FIELD

[0001] The present disclosure relates in general to wind turbine towers, and more particularly to methods for manufacturing wind turbine tower structures using materials having different cure rates.

BACKGROUND

[0002] Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

[0003] The wind turbine tower is generally constructed of steel tubes, pre- fabricated concrete sections, or combinations thereof. Further, the tubes and/or concrete sections are typically formed off-site, shipped on-site, and then arranged together to erect the tower. For example, one manufacturing method includes forming pre-cast concrete rings, shipping the rings to the site, arranging the rings atop one another, and then securing the rings together. As wind turbines continue to grow in size, however, conventional manufacturing methods are limited by transportation regulations that prohibit shipping of tower sections having a diameter greater than about 4 to 5 meters. Thus, certain tower manufacturing methods include forming a plurality of arc segments and securing the segments together on site to form the diameter of the tower, e.g. via bolting. Such methods, however, require extensive labor and can be time-consuming.

[0004] In view of the foregoing, the art is continually seeking improved methods for manufacturing wind turbine towers. Accordingly, the present disclosure is directed to methods for manufacturing wind turbine tower structures using materials having different cure rates. In particular, the present disclosure is directed to methods for manufacturing wind turbine tower structures that utilize multiple additive printing devices that deposit different materials having varying cure rates and strengths.

BRIEF DESCRIPTION

[0005] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0006] In one aspect, the present disclosure is directed to a method for manufacturing a tower structure of a wind turbine. The method includes additively printing at least a portion of a frame shape of the tower structure of the wind turbine from a first material on a foundation of the tower structure. The first material has a first cure rate. The method also includes allowing the portion of the frame shape of the tower structure to at least partially solidify. Further, the method includes providing a second material around and/or within the portion of the frame shape such that the portion of the frame shape provides support for the second material. The second material has a second cure rate, the second cure rate slower than the first cure rate. Moreover, the method includes allowing the second material to at least partially solidify so as to form the tower structure.

[0007] In one embodiment, providing the second material around and/or within the portion of the frame shape may include at least one of pouring the second material into one or more molds placed around and/or within the portion of the frame shape, spraying the second material around and/or within the portion of the frame shape, or additively printing the second material around and/or within the portion of the frame shape.

[0008] In one embodiment, the method may include forming one or more voids in the second material. In such embodiments, the method may include providing a third material at least partially within the one or more voids to form one or more reinforcement elements in the tower structure. For example, providing the third material at least partially within the one or more voids may include printing, pouring, and/or inserting the third material at least partially within the void(s). [0009] For example, in certain embodiments, the reinforcement element(s) may include, for example, one or more sensors, elongated cables or wires, helical cables or wires, reinforcing bars (hollow or solid), reinforcing fibers (metallic or polymeric), reinforcing metallic rings (circular, oval, spiral and others as may be relevant) or couplings, mesh, and/or any such elements as may be known in the art to reinforce cementitious structures. In further embodiments, additively printing the second material around and/or within the portion of the frame shape may include additively printing the first material with void(s) formed therein and printing the second material within the void(s).

[0010] In several embodiments, the method may include additively printing one or more heat exchange elements into at least one of the first material or the second material to control the curing process. For example, in such embodiments, the heat exchange element(s) may include one or more resistance heating wires and/or one or more cooling tubes configured to receive a coolant therethrough. In addition, the heat exchange element(s) may also include one or more protrusions for providing additional reinforcement to the tower structure.

[0011] In particular embodiments, the first, second, or third materials may include a cementitious material, a polymeric material, and/or a metallic material. In another embodiment, the method may include providing an adhesive material between one or more of the first material and the foundation, the first material and the second material, the second material and the third material, and/or multiple layers of the first, second, or third materials.

[0012] In yet another embodiment, the various materials may be printed using an additive printing device that includes a first printer head for printing the first material and a second printer head for printing the second material. In such embodiments, the additive printing device may further include, at least, a first robotic arm and a second robotic arm. As such, the first robotic arm may include the first printer head at a distal end thereof for dispensing the first material and the second robotic arm may include the second printer head at a distal end thereof for dispensing the second material.

