Patent Publication Number: US-2021170714-A1

Title: Bonded joint with surface structures and methods of preparing and joining same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional patent application 62/943,345 filed Dec. 4, 2019, the entire contents of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The application relates generally to joints between components and, more particularly, to bonded joints. 
     BACKGROUND 
     Parts can be joined together by being bonded with adhesives. To improve the bond between the parts, the areas or regions of the parts that will be bonded together may be treated. For example, the regions may be sandblasted to roughen the regions and prepare them to receive the adhesive. It may also be necessary to control the adhesive that will be placed between the parts, so as to control its adhesive abilities, its thickness, or its flow between the two parts. This control may be performed by adding different media to the adhesive, such as glass beads, scrim cloth, veil, threads, wire, mesh, etc. Once added to the adhesive, these media are permanently made part of the joint when the adhesive cures. 
     Adding such media may introduce discontinuities, local defects or impurities into the adhesive and joint. Adding such media to the adhesive is labor-intensive, manual and not easily repeatable. 
     SUMMARY 
     There is disclosed a method of bonding components along a bond line, the bond line formed along a first surface of one of the components and a second surface on another one of the components facing the first surface, the method comprising: providing a surface structure on the first surface of the bond line, the surface structure having a plurality of surface protrusions arranged in a pattern and occupying an area of the first surface, each of the surface protrusions protruding outwardly from a first end at the first surface to a second end, a thickness of the surface protrusions defined between the first and second ends; applying an adhesive on one or both of the first and second surfaces along the bond line; joining the first and second surface surfaces together to bring the second ends of the surface protrusions in proximity to the second surface, the adhesive defining a thickness of the bond line being substantially equal to the thickness of the surface protrusions; and curing the adhesive between the joined first and second surfaces to bond the components along the bond line. 
     There is disclosed a method of preparing a surface of a component to be bonded with another surface of another component along a bond line, the method comprising: selecting a pattern of surface protrusions for the surface to define a thickness of the bond line; and providing the surface protrusions onto an area of the surface within the bond line. 
     There is disclosed a bonded part, comprising: a first component having a first surface facing toward a second surface of a second component; a cured adhesive between the first and second surfaces and defining a bond line, a thickness of the bond line defined between the first and second surfaces; a surface structure on the first surface within the bond line, the surface structure having a plurality of surface protrusions arranged in a pattern and occupying an area of the first surface, each of the surface protrusions protruding outwardly from a first end at the first surface to a second end adjacent to the second surface, a thickness of the surface protrusions defined between the first and second ends and being substantially equal to the thickness of the bond line; and the cured adhesive extending around the surface protrusions, the thickness of the bond line between the first and second surfaces being substantially constant along the bond line, and being greater than a thickness of the cured adhesive between the second ends of the protrusions and the second surface. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG. 1A  is a schematic cross-sectional view of a bonded joint, showing a bond line; 
         FIG. 1B  is an enlarged view of a surface structure within the bond line of  FIG. 1A ; 
         FIG. 10  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 1D  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 1E  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 1F  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 1G  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 2A  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 2B  is a cross-sectional view of the surface structure of  FIG. 2A ; 
         FIG. 3A  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 3B  is a cross-sectional view of the surface structure of  FIG. 3A ; 
         FIG. 4A  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 4B  is a cross-sectional view of the surface structure of  FIG. 4A ; 
         FIG. 5A  is an enlarged view of another surface structure within the bond line of  FIG. 1A ; 
         FIG. 5B  is a cross-sectional view of the surface structure of  FIG. 5A ; 
         FIG. 6A  is a schematic cross-sectional view of the bonded joint of  FIG. 1A , showing a configuration of the surface structure of the bonded joint; 
         FIG. 6B  is a schematic cross-sectional view of the bonded joint of  FIG. 1A , showing another configuration of the surface structure of the bonded joint; 
         FIG. 7A  is a schematic cross-sectional view of the bonded joint of  FIG. 1A , showing another configuration of the surface structure of the bonded joint; 
         FIG. 7B  is a schematic cross-sectional view of the bonded joint of  FIG. 1A , showing another configuration of the surface structure of the bonded joint; 
         FIG. 8A  is a schematic cross-sectional view of the bonded joint of  FIG. 1A , showing another configuration of the surface structure of the bonded joint; 
         FIG. 8B  is a schematic cross-sectional view of the bonded joint of  FIG. 1A , showing another configuration of the surface structure of the bonded joint; 
         FIG. 9  is a schematic cross-sectional view of the bonded joint of  FIG. 1A , showing another configuration of the surface structure of the bonded joint; 
         FIG. 10A  is a top view of a component having another surface structure; 
         FIG. 10B  is a cross-sectional view of the bonded joint of  FIG. 1A , including a cross-sectional view of the component of  FIG. 10A  taken along the line XB-XB; 
         FIG. 11A  is a top view of a component having another surface structure; 
         FIG. 11B  is a cross-sectional view of the bonded joint of  FIG. 1A , including a cross-sectional view of the component of  FIG. 11A  taken along the line XIB-XIB; 
         FIG. 12  is a cross-sectional view of the bonded joint of  FIG. 1A ; and 
         FIG. 13  is a schematic view of a tool used to form a surface structure of the bonded joint of  FIG. 1A . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  illustrates a part  9  formed between components  12 . The part  9  has a bonded joint  10  formed between the components  12 . The bonded joint  10  is a region or area of the components  12  along which they are joined to each other, such that the part  9  is a bonded part  9 . In  FIG. 1A , two components  12 , specifically a first component  14  and a second component  16 , are joined to each other along the bonded joint  10 . In alternate embodiments, more than two components  12  are joined together at the bonded joint  10 . For example, in one possible embodiment, three components  12  are joined together at the bonded joint  10 . In another possible embodiment, two components  12  are joined together at the bonded joint  10  to form an assembly, and the assembly is itself joined to one or more other components  12  at another bonded joint  10  to form a multi-component stacked assembly. One or more of the components  12  may be planar or have a curvature. It will therefore be appreciated that many configurations for the bonded joint  10  and resulting bonded part  9  are within the scope of the present disclosure, and that the configuration of the bonded part  9  is therefore not limited to that shown in  FIG. 1A . The components  12  may be any structure, or portions of structure, which are to be bonded together. 
     The bonded joint  10  includes mating surfaces of the components  12 . In  FIG. 1A , the first component  14  has a first surface  14 A facing a second surface  16 A of the second component  16 . The first and second surfaces  14 A, 16 A face each at least partially because the first and second components  14 , 16  are bonded together along part of the first and second surfaces  14 A, 16 A. The first and second surfaces  14 A, 16 A are spaced apart from each other, as described in greater detail below. In an alternate configuration, some or all of the first and second surfaces  14 A, 16 A abut directly. In  FIG. 1A , the bonded joint  10  includes only an area or portion  14 A′ of the first surface  14 A, and only an area or portion  16 A′ of the second surface  16 A. The portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A are those which mate with each other. The portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A are those along which the bonding of the first and second components  14 , 16  will occur. The portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A are less than an entirety of the first and second surfaces  14 A, 16 A in  FIG. 1A . In an alternate embodiment, the bonded joint  10  includes all of the first surface  14 A and all of the second surface  16 A. The use of “first” and “second” to describe the surfaces  14 A, 16 A does not limit the bonded joint  10  to being between only two surfaces. The bonded joint  10  requires a minimum of two surfaces bonded together, and may include more than two surfaces bonded together. In  FIG. 1A , the first and second components  14 , 16  are separate and distinct from one another, and thus define respective first and second surfaces  14 A, 16 A which are separate and distinct from each other before being bonded. In an alternate embodiment, the first and second surfaces  14 A, 16 A are portions of the same surface of the same component  12 , which are folded towards each other and bonded together. In such an embodiment, the components  12  are not separate from one another, and are instead portions of the same component  12 . 
