Patent Publication Number: US-2021179256-A1

Title: Method for manufacturing a composite preform for the manufacture of a composite panel with double curvature geometry

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/EP2019/072893, filed on Aug. 27, 2019, which claims priority to and the benefit of FR 18/57693, filed on Aug. 27, 2018. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a method for manufacturing a preform for the manufacture of a non-developable final shape part made of a composite material and a preform thus obtained, along with a part manufactured with the preform. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Non-woven fabrics have the particularity of having in a single ply, layers of fibers in several directions. In other words, the non-woven fabrics are fiber preforms composed by the assembly of several layers of fibers each having a different orientation and held together by sewing threads. The biaxial non-woven fabrics include two layers each of which includes fibers oriented in a different direction, and therefore two different fiber orientations, while tri-axial non-woven fabrics include three layers each of which includes fibers oriented in a different direction, and therefore three different fiber orientations, quadri-axial non-woven fabrics include four layers and therefore four fiber orientations, etc. 
     Usually, the non-developable final shape parts made of composite material are made from a fabric preform formed from a generally biaxial woven fabric, that is to say comprising two directions of fibers, or from a biaxial non-woven fabric, applied on a non-developable shape element. The fabric preform may be pre-impregnated with resin, or a step of impregnating resin may follow the step of applying the fabric preform on the non-developable shape element. Finally, the non-developable final shape part made of composite material is obtained following a step of polymerizing the resin. This polymerization step can be carried out cold or hot depending on the used resin. 
     The biaxial woven and non-woven fabrics are capable of unraveling and can therefore be used to manufacture non-developable final shape parts without causing wrinkling or breakage of the fibers. 
     However, a biaxial fabric includes only two orientations of fibers and therefore offers main orthotropic properties, that is to say in two perpendicular directions of fibers, which do not make it possible to obtain a composite material having good stiffness properties and good mechanical strength. It is then necessary to apply many thicknesses of fabric, according to different orientations of fibers, to obtain good stiffness properties and high mechanical strength. 
     One solution consists in manufacturing non-developable final shape parts made of a composite material from tri-axial non-woven fabric, also called multiaxial fabric. The difficulty is to avoid fiber breaks because the tri-axial non-woven fabric is non-deformable. To this end, it is known from U.S. Pat. No. 8,234,990 B2 to play on the nature, spacing, tension and/or density of the seams of the tri-axial non-woven fabric. 
     However, this type of non-woven fabric applied to elements of non-developable shape, more particularly to revolution surfaces having a longitudinal axis, has a tendency to generate fiber corrugations. Such part elements have a curved generatrix whose radius of curvature changes along the longitudinal axis. 
     It is also known from EP 2 456 049, to use a fiber preform produced flat and then deformed to obtain a three-dimensional fiber preform, in which the fibers are in the form of a fabric comprising several layers of fibers in different orientations, the fibers being interconnected by seams allowing the fibers to slide relative to each other during the deformation. 
     SUMMARY 
     This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features. 
     The manufacturing method according to the present disclosure is a method for manufacturing a preform for the manufacture of a part made of a composite material of the revolution or quasi-revolution non-developable final shape type, having a longitudinal axis, characterized in that it includes the following steps: 
     a tri-axial non-woven fabric is provided comprising: 
     a first layer comprising so-called circumferential fibers oriented in a first direction, 
     a second layer comprising fibers, oriented in a second direction, 
     a third layer comprising fibers, oriented in a third direction, 
     and seams binding the fibers of the first, second and third layers, the seams extending parallel to each other and forming sheaths for the circumferential fibers, 
     said fabric is disposed on or in a non-developable shape element, either identical to the desired non-developable final shape, or of reduced dimensions compared to the desired non-developable final shape, by placing the seams parallel to the circumferential direction of the element, 
     the circumferential fibers are made to slide in the sheaths formed by the seams, so that the fabric is in continuous contact with the non-developable shape element and thus is adapted to the non-developable shape of the non-developable shape element. 
     Thus, the method according to the present disclosure makes it possible to obtain from a single thickness of fabric, a preform made of composite material whose seams are in directions parallel to each other and form sheaths for strands of fibers, called circumferential, of a first layer of said fabric. 
     In a single thickness of tri-axial fabric, a preform is thus produced which can have quasi-isotropic mechanical properties in the planes of the fabric. 
     The expression “quasi-revolution final shape” means a final non-developable shape which is not limited to parts at 360°. It can be portions of revolution parts. 