[0013] In another aspect, the present disclosure is directed to a method for manufacturing a tower structure of a wind turbine. The method includes additively printing one or more walls of the tower structure of the wind turbine of a cementitious material on a foundation of the tower structure. The wall(s) have one or more voids formed therein. Further, the cementitious material has a first cure rate. The method also includes allowing the cementitious material to at least partially solidify. Further, the method includes additively printing an additional material within the one or more voids so as to reinforce the wall(s). The additional material has a second cure rate that is slower than the first cure rate. Moreover, the method includes allowing the additional material to at least partially solidify so as to form the tower structure.

[0014] In yet another aspect, the present disclosure is directed to a system for manufacturing a tower structure of a wind turbine. The system includes an additive printing device having a central frame structure and a plurality of robotic arms secured to the central frame structure. The robotic arms each include a plurality of printer heads. More specifically, the printer heads are configured for printing at least a portion of a frame shape of the tower structure of the wind turbine of a first material having a first cure rate on a foundation of the tower structure. Further, the printer heads are configured for printing a second material having a second cure rate around and/or within at least a portion of the first material such that the first material provides support for the second material. Moreover, the plurality of printer heads are configured for printing a third material having a third cure rate within one or more voids formed into the second material so as to reinforce the tower structure, the second cure rate being slower than the first cure rate, the third rate being slower than the first and second cure rates. Further, the system includes a controller for controlling the plurality of robotic arms of the additive printing device. It should be understood that the system may further include any of the additional features as described herein.

[0015] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0016] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the

specification, which makes reference to the appended figures, in which:

[0017] FIG. 1 illustrates a perspective view of one embodiment of a wind turbine according to the present disclosure;

[0018] FIG. 2 illustrates a partial, perspective view of one embodiment of a tower structure for a wind turbine manufactured with an additive printing device according to the present disclosure;

[0019] FIG. 3 illustrates a schematic diagram of one embodiment an additive printing device according to the present disclosure;

[0020] FIG. 4 illustrates a flow diagram of one embodiment of a method for manufacturing a tower structure of a wind turbine according to the present disclosure; and

[0021] FIG.5 illustrates a flow diagram of another embodiment of a method for manufacturing a tower structure of a wind turbine according to the present disclosure; and

[0022] FIG. 6 illustrates a block diagram of one embodiment of a controller of an additive printing device according to the present disclosure.

DETAILED DESCRIPTION

[0023] Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further

embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0024] Generally, the present disclosure is directed to methods for manufacturing tall structures (e.g. tall towers including wind turbine towers, homes, bridges, etc.) using automated deposition of cementitious materials via technologies such as additive manufacturing, 3-D Printing, spray deposition, extrusion additive

manufacturing, concrete printing, automated fiber deposition, as well as other techniques that utilize computer numeric control and multiple degrees of freedom to deposit material. More specifically, methods of the present disclosure include printing large concrete structures with sufficient strength to sustain structural and external loads during the printing process, and at a deposition rate that is cost- effective. In one embodiment, for example, methods of the present disclosure include using multiple printers to deposit different materials with combinations of cure rates and strengths to form a single tower structure.

[0025] More specifically, in certain embodiments, a fast-curing frame shape or skeleton of the tower structure can be printed with a relatively low-strength material, and a slower-curing (but stronger) primary material can be printed around it, using the already-cured frame shape for support during the curing process. In addition, the primary material may be printed to include one or more voids therein. As such, an additional, stronger material can printed and/or placed into the voids for providing even more strength to the tower structure. For example, the additional material may include spiral-wound cables/wires or similar to further reinforce the structure. In additional embodiments, internally-printed or placed wires or tubes can be used to control the curing process by introducing heating (via wire resistance) or cooling (coolant flowing through the tubes). The embedded reinforcements may also have protrusions (similar to barbed wire) to provide additional reinforcement capability. In still further embodiments, the tower structure may also be reinforced by a mesh through which the primary material is deposited, which essentially embeds the mesh into the overall tower structure. Additional supporting reinforcements can be printed or placed in regions of high stress, such as doors or other features. Multiple printers can also be used to simultaneously print a primary material and a curing agent, to enable the printed medium to be delivered in a more liquid form and enable the curing time to be controlled more precisely.

