Patent Description:
In the manufacturing of composite panels, and in particular composite panels manufactured as aircraft components such as an aircraft wing panel, some type of stiffener is often employed to stiffen the panel. The panel and the stiffener are often manufactured of composite materials, and are often manufactured of the same composite materials.

The composite panel is often constructed of layers of composite material. The layers of composite material are stacked or laid up on each other, and the layers are then co-cured or co-bonded to form the panel. The panel often has a general planar configuration, and could be substantially flat, or have some curvature.

The stiffener is also often constructed of layers of composite materials. Stiffeners have various different configurations. One such stiffener configuration is that of a plank. A "plank" is often defined as a piece of lumber cut thicker than a board, or a heavy thick board. Thus, a "plank" stiffener of composite material has a configuration similar to that of a thick piece of lumber or a heavy thick board.

Since the early days of research and development of composite materials used in the construction of stiffeners for composite panels, stiffeners configured as planks have been studied numerous times. However, these studies of stiffeners configured as planks have failed to produce a workable concept. This was mainly due to planks constructed of layers of composite material stacked or laid up on each other and then co-cured or co-bonded fail to address inherent weaknesses of the layers of composites in the short, transverse or width dimension of the plank configuration with respect to the length dimension of the plank configuration and the thickness dimension of the plank configuration. Also, planks constructed of layers of composite material would exhibit high free edge intralaminar/interlaminar stresses, and high exothermal stresses, all associated with the size of the plank and in particular the thickness dimension of the plank. Mechanical stresses and thermal stresses in a plank constructed of layers of composite material are directly related to the size of the plank and in particular the thickness dimension of the plank. The mechanical stresses and thermal stresses in the plank are also related to the ply percentages of the fibers in the layers of composite material that make up the plank, (or the percentage of <NUM>° fiber layers, + fiber layers, <NUM>° fiber layers and - fiber layers). Also, the stacking sequence of the fiber layers all contribute to the mechanical stress and thermal stress in the construction of the plank.

Document <CIT>, according to its abstract, states an omega aircraft stiffener. The stiffener comprises two legs, one end of which is joined by a wing and each other end of which is extended respectively by a foot. It includes a rib protruding from the surface of the wing.

<CIT> and <CIT> also disclose assemblies of a stiffener and a composite pane.

There is provided an assembly of a stiffener and a composite panel, the stiffener comprising a plank, the plank having an elongate configuration with a longitudinal length dimension, a lateral width dimension and a thickness dimension; a bottom sub-plank in the plank, the bottom sub-plank being constructed of layers of composite material; a first layer of adhesive on the bottom sub-plank; and, an intermediate sub-plank in the plank, the intermediate sub-plank being constructed of layers of composite material, the intermediate sub-plank engaging against the first layer of adhesive with the first layer of adhesive securing the intermediate sub-plank to the bottom sub-plank; the composite panel having an elongate configuration with a longitudinal length dimension, a lateral width dimension and a thickness dimension, the composite panel being constructed of layers of composite material; the plank being secured to the composite panel; and, layers of tapes of composite material in the composite panel, the tapes of composite material being interleaved in the layers of composite material of the composite panel, the tapes of composite material extending along the longitudinal length dimension of the composite panel and along the longitudinal length dimension of the plank, the tapes of composite material being positioned in the thickness dimension of the composite panel only beneath the plank on the composite panel.

The interleaved construction of the panel of this disclosure and the construction of the plank that is secured to and stiffens the panel overcome the detrimental effects associated with stiffening a composite panel with a conventional plank constructed of layers of composite material.

The plank has an elongate configuration with a longitudinal length dimension, a lateral width dimension and a thickness dimension. The plank is constructed of two or more sub-planks, and in this disclosure three sub-planks. The plank is comprised of a bottom sub-plank in the plank, an intermediate sub-plank in the plank and a top sub-plank in the plank.

The bottom sub-plank in the plank is configured for engagement with the composite panel to stiffen the composite panel with the plank. The bottom sub-plank is constructed of layers of composite material that have been co-bonded together.

The intermediate sub-plank in the plank is configured for engagement with the bottom sub-plank. The intermediate sub-plank is also constructed of layers of composite material that have been co-bonded together.

The top sub-plank in the plank is configured for engagement with the intermediate sub-plank. The top sub-plank is also constructed of layers of composite material that have been co-bonded together.