     Furthermore, the quasi-revolution shape comprises a set of generatrixes in planes parallel to the longitudinal axis, whose at least one generatrix is a curve of order greater than or equal to two, and whose curves contained in perpendicular planes at the longitudinal axis intercept at least one point of each generatrix. 
     In one form, the quasi-revolution shape has a tonnoid shape. It can also have local peculiarities such as slight bosses or shrinkage. 
     The first, second and third layers of fibers constituting the fabric can have different surface masses, or even variable surface masses within the same layer, for example by variation in fiber density within said layer. 
     The non-developable shape element has a surface close to a revolution surface and a longitudinal axis. 
     Steps b) and c) allow the fabric to be shaped, so as to obtain the preform. 
     More particularly, step c) makes it possible to slide the circumferential fibers in their sheaths, which causes an unraveling of the fibers of the second and third layers of the fabric, which are held by the seams. 
     The term “unraveling” means that the angles of the fibers of the second and third layers, relative to the circumferential fibers, vary within the fabric. 
     The unraveling is performed according to the gradient of curvature of the non-developable shape element. 
     Thus, the fabric is pressed against the non-developable shape element. 
     This shaping is accompanied by relative displacements of the fibers of the different layers of the fabric. The fabric then acquires a non-developable shape identical to that of the non-developable shape element to which it is applied, so as to obtain the preform. 
     The non-developable shape of the preform is retained, this is referred to as plastic or durable deformation as opposed to elastic deformation, thanks to the friction resulting from the seams binding the fibers of the different layers. 
     According to other characteristics of the present disclosure, the method includes one or more of the following optional characteristics considered alone or according to all possible combinations. 
     In a first variant, step c) is carried out by tensioning the circumferential fibers, so as to slide the circumferential fibers in the sheaths formed by the seams and to unravel the fibers of the second and third layers. 
     According to this variant, the ends of the fibers of the second and third layers can also be held by holding means such as clamps or adhesives. 
     Advantageously, according to this variant, it is also possible to apply pressure on the fabric in the direction of the non-developable shape element, by means of a pressure such as a bar. 
     Thus, the pressure makes it possible to keep the fibers of the second and third layers pressed against the non-developable shape element and to promote the sliding of the circumferential fibers and therefore the unraveling of the fibers of the second and third layers. 
     In another form, the pressure is displaced tangentially to the non-developable shape towards one or more free ends of the preform. 
     During step c), the fibers of the second and third layers are advantageously put in tension. 
     In yet another variant, step c) is carried out by putting the fibers of the second and third layers in tension and by applying pressure on the fabric in the direction of the non-developable shape element, by means of a pressure such as a bar, so as to slide the circumferential fibers in the sheaths formed by the seams and to unravel the fibers of the second and third layers. 
     In another variant, the pressure is displaced tangentially to the non-developable shape towards one or more free ends of the preform. 
     These variants can also be combined simultaneously or successively or alternately. 
     The tensioning is advantageously carried out gradually, by pulling on the ends of the circumferential fibers and/or of the fibers of the second and third layers. 
     The tensioning is applied manually or mechanically. 
     According to a characteristic, the non-developable shape element is a convex shape element, called male shape element. 
     According to this characteristic, step c) is carried out by rolling up the fabric about the male shape element. 
     According to another characteristic, the non-developable shape element is a concave shape element, called female shape element. 
     According to this characteristic, step c) is carried out by applying at least one roller to the fabric, along the circumference of the female-shape element, to shape the fabric. 
     In one variant, the non-developable shape element has an identical circumference with respect to the desired non-developable final shape part. 
     In another variant, the non-developable shape element has a reduced circumference relative to the desired non-developable final shape part. 
     By “reduced circumference,” it is meant that the geometry is reduced compared to the final shape, the radius of curvature being reduced by the same factor. 
     In the case of the quasi-revolution final shape, the non-developable shape element may have a revolution shape of an identical or reduced circumference with respect to the circumference of the final non-developable shape. 
     According to a characteristic, during step b) the fabric is blocked against the non-developable shape element, using a blocking means, along a generatrix of the non-developable shape element. 
     This blocking step is performed either at a central zone of the fabric or at one end of the fabric. 
     As a result, the fabric has surface masses of fibers per layer of fibers, which are identical or different. 
     Furthermore, the fabric advantageously has constant or variable surface masses within the same layer of fibers, by variation in the surface density of the fibers. 
     In one variant, the fibers of the second and third layers have, during step a), angles relative to the circumferential fibers, respectively less than 90° and greater than 90°. 