     Referring to  FIG. 1A , the bonded part  9  includes an adhesive  11  forming part of the bonded joint  10 . The adhesive  11  extends between the first and second components  12 , 14  and joins them together along the portions  14 A′, 16 A′ of the first and second surfaces  14 A, 14 B. In  FIG. 1A , the adhesive  11  is shown in its dried or cured form, and it will be appreciated that it may applied while it is in a flowable or uncured form to wet the portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A. In  FIG. 1A , the adhesive  11  is a layer of resin. 
     The components  12  are joined together along a bond line  18 . The bond line  18  is part of the bonded joint  10 , and is a region of the first and second surfaces  14 A, 16 A along which the components  12  are joined together. The bond line  18  is defined by overlapping portions. Referring to  FIG. 1A , the bond line  18  extends over the area of the portion  14 A′ of the first surface  14 A that is overlapped by, or facing, the portion  16 A′ of the second surface  16 A, and vice versa. The bond line  18  refers to where the adhesive  11  contacts and engages the components  12 . The bond line  18  is partly defined by the extent of the cured adhesive  11 . The bond line  18  has a three-dimensional extent. The bond line  18  has a thickness T that is measured in a direction perpendicular to the first and second surfaces  14 A, 16 A. In  FIG. 1A , the thickness T of the bond line  18  is substantially equal to the thickness of part of the layer of cured adhesive  11 . The thickness of the adhesive  11  may vary, as described in greater detail below. The bond line  18  has a width W measured in a direction parallel to the first and second surfaces  14 A, 16 A, and to the dotted line shown in  FIG. 1A . The bond line  18  has a length L measured in a direction parallel to the first and second surfaces  14 A, 16 A, and perpendicular to the direction along which the width W is measured. 
     Referring to  FIG. 1B , the bonded part  9  includes a surface structure  20  on one or more of the mating surfaces  14 A, 16 A within the bond line  18 . The surface structure  20  is an arrangement of elements or features along only the surface of one or more of the components  12 . The surface structure  20  does not form part of the underlying geometry of the component  12 . The surface structure  20  is selected or designed in advance, and then applied to the surface to impact a property of the bond along the bond line  18 . The application of the surface structure  20  to the component  12  leaves unchanged the underlying geometry and properties of the component  12 . Thus, if the component  12  treated to receive the surface structure  20 , it will not result in a modification of the component  12  itself. The surface structure  20  is part of, or located within, the bond line  18 . The widthwise and lengthwise extent of the surface structure  20  thus overlaps, or is within, the widthwise and lengthwise extent of the bond line  18 . When the components  12  are bonded together, the surface structure  20  is covered with the adhesive  11 . 
     The surface structure  20  includes a plurality of structural surface features  22 . The structural surface features  22  are physical objects or formations along one or both of the mating surfaces of the bonded joint  10 , which are selected and applied to the mating surface in advance of forming the bond joint  10  to impact a property of the bond line  18 . Examples of some possible structural surface features  22  within the scope of the present disclosure are provided below. The structural surface features  22  are arranged in a pattern  23  to achieve the desired impact on the bond line  18 . The pattern  23  of the structural surface features  22  repeats over an area of the surface. The pattern  23  is a repeating design of the structural surface features  22  themselves and/or a repeating arrangement of the structural surface features  22 . The pattern  23  is planned and systemic. The pattern  23  is not random. The pattern  23  occupies some or all of the area of one or more of the mating surfaces  14 A, 16 A. For example, the pattern  23  may occupy some or all of the area of the portion  14 A′ of the first surface  14 A and/or some or all of the area of the portion  16 A′ of the second surface  16 A. In  FIG. 1A , the pattern  23  of the structural surface features  22  is applied to only those portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A which mate with each other, and which form the interface of the bonded joint  10 . In an alternate embodiment, the pattern  23  of the structural surface features  22  is applied to more of the first and second surfaces  14 A, 16 A. In an embodiment, the pattern  23  of the structural surface features  22  is applied to only those portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A which engage with the adhesive  11 . 
     The pattern  23  of the structural surface features  22  thus helps to create a special or unique surface design for one or more of the mating surfaces of the components  12 . The one or more of the mating surfaces  14 A, 16 A are thus “engineered” or designed to impact the bond between the components  12 , typically to improve a property of the bond line  18 . For example, and as will be described in greater detail below, the pattern  23  of the structural surface features  22  may be selected to improve one or more of the following properties of the bond line  18 , in any combination: the mechanical interlocking between the mated surfaces, the alignment of the mated surfaces, the flow of the adhesive  11  between the surfaces, the thickness T of the bond line  18 , and the wetting of the surfaces  14 A, 16 A. 
     The structural surface features  22  may be raised above or formed below the remainder of the mating surface. The pattern  23  may repeat throughout the entirety of the area of the mating surface or be present in only one portion. The shape of each structural surface feature  22  may vary and include one or more of the following possible shapes, in any combination: circular, cylindrical, square, diamond, hexagonal, etc. Thus, many patterns  23  of the structural surface features  22  are possible and within the scope of the present disclosure. Non-limiting examples of possible patterns  23  of the structural surface features  22  are described in greater detail below with reference to  FIGS. 1B to 1G . The size or scale of the structural surface features  22  in the pattern  23  may vary. For example, in one possible configuration, the structural surface features  22  are cylindrical or tubular protrusions extending from one or both of the mating surfaces  14 A, 16 A which have a diameter of about 75 thou (i.e., thousandths of an inch) and a length or height of about 5-10 thou. In such a configuration, the structural surface features  22  are spaced apart from each other by about 500 thou. The pattern  23  of the structural surface features  22  is visible to the naked eye in some embodiments. The structural surface features  22  may be in the range of the millimeter scale. 
     The pattern  23  shown in  FIG. 1B  is now described in greater detail. The pattern  23  of the surface structure  20  includes structural surface protrusions  22 A that are symmetric. In the area of the mating surface that is occupied by the pattern  23 , the surface protrusions  22 A are exactly the same around different lines which form different axes of symmetry. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A are arranged throughout the pattern  23  to have an orientation that is parallel to one or more both of the length L and width W of the bond line  18 . The surface protrusions  22 A repeat throughout the pattern  23 . One of the surface protrusions  22 A is repeated over the area of the mating surface to define the pattern  23 . The same surface protrusion  22 A is repeated and used throughout the area of the mating surface to define the pattern  23 . In  FIG. 1B , two or more of the surface protrusions  22 A are also repeated over the area of the mating surface  22  to define the pattern  23 . Thus, the pattern  23  may be defined by the repetition or replication of one surface protrusion  22 A, or by the repetition or replication of two or more surface protrusions  22 A. The surface protrusions  22 A include rectangular-shaped elements extending outwardly from the mating surface. The distal extremities of the rectangular-shaped elements are out of plane with the remainder of the mating surface. The distal extremities of the rectangular-shaped elements are raised relative to the remainder of the mating surface. 
     The pattern  23  shown in  FIG. 10  is now described in greater detail. The pattern  23  of the surface structure  20  includes structural surface features  22  that are symmetric. The structural surface features  22  are arranged in parallel within the pattern  23 . The structural surface features  22  repeat throughout the pattern  23 . In  FIG. 10 , the pattern  23  is defined by the repetition or replication of one structural surface feature  22 , or by the repetition or replication of two or more structural surface features  22 . The structural surface features  22  include circular depressions or indentations extending into the mating surface. The mating surface is raised relative to a bottom of the circular depressions. In an alternate embodiment, the structural surface features  22  include circular protrusions or mounds extending from the mating surface. The mating surface is flat and planar below a summit of the circular protrusions. 