A first layer of adhesive is applied between and engages with the bottom sub-plank and the intermediate sub-plank. The first layer of adhesive secures the intermediate sub-plank to the bottom sub-plank. Additionally, the first layer of adhesive securing the intermediate sub-plank to the bottom sub-plank is a first barrier layer that obstructs stresses from being transmitted between the bottom sub-plank and the intermediate sub-plank.

A second layer of adhesive is applied between and engages with the top sub-plank and the intermediate sub-plank. The second layer of adhesive secures the top sub-plank to the intermediate sub-plank. Additionally, the second layer of adhesive securing the top sub-plank to the intermediate sub-plank is a second barrier layer that obstructs stresses from being transmitted between the top sub-plank and the intermediate sub-plank.

The layers of composite material of the bottom sub-plank have been co-bonded and the layers of composite material of the intermediate sub-plank have been co-bonded prior to the intermediate sub-plank and the bottom sub-plank engaging against the first layer of adhesive with the first layer of adhesive securing the intermediate sub-plank to the bottom sub-plank.

The layers of composite material of the intermediate sub-plank have been co-bonded and the layers of composite material of the top sub-plank have been co-bonded prior to the intermediate sub-plank and the top sub-plank engaging against the second layer of adhesive with the second layer of adhesive securing the intermediate sub-plank to the top sub-plank.

The composite panel has an elongate configuration with a longitudinal length dimension, a lateral width dimension and a thickness dimension. The composite panel is constructed of layers of composite material that have been co-bonded together and that extend along the longitudinal length dimension of the composite panel and along the lateral width dimension of the composite panel.

There are layers of tapes of composite material in the thickness dimension of the composite panel. The tapes of composite material are interleaved in the layers of composite material of the composite panel and have been co-bonded with the layers of composite material of the composite panel. The tapes of composite material extend along the length dimension of the composite panel. The layers of tapes interleaved in the layers of composite material of the composite panel form a raised ridge in the top surface of the composite panel. The raised ridge extends along the length dimension of the composite panel. The raised ridge also forms a stiffener of the composite panel.

The plank is secured by a third layer of adhesive to the raised ridge on the top surface of the composite panel with the plank extending along the lengths of the tapes of composite material interleaved in the layers of composite material of the composite panel. The tapes of the composite material are positioned in the thickness dimension of the composite panel only beneath the plank secured to the raised ridge of the composite panel.

The composite panel is stiffened by the layers of tapes of composite material interleaved in the layers of composite material of the composite panel forming the raised ridge on the composite panel, and the plank comprised of the bottom sub-plank, the intermediate sub-plank and the top sub-plank secured to the raised ridge.

The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings.

<FIG> is a representation of a perspective view of the plank <NUM> of this disclosure secured to the top surface of the panel <NUM> of this disclosure. The horizontal orientations of the plank <NUM> and panel <NUM> represented in <FIG> are only for the purposes of this disclosure. The plank <NUM> and panel <NUM> could be oriented vertically. The orientations of the plank <NUM> and panel <NUM> could be rotated <NUM>°, where the plank <NUM> would then be secured to a bottom surface of the panel <NUM>. Additionally, the plank <NUM> and panel <NUM> are represented in <FIG> as having general rectangular configurations. The plank <NUM> and panel <NUM> could have other equivalent configurations, depending on the operative environment of the plank <NUM> and panel <NUM>.

The plank <NUM> has an elongate configuration with a longitudinal length dimension L, a lateral width dimension W and a thickness dimension T. The plank <NUM> is constructed of two or more sub-planks, and in this disclosure three sub-planks. The plank <NUM> is comprised of a bottom sub-plank <NUM> in the plank, an intermediate sub-plank <NUM> in the plank and a top sub-plank <NUM> in the plank.

