Patent Publication Number: US-2019168898-A1

Title: Separation device assemblies

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from U.S. Provisional Patent Application No. 62/593,355, filed Dec. 1, 2017. The contents of the priority application are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     The subject matter disclosed herein generally relates to separation device assemblies and, more particularly, to modular frangible joint separation device assemblies. 
     Linear explosive frangible joints are used to explosively separate two components, such as that of a launch vehicle, satellite, or other type of space or air travel vehicle during flight or operation (e.g., to separate two vehicle stages or to separate a payload from a launch vehicle). For example, it is known to utilize a single, elongated, flexible continuous explosive cord that comprises, e.g., a mild detonating fuse (“MDF”) that explodes upon detonation. The explosive cord may be encased in a silicone rubber or other pliable material that is surrounded by a stainless steel tube. This arrangement may be applied to a portion or all of the periphery or circumference of a joint, connection point or location between two components that are desired to be explosively separated at that location at a predetermined time. The explosive cord is typically initiated at one or more ends of the cord and the cord causing the cord to explosively detonate along its length to separate the components. 
     However, due to the nature of the structural components that are joined (and then separated) by the frangible joints, each application is unique. For example, the frangible joints may include one or more flanges or other structures that are arranged to specifically attach to a portion of the structural component. Each application is different and thus each application may require a different arrangement of flanges or other attachment mechanisms. Accordingly, it may be desirable to improve frangible joints to be more versatile in application. 
     SUMMARY 
     According to some embodiments, separation device assemblies are provided. The assemblies include a plurality of first segment elements, each first segment element having an attachment portion and a frangible portion, the attachment portion of the first segment elements is arranged to fixedly connect to a first structural component and at least one second segment element having an attachment portion and a securing portion, wherein the attachment portion of the at least one second segment element is arranged to fixedly connect to a second structural component. At least two of the plurality of first segment elements are attached to the at least one second segment element adjacent to each other, wherein a first segment joint is formed between adjacent first segment elements. An expansion device cavity is formed between the attached first and second segment elements. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that each first segment element includes a fracture groove. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that the frangible portion of each first segment element comprises a first arm and a second arm. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include a gap located between adjacent first segment elements when attached to the at least one second segment element. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that the at least one second segment element has a length that is longer than a single first segment element. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include an expansion device located within the expansion device cavity, wherein expansion of the expansion device causes the frangible portions of the first segment elements to separate the separation device assembly. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that the at least one second segment element comprises a plurality of second segment elements. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that each second segment element is a same length as each first segment element. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that each second segment element is a length that is shorter than each first segment element. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that each first segment element comprises a plurality of fastener apertures and each second segment element comprises a plurality of fastener apertures, wherein when attaching the first segment elements to the second segment 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that a first segment joint is formed between adjacent first segment elements and a second segment joint is formed between adjacent second segment elements, and wherein when the first segment elements are attached to the second segment elements, the first segment joints do not align with the second segment joints. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that at least one of the first segment joints and the second segment joints includes a gap between the adjacent first segment elements or the adjacent second segment elements. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that the gap is a spacing that is at or below a predetermined or preset distance. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that both the first segment joints and the second segment joints include a gap between the adjacent first segment elements and the adjacent second segment elements. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that each first segment element is five feet in length or less and each second segment element five feet in length or less. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that each first segment element is five feet in length or less. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the separation device assembly may include that the second segment element is ten feet in length or longer. 
     According to some embodiments, separation devices and assemblies as shown and described herein are provided. 