[0026] Thus, the methods described herein provide many advantages not present in the prior art. For example, methods of the present disclosure utilize materials having different cure rates and/or strengths to reduce the net printing time for the overall tower structure. In addition, methods of the present disclosure take advantage of the fast-curing capabilities of the first material and the strength properties of the second material. As such, the fast-curing capability and high strength property come from different materials. Thus, methods of the present disclosure enable faster tower printing, with a lower overall cost of construction.

[0027] Referring now to the drawings, FIG. 1 illustrates one embodiment of a wind turbine 10 according to the present disclosure. As shown, the wind turbine 10 includes a tower 12 extending from a foundation 15 or support surface with a nacelle 14 mounted atop the tower 12. A plurality of rotor blades 16 are mounted to a rotor hub 18, which is in turn connected to a main flange that turns a main rotor shaft. The wind turbine power generation and control components are housed within the nacelle 14. The view of FIG. 1 is provided for illustrative purposes only to place the present invention in an exemplary field of use. It should be appreciated that the invention is not limited to any particular type of wind turbine configuration. In addition, the present invention is not limited to use with wind turbine towers, but may be utilized in any application having concrete constructions and/or tall towers in addition to wind towers, including for example homes, bridges, tall towers and other aspects of the concrete industry. Further, the methods described herein may also apply to manufacturing any similar structure that benefits from the advantages described herein.

[0028] Referring now to FIG. 2, a partial, cross-sectional view of one embodiment of the tower structure 12 of the wind turbine 10 according to the present disclosure is illustrated. As shown, the tower structure 12 defines a circumferential tower wall 20 having an outer surface 22 and an inner surface 24. Further, as shown, the

circumferential tower wall 20 generally defines a hollow interior 26 that is commonly used to house various turbine components (e.g. a power converter, transformer, etc.). In addition, as will be described in more detail below, the tower structure 12 is formed, at least in part, using additive manufacturing. Moreover, as shown in the illustrated embodiment, the tower structure 12 may be formed, at least in part, of a frame shape 29 or skeleton formed of a first material 28 having a first cure rate (such as a first, fast-curing cementitious material), a second bulk material 30 having a second cure rate (such as a second, slower-curing cementitious material) that forms the majority of the tower wall 20, and a third material 31 having a third cure rate (such as a third, slowest curing metallic or polymeric material) that provides additional reinforcement to the tower structure 12. In such embodiments, the third cure rate is slower than the second cure rate, which is slower than the first cure rate. As such, the slower-curing second material 30 is configured to provide strong bonding and creates a reinforcement structure over time. In additional embodiments, an adhesive material 33 (e.g. FIG. 3) may also be provided between one or more of the first material 28 and the foundation, the first material 28 and the second material 30, the second material 30 and the third material 31, or multiple layers of the first, second, or third materials 28, 30, 31. Thus, the adhesive material 33 may further supplement interlayer bonding between materials.

[0029] In addition, it should be understood that the first, second, and third materials 28, 30, 31 may be any suitable cementitious material, polymeric material, metallic material, adhesive material, and/or combinations thereof. As used herein, the cementitious material described herein may include any suitable workable paste that is configured to bind together after curing to form a structure. As examples, a cementitious material may include lime or calcium silicate based hydraulically setting materials such as Portland cement, fly ash, blast furnace slag, pozzolan, limestone fines, gypsum, or silica fume, as well as combinations of these. In some

embodiments, the cementitious material 28 may additionally or alternatively include non-hydraulic setting material, such as slaked lime and/or other materials that harden through carbonation. Cementitious materials may be combined with fine aggregate (e.g., sand) to form mortar, or with rough aggregate (sand and gravel) to form concrete. A cementitious material may be provided in the form of a slurry, which may be formed by combining any one or more cementitious materials with water, as well as other known additives, including accelerators, retarders, extenders, weighting agents, dispersants, fluid-loss control agents, lost-circulation agents, strength- retrogression prevention agents, free-water/free-fluid control agents, expansion agents, plasticizers (e.g., superplasticizers such as polycarboxylate superplasticizer or polynaphthalene sulfonate superplasticizer), and so forth. The relative amounts of respective materials to be provided in a cementitious material may be varied in any manner to obtain a desired effect.