The bottom sub-plank <NUM> is constructed of layers of composite material. In this disclosure the layers of composite material are pre-preg composite material. However, other equivalent types of composite materials could be used in constructing the bottom sub-plank <NUM>. Each of the layers of pre-preg composite material are comprised of unidirectional fibers, for example carbon fibers in a matrix material such as an epoxy matrix. In each layer of composite material, the fibers embedded in the matrix material are all oriented in a single direction. Some layers of composite material in the bottom sub-plank <NUM> have fibers that are oriented at <NUM>° relative to the longitudinal length dimension of the plank <NUM>, forming a <NUM>° layer of fibers. Some layers of composite material in the bottom sub-plank <NUM> have fibers that are oriented at an acute angle relative to the length dimension L of the plank <NUM>, for example at +<NUM>°, forming a + layer of fibers. Some of the layers of composite material in the bottom sub-plank <NUM> have fibers that are oriented at an acute angle, for example -<NUM>° relative to the length dimension L of the plank <NUM>, forming a - layer. Some of the layers of composite material in the bottom sub-plank <NUM> have fibers that are oriented at a <NUM>° angle relative to the length dimension L of the plank <NUM>, forming a <NUM>° layer. In the layers of composite material that make up the bottom sub-plank <NUM>, the <NUM>° layers or layers with unidirectional fibers oriented along the length dimension L of the plank <NUM> predominate. The layers of composite material that make up the bottom sub-plank <NUM> are laid up and then co-bonded, producing the bottom sub-plank <NUM>. Each of the layers of composite material has a lateral width dimension that reduces or gets slightly smaller as each layer of composite material is sequentially laid up in forming the bottom sub-plank <NUM>. This gives the bottom sub-plank <NUM> a general trapezoidal cross-section configuration. The trapezoidal cross-section configuration of the bottom sub-plank <NUM> alleviates high free-edge interlaminar stresses which could lead to delamination of the layers of composite material in the bottom sub-plank <NUM>. The trapezoidal cross-section configuration of the bottom sub-plank <NUM> also prevents bow waves in the layers of composite material after they have been cured and co-bonded along the length dimension of the bottom sub-plank <NUM>. The bottom sub-plank <NUM>, constructed in the manner described above has a bottom surface <NUM> that is configured for engagement with the panel <NUM> to stiffen the panel with the plank <NUM>. The bottom sub-plank <NUM> also has a top surface <NUM> that is opposite the bottom surface <NUM> of the bottom sub-plank <NUM>. The bottom sub-plank <NUM> also has a left side surface <NUM> and an opposite right side surface <NUM>. Together, the bottom surface <NUM>, the top surface <NUM>, the left side surface <NUM> and the right side surface <NUM> define the trapezoidal cross-section configuration of the bottom sub-plank <NUM>.

The intermediate sub-plank <NUM> is constructed of layers of composite material. In this disclosure the layers of composite material are pre-preg composite material. However, other equivalent types of composite materials could be used in constructing the intermediate sub-plank <NUM>. Each of the layers of pre-preg composite material are comprised of unidirectional fibers, for example carbon fibers in a matrix material such as an epoxy matrix. In each layer of composite material, the fibers embedded in the matrix material are all oriented in a single direction. Some layers of composite material in the intermediate sub-plank <NUM> have fibers that are oriented at <NUM>° relative to the longitudinal length dimension of the plank <NUM>, forming a <NUM>° layer of fibers. Some layers of composite material in the intermediate sub-plank <NUM> have fibers that are oriented at an acute angle relative to the length dimension L of the plank <NUM>, for example at +<NUM>°, forming a + layer of fibers. Some of the layers of composite material in the intermediate sub-plank <NUM> have fibers that are oriented at an acute angle, for example -<NUM>° relative to the length dimension L of the plank <NUM>, forming a - layer. Some of the layers of composite material in the intermediate sub-plank <NUM> have fibers that are oriented at a <NUM>° angle relative to the length dimension L of the plank <NUM>, forming a <NUM>° layer. In the layers of composite material that make up the intermediate sub-plank <NUM>, the <NUM>° layers or layers with unidirectional fibers oriented along the length dimension L of the plank <NUM> predominate. The layers of composite material that make up the intermediate sub-plank <NUM> are laid up and then co-bonded, producing the intermediate sub-plank <NUM>. Each of the layers of composite material has a lateral width dimension that reduces or gets slightly smaller as each layer of composite material is sequentially laid up in forming the intermediate sub-plank <NUM>. This gives the intermediate sub-plank <NUM> a general trapezoidal cross-section configuration. The trapezoidal cross-section configuration of the intermediate sub-plank <NUM> alleviates high free-edge interlaminar stresses which could lead to delamination of the layers of composite material in the intermediate sub-plank <NUM>. The trapezoidal cross-section configuration of the intermediate sub-plank <NUM> also prevents bow waves in the layers of composite material after they have been cured and co-bonded along the length dimension of the intermediate sub-plank <NUM>. The intermediate sub-plank <NUM>, constructed in the manner described above has a bottom surface <NUM> that is configured for engagement with the top surface <NUM> of the bottom sub-plank <NUM>. The intermediate sub-plank <NUM> also has a top surface <NUM> that is opposite the bottom surface <NUM> of the intermediate sub-plank <NUM>. The intermediate sub-plank <NUM> also has a left side surface <NUM> and an opposite right side surface <NUM>. Together, the bottom surface <NUM>, the top surface <NUM>, the left side surface <NUM> and the right side surface <NUM> define the trapezoidal cross-section configuration of the intermediate sub-plank <NUM>.