     The pattern  23  shown in  FIG. 1D  is now described in greater detail. The pattern  23  of the surface structure  20  includes structural surface features  22  that are symmetric. The structural surface features  22  are arranged in parallel within the pattern  23 . The structural surface features  22  repeat throughout the pattern  23 . In  FIG. 1D , the pattern  23  may be defined by the repetition or replication of one structural surface feature  22 , or by the repetition or replication of two or more structural surface features  22 . The structural surface features  22  include pyramid-shaped elements, which extend outwardly from the mating surface to an apex of each pyramid-shaped element. The direction of extension from the mating surface of the pyramid-shaped elements is toward the other mating surface. The apex of the pyramid-shaped elements is spaced above, or apart, from the mating surface. 
     The pattern  23  shown in  FIG. 1E  is now described in greater detail. The pattern  23  of the surface structure  20  includes surface protrusions  22 A that are symmetric. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . In  FIG. 1E , the pattern  23  may be defined by the repetition or replication of one surface protrusion  22 A, or by the repetition or replication of two or more surface protrusions  22 A. The surface protrusions  22 A include rectangular-shaped elements, which extend outwardly from the mating surface to a plateau of each rectangular-shaped element. The direction of extension from the mating surface of the rectangular-shaped elements is toward the other mating surface. The plateau of the rectangular-shaped elements is spaced above, or apart, from the mating surface. Channels or grooves are defined between the raised rectangular-shaped elements. The channels have a height measured from the mating surface to the plateaus of the rectangular-shaped elements. 
     The pattern  23  shown in  FIG. 1F  is now described in greater detail. The structural surface features  22  are arranged in parallel within the pattern  23 . The structural surface features  22  repeat throughout the pattern  23 . In  FIG. 1F , the pattern  23  may be defined by the repetition or replication of one structural surface feature  22 , or by the repetition or replication of two or more structural surface features  22 . The structural surface features  22  include hexagonal-shaped elements, which extend outwardly from the mating surface. The direction of extension from the mating surface of the hexagonal-shaped elements is toward the other mating surface. The summit of the hexagonal-shaped elements is spaced above, or apart, from the mating surface. 
     The pattern  23  shown in  FIG. 1G  is now described in greater detail. The pattern  23  of the surface structure  20  includes surface protrusions  22 A that are symmetric. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . In  FIG. 1F , the pattern  23  may be defined by the repetition or replication of one surface protrusion  22 A, or by the repetition or replication of two or more surface protrusions  22 A. The surface protrusions  22 A include first rounded elements, which extend outwardly from the mating surface, and second rounded elements mounted on top of each of the first rounded elements and which also extend outwardly from the mating surface. The direction of extension from the mating surface of the first and second rounded elements is toward the other mating surface. The tops of the first and second rounded elements are spaced above, or apart, from the mating surface. Channels or grooves are defined between the raised first and second rounded elements. The channels have a height measured from the mating surface to the tops of the first and second rounded elements. 
     The pattern  23  shown in  FIGS. 2A and 2B  is now described in greater detail. The pattern  23  of the surface structure  20  includes structural surface protrusions  22 A that are symmetric. In the area of the mating surface that is occupied by the pattern  23 , the surface protrusions  22 A are exactly the same around different lines which form different axes of symmetry. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . One of the surface protrusions  22 A is repeated over the area of the mating surface to define the pattern  23 . The same surface protrusion  22 A is repeated and used throughout the area of the mating surface to define the pattern  23 . In  FIGS. 2A and 2B , two or more of the surface protrusions  22 A are also repeated over the area of the mating surface  22  to define the pattern  23 . Thus, the pattern  23  may be defined by the repetition or replication of one surface protrusion  22 A, or by the repetition or replication of two or more surface protrusions  22 A. 
     The surface protrusions  22 A are extensions from the mating surface  14 A, 16 A shown in  FIGS. 2A and 2B . Each surface protrusion  22 A extends from a first end  24 A that is at the mating surface  14 A, 16 A, to a distal second end  24 B that is spaced apart from the first end  24 A. In  FIGS. 2A and 2B , each surface protrusion  22 A is a solid or filled body. The second end  24 B of each surface protrusion  22 A is out of plane with the remainder of the mating surface  14 A, 16 A. The second ends  24 B are spaced from the remainder of the mating surface  14 A, 16 A. The second ends  24 B of the surface protrusions  22 A lie in the same plane spaced apart from a plane of the remainder of mating surface  14 A, 16 A around the surface protrusions  22 A. Referring to  FIGS. 2A and 2B , the surface protrusions  22 A include parallelogram-shaped elements extending outwardly from the mating surface  14 A, 16 A. A height or thickness TSP of each surface protrusion  22 A is measured from the first end  24 A to the second end  24 B. 
     The pattern  23  shown in  FIGS. 3A and 3B  is now described in greater detail. The surface protrusions  22 A repeat throughout the pattern  23 . In  FIGS. 3A and 3B , the pattern  23  may be defined by the repetition or replication of one surface protrusion  22 A, or by the repetition or replication of two or more surface protrusions  22 A. The surface protrusions  22 A include hexagonal or honeycomb shaped elements, which extend outwardly from the mating surface. In the cross-sectional view of  FIG. 3B , the projecting honeycomb elements have a trapezoidal cross-sectional shape. The direction of extension from the mating surface of the honeycomb-shaped elements is toward the other mating surface. The summit of the honeycomb-shaped elements is spaced above, or apart, from the mating surface. The honeycomb-shaped elements are hollow. 
     The pattern  23  shown in  FIGS. 4A and 4B  is now described in greater detail. The pattern  23  of the surface structure  20  includes surface protrusions  22 A that are symmetric. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . In  FIGS. 4A and 4B , the pattern  23  is defined by the repetition or replication of one surface protrusion  22 A, or by the repetition or replication of two or more surface protrusions  22 A. The surface protrusions  22 A include circular protrusions or dots extending from the mating surface. The mating surface is beneath the summit of the circular protrusions. The circular protrusions are full-bodied. The circular protrusions are not hollow. The circular protrusions may have a density in the pattern  23  of about 5 per square inch. 
     The pattern  23  shown in  FIGS. 5A and 5B  is now described in greater detail. The pattern  23  of the surface structure  20  includes surface protrusions  22 A that are symmetric. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . In  FIGS. 5A and 5B , the pattern  23  may be defined by the repetition or replication of one surface protrusion  22 A, or by the repetition or replication of two or more surface protrusions  22 A. The surface protrusions  22 A include truncated pyramidal-shaped elements, which extend outwardly from the mating surface to a plateau of each truncated pyramidal-shaped element. The direction of extension from the mating surface of the truncated pyramidal-shaped elements is toward the other mating surface. The plateau of the truncated pyramidal-shaped elements is spaced above, or apart, from the mating surface. Channels or grooves are defined between the raised truncated pyramidal-shaped elements. The channels have a height measured from the mating surface to the plateaus of the truncated pyramidal-shaped elements. The truncated pyramidal-shaped elements are full-bodied. The truncated pyramidal-shaped elements are not hollow. 
     Non-limiting examples of additional possible patterns  23  of the structural surface features  22 , as well as their anticipated impact on the bond or a property of the bond along the bond line  18 , are described in greater detail below. 
     The pattern  23  of the bond line  18  shown in  FIG. 6A  is now described in greater detail. The pattern  23  and the structural surface features  22  are “one-sided”, and is present on only the portion  16 A′ of the second surface  16 A of the second component  16 . The portion  14 A′ of the first surface  14 A of the first component  14  is free of a pattern  23 . The portion  14 A′ of the first surface  14 A of the first component  14  is flat. The structural surface features  22  of the pattern  23  in the portion  16 A′ of the second surface  16 A are surface protrusions  22 A extending outwardly from the first end  24 A at the second surface  16 A toward the second end  24 B near the first surface  14 A, and being separate from the first surface  14 A. The second ends  24 B of the surface protrusions  22 A are spaced apart from the first surface  14 A. The surface protrusions  22 A are spaced apart from one another along the width W of the bond line  18 . The surface protrusions  22 A are spaced apart from one another some or all of the length L of the bond line  18 . Channels are defined between the surface protrusions  22 A. The channels have a height measured from the portion  16 A′ of the second surface  16 A to the second ends  24 B of the surface protrusions  22 A. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . 