     According to some embodiments, segments for forming separation devices and separation assemblies as shown and described herein are provided. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter is particularly pointed out and distinctly claimed at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view of a segmented separation structure in accordance with one embodiment of the present disclosure; 
         FIG. 2A  is a partial cross-sectional view of an example prior art separation device assembly; 
         FIG. 2B  is a view similar to that of  FIG. 2A  of the prior art separation device assembly after detonation; 
         FIG. 3  is a schematic illustration of a separation device assembly in accordance with an embodiment of the present disclosure; 
         FIG. 4  is a schematic illustration of a separation device assembly in accordance with an embodiment of the present disclosure; 
         FIG. 5  is a schematic illustration of a separation device assembly in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As shown and described herein, various features of the disclosure will be presented. Various embodiments may have the same or similar features and thus the same or similar features may be labeled with the same reference numeral, but preceded by a different first number indicating the figure to which the feature is shown. Although similar reference numbers may be used in a generic sense, various embodiments will be described and various features may include changes, alterations, modifications, etc. as will be appreciated by those of skill in the art, whether explicitly described or otherwise would be appreciated by those of skill in the art. 
       FIG. 1  schematically illustrates a segmented separation structure  101 , such as a frangible joint. The segmented separation structure  101 , having a plurality of segments  103 . The segments  103  are jointed or attached at seams  105 , with connections achieved as will be appreciated by those of skill in the art. An expansion device  107  is positioned within the segments  103 . The ends of the expansion device  107  are connected to a detonation manifold  109  that is in signal transfer communication with one or more of signal transfer lines  111  in a manner well known to those skilled in the art. 
     The signal transfer lines  111  are used to communicate an activation signal to the detonation manifold  109 . Activation of the detonation manifold  109  triggers expansion of the expansion device  107  within the segments  103 . As the expansion device  107  expands, the segments  103  will separate or split apart such that two ends of the segments will separate from each other. In one example, the segmented separation structure  101  can be mounted between and removably attach two structural components (e.g., portions of a launch vehicle). When the segments  103  are split apart, the two structural components can be separated. 
     Turning now to  FIGS. 2A-2B , a typical segment  221  of a separation device assembly is shown in cross section. The segment  221  may be a portion of a separation device assembly such as that shown in  FIG. 1 . As shown, an expansion device  223  is disposed within a frangible joint  225  which may be an aluminum member having a release portion comprising separation walls  227 ,  229 , which in part define an internal channel, cavity, or chamber for receiving the expansion device  223 . As shown, mounting flanges  231 ,  233  extend from the frangible joint  225  and are each arranged to attach to a portion of a respective structural component. For example, the mounting flanges  231 ,  233  can be designed to fixedly attach or connect two adjacent structural components, as will be appreciated by those of skill in the art. Thus, the mounting flanges  231 ,  233  may be customized to a specific application to properly connect to and join two structural components. That is, although shown as flat mounting flanges  231 ,  233  extending from the frangible joint  225 , those of skill in the art will appreciate that various geometries, shapes, sizes, etc. may be employed for the mounting flanges, which can be dictated by specific applications and/or requirements. In the arrangement of  FIG. 2A , illustrating pre-separation, the frangible joint  225  of the segment  221  can function like a butt plate between two structural components to be separated. 
     The expansion device  223  is positioned lengthwise in the channel formed in the frangible joint  225 . The separation walls  227 ,  229  each have fracture grooves  235 ,  237  that are designed to provide a clean fracture of the separation walls  227 ,  229  in response to expansion of the expansion device  223 . The expansion of the expansion device  223  is achieved by detonation of a charge  239 . As shown, the charge  239  includes a fuse  241  and an explosive  243 . Activation (detonation) of the charge  239  will cause the expansion device  223  to expand laterally outward to a substantially circular cross-sectional configuration as shown in  FIG. 2B . As the expansion device  223  expands it will apply force upon the separation walls  227 ,  229  along the length of the segment  221 . The force applied by the expanding expansion device  223  will cause the separation walls  227 ,  227  to break or fail at the fracture grooves  235 ,  237 , thus separating the two mounting flanges  231 ,  233  from each other at the location of the frangible joint  225 . That is, the mounting flanges  231 ,  233  and any associated structural components are separated upon detonation of the charge  239  and expansion of the expansion device  223 . 