The top sub-plank <NUM> is constructed of layers of composite material. In this disclosure the layers of composite material are pre-preg composite material. However, other equivalent types of composite materials could be used in constructing the top sub-plank <NUM>. Each of the layers of pre-preg composite material are comprised of unidirectional fibers, for example carbon fibers in a matrix material such as an epoxy matrix. In each layer of composite material, the fibers embedded in the matrix material are all oriented in a single direction. Some layers of composite material in the top sub-plank <NUM> have fibers that are oriented at <NUM>° relative to the longitudinal length dimension of the plank <NUM>, forming a <NUM>° layer of fibers. Some layers of the layers of composite material in the top sub-plank <NUM> have fibers that are oriented at an acute angle relative to the length dimension L of the plank <NUM>, for example at +<NUM>°, forming a + layer of fibers. Some of the layers of the layers of composite material in the top sub-plank <NUM> have fibers that are oriented at an acute angle, for example -<NUM>° relative to the length dimension L of the plank <NUM>, forming a - layer. Some of the layers of composite material in the top sub-plank <NUM> have fibers that are oriented at a <NUM>° angle relative to the length dimension L of the plank <NUM>, forming a <NUM>° layer. In the layers of composite material that make up the top sub-plank <NUM>, the <NUM>° layers or layers with unidirectional fibers oriented along the length dimension L of the plank <NUM> predominate. The layers of composite material that make up the top sub-plank <NUM> are laid up and then co-bonded, producing the top sub-plank <NUM>. Each of the layers of composite material has a lateral width dimension that reduces or gets slightly smaller as each layer of composite material is sequentially laid up in forming the top sub-plank <NUM>. This gives the top sub-plank <NUM> a general trapezoidal cross-section configuration. The trapezoidal cross-section configuration of the top sub-plank <NUM> alleviates high free-edge interlaminar stresses which could lead to delamination of the layers of composite material in the top sub-plank <NUM>. The trapezoidal cross-section configuration of the top sub-plank <NUM> also prevents bow waves in the layers of composite material after they have been cured and co-bonded along the length dimension of the top sub-plank <NUM>. The top sub-plank <NUM>, constructed in the manner described above has a bottom surface <NUM> that is configured for engagement with the top surface <NUM> of the intermediate sub-plank <NUM>. The top sub-plank <NUM> also has a top surface <NUM> that is opposite the bottom surface <NUM> of the top sub-plank <NUM>. The top sub-plank <NUM> also has a left side surface <NUM> and an opposite right side surface <NUM>. Together, the bottom surface <NUM>, the top surface <NUM>, the left side surface <NUM> and the right side surface <NUM> define the trapezoidal cross-section configuration of the top sub-plank <NUM>.

A first layer of adhesive <NUM> is applied between and engages with the top surface <NUM> of the bottom sub-plank <NUM> and the bottom surface <NUM> of the intermediate sub-plank <NUM>. The first layer of adhesive <NUM> secures the intermediate sub-plank <NUM> to the top surface <NUM> of the bottom sub-plank <NUM>. The first layer of adhesive <NUM> has a configuration that matches the configuration of the top surface <NUM> of the bottom sub-plank <NUM> and the bottom surface <NUM> of the intermediate sub-plank <NUM>. Additionally, the first layer of adhesive <NUM> securing the intermediate sub-plank <NUM> to the top surface <NUM> of the bottom sub-plank <NUM> forms a first barrier layer <NUM> between the intermediate sub-plank <NUM> and the bottom sub-plank <NUM>. The first barrier layer <NUM> obstructs stresses, for example fractures from being transmitted from the bottom sub-plank <NUM> through the first barrier layer <NUM> to the intermediate sub-plank <NUM>, and also obstructs stresses such as fractures from being transmitted from the intermediate sub-plank <NUM> through the first barrier layer <NUM> to the bottom sub-plank <NUM>.