[0030] The adhesive material 33 described herein may include, for example, cementitious material such as mortar, polymeric materials, and/or admixtures of cementitious material and polymeric material. Adhesive formulations that include cementitious material are referred to herein as“cementitious mortar.” Cementitious mortar may include any cementitious material, which may be combined with fine aggregate. Cementitious mortar made using Portland cement and fine aggregate is sometimes referred to as“Portland cement mortar,” or“OPC”. Adhesive formulations that include an admixture of cementitious material and polymeric material are referred to herein as“polymeric mortar.” Any cementitious material may be included in an admixture with a polymeric material, and optionally, fine aggregate. Adhesive formulations that include a polymeric material are referred to herein as“polymeric adhesive.”

[0031] Exemplary polymeric materials that may be utilized in an adhesive formulation include may include any thermoplastic or thermosetting polymeric material, such as acrylic resins, polyepoxides, vinyl polymers (e.g., polyvinyl acetate (PVA), ethylene-vinyl acetate (EVA)), styrenes (e.g., styrene butadine), as well as copolymers or terpolymers thereof. Characteristics of exemplary polymeric materials are described in ASTM C1059 / C1059M-13, Standard Specification for Latex Agents for Bonding Fresh To Hardened Concrete.

[0032] In particular embodiments, the reinforcing third material 31 may form, for example, one or more sensors, elongated cables or wires, helical cables or wires, reinforcing bars (hollow or solid), reinforcing fibers (metallic or polymeric), reinforcing metallic rings (circular, oval, spiral and others as may be relevant) or couplings, mesh, and/or any such elements as may be known in the art to reinforce cementitious structures. For example, as shown in the illustrated embodiment, the slower-curing reinforcing third material 31 may form vertical components that are optionally interconnected via one or more reinforcing members 36. As such, the reinforced tower structure 12 is configured to withstand wind loads that can cause the tower 12 to be susceptible to cracking.

[0033] Referring now to FIGS. 3-4, the present disclosure is directed to methods for manufacturing wind turbine towers via additive manufacturing. Additive manufacturing, as used herein, is generally understood to encompass processes used to synthesize three-dimensional objects in which successive layers of material are formed under computer control to create the objects. As such, objects of almost any size and/or shape can be produced from digital model data. It should further be understood that the additive manufacturing methods of the present disclosure may encompass three degrees of freedom, as well as more than three degrees of freedom such that the printing techniques are not limited to printing stacked two-dimensional layers, but are also capable of printing curved and/or irregular shapes.

[0034] Referring particularly to FIG. 3, a schematic diagram of one embodiment of a system 32 for manufacturing the tower structure 12 of the wind turbine 10 at a wind turbine site is illustrated. As shown, the system 32 includes the additive printing device 34, such as a 3D printer. It should be understood that the additive printing device 34 described herein generally refers to any suitable additive printing device having one or more printer heads and/or nozzles for depositing multiple materials with varying cure rates onto a surface that is automatically controlled by a controller 76 to form an object programmed within the computer (such as a CAD file). More specifically, as mentioned, the multiple materials may include the first material 28 having a first cure rate, the second material 30 having a second cure rate, and the third material 31 having a third cure rate, wherein the third cure rate is slower than the second cure rate, which is slower than the first cure rate. Further, as shown in FIG. 3, each of the different materials may include separate fluid transfer systems 68, 70, 71.

[0035] More specifically, as shown, the additive printing device 34 includes a central frame structure 38 having a platform 40 and an arm member 42 extending generally perpendicular therefrom. Further, as shown, the arm member 42 extends generally parallel to a central, longitudinal axis 44 of the tower structure 12. In addition, as shown, the additive printing device 34 includes a plurality of robotic arms 46, 48 secured to the arm member 42 of the central frame structure 38. For example, as shown, the additive printing device 34 includes a first robotic arm 46 and a second robotic arm 48 secured to the arm member 42 of the central frame structure 38.