     As shown in  FIGS. 2A-2B , the mounting flanges  231 ,  233  are integrally formed with the frangible joint  225  as a unitary body or structure, with the charge  239  located therein. As noted above, the shape, size, dimensions, etc. of the mounting flanges  231 ,  233  are customized to application specifications. Thus, each time a new arrangement of structural component to be separated is designed, a new and specifically customized separation device assembly must be designed and prepared. 
     Typical segments of prior art segmented separation structures and/or assemblies are formed from relatively long segments (e.g., on the order of ten feet or longer). The long segments are manufactured as such due to costs associated with manufacturing and machining constraints. For example, referring to  FIGS. 1 and 2A , each prior art segment  103  may be ten feet or longer in length and have a cross-sectional construction similar to the segment  221  shown in  FIG. 2A . In some cases these large prior art segments  103 , when combined together, can form separation structures having a desired length, and in some non-limiting embodiments a length that is greater than 20 feet. Such large or long segments thus require certain manufacturing capabilities, which results in increased manufacturing costs and slower production times. However, it may be advantageous to enable smaller scale manufacturing process through the manufacture of relatively short (or shorter) segments for separation assemblies. 
     Accordingly, embodiments provided herein are directed to separation device assemblies that enable short segments (“segment elements”) and ease of manufacture. Such segment elements, in accordance with some embodiments of the present disclosure, may be on the order of five feet or less, and thus may be half the length of typical segments (or even less). In accordance with embodiments of the present disclosure, each segment element can be manufactured to a required curvature as a stand-alone piece that is configured to join with one or more other segment elements (e.g., a non-unitary segment, as shown in  FIGS. 1 and 2A ). 
     The segment elements of the present disclosure can be fastened or joined together to form a full arc or ring frangible joint assembly (e.g., similar to the segmented separation structure  101  shown in  FIG. 1 ). In some embodiments, the segment elements are arranged such that a first segment element does not align with a second segment element, as least with respect to joints and/or adjacent first segments elements relative to adjacent second segment elements, as shown and described herein. 
     Turning now to  FIG. 3 , a schematic illustration of an embodiment of a separation device assembly  300  in accordance with the present disclosure is shown. The separation device assembly  300  is formed from a plurality of first segment elements  302  and a plurality of second segment elements  304 . The first segment elements  302  are joined, connected, or attached to the second segment element  304  by fasteners  306 . When joined together, the first segment elements  302  and the second segment elements  304  define a portion of the separation device assembly  300 , and, as shown, an expansion device cavity  308  is defined as a space between the first segment elements  302  and the second segment elements  304 . The expansion device cavity  308  is arranged to receive and contain an expansion device therein. The expansion device is designed to expand and separate at least a portion of the first segment elements  302  from the second segment elements  304  and thus enable separation of structural components attached to the respective first and second segment elements  302 ,  304 . 
     As shown, the first segment elements  302  include respective attachment portions  310  and frangible portions  312 . Similarly, the second segment elements  302  include respective attachment portions  314  and securing portions  316 . The attachment portions  310 ,  314  of the first and second segment elements  302 ,  304  are arranged to fixedly attach and/or mount to structural components, such as portions of launch vehicles, with the structural components designed to be attached to each other by the separation device assembly  300  until an expansion device is activated and then the structural components are separated as the separation device assembly  300  is activated/separated. 
     Each first segment element  302  is substantially the same as the other first segment elements  302 , thus, when positioned adjacent to each other, as shown in  FIG. 3 , a substantially uniform structure is formed. The frangible portions  312  of the first segment elements  302  are arranged to secure to the securing portions  316  of the second segment elements  304 . In the illustrative embodiment of  FIG. 3 , the frangible portions  312  of the first segment elements  302  have a clevis or forked shape. That is, the frangible portions  312  of the first segment elements  302  include a first arm  318   a  and a second arm  318   b.  The arms  318   a,    318   b  are separated by a distance to enable both an expansion device to fit therebetween and also to enable receiving and engaging with the securing portion  316  of the second segment elements  304 , as shown. 