A second layer of adhesive <NUM> is applied between and engages with the bottom surface <NUM> of the top sub-plank <NUM> and the top surface <NUM> of the intermediate sub-plank <NUM>. The second layer of adhesive <NUM> has a configuration that matches the configuration of the bottom surface <NUM> of the top sub-plank <NUM> and the top surface <NUM> of the intermediate sub-plank <NUM>. Additionally, the second layer of adhesive <NUM> securing the top sub plank <NUM> to the top surface <NUM> of the intermediate sub-plank <NUM> forms a second barrier layer <NUM> between the top sub-plank <NUM> and the intermediate sub-plank <NUM>. The second barrier layer <NUM> obstructs stresses, for example fractures from being transmitted from the top sub-plank <NUM> through the second barrier layer <NUM> to the intermediate sub-plank <NUM>, and also obstructs stresses such as fractures from being transmitted from the intermediate sub-plank <NUM> through the second barrier layer <NUM> to the top sub-plank <NUM>.

The layers of composite material of the bottom sub-plank <NUM> have been co-bonded and the layers of composite material of the intermediate sub-plank <NUM> have been co-bonded prior to the bottom sub-plank <NUM> and the intermediate sub-plank <NUM> being adhered together by the first layer of adhesive <NUM> or the first barrier layer <NUM>. Additionally, the layers of composite material of the intermediate sub-plank <NUM> have been co-bonded and the layers of composite material of the top sub-plank <NUM> have been co-bonded prior to the intermediate sub-plank <NUM> being adhered to the top sub-plank <NUM> by the second layer of adhesive <NUM> or second barrier layer <NUM>.

Forming the plank <NUM> comprised of the bottom sub-plank <NUM>, the intermediate sub-plank <NUM> and the top sub-plank <NUM> that are each separately formed as sub-planks and that are adhered together to form the plank <NUM> enables the plank <NUM> to be constructed with a thickness dimension of the combined layers of composite material of the three sub-planks, while alleviating high mechanical and thermal residual stresses by dividing the plank <NUM> into three co-bonded sub-planks and using the layers of adhesive <NUM>, <NUM> as barriers separating the three sub-planks. This would not have been possible by forming the plank <NUM> comprised of the layers of composite material in the bottom sub-plank <NUM>, the layers of composite material in the intermediate sub-plank <NUM> and the layers of composite material in the top sub-plank <NUM> being laid up on or stacked on each other and then co-bonding the stacked layers. Such a plank would have the high mechanical and thermal residual stresses that are avoided by the plank <NUM> of the disclosure that employs the first layer of adhesive <NUM> and the second layer of adhesive <NUM> to divide the stacked layers of composite material into three separate sub-planks.

The panel <NUM> has an elongate configuration with a longitudinal length dimension that is substantially the same as the longitudinal length dimension L of the plank <NUM>, a lateral width dimension and a thickness dimension. The panel <NUM> is constructed in substantially the same manner as each of the individual sub-planks <NUM>, <NUM>, <NUM>. The panel <NUM> is constructed of layers of composite material <NUM> that have been laid up and co-bonded, forming the panel <NUM> as a composite panel <NUM>. The layers of composite material <NUM> that make up the composite panel <NUM> in this disclosure are pre-preg composite materials. However, other equivalent types of composite materials may be employed in constructing the composite panel <NUM>. In laying up the layers of pre-preg composite material in constructing the composite panel <NUM>, some of the layers are <NUM>° layers, some of the layers are + layers, some of the layers are <NUM>° layers and some of the layers are - layers.

