Fully-redundant frangible separation system

Abstract

A frangible joint for a structure is provided. The structure is provided having a first portion and a second portion with a feature defining a fracture plane disposed therebetween. A first housing is coupled to a first side of the first portion, the first housing having a first slot adjacent the first side and a first wall member adjacent the feature. A second housing is coupled to the second portion the first housing, the second housing having a second slot adjacent the second side and a second wall adjacent the feature opposite the first wall. A first expanding tube assembly is disposed within the first slot. The first expanding tube assembly having a first tube containing a first explosive core. A second expanding tube assembly is disposed within the second slot. The second expanding tube assembly having a second metallic tube containing a second explosive core.

1 . A frangible joint, comprising:
 a structure having a first portion and a second portion with a feature defining a fracture plane disposed therebetween;   a first housing coupled to a first side of the first portion, the first housing having a first slot adjacent the first side and a first wall member adjacent the feature;   a second housing coupled to the second portion on a second side opposite the first housing, the second housing having a second slot adjacent the second side and a second wall adjacent the feature opposite the first wall;   a first expanding tube assembly disposed within the first slot, the first expanding tube assembly having a first metallic tube containing a first explosive core disposed within a first elastomer member; and   a second expanding tube assembly disposed within the second slot, the second expanding tube assembly having a second metallic tube containing a second explosive core disposed within a second elastomer member.   
     
     
         2 . The frangible joint of  claim 1  further comprising:
 a third housing coupled to the second portion opposite the second housing, the third housing defining a first open space directly adjacent the second portion; and 
 a fourth housing coupled to the first position opposite the first housing, the fourth housing defining a second open space directly adjacent the first portion. 
 
     
     
         3 . The frangible joint of  claim 2  wherein the first housing is removably coupled to the third housing adjacent the feature, and the second housing is removably coupled to the fourth housing adjacent the feature. 
     
     
         4 . The frangible joint of  claim 3  wherein the first slot has a first open end adjacent the feature, and the second slot has a second open end adjacent the feature and opposite the first open end. 
     
     
         5 . The frangible joint of  claim 3  wherein the first housing is coupled to the third housing by a first keyway, and the second housing is coupled to the third housing by a second keyway. 
     
     
         6 . The frangible joint of  claim 1  wherein the first slot and the first expanding tube assembly are configured to fracture the structure along the fracture plane when the first explosive core is detonated. 
     
     
         7 . A frangible joint comprising:
 a structure having a first portion, an opposing second portion and a notch disposed between the first portion and the second portion, the structure having a first side and an opposing second side, the notch defining a fracture plane;   a first housing coupled to the first portion on the first side, the first housing having a first slot with a first wall on an end adjacent the notch, the first wall having an end in contact with the first side;   a second housing coupled to the second portion on the second side, the second housing having a second slot with a second wall on an end adjacent the notch, the second wall having an end in contact with the second side;   a first expanding tube assembly disposed within the first slot and having a first metallic tube containing a first explosive core disposed within a first elastomer member, the first expanding tube assembly configured to fracture the structure along the fracture plane in response to a detonation of the first explosive core; and   a second expanding tube assembly disposed within the second slot and having a second metallic tube containing a second explosive core disposed within a second elastomer member, the second expanding tube assembly configured to fracture the structure along the fracture plane in response to a detonation of the second explosive core.   
     
     
         8 . The frangible joint of  claim 7  further comprising:
 a third housing coupled to the second portion on the first side, the third housing defining a first open space on a side adjacent the structure and opposite the second expanding tube assembly, the third housing having an first end in contact with the first housing; and 
 a fourth housing coupled to the first portion on the second side, the fourth housing defining a second open space on a side adjacent the structure and opposite the first expanding tube assembly, the fourth housing having a second end in contact with the second housing. 
 
     
     
         9 . The frangible joint of  claim 8  wherein the first end and second end are substantially co-planar with the fracture plane. 
     
     
         10 . The frangible joint of  claim 8  wherein:
 the at least one notch includes a first V-shaped notch on the first side and a second V-shaped notch on the second side; 
 the first wall has an edge adjacent the first V-shaped notch; and 
 the second wall has an edge adjacent the second V-shaped notch. 
 
     
     
         11 . The frangible joint of  claim 10  wherein:
 the first V-shaped notch has an open side contiguous with the first open space; and 
 the second V-shaped notch has an open side contiguous with the second open space. 
 
     
     
         12 . The frangible joint of  claim 11  wherein:
 the first end includes a first keyway that removably couples the first housing and the third housing; and 
 the second end includes a second keyway that removably couples the second housing to the fourth housing. 
 
     
     
         13 . The frangible joint of  claim 12  wherein the first housing is coupled to the fourth housing and the first portion by a plurality of first fasteners. 
     
     
         14 . The frangible joint of  claim 13  wherein the second housing is found to the third housing and the second portion by a plurality of second fasteners. 
     
     
         15 . A method of separating portions of a structure, the method comprising:
 providing a structure having a first portion and an adjacent second portion with a notch disposed therebetween;   providing a first housing coupled to the first portion and having a first slot adjacent the first portion;   providing a second housing coupled to the second portion on a side of the structure opposite the first housing, the second housing having a second slot adjacent the second portion;   providing a first expanding tube assembly having a first metallic tube containing a first explosive core disposed within a first elastomeric member;   providing a second expanding tube assembly having a second metallic tube containing a second explosive core disposed within a second elastomeric member;   detonating the first explosive core to expand the first metallic tube; and   fracturing structure at the notch in response to the expansion of the first metallic tube.   
     
     
         16 . The method of  claim 15  further comprising detonating the second explosive core and expanding the second metallic tube when the first explosive cord does not activate. 
     
     
         17 . The method of  claim 16  wherein the first slot has a first wall adjacent the notch and the second slot has a second wall adjacent the notch. 
     
     
         18 . The method of  claim 17  further comprising providing a first open space on a side of the first portion opposite the first expanding tube assembly, the first open space having an end defined by the second wall. 
     
     
         19 . The method of  claim 18  further comprising deflecting a portion of the first portion into the first space when the first explosive core detonates. 
     
     
         20 . The method of  claim 19  further comprising:
 providing a second open space on a side of the second portion opposite the second expanding tube assembly, the second open space having an end defined by the first wall; and 
 deflecting a portion of the second portion into the second space when the second explosive core detonates.