Moreover, as shown, the first and second robotic arms 46, 48 include first and second printer heads 50, 52 secured at distal ends thereof, respectively, for additively printing the multiple materials with varying cure rates as described herein. In addition, as shown, the robotic arms 46, 48 may be mounted to rotate around the arm member 42 of the central frame structure 38 during printing of the various materials to build up the tower structure 12.

[0036] More specifically, as shown, the first printer head 50 may be configured for printing the frame shape 29 of the tower structure 12 of the first material 28, e.g. on the foundation 15 of the wind turbine 10. For example, referring back to FIG. 2, the frame shape 29 may generally correspond to a base shape or skeleton of the tower structure 12. As such, the second printer head 52 may be configured for printing the second material 30 around and/or within at least a portion of the cured first material 28 to form the tower wall 20 such that the cured first material 28 provides support for the second material 30 during printing. In addition, the tower wall 20 may be formed to include one or more voids 57. In such embodiments, one or more of the printer heads 50, 52 may also be configured for printing the third material 31 within the one or more voids 57 formed into the tower wall 20 so as to further reinforce the tower structure 12.

[0037] Further, the additive printing device 34 may include at least one nozzle 54 or injector configured for dispensing the cementitious material 28. Moreover, as shown, the system 32 may include one or more optional molds 56 additively printed via the additive printing device 34, e.g. via a polymeric material. It should be understood that the molds 56 described herein may be solid, porous, and/or printed with openings to inject the cementitious material 28. Thus, as shown, the mold(s) 56 define inner and outer wall limits 58, 60 of the tower structure 12. Suitable polymeric materials may include, for example, a thermoset material, a thermoplastic material, a biodegradable polymer (such as a corn-based polymer system, fungal-like additive material, or an algae-based polymer system) that is configured to degrade/dissolve over time, or combinations thereof. As such, in one embodiment, the outer polymer mold may be biodegradable over time, whereas the inner polymer mold remains intact. In alternative embodiments, the outer and inner molds may be constructed of the same material.

[0038] In addition, the central frame structure 38 may be mounted between the cured mold(s) 56, or a central location of the tower 12. Thus, after the mold(s) 56 are printed and cured, the printer heads 50, 52 and/or the nozzle 54 of the additive printing device 34 are configured to dispense the cementitious material 28 into the mold(s) 56 within the inner and outer wall limits 58, 60. [0039] Referring still to FIG. 3, the platform 40 of the central frame structure 38 is movable in a vertical direction so as to move the central frame structure 38 (and therefore the plurality of robotic arms 46, 48) along the central, longitudinal axis 44 of the tower structure 12 during printing. Thus, the additive printing device 34 can be linearly translated in the vertical direction for building up the tower structure 12.

More specifically, as shown, the additive printing device 34 may include a linear translation mechanism 62 having one or more motorized wheels 64 and at least one linkage mechanism 66 to allow for changes in a diameter of the tower structure 12 as the additive printing device 34 moves along the longitudinal axis 44 to print multiple tower sections.

[0040] In addition, as mentioned, the system 32 for manufacturing the tower structure 12 of the wind turbine 10 may also include separate fluid transfer systems for each of the differing materials that can be printed via the additive printing device 34. For example, as shown, the system 32 may include a first fluid transfer system 68 for storing the first material 28, a second fluid transfer system 70 for storing the second material 30, a third fluid transfer system 71 for storing the third material 31, and so on (as well as any other materials used to manufacture the tower structure 12), the connections of which are not shown. However, it should be understood that each of the fluid transfer systems 68, 70, 71 may include, at a minimum, a pump and a storage tank for the respective liquid material that is configured to store and transfer the respective liquid medium to the additive printing device 34.

[0041] Referring particularly to FIG. 4, a flow diagram of one embodiment of a method 100 for manufacturing a tower structure of a wind turbine at a wind turbine site. In general, the method 100 will be described herein with reference to the wind turbine 10, tower structure 12, and system 32 shown in FIGS. 1-3. However, it should be appreciated that the disclosed method 100 may be implemented with tower structures having any other suitable configurations. In addition, although FIG. 4 depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

[0042] As shown at (102), the method 100 may include additively printing (e.g. via the additive printing device 34) the frame shape 29 of the tower structure 12 of the wind turbine 10 of the first material 28 on a foundation, e.g. the foundation 15 of the wind turbine 10. As shown at (104), the method 100 may include allowing the first material 28 to at least partially solidify or harden. As mentioned, the first material 28 may correspond to a fast-curing material; therefore, the required solidification time may be minimal.