There are layers of composite tapes <NUM> in the thickness dimension of the composite panel <NUM>. Each layer of composite tape <NUM> has a length dimension that is substantially the same length dimension L as the plank <NUM> and the panel <NUM>, and a lateral width dimension that is slightly larger than the lateral width dimension W of the plank <NUM>. The tapes of composite material <NUM> are interleaved in the layers of composite material <NUM> of the composite panel <NUM> and have been co-bonded with the layers of composite material <NUM> of the composite panel <NUM>. The tapes <NUM> are unidirectional tapes with the fibers of each tape forming the tapes as <NUM>° tapes. The <NUM>° fibers of the layers of composite tapes <NUM> extend along the longitudinal length dimension L of the plank <NUM> and the longitudinal length dimension of the panel <NUM>. The layers of composite tapes <NUM> interleaved in the layers of composite material <NUM> of the composite panel <NUM> are positioned in the thickness dimension of the composite panel <NUM> closer to a top surface <NUM> of the composite panel <NUM> than to a bottom surface <NUM> of the composite panel <NUM>. The positioning of the layers of tapes <NUM> in the thickness dimension of the composite panel <NUM> closer to the top surface <NUM> of the composite panel <NUM> forms a raised ridge <NUM> in the top surface <NUM> of the composite panel <NUM>. The raised ridge <NUM> extends along the longitudinal length dimension of the composite panel <NUM>. The raised ridge <NUM> also forms a stiffener in the composite panel <NUM>. The raised ridge <NUM> has a lateral width dimension at a top surface <NUM> of the ridge <NUM> that is slightly larger than the lateral width dimension of the bottom surface <NUM> of the bottom sub-plank <NUM> in the plank <NUM>.

The plank <NUM> is secured by a third layer of adhesive <NUM> to the raised ridge <NUM>. The third layer of adhesive <NUM> has a configuration substantially the same as the configuration of the bottom surface <NUM> of the bottom sub-plank <NUM>. The third layer of adhesive <NUM> secures the bottom surface <NUM> of the bottom sub-plank <NUM> to the top surface <NUM> of the raised ridge <NUM>, and thereby secures the plank <NUM> to the panel <NUM>. The longitudinal length dimension L of the plank <NUM> extends along the longitudinal length of the raised ridge <NUM> and along the longitudinal length of the layers of composite tapes <NUM> in the panel <NUM>. The layers of composite tapes <NUM> interleaved in the layers of composite material <NUM> of the composite panel <NUM> are positioned in the composite panel <NUM> only beneath the plank <NUM> secured to the raised ridge <NUM> of the composite panel <NUM>.

The composite panel <NUM> is stiffened by the layers of tapes of composite material <NUM> interleaved in the layers of composite material <NUM> of the composite panel <NUM> forming the raised ridge <NUM> on the composite panel <NUM>, and by the plank <NUM> comprised of the bottom sub-plank <NUM>, the intermediate sub-plank <NUM> and the top sub-plank <NUM> secured to the raised ridge <NUM>.

Constructing the plank <NUM> of the bottom sub-plank <NUM>, the intermediate sub-plank <NUM> and the top sub-plank <NUM> that are adhered together by the first layer of adhesive <NUM> and the second layer of adhesive <NUM> enables the plank <NUM> to be constructed with a thickness dimension of the combined layers of composite material of the three sub-planks <NUM>, <NUM>, <NUM>, while alleviating high mechanical and thermal residual stresses by dividing the plank <NUM> into three co-bonded sub-planks <NUM>, <NUM>, <NUM> and using the layers of adhesives <NUM>, <NUM> as barriers separating the three sub-planks <NUM>, <NUM>, <NUM>.

Claim 1:
An assembly of a stiffener and a composite panel (<NUM>),
the stiffener comprising:
a plank (<NUM>), the plank having an elongate configuration with a longitudinal length dimension, a lateral width dimension and a thickness dimension;
a bottom sub-plank (<NUM>) in the plank, the bottom sub-plank being constructed of layers of composite material;
a first layer of adhesive (<NUM>) on the bottom sub-plank; and,
an intermediate sub-plank (<NUM>) in the plank, the intermediate sub-plank being constructed of layers of composite material, the intermediate sub-plank engaging against the first layer of adhesive with the first layer of adhesive securing the intermediate sub-plank to the bottom sub-plank;
the composite panel having an elongate configuration with a longitudinal length dimension, a lateral width dimension and a thickness dimension, the composite panel being constructed of layers of composite material;
the plank (<NUM>) being secured to the composite panel (<NUM>); and,
layers of tapes of composite material being in the composite panel (<NUM>), the tapes of composite material being interleaved in the layers of composite material of the composite panel (<NUM>), the tapes of composite material extending along the longitudinal length dimension of the composite panel (<NUM>) and along the longitudinal length dimension of the plank, the tapes of composite material being positioned in the thickness dimension of the composite panel (<NUM>) only beneath the plank on the composite panel (<NUM>).