     Referring to  FIG. 6A , the structural surface protrusions  22 A are cylindrical or tubular protrusions extending from only the second surface  16 A. The diameter of the cylindrical surface protrusions  22 A may be about 75-100 thou, and may have a length or height of about 5-10 thou. The structural surface protrusions  22 A may be spaced apart from each other by about 500 thou. The pattern  23  of the surface protrusions  22 A is visible to the naked eye in  FIG. 6A . 
     In  FIG. 6A , the thicknesses TSP of the surface protrusions  22 A are substantially constant along the bond line  18 . It is meant by “substantially constant” that the thicknesses TSP of the surface protrusions  22 A do not vary, or vary slightly by an acceptable manufacturing deviation. The surface structure  20  in  FIG. 6A  thus has a fixed or constant height and repeated pattern, which may facilitate obtaining a constant thickness T for the bond line  18 . In an alternate configuration, the thicknesses TSP of the surface protrusions  22 A varies such that some surface protrusions  22 A are substantively thicker than others. The thicker surface protrusions  22 A in this configuration are positioned adjacent to, or in abutment with, the first surface  14 A, whereas the thinner or “shorter” surface protrusions  22 A are present to increase the adhesive surface area within the bond line  18 . 
     The pattern  23  of the structural surface features  22  shown in  FIG. 6A  is selected and applied to the portion  16 A′ of the second surface  16 A to help control the thickness T of the bond line  18 . The thickness TSP of each surface protrusion  22 A is substantially equal to the thickness T of the bond line  18 . It is meant by “substantially equal” that the thickness TSP of each surface protrusion  22 A is identical to the thickness T of the bond line  18  at the location of a given surface protrusion  22 A, or differs slightly from the thickness T of the bond line  18  by an acceptable manufacturing deviation. For example, and referring to  FIG. 6A , the second ends  24 B of one or more of the surface protrusions  22 A are spaced apart from the first surface  14 A a distance less than the thickness TSP of the surface protrusion  22 A. 
     The thickness T of the bond line  18  between the first and second surfaces  14 A, 16 A is substantially constant along the bond line  18 . It is meant by “substantially constant” that the thickness T of the bond line  18  does not change between the first and second surfaces  14 A, 16 A, or varies slightly by an acceptable manufacturing deviation. The cured adhesive  11  is present around the surface protrusions  22 A. The thickness of the cured adhesive  11  varies in  FIG. 6A . In the portions of the bond line  18  that are between the surface protrusions  22 A, the thickness of the cured adhesive  11  is substantially equal to the thickness T of the bond line  18 . In the portions of the bond line  18  that are between the surface protrusions  22 A, the thickness of the cured adhesive  11  is identical to the thickness TSP of the surface protrusions  22 A. In  FIG. 6A , where the second ends  24 B of the surface protrusions  22 A are spaced apart from the first surface  14 A, the thickness of the cured adhesive  11  is less than the thickness T of the bond line  18  in the regions of the bond line  18  that are between the second ends  24 B of the surface protrusions  22 A and the first surface  14 A. 
     As the first and second components  14 , 16  are brought together to be bonded, the first component  14  is prevented from being displaced past the surface protrusions  22 A because of their thickness TSP, thereby ensuring a minimum thickness T for the bond line  18 . Thus, in  FIG. 6A , the pattern  23  of the structural surface features  22  is selected to control or determine the thickness T of the bond line  18 , which may help to ensure optimal mechanical properties for the bonded joint  10 . The pattern  23  of surface protrusions  22 A in  FIG. 6A  allows for controlling the thickness T of the bond line  18  by modifying or adapting the surface geometry of only one of the surfaces of one of the components  14 , 16 . The pattern  23  of the structural surface features  22  in  FIG. 6A  also allows for controlling or determining the thickness T of the bond line  18  without having to use accessories or additives that are not structurally needed for the bonded part  9 , such as glass beads, scrim cloth, veil, threads, wire, mesh, etc. Thus, the pattern  23  of the structural surface features  22  in  FIG. 6A  may allow for replacing or eliminating conventional bond line fillers with a pattern  23  on the surface of one or more of the bonded components  14 , 16 . The pattern  23  of the structural surface features  22  in  FIG. 6A  may also allow for determining or maintaining a thickness T for the bond line  18  that remains constant throughout the bond line  18  because of the constant thickness TSP of the surface protrusions  22 A. Such a control of the thickness T of the bond line  18  may allow for controlling the flow of adhesive  11  between the components  14 , 16 . In an alternative configuration, in addition to the pattern  23  of the structural surface features  22 , the bond line  18  may have one or more fillers or media. 
     The pattern  23  of the bond line  18  shown in  FIG. 6B  is now described in greater detail. The pattern  23  and its structural surface features  22  are “two-sided”, and are present on both the portion  16 A′ of the second surface  16 A of the second component  16  and on the portion  14 A′ of the first surface  14 A of the first component  14 . The bond line  18  in  FIG. 6B  thus has a first pattern  23 A with first surface protrusions  22 A 1  on the first surface  14 A, and a second pattern  23 B with second surface protrusions  22 A 2  on the second surface  16 A. Both the first and second surface protrusions  22 A 1 , 22 A 2  extend outwardly from their respective surfaces  14 A, 16 A on one of the components  14 , 16  toward the other surface  14 A, 16 A of the other component  14 , 16 . The first and second surface protrusions  22 A 1 , 22 A 2  are spaced apart from one another on their respective surface  14 A, 16 A along the width W of the bond line  18 . The first and second surface protrusions  22 A 1 , 22 A 2  are spaced apart from one another on their respective surfaces  14 A, 16 A along some or all of the length L of the bond line  18 . Channels are defined between the first and second surface protrusions  22 A 1 , 22 A 2  on each surface  14 A, 16 A. The channels have a height measured from the portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A to the second ends  24 B of the first and second surface protrusions  22 A 1 , 22 A 2 . The first and second surface protrusions  22 A 1 , 22 A 2  are arranged in parallel within the first and second patterns  23 A, 23 B. The first and second surface protrusions  22 A 1 , 22 A 2  repeat throughout the first and second patterns  23 A, 23 B. In  FIG. 6B , the first and second patterns  23 A, 23 B of surface protrusions  22 A are the same. In an alternate configuration, the first and second patterns  23 A, 23 B of surface protrusions  22 A are different. The description of the surface protrusions  22 A, their thicknesses TSP, the thickness T of the bond line  18 , and the thickness of the cured adhesive  11  provided above in reference to  FIG. 6A  applies mutatis mutandis to those same features shown in  FIG. 6B . 