     In operation, when an expansion device is active (within the expansion device cavity  308 , the expansion device will apply force to the arms  318   a,    318   b  to cause the separation device assembly  300  to break apart or separate, as will be appreciated by those of skill in the art. However, to retain the structural integrity of the separation device assembly  300  prior to activation of the expansion device, the first segment elements  302  and the second segment elements  304  are rigidly and fixedly connected such that they can hold two structural components together. To achieve such connection and rigidity, the fasteners  306  are spaced and number sufficiently to maintain such rigidity. In some embodiments, rather than employing fasteners, other types of connection mechanisms and/or means may be employed. For example, various types of fasteners, adhesives, interlock elements, etc. can be employed. Further, in some embodiments, welding, or other types of bonding between the first and second segment elements  302 ,  304  can be used. 
     As shown in  FIG. 3 , adjacent first segment elements  302  have a first segment joint  320  therebetween. Similarly, adjacent second segment elements  304  have a second segment joint  322  therebetween. When assembled to form the separation device assembly  300 , the first segment joints  320  are offset or not aligned with the second segment joints  322 . Such offset can aid in the structural integrity and rigidity of the separation device assembly  300  as a single unit or structure. In some embodiments, the first and/or second segment joints  320 ,  322  can be joined, such as by welding, although in other embodiments, no direct connection may be made between adjacent segment elements. 
     Turning now to  FIG. 4 , a side elevation view of a separation device assembly  400  in accordance with an embodiment of the present disclosure is shown. The separation device assembly  400  is similar to the separation device assembly  300  shown in  FIG. 3 , and includes multiple first and second segment elements  402 ,  404 . The first segment elements  402  of the separation device assembly  400  include attachment portions  410  and frangible portions  412 . Similarly, the second segment elements  404  include attachment portions  414  and securing portions  416 . The frangible portions  412  and the securing portions  416  of the first and second segment elements  402 ,  404 , respectively, are configured to be mated and connected, and also define an expansion device cavity, as shown and described with respect to  FIG. 3 . 
     The first segment elements  402  include arms  418  that extend from the attachment portions  410  and form a part of the frangible portions  412 . The arms  418  may be arranged in a forked or clevis manner (e.g., as shown in  FIG. 3 ). As shown, the arms  418  in the embodiment shown in  FIG. 4  extend below a fracture groove  424 . The fracture groove  424  is a groove or depression in the surface or material of the frangible portion  412  that aids in the fracturing or separation of the separation device assembly  400  when an expansion device expands within an expansion device cavity of the separation device assembly  400 . For example, the fracture grooves  424  can aid in the separation or breaking of the arms  418  from the first segment elements  402 . 
     As noted the first segment elements  402  are attachable to the second segment elements  404 . As shown, the frangible portions  412  of the first segment elements  402  include a plurality of fastener apertures  426 . Similarly, the securing portions  416  of the second segment elements  404  include a plurality of fastener apertures  428 . When the first segment portions  402  are fit to or arranged relative to the second segment portion  404  to form the separation device assembly  400 , the fastener apertures  426 ,  428  of the first and second segment elements  402 ,  404  align to allow for a fastener to pass therethrough and securely fasten the first segment elements  402  to the second segment elements  404 . 
     However, although the fastener apertures  426 ,  428  align when forming the separation device assembly  400 , in this illustrative embodiment, a set of fastener apertures  426  on a single first segment element  402  will align with fastener apertures  428  of two different but adjacent second segment elements  404 . Such arrangement allows for a rigid and/or solid separation device assembly  400  even though it is composed of a plurality of first and second segment elements  402 ,  404  which are relatively short. As shown, a first segment joint  420  does not align with a second segment joint  422 , and thus an offset or unaligned arrangement employed. 
