distance between the first eye and the second eye.

14. The tie rod of claim 13, wherein the one or more continuous fibers of the set of continuous fibers extend continuously along the curved portion of the second eye.

15. The tie rod of claim 14, wherein the one or more continuous fibers of the set of continuous fibers form a closed loop extending from the first eye, along the length of the elongated shaft, to the second eye.

16. The tie rod of claim 13, wherein the elongated shaft further comprises a first set of discontinuous fibers formed in an empty space between the set of continuous set of fibers located at the first eye, and a second set of discontinuous fibers formed in an empty space between the set of continuous set of fibers located at the second eye.

17. The tie rod of claim 16, wherein the first and the second set of discontinuous fibers are laid in a circuitous path to enhance compressive strength in respective portions of the elongated shaft.

18. A method of three-dimension (3D) printing of a tie rod, the method comprising: receiving a set of instructions comprising a layout of a set of continuous fibers, and a variable density infill, the layout comprising geometric information of the tie rod, the geometric information comprising a length of an elongated shaft and a shape of an eye of the tie rod; configuring a first set of parameters of a 3D printer to print the set of continuous fibers such that the set of continuous fibers extend continuously along the length of the elongated shaft and the shape of the eye of the tie rod; and configuring a second set of parameters of the 3D printer to print the variable density infill subsequent to printing of the set of continuous fibers, the variable density infill having a variable density at least along the length of the elongated shaft.

19. The method of claim 18, wherein the first set of parameters comprises a first material, a geometry of the continuous fibers to form the tie rod, and wherein the second set of parameters comprises a second material, and location information along a length of the tie rod.

20. The method of claim 18, wherein the geometric information of the tie rod comprises a set of internal threads of the elongated shaft, and wherein the configuring of the first set of parameters of the 3D printer comprises printing the internal threads such that the set of continuous fibers are successively trimmed at the internal threads.