     Referring to  FIG. 6B , the second ends  24 B of the first and second surface protrusions  22 A 1 , 22 A 2  face each other and are in close proximity. The first and second surface protrusions  22 A 1 , 22 A 2  are aligned along a direction that is parallel to the thickness T of the bond line  18 . In  FIG. 6B , the first and second surface protrusions  22 A 1 , 22 A 2  are aligned such that there is no nesting between the first and second components  14 , 16 . The second ends  24 B of the first and second surface protrusions  22 A 1 , 22 A 2  are spaced apart from each to define a gap between the aligned second ends  24 B. The size of the gap is small in comparison to the thickness T of the bond line  18 . For example, the second ends  24 B are spaced apart from each other a distance less than the thicknesses TSP of the first and second surface protrusions  22 A 1 , 22 A 2 . In  FIG. 6B , the thicknesses TSP of the first surface protrusions  22 A 1  is the same as the thicknesses TSP of the second surface protrusions  22 A 2 . In an alternate configuration, the thicknesses TSP of the first and second surface protrusions  22 A 1 , 22 A 2  are different. In an alternate configuration, the gap between the aligned second ends  24 B is zero, such that the second ends  24 B of the first and second surface protrusions  22 A 1 , 22 A 2  are in abutting contact. In an alternate configuration, the first and second surface protrusions  22 A 1 , 22 A 2  are misaligned and the thickness TSP of the second surface protrusions  22 A 2  is greater than the thickness of the first surface protrusion  22 A 1 , such that the thicker second surface protrusions  22 A 2  help define the thickness T of the bond line  18  and the thinner or shorter first surface protrusions  22 A 1  are present to increase the adhesive surface area within the bond line  18 . 
     Referring to  FIG. 6B , the thickness T of the bond line  18  is substantially equal to the combined thickness TSPC of the first and second surface protrusions  22 A 1 , 22 A 2 . It is meant by “substantially equal” that the combined thickness TSPC of the first and second surface protrusions  22 A 1 , 22 A 2  is identical to the thickness T of the bond line  18  at the location of an aligned pair of the first and second surface protrusions  22 A 1 , 22 A 2 , or differs slightly from the thickness T of the bond line  18  by an acceptable manufacturing deviation. The thickness T of the bond line  18  may thus be defined by surface structure  22  on each of the first and second components  14 , 16  forming the bonded part  9 . 
     As the first and second components  14 , 16  are brought together to be bonded in  FIG. 6B , the first component  14  is prevented from being displaced past the second surface protrusions  22 A 2  of the second component  16  because of their thickness TSP, and the second component  16  is prevented from being displaced past the first surface protrusions  22 A 1  of the first component  14  because of their thickness TSP, thereby ensuring a minimum thickness T for the bond line  18 . Thus, in  FIG. 6B , the pattern  23  of the structural surface features  22  is selected to control or determine the thickness T of the bond line  18 , which may help to ensure optimal mechanical properties for the bonded joint  10 . The pattern  23  of first and second surface protrusions  22 A 1 , 22 A 2  in  FIG. 6B  allows for controlling the thickness T of the bond line  18  by modifying or adapting the surface geometry of both surfaces  14 A, 16 A of both components  14 , 16 . The first and second patterns  23 A, 23 B of structural surface features  22  in  FIG. 6B  also allows for controlling or determining the thickness T of the bond line  18  without having to use accessories or additives that are not structurally needed for the bonded part  9 , such as glass beads, scrim cloth, veil, threads, wire, mesh, etc. Thus, the first and second patterns  23 A, 23 B of the structural surface features  22  in  FIG. 6B  may allow for replacing or eliminating conventional bond line fillers with patterns  23 A, 23 B on both surfaces  14 A, 16 A of the bonded components  14 , 16 . The first and second patterns  23 A, 23 B of the structural surface features  22  in  FIG. 6B  may also allow for determining or maintaining a thickness T for the bond line  18  that remains constant throughout the bond line  18  because of the combined constant thickness TSPC of the first and second surface protrusions  22 A 1 , 22 A 2 . Such a control of the thickness T of the bond line  18  may allow for controlling the flow of adhesive  11  between the components  14 , 16 . 
     The pattern  23  of the bond line  18  shown in  FIG. 7A  is now described in greater detail. The pattern  23  is “one-sided”, and is present on only the portion  16 A′ of the second surface  16 A of the second component  16 . The portion  14 A′ of the first surface  14 A of the first component  14  is free of a pattern  23 . The structural surface features  22  of the pattern  23  in the portion  16 A′ of the second surface  16 A are grooves extending inwardly into the second surface  16 A. The grooves are spaced apart from one another along the width W of the bond line  18 . The grooves extend along some or all of the length L of the bond line  18 . The grooves are arranged in parallel within the pattern  23 . The grooves repeat throughout the pattern  23 . The pattern  23  of the structural surface features  22  shown in  FIG. 7A  is selected and applied to the portion  16 A′ of the second surface  16 A to help control the flow of the adhesive  11  through the bond line  18 . As the first and second components  14 , 16  are brought together to be bonded, the adhesive  11  is squeezed and displaced through the bond line  18 . The pattern  23  shown in  FIG. 7A  is selected to increase the rate of flow of the adhesive  11 . This may allow for using an adhesive  11  that has a high viscosity in the bond joint  10 , which is typically avoided because of the difficulty in applying such a high-viscosity adhesive  11 . This may also allow for avoiding the use of a low-viscosity adhesive  11 , which is typically used because of the ease by which it can be applied, but which creates overflow issues. 
     The pattern  23  of the bond line  18  shown in  FIG. 7B  is now described in greater detail. The pattern  23  is “two-sided”, and is present on both the portion  16 A′ of the second surface  16 A of the second component  16  and on the portion  14 A′ of the first surface  14 A of the first component  14 . The structural surface features  22  of the pattern  23  are grooves extending inwardly into the second surface  16 A, and inwardly into the first surface  14 A. The grooves are spaced apart from one another along the width W of the bond line  18 . The grooves extend along some or all of the length L of the bond line  18 . The grooves are arranged in parallel within the pattern  23 . The grooves repeat throughout the pattern  23 . The pattern  23  of the structural surface features  22  shown in  FIG. 7B  is selected to help control the flow of the adhesive  11  through the bond line  18 . As the first and second components  14 , 16  are brought together to be bonded, the adhesive  11  is squeezed and displaced through the bond line  18 . The pattern  23  shown in  FIG. 7B  is selected to decrease the rate of flow the adhesive  11 . The deep and wide grooves of the pattern  23  help to prevent the adhesive  11  from flowing out of the bond line  18 . This may help to improve adhesion. Limiting the flow of the adhesive  11  using this surface pattern  23  may help to reduce squeeze-out, which impacts the quantity of adhesive  11  required and the operations to clean the excess adhesive  11  or remove the cured adhesive  11  after squeeze-out. 
     The pattern  23  of the bond line  18  shown in  FIG. 8A  is now described in greater detail. The pattern  23  is “two-sided”, and is present on both the portion  16 A′ of the second surface  16 A of the second component  16  and on the portion  14 A′ of the first surface  14 A of the first component  14 . The structural surface features  22  of the pattern  23  include first protrusions extending outwardly from the second surface  16 A toward the first surface  14 A, and first grooves extending inwardly into the second surface  16 A. The structural surface features  22  of the pattern  23  also include second protrusions extending outwardly from the first surface  14 A toward the second surface  16 A, and second grooves extending inwardly into the first surface  14 A. The protrusions and grooves are spaced apart from one another along the width W of the bond line  18 . The protrusions and grooves extend along some or all of the length L of the bond line  18 . The protrusions and grooves are arranged in parallel within the pattern  23 . The protrusions and grooves repeat throughout the pattern  23 . The first protrusions are aligned with the second grooves, and the second protrusions are aligned with the first grooves. The first protrusions are offset along a direction of the width W from the second protrusions, and the first grooves are offset along a direction of the width W from the second grooves. The pattern  23  of the structural surface features  22  shown in  FIG. 8A  is selected and applied to the portions  14 A′, 16 A′ to help with interlocking of the portions  14 A′, 16 A′ and alignment along the bond line  18 . As the first and second components  14 , 16  are brought together to be bonded, the first protrusions are moved into the second grooves and the second protrusions are moved into the first grooves. This mechanical interlocking of the first and second components  14 , 16  may improve their resistance to separation due to the shear forces, and may improve the alignment of the bonded joint  10 . This mechanical interlocking of the first and second components  14 , 16  may also reinforce the bonded joint  10  against compressive forces, or tensile forces. Thus, in  FIG. 8A , the surface pattern  23  may increase mechanical adhesion due to the structural surface features  22  increasing mechanical interlocking in the bonded joint  10 . 