     Also shown in  FIG. 4  is a gap defined between end walls of adjacent segment elements. The gap is present at the segment joints, and thus a first gap  430  exists between adjacent first segment elements  402  at the first segment joint  420  and a second gap  432  exists between adjacent second segment elements  404 . The gaps  430 ,  432  can be set to predetermined or preset distances to allow for various movement and/or expansion/contraction of the material of the segment elements  402 ,  404 . For example, the separation device assembly  400  may be used on a launch vehicle that is subject to extreme temperatures and/or vibrations and the gaps  430 ,  432  can prevent material or structural fatigue of the separation device assembly  400  during operation. 
     In the embodiments shown in  FIGS. 3-4 , the segment elements are substantially shorter than typical sections of segmented separation device assemblies. For example, a typical segment of a segmented separation device assembly may be about ten feet in length or longer. In contrast, segment elements of the present disclosure may be five in length or shorter. As noted above, an assembled separation structure can have a length greater than 20 feet. Thus, in prior systems, the typical segments may have comprised anywhere from 30-50% of the length of the entire assembled separation structure. In contrast, embodiments of the present disclosure are directed to segment elements that may each have a length of 25% or less of a total assembled length of the separation structure. The above described percentages and lengths are merely for example, and those of skill in the art will appreciated that embodiment of the present disclosure are not so limited. 
     In the above shown and described embodiments, the first and second segment elements are both of the shorter length. However, such arrangement is not required in accordance with embodiments of the present disclosure. For example, one of the first or second segment elements may be replaced by a unitary or substantially longer body, and a plurality of the other of the first or second segment elements may retain the shorter length. 
     For example, turning not to  FIG. 5 , another separation device assembly  500  in accordance with an embodiment of the present disclosure is shown. The separation device assembly  500  is similar to that shown and described above, and thus similar features will not be described again for brevity. In this embodiment, the separation device assembly  500  includes a plurality of first segment elements  502  that are attachable to a longer second segment element  534 . Also shown in  FIG. 5  is an example of an expansion device  536  that is located within an expansion device cavity formed between the first segment elements  502  and the second segment element  534 . In one embodiment, there is a gap between end walls of adjacent first segment elements  502 . In another embodiment, the end walls of adjacent first segment elements  502  are in contact or are coupled together. 
     In some embodiments, the first and second segment elements may be the same size, but are offset from each other. In other embodiments, the first and second segment elements can be of different lengths. For example, as shown and described above, in some embodiments, each of the first and second segment elements include fastener apertures that can align to permit fasteners to securely attach the first and second segment elements to form a separation device assembly (see, e.g.,  FIG. 4 ). In some embodiments, each first segment element can be of a length that includes six or more fastener apertures whereas the second segment elements can be of a length that includes five or fewer fastener apertures. Such arrangement can ensure sufficient overlap and/or offset to provide structural rigidity to the formed separation device assembly. 
     Advantageously, embodiments described herein provide segmented separation assemblies (e.g., frangible joint assemblies) that can be manufactured in high quantities, regardless of the specific application for joining (and then separating) structural components (e.g., components of spacecraft, launch vehicles, etc.). That is, separation assemblies in accordance with embodiments of the present disclosure can be manufactured to any desired length by joining a given number of segment elements. Embodiments of the present disclosure provide improved manufacturing and reduced costs due to much smaller and segmented construction, as compared to typical separation device assemblies. 
     Components of the present disclosure, e.g., the first and second segment elements of the separation device assemblies can be fabricated using various techniques. For example, machining, extruding, and/or additive manufacturing can be employed without departing from the scope of the present disclosure. 
     The use of the terms “a”, “an”, “the”, and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. 
     While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions, combinations, sub-combinations, or equivalent arrangements not heretofore described, but which are commensurate with the scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. 
     Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.