# US 10,308,344 B2 · Disbond resistant composite stiffener runout > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,308,344 B2 - Document ID: US10308344B2 - Status: Granted - Kind: B2 - Application number: 15/592,996 - Filed: 2017-05-11 - Published: 2017-08-31 - Granted: 2019-06-04 - Earliest claimed: 2012-04-25 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Lyle R. Deobald; Kenneth L. Brook; Timothy D. Jackson; Kenneth J. Duffie; Gregory B. Doty - Web page: https://patentgrep.com/patent/US10308344B2 ## CPC - B64C 1/12: Construction or attachment of skin panels - B29C 70/302: {Details of the edges of fibre composites, e.g. edge finishing or means to avoid delamination} - B29D 99/0014: {provided with ridges or ribs, e.g. joined ribs} - B32B 3/263: {characterised by a layer having non-uniform thickness} - B32B 3/28: characterised by a layer comprising a deformed thin sheet {, i.e. the layer having its entire thickness deformed out of the plane}, e.g. corrugated, crumpled (B32B29/08 takes precedence) - B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)} - B32B 37/18: involving the assembly of discrete sheets or panels only - B32B 38/0004: {Cutting, tearing or severing, e.g. bursting; Cutter details (cutting in general B26D; laminating combined with punching or perforating B32B38/04; removing all or part of the layers B32B38/10; cutting in combination with laying up and registration B32B38/185 takes precedence)} - B64C 1/064: {Stringers; Longerons} - B64C 3/182: {Stringers, longerons} - B64C 3/20: Integral or sandwich constructions - B64C 3/26: Construction, shape, or attachment of separate skins, e.g. panels - B32B 2262/101: Glass fibres - B32B 2305/08: Reinforcements - B32B 2315/085: Glass fiber cloth or fabric - B32B 2605/18: Aircraft - B32B 2607/00: Walls, panels - B64C 2001/0072: {from composite materials} - Y02T 50/40: Weight reduction - Y10T 156/1062: Prior to assembly - Y10T 156/1064: Partial cutting [e.g., grooving or incising] - Y10T 428/24174: including sheet or component perpendicular to plane of web or sheet - Y10T 428/24182: Inward from edge of web or sheet - B64C: AEROPLANES; HELICOPTERS - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The disclosure herein provides for disbond resistant stringer runouts. Various aspects may be used independently or in combination to mitigate disbonding associated with the stiffener runout under operational loads. Aspects include a stiffener runout having rounded base flange corners. A recessed notch may be incorporated within the base flange to provide a flange termination point that is forward of the web termination point, allowing the web to terminate prior to the base flange. The web may be trimmed from a full height to a reduced height at the web termination point. The base flange may be co-bonded to the underlying composite structure via a scarf joint. Perimeter clamp radius fillers may be used to concentrate a clamping force around the perimeter of the base flange. ## Claims ### Claim 1 A method of controlling bondline separation between a composite stiffener and a composite structure, the method comprising: providing a composite stiffener comprising a web and a base flange, wherein the web terminates at a web termination point, wherein the base flange terminates at a flange termination point forward of the web termination point, and wherein the base flange comprises rounded corners; trimming the web from a full height at a location prior to a web termination point to a reduced height at the web termination point; providing a recessed notch within the base flange at the flange termination point such that the web termination point is positioned substantially at a center of the recessed notch; providing at least one perimeter clamp radius filler comprising a bottom surface configured to contact a top surface of the base flange around a portion of a perimeter of the top surface to create a contact area between the perimeter clamp radius filler and the portion of the perimeter of the top surface, and wherein the contact area defines a relief cavity between the perimeter clamp radius filler and the top surface; and bonding a bottom surface of the base flange to a top surface of the composite structure. ### Claim 2 (depends on 1) The method of claim 1, further comprising: securing the at least one perimeter clamp radius filler to the top surface of the base flange using a plurality of fasteners extending through a top surface of the perimeter clamp radius filler, through the relief cavity, through the base flange, and through the composite structure. ### Claim 3 (depends on 1) The method of claim 1, comprising forming the contact surface of the at least one perimeter clamp radius filler with a C-shape. ### Claim 4 (depends on 1) The method of claim 1, further comprising filling the relief cavity of the at least one perimeter clamp radius filler with a compliant filler material. ### Claim 5 (depends on 1) The method of claim 1, wherein the composite structure comprises a non-uniform thickness, and wherein the base flange comprises a non-uniform thickness corresponding to the non-uniform thickness of the composite structure such that bonding the bottom surface of the base flange to the top surface of the composite structure creates a scarf joint between the composite stiffener and the composite structure. ### Claim 6 (depends on 5) The method of claim 5, in which each of the base flange and the composite structure is formed of multiple plies of composite material, the method further comprising forming the non-uniform thickness of the base flange by reducing a number of plies of composite material in the base flange, and forming the non-uniform thickness of the composite structure by increasing a number of plies of composite material in the composite structure. ### Claim 7 (depends on 1) The method of claim 1, in which trimming the web from the full height to the reduced height comprises forming a leading edge of the web with a curved configuration. ### Claim 8 A method of