     The pattern  23  of the bond line  18  shown in  FIG. 8B  is now described in greater detail. The pattern  23  is “two-sided”, and is present on both the portion  16 A′ of the second surface  16 A of the second component  16  and on the portion  14 A′ of the first surface  14 A of the first component  14 . The structural surface features  22  of the pattern  23  include protrusions extending outwardly from the first surface  14 A toward the second surface  16 A, and grooves extending inwardly into the second surface  16 A. The protrusions and grooves are spaced apart from one another along the width W of the bond line  18 . The protrusions and grooves extend along some or all of the length L of the bond line  18 . The protrusions and grooves are arranged in parallel within the pattern  23 . The protrusions and grooves repeat throughout the pattern  23 . The protrusions are aligned with the grooves. The pattern  23  of the structural surface features  22  shown in  FIG. 8B  is selected and applied to the portions  14 A′, 16 A′ to help with interlocking of the portions  14 A′, 16 A′ and alignment along the bond line  18 . As the first and second components  14 , 16  are brought together to be bonded, the protrusions are moved into the grooves. This mechanical interlocking of the first and second components  14 , 16  may improve their resistance to separation due to the shear forces, and may improve the alignment of the bonded joint  10 . This mechanical interlocking of the first and second components  14 , 16  may also reinforce the bonded joint  10  against compressive forces, or tensile forces. Thus, in  FIG. 8B , the surface pattern  23  may increase mechanical adhesion due to the structural surface features  22  increasing mechanical interlocking in the bonded joint  10 . 
     The pattern  23  of the bond line  18  shown in  FIG. 9  is now described in greater detail. The pattern  23  is “two-sided”, and is present on both the portion  16 A′ of the second surface  16 A of the second component  16  and on the portion  14 A′ of the first surface  14 A of the first component  14 . The structural surface features  22  of the pattern  23  are protrusions extending outwardly from the second surface  16 A toward the first surface  14 A, and from the first surface  14 A toward the second surface  16 A. The protrusions are spaced apart from one another along the width W of the bond line  18 . The protrusions are spaced apart from one another along some or all of the length L of the bond line  18 . Channels are defined between the protrusions. The channels have a height measured from the portions  14 A′, 16 A′ of the first and second surfaces  14 A, 16 A to the top of the protrusions. The protrusions are arranged in parallel within the pattern  23 . The protrusions on the second surface  16 A are misaligned with the protrusions on the first surface  14 A. The protrusions repeat throughout the pattern  23 . 
     The pattern  23  of the bond line  18  shown in  FIG. 10A  is now described in greater detail.  FIG. 10A  is a top view of the second surface  16 A of the second component  16  having the pattern  23 . The pattern  23  is “one-sided”, and is present on only the portion  16 A′ of the second surface  16 A of the second component  16 . The structural surface features  22  of the pattern  23  are surface protrusions  22 A extending outwardly from the second surface  16 A. The surface protrusions  22 A are spaced apart from one another along the width W of the bond line  18 . The surface protrusions  22 A are spaced apart from one another along some or all of the length L of the bond line  18 . Channels are defined between the surface protrusions  22 A. The channels have a height measured from the portions  16 A′ of the second surface  16 A to the second ends  24 B of the surface protrusions  22 A. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . 
     Referring to  FIG. 10B , the second component  16  of  FIG. 10A  is shown in cross-section and bonded to the first component  14 . The thickness TSP of each surface protrusion  22 A of the second component  16  is substantially equal to the thickness T of the bond line  18 . In  FIG. 10B , the thickness TSP of each surface protrusion  22 A is identical to the thickness T of the bond line  18  at the location of a given surface protrusion  22 A. In  FIG. 10B , the second end  24 B of each surface protrusion  22 A is abutted directly against the surface  14 A of the first component  14 . The thickness T of the bond line  18  between the first and second surfaces  14 A, 16 A is substantially constant along the bond line  18 . It is meant by “substantially constant” that the thickness T of the bond line  18  does not change between the first and second surfaces  14 A, 16 A, or varies slightly by an acceptable manufacturing deviation. For example, and referring to  FIG. 10B , the thickness T of the bond line  18  to the left of the surface protrusion  22 A is 10.3 thou, and the thickness T of the bond line  18  to the right of the surface protrusion  22 A is 10.9 thou. Thus, in  FIG. 10B , the constant thickness T of the bond line  18  is about 10 thou and has been obtained without placing fillers and media into the bond line  18 . Referring to  FIG. 10B , the thickness TSP of each surface protrusion  22 A is substantially equal to the thickness T of the bond line  18  and to the thickness of the cured adhesive  11 . The portions of the second surface  16 A that are between the surface protrusions  22 A are spaced apart an equal distance from the first surface  14 A. 
     Referring to  FIG. 10B , the second component  16  includes a substrate  17  that defines the body of the second component  16 . The substrate  17  may be made of any suitable material, for example composite materials, a metal material, or combinations or alloys thereof. In  FIG. 10B , the substrate  17  is a metal material. In  FIG. 10B , the substrate  17  is Aluminum or Titanium. The metal second component  16  is bonded to a composite first component  14 . The second component  16  also includes a structural adhesive  19 . The structural adhesive  19  is a solid object which defines or forms the surface structure  20 , and is intended to provide structure to the bond line  18  to help control its thickness T. The structural adhesive  19  defines the surface structure  20  and is used to distance the first and second surfaces  14 A, 16 A. In  FIG. 10B , the structural adhesive  19  is a layer of cured epoxy resin. The structural adhesive  19  is shown in  FIG. 10A  as the outermost surface  16 A of the second component  16 . Referring to  FIGS. 10A and 10B , the structural adhesive  19  is bonded to the metal substrate  17 . The adhesive  11  is then subsequently applied to the cured structural adhesive  19  to bond the structural adhesive  19  (and thus the second component  16 ) to the first component  14 . Thus, at least in the configuration shown in  FIGS. 10A and 10B , the structural adhesive  19  functions to both define the surface structure  20  and to help bond the components  14 , 16  together, whereas the cured adhesive  11  serves to merely bond the components  14 , 16  together. The cured adhesive  11  may be a different material than the material of the structural adhesive  19 . For example, in  FIG. 10B , the structural adhesive  19  is a layer of cured epoxy resin, and the cured adhesive  11  is another resin with aluminum particle filler. The aluminum particle filter may be omitted from the cured adhesive  11 . 
     Referring to  FIG. 10B , the structural adhesive  19  is disposed on the substrate  17 . The structural adhesive  19  is the portion of the surface structure  20  which defines the outermost and visible second surface  16 A of the second component  16 . The surface protrusions  22 A extending outwardly from the second surface  16 A are composed of the material of the structural adhesive  19 . The surface protrusions  22 A are formed from the material of the structural adhesive  19 . The surface protrusions  22 A are made from the material of the structural adhesive  19 . The surface protrusions  22 A are part of the structural adhesive  19 . Thus, in  FIG. 10B , the surface structure  20  of the second component  16  is a layer of solid adhesive  19  that is separate from, and applied on, the substrate  17  of the second component  16 . It will thus be apparent that the surface structure  20  does not form part of the underlying geometry of the second component  16 , and is applied to the substrate  17  to impact a property of the bond line  18 . The application of the surface structure  20  composed of the structural adhesive  19  to the second component  16  leaves unchanged the underlying geometry and properties of the second component  16 . 