[0043] Thus, as shown at (106), the method 100 may include providing (e.g. by additively printing via the additive printing device 34, spraying, or pouring) the second material 30 around and/or within at least a portion of the first material 28 such that the first material 28 provides support for the second material 30. As shown at (108), the method 100 includes allowing the second material 30 to at least partially solidify so as to form the tower structure 12.

[0044] As mentioned, the second material 30 may be a cementitious material having a second cure rate that is slower than the first cure rate. Thus, the second material 30 is also stronger than the first material 28. In addition, as shown in FIG. 2, the second material 30 of the tower structure 12 may be printed to include one or more voids 57. As such, the additive printing device 34 may also be configured to print the third material 31 within the voids 57 to form one or more reinforcement elements 36. As such, the reinforcement element(s) 36 may include, for example, one or more reinforcing sensors, elongated cables or wires, helical cables or wires, reinforcing bars (hollow or solid), reinforcing fibers (metallic or polymeric), reinforcing metallic rings (circular, oval, spiral and others as may be relevant) or couplings, mesh, and/or any such elements as may be known in the art to reinforce cementitious structures.

[0045] In several embodiments, the additive printing device 34 may also be configured to print the third material 31 to form one or more heat exchange elements 72, i.e. to further control the curing process. For example, in such embodiments, the heat exchange element(s) 72 may include one or more resistance heating wires and/or one or more cooling tubes configured to receive a coolant therethrough. More specifically, referring back to FIG. 2, the heat exchange elements 72 may correspond to resistance heating wires. In addition, the heat exchange element(s) 72 (and/or any of the reinforcement elements 36 described herein) may also include one or more protrusions 74 for providing additional reinforcement to the tower structure 12.

[0046] Referring now to FIG. 5, a flow diagram of another embodiment of a method 200 for manufacturing a tower structure of a wind turbine at a wind turbine site. In general, the method 200 will be described herein with reference to the wind turbine 10, tower structure 12, and system 32 shown in FIGS. 1-3. However, it should be appreciated that the disclosed method 200 may be implemented with tower structures having any other suitable configurations. In addition, although FIG. 5 depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

[0047] As shown at (202), the method 200 may include additively printing (e.g. via the additive printing device 34) one or more walls 20 of the tower structure 12 of the wind turbine 10 of a cementitious material on a foundation of the tower structure 12. Further, the wall(s) include one or more voids 57 formed therein. In addition, the cementitious material has a first cure rate. As shown at (204), the method 200 may include allowing the cementitious material to at least partially solidify or harden. As shown at (206), the method 200 may include additively printing (e.g. via the additive printing device 34) an additional material 31 within the one or more voids 57 so as to reinforce the wall(s) 20. The additional material 31 has a second cure rate that is slower than the first cure rate. Thus, as shown at (208), the method 200 may include allowing the second material to at least partially solidify within the one or more voids 57 so as to form the tower structure 12.

[0048] Referring now to FIG. 6, a block diagram of one embodiment of the controller 76 of the additive printing device 34 is illustrated. As shown, the controller 76 may include one or more processor(s) 78 and associated memory device(s) 80 configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and the like and storing relevant data as disclosed herein). Additionally, the controller 76 may also include a communications module 82 to facilitate communications between the controller 76 and the various components of the additive printing device 34. Further, the communications module 82 may include a sensor interface 84 (e.g., one or more analog-to-digital converters) to permit signals transmitted from one or more sensors (not shown) to be converted into signals that can be understood and processed by the processors 78. It should be appreciated that the sensors may be communicatively coupled to the communications module 82 using any suitable means.

[0049] As used herein, the term“processor” refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. The processor 78 is also configured to compute advanced control algorithms and communicate to a variety of Ethernet or serial -based protocols (Modbus, OPC, CAN, etc.). Additionally, the memory device(s) 80 may generally comprise memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) 80 may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) 78, configure the controller 76 to perform the various functions as described herein.

[0050] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.