controlling bondline separation between a composite stiffener and a composite structure, the method comprising: providing a composite stiffener comprising a web and a base flange, wherein the web terminates at a web termination point, wherein the base flange terminates at a flange termination point forward of the web termination point, and wherein the base flange comprises rounded corners; trimming the web from a full height at a location prior to a web termination point to a reduced height at the web termination point; providing a recessed notch within the base flange at the flange termination point such that the web termination point is positioned substantially at a center of the recessed notch; and providing a fiberglass wedge, wherein bonding the bottom surface of the base flange to the top surface of the composite structure comprises bonding a bottom surface of the fiberglass wedge to the top surface of the composite structure and bonding a top surface of the fiberglass wedge to the bottom surface of the base flange, wherein the base flange comprises a non-uniform thickness corresponding to a configuration of the fiberglass wedge. ### Claim 9 (depends on 8) The method of claim 8, in which the base flange is formed of multiple plies of composite material, the method further comprising forming the non-uniform thickness of the base flange by reducing a number of plies of composite material in the base flange. ### Claim 10 (depends on 8) The method of claim 8, further comprising providing at least one perimeter clamp radius filler comprising a bottom surface configured to contact a top surface of the base flange around a portion of a perimeter of the top surface to create a contact area between the perimeter clamp radius filler and the portion of the perimeter of the top surface, and wherein the contact area defines a relief cavity between the perimeter clamp radius filler and the top surface. ### Claim 11 (depends on 10) The method of claim 10, further comprising securing the at least one perimeter clamp radius filler to the top surface of the base flange using a plurality of fasteners extending through a top surface of the perimeter clamp radius filler, through the relief cavity, through the base flange, and through the composite structure. ### Claim 12 (depends on 10) The method of claim 10, comprising forming the contact surface of the at least one perimeter clamp radius filler with a C-shape. ### Claim 13 (depends on 10) The method of claim 10, further comprising filling the relief cavity of the at least one perimeter clamp radius filler with a compliant filler material. ### Claim 14 (depends on 8) The method of claim 8, wherein the composite structure comprises a non-uniform thickness, and wherein the base flange comprises a non-uniform thickness corresponding to the non-uniform thickness of the composite structure such that bonding the bottom surface of the base flange to the top surface of the composite structure creates a scarf joint between the composite stiffener and the composite structure. ### Claim 15 (depends on 14) The method of claim 14, in which each of the base flange and the composite structure is formed of multiple plies of composite material, the method further comprising forming the non-uniform thickness of the base flange by reducing a number of plies of composite material in the base flange, and forming the non-uniform thickness of the composite structure by increasing a number of plies of composite material in the composite structure. ### Claim 16 (depends on 8) The method of claim 8, in which trimming the web from the full height to the reduced height comprises forming a leading edge of the web with a curved configuration. ### Claim 17 A method of controlling bondline separation between a composite stiffener and a composite structure, the method comprising: providing a composite stiffener comprising a web and a base flange, wherein the web terminates at a web termination point and defines a web forward edge having a curved configuration, wherein the base flange terminates at a flange termination point forward of the web termination point, and wherein the base flange comprises rounded corners; trimming the web from a full height at a location prior to a web termination point to a reduced height at the web termination point; providing a recessed notch within the base flange at the flange termination point such that the web termination point is positioned substantially at a center of the recessed notch; providing at least one perimeter clamp radius filler comprising a bottom surface configured to contact a top surface of the base flange around a portion of a perimeter of the top surface to create a contact area between the perimeter clamp radius filler and the portion of the perimeter of the top surface, and wherein the contact area defines a relief cavity between the perimeter clamp radius filler and the top surface; and bonding a bottom surface of the base flange to a top surface of the composite structure. ### Claim 18 (depends on 17) The method of claim 17, further comprising: securing the at least one perimeter clamp radius filler to the top surface of the base flange using a plurality of fasteners extending through a top surface of the perimeter clamp radius filler, through the relief cavity, through the base flange, and through the composite structure. ### Claim 19 (depends on 17) The method of claim 17, further comprising providing a fiberglass wedge, wherein bonding the bottom surface of the base flange to the top surface of the composite structure comprises bonding a bottom surface of the fiberglass wedge to the top surface of the composite structure and bonding a top surface of the fiberglass wedge to the bottom surface of the base flange, wherein the base flange comprises a non-uniform thickness corresponding to a configuration of the fiberglass wedge. ### Claim 20 (depends on 17) The method of claim 17, comprising forming the contact surface of the at least one perimeter clamp radius filler with a C-shape.