     The pattern  23  of the bond line  18  shown in  FIG. 11A  is now described in greater detail.  FIG. 11A  is a top view of the second surface  16 A of the second component  16  having the pattern  23 . The pattern  23  is “one-sided”, and is present on only the portion  16 A′ of the second surface  16 A of the second component  16 . The structural surface features  22  of the pattern  23  are surface protrusions  22 A extending outwardly from the second surface  16 A. The surface protrusions  22 A are spaced apart from one another along the width W of the bond line  18 . The surface protrusions  22 A are spaced apart from one another along some or all of the length L of the bond line  18 . Channels are defined between the surface protrusions  22 A. The channels have a height measured from the portions  16 A′ of the second surface  16 A to the second ends  24 B of the surface protrusions  22 A. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . 
     Referring to  FIG. 11B , the second component  16  of  FIG. 11A  is shown in cross-section and bonded to the first component  14 . The thickness TSP of each surface protrusion  22 A of the second component  16  is substantially equal to the thickness T of the bond line  18 . In  FIG. 11B , the thickness TSP of each surface protrusion  22 A differs slightly from the thickness T of the bond line  18  by an acceptable manufacturing deviation. For example, and referring to  FIG. 11B , the second end  24 B of the illustrated surface protrusion  22 A is spaced apart from the first surface  14 A a distance less than the thickness TSP of the surface protrusion  22 A. For example, in  FIG. 11B , the second end  24 B of the surface protrusion  22 A is spaced apart from the first surface  14 A by about 1.4 thou, and the thickness TSP of the surface protrusion  22 A is about 10 thou. The thickness T of the bond line  18  between the first and second surfaces  14 A, 16 A is substantially constant along the bond line  18 . It is meant by “substantially constant” that the thickness T of the bond line  18  does not change between the first and second surfaces  14 A, 16 A, or varies slightly by an acceptable manufacturing deviation. For example, and referring to  FIG. 11B , the thickness T of the bond line  18  to the left of the surface protrusion  22 A is 12.9 thou, and the thickness T of the bond line  18  to the right of the surface protrusion  22 A is 12.4 thou. Thus, in  FIG. 11B , a constant thickness T of the bond line  18  is about 12 thou and has been obtained without placing fillers and media into the bond line  18 . Referring to  FIG. 11B , the width of the surface protrusion  22 A is about 90.9 thou, and the thickness TSP of the surface protrusion  22 A is substantially equal to the thickness T of the bond line  18  and to the thickness of the cured adhesive  11 . The portions of the second surface  16 A that are between the surface protrusions  22 A are spaced apart an equal distance from the first surface  14 A. 
     Referring to  FIG. 11B , the second component  16  includes a substrate  17  that defines the body of the second component  16 . The substrate  17  is a composite material. In  FIG. 11B , the substrate consists of carbon fiber plies  17 A impregnated with epoxy resin  17 B, giving the appearance of a “sandwich” structure for the substrate  17  with alternating layers of carbon fiber plies  17 A and resin  17 B. Some non-limiting examples of other materials for the fiber plies  17 A include glass and aramid. Some non-limiting examples of other materials for the resin  17 B include other thermosets such as bismaleimide (BMI) or thermoplastic. The composite substrate  17  may be a thermoplastic. In  FIG. 11B , the composite substrate  17  of the second component  16  is bonded to a composite first component  14 . The second component  16  also includes the structural adhesive  19 , similar to as described above. In  FIG. 11B , the structural adhesive  19  is one of the cured layers of resin  17 B. In  FIG. 11B , the structural adhesive  19  is the outermost layer of cured resin  17 B. The structural adhesive  19  is shown in  FIG. 11A  as the outermost surface  16 A of the second component  16 . 
     Referring to  FIG. 11B , the structural adhesive  19  is disposed on one of the fiber plies  17 A of the substrate  17 . The structural adhesive  19  is the portion of the surface structure  20  which defines the outermost and visible second surface  16 A of the second component  16 . The surface protrusions  22 A extending outwardly from the second surface  16 A are composed of, formed from, and/or made from the material of the structural adhesive  19 . Thus, in  FIG. 11B , the surface protrusions  22 A are formed from the outermost layer of cured resin  17 B. The surface protrusion  22 A is formed from an epoxy of the outermost layer of cured resin  17 B, and there is no separate resin layer applied to the cured composite substrate  17  to form the surface protrusions  22 A. The surface protrusions  22 A may be formed from the outermost layer of cured resin  17 B while the second component  16  is being manufactured (i.e. “in-process”), or after the second component  16  has been manufactured (i.e. “post-process”). In  FIG. 11B , the surface structure  20  of the second component  16  is a layer of solid adhesive  19  that is separate from a remainder of the fiber plies  17 A and the remainder of the cured resins  17 B of the substrate  17  of the second component  16 . It will thus be apparent that the surface structure  20  does not form part of the underlying geometry of the second component  16 , and is applied to the substrate  17  to impact a property of the bond line  18 . The application of the surface structure  20  to the second component  16  leaves unchanged the underlying geometry and properties of the second component  16 . 
     The pattern  23  of the bond line  18  shown in  FIG. 12  is now described in greater detail. The pattern  23  is “one-sided”, and is present on only the portion  16 A′ of the second surface  16 A of the second component  16 . The structural surface features  22  of the pattern  23  are surface protrusions  22 A extending outwardly from the second surface  16 A. The surface protrusions  22 A are spaced apart from one another along the width W of the bond line  18 . The surface protrusions  22 A are spaced apart from one another along some or all of the length L of the bond line  18 . Channels are defined between the surface protrusions  22 A. The channels have a height measured from the portions  16 A′ of the second surface  16 A to the second ends  24 B of the surface protrusions  22 A. The surface protrusions  22 A are arranged in parallel within the pattern  23 . The surface protrusions  22 A repeat throughout the pattern  23 . 
     Referring to  FIG. 12 , the second component  16  includes a substrate  17  that defines the body of the second component  16 . The substrate  17  is a metal material. In  FIG. 12 , the substrate  17  is Aluminum or Titanium. The metal second component  16  is bonded to a metal first component  14 . The second component  16  also includes a structural metal material  19 A. The metal material  19 A is a solid object which defines or forms the surface structure  20 , and is intended to provide structure to the bond line  18  to help to control its thickness T. 
     Referring to  FIG. 12 , the metal material  19 A is disposed on the substrate  17 . The metal material  19 A is the portion of the surface structure  20  which defines the outermost and visible second surface  16 A of the second component  16 . The surface protrusions  22 A extending outwardly from the second surface  16 A are composed of, formed from, and/or made from the metal material  19 A. The surface protrusions  22 A may be formed by machining, cutting or lasering the metal material  19 A to form grooves in the metal material  19 A that define the surface protrusions  22 A. The metal material  19 A is thus a sacrificial layer or element of the second component  16  which is intended to be modified to impart the desired surface structure  20  to the second component  16  without affecting the remainder of the second component  16  (i.e. the substrate  17 ). Thus, in  FIG. 12 , the surface structure  20  of the second component  16  is a layer of metal material  19 A that is separate from, and applied on, the metal substrate  17  of the second component  16 . It will thus be apparent that the surface structure  20  does not form part of the underlying geometry of the second component  16 , and is applied to the substrate  17  to impact a property of the bond line  18 . The application of the surface structure  20  to the second component  16  leaves unchanged the underlying geometry and properties of the second component  16 . The description above with respect to  FIG. 12  applies mutatis mutandis to a configuration of the bonded part  9  where the second component  16  includes a substrate  17  made of composite material that is bonded to a first component  14  that is also a composite material. 
     It will therefore be appreciated that the structural surface features  22  and/or the pattern  23  may be selected to affect or impact different desired properties of the bond line  18 . Yet another possible property of the bond line  18  that may be impacted by the pattern  23  is adhesive wetting on the one or more mating surfaces, which may be increased by increasing the amount of surface area of the one or more mating surfaces exposed to the adhesive  11 . Thus, the selected surface pattern  23  may allow for controlling the geometry of the bond line  18  at the interface of the components  12 , controlling the thickness T of the bond line  18 , improving alignment of the mating surfaces, increasing adhesive wetting on one or both of the mating surfaces, increasing or decreasing the flow of adhesive  11  through the bond line  18 , and/or improving mechanical adhesion. The surface pattern  23  may allow for removing or avoiding objects in the bond line  18 , such as media like glass beads, which are typically used to provide some properties to the bond line  18 . Such conventional objects may introduce contamination into the bond line  18 , or allow for its introduction. The surface pattern  23  may allow for using fasteners in the bond line  18 , which is often not possible or recommended when permanent media such as glass beads are present in conventional bond joints. 
     Referring to  FIG. 6A , there is disclosed a method of bonding the components  12  along the bond line  18 . The method includes providing the surface structure  20  with the surface protrusions  22 A on one or both of the first and second surfaces  14 A, 16 A of the bond line  18 . The method includes applying the adhesive  11  along the bond line  18  between the first and second surfaces  14 A, 16 A. The method includes joining the first and second surface surfaces  14 A, 16 A together along the bond line  18  to wet both the first and second surfaces with the adhesive  11 . The method includes curing the adhesive  11  between the joined first and second surfaces  14 A, 16 A to bond the components  12  along the bond line  18 . 
     In one possible configuration, only one of the components  12  is provided with the surface structure and has a film bonded onto its mating surface and surface structure  20 . This film-bonded surface is then prepared to be bonded to the other component  12 . Such a joint may be referred to as a composite bond involving two steps and two applications of adhesive  11 . 
     In one possible configuration of the method, the surface structure  20  is provided to the mating surface during manufacturing of the components  12 . This may be referred to as applying the surface structure  20  “in-process”, i.e. while the component  12  is being formed or made. The desired surface structure  20  may be applied during part of component fabrication using any suitable technique, some of which are described in greater detail below. 
     Some possible techniques for forming the surface structure  20  on composite components  12  during part or component fabrication are now described. One possible technique involves applying a removable media to one or both of the first and second surfaces  14 A, 16 A to form the desired surface structure  20 , removing the media from the first or second surfaces  14 A, 16 A after forming the surface structure  20 , and then curing the components  12  (e.g. in the embodiment where they are composite materials) to form the surface structure  20 . Such a removable media may include placing a grid, cloth, mesh, or peel ply on the desired mating surface to create the desired surface design. The media does not form part of the fabricated component  12 . The media in this technique does not include glass beads, or other media which would remain part of the fabricated component or the bonded joint  10 . Another possible technique involves adding material to, or removing material from, one or both of the first and second surfaces  14 A, 16 A, such as the structural adhesive  19 , and co-curing the structural adhesive  19  with the composite components  12  to form the surface structure  20 . This may involve creating the desired protrusions or grooves described above. 
     Referring to  FIG. 13 , yet another possible technique for forming the surface structure  20  involves pressing a specialised forming tool  50 , such as a textured caul plate, which has a textured surface representative of the pattern  23  of structural surface features  22 , against the first and/or second surfaces  14 A, 16 A to imprint the pattern  23 , and curing the composite components  12  to form the surface structure  20 . Such a tool  50  may have an imprint pattern that is opposite to, or the inverse of, the desired pattern  23  to be imprinted on the mating surface. One possible tool  50  is shown in  FIG. 13 , and includes multiple grooves  52  which are spaced apart from each other by the optional dimensions shown, and which form the surface protrusions  22 A when the illustrated face of the plate  50  is applied with pressure against the mating surface  14 A, 16 A of the component  14 , 16 . Another possible technique for forming the surface structure  20 , which may be suitable for components  12  made of metal, includes adding material to one or both of the first and second surfaces  14 A, 16 A using additive manufacturing, or adding the sacrificial metal material  19 A. 
     One possible configuration for making the surface structure  20  from the structural adhesive  19  includes adding a resin or a film epoxy onto the substrate  17  such that the resin/film defines the first surface  14 A, and then forming the surface protrusions  22 A from the resin/film, and curing the surface protrusions  22 A and the resin/film to form the structural adhesive  19  layer. The adhesive  11  used for bonding the components  12  together is then subsequently applied to the structural adhesive  19  and its first surface  14 A, and/or to the second surface  16 A. The tool  50  may be used to form the surface protrusions  22 A in the resin/film. 
     After the surface structure  20  and the component  12  have been formed together, the method may involve preparing, or “prepping”, the mating surface using one or more of the following techniques: etching, sandblasting, and hand sanding. This may further prepare the portion of the mating surface for bonding with the other component. Some of these preparation techniques may be more suitable than others, depending on the scale of the pattern  23  and the structural surface features  22 . 
     In another possible configuration of the method, the surface structure  20  is provided to the mating surface after the components  12  have been manufactured. This may be referred to as applying the surface structure  20  “post-process”, i.e. after the component  12  part has been made. The desired surface structure  20  may be applied after component fabrication using any suitable technique, some of which are described in greater detail below. 
     Some possible techniques for forming the surface structure  20  on the components  12  after fabrication of the component  12  are now described. One possible technique includes forming the surface structure  20  with one or both of etching and machining the first and/or second surfaces  14 A, 16 A to form the surface protrusions  22 A arranged in the pattern  23 . In configurations where the component  12  is made of metal, a mesh may be used to perform the etching. Another possible technique includes forming the surface structure  20  with lasering, or laser cutting, the first and/or second surfaces  14 A, 16 A to form the surface protrusions  22 A arranged in the pattern  23 . In such a technique, the laser may perform a first pass to achieve the desired pattern  23 , and may then subsequently complete a second pass to prepare the mating surface for bonding. 
     After the surface structure  20  has been provided to the already-made component  12 , the method may involve preparing, or “prepping”, the mating surface using one or more of the following techniques: etching, sandblasting, laser ablation, and hand sanding. This may further prepare the portion of the mating surface for bonding with the other component. Some of these preparation techniques may be more suitable than others, depending on the scale of the pattern  23  and the surface protrusions  22 A. In an embodiment, the surface structure  20  provided on the already-made component  12  does not require further preparation, and may be bonded without further processing. In an alternative embodiment, the surface pattern  23  may be applied on the already-made component  12  at the same time as performing the surface preparation. 
     Referring to  FIG. 6A , there is disclosed a method of preparing the mating surface of the component  12  to be bonded with another surface of another component  12  along the bond line  18 . The method includes selecting structural surface features  22 , such as the surface protrusions  22 A, for the surface. The surface protrusions  22 A may be selected by choosing a sheet media, choosing a laser cutting pattern, or choosing an additive manufacturing pattern, etc. to achieve the desired pattern  23  and impact a property of the bond line  18 . The impact that is selected is typically an improvement or optimisation, or to impart a desired value for the property of the bond line  18 , such as its thickness T. The method includes providing the structural surface features  22  onto an area of the mating surface, such as by using one or more of the “in-process” or “post-process” techniques described above. 
     The bonded joint  10  and methods disclosed herein may allow for improved cycle times and provide cost savings. The bonded joint  10  and methods may help to control the properties of the bond line  18 , such as its thickness T, without having to use traditional process which are more labour intensive, manual and not repetitive. The bond line  18  is formed without permanent media, and may thus be more continuous and have fewer stress concentrations. The bonded joint  10  and methods allow for avoiding the addition of permanent media to the bond line  18 , which prior to its addition, needs to be purchased, controlled through spec, stored and processed. The bonded joint  10  and methods allow for removing or avoiding complex tooling which is conventionally used to control the gap with an arresting feature. The bonded joint  10  and methods allow for controlling the quantity of adhesive  11  used and for removing permanent media, which may allow for optimizing the bonded joint  10  and reducing its weight. The bonded joint  10  and methods allow for using fasteners in the bond line  18 . 
     The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.