     Furthermore, to constitute a balanced distribution of fibers, the angles of the second layer have a value of α, while the angles of the third layer have a value of β=180−α. 
     In one variant, the a is comprised between 15° and 80°. 
     In another variant, the seams are in the shape of a chain knit. 
     The chain-knit shape seams include, in a known manner, a knit pattern, also called a zig-zag, on a first face and a chain pattern on the opposite face. 
     In this variant, the first layer comprising the circumferential fibers is placed either against the knit pattern of the seams, or between the second and third layers. 
     According to a characteristic, the fabric further includes at least one strip of additional fibers, whose orientation is perpendicular to the seams. 
     According to this characteristic, the means for blocking the fabric on the non-developable shape element is placed on this strip of additional fibers. 
     The present disclosure also relates to a preform obtained by the method as described above. 
     Such a preform includes a tri-axial fabric including a first layer including circumferential fibers oriented in a first direction, a second layer comprising fibers oriented in a second direction, and a third layer comprising fibers oriented in a third direction, the fibers of the second and third layers having angles relative to the circumferential fibers which are variable within the preform. 
     The present disclosure also concerns a method for obtaining a part made of a composite material of the revolution or quasi-revolution non-developable final shape type, having a longitudinal axis, characterized in that it includes a step of manufacturing a preform according to the method as described above, and an additional step of applying the preform on a non-developable shape module identical to the desired non-developable final shape part and of consolidation by insertion and hot or cold polymerization of the matrix. 
     According to a characteristic, during the additional step, several preforms are applied to the non-developable shape module identical to the desired non-developable final shape part. 
     According to another characteristic, other fabric structures can be added locally. 
     These other structures are advantageously added in the stack of fabric layers. 
     Alternatively, at least a portion of these other structures is added on top of the fabric layers. 
     As a further variant, at least part of these other structures is added below the fabric layers. 
     The present disclosure further concerns a part made of composite material of the revolution or quasi-revolution non-developable final shape type, manufactured using the preform obtained by the method as described above. 
     The part made of a composite material of the revolution or quasi-revolution non-developable final shape type, is delimited by a surface defined by a set of generatrixes in planes parallel to the longitudinal axis, whose at least one generatrix is a curve of order greater than or equal to two, and whose curves contained in planes perpendicular to the longitudinal axis intercept at least one point of each generatrix. 
     In one variant, the part made of composite material has a tonnoid shape. 
     It can further have local peculiarities such as slight bosses or shrinkage. 
     The part made of composite material of the revolution or quasi-revolution non-developable final shape type comprises the preform obtained by the method as described above. 
     The part made of composite material of the revolution or quasi-revolution non-developable final shape type is characterized in that it includes a fabric whose seams form sheaths for the so-called circumferential fibers of the same layer of the fabric, said seams being parallel to the circumferential direction of the part. 
     This part made of composite material has the characteristic that the fibers do not exhibit wrinkles or breaks. It includes a fabric with fibers of the same layer oriented parallel to each other and parallel to the circumferential direction of the part made of composite material and fibers of two other layers having angles which evolve along the longitudinal direction of the part made of composite material. 
     The present disclosure also concerns a nacelle comprising a part as described above. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a schematic perspective side view of a quasi-revolution non-developable final shape part about a longitudinal axis according to the present disclosure, including a tri-axial non-woven fabric; 
         FIG. 2  is a schematic sectional view illustrating the fabric used for the manufacture of the part of  FIG. 1 ; 
         FIG. 3  is a schematic top view of the fabric of  FIG. 2 ; 
         FIG. 4  is a schematic top view of a variant of the fabric of  FIG. 3 ; 
         FIGS. 5 a , 5 b   ,  6 ,  7 ,  8 ,  9   a  and  9   b  illustrate a first variant of the method for manufacturing the part of  FIG. 1 ; 
         FIG. 10  is a schematic side view of the part of  FIG. 1 , illustrating the angles between the circumferential fibers and the fibers of the second and third layers; and 
         FIG. 11  is a partial schematic view of the part of  FIG. 1 , including a strip of additional fibers. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
       FIG. 1  represents a part  10  of a quasi-revolution non-developable final shape according to the present disclosure. 
     The part  10  is a panel having the shape of a half barrel. 
     In one form, the shape of the part  10  may be ovoid or irregular potato-shape. 
     The part  10  has a longitudinal axis A. It has a circumferential direction  11 , and a curved generatrix  12  whose radius of curvature changes along the longitudinal axis A. 
     The part  10  is made of a composite material. It includes a tri-axial non-woven fabric  13 . 
     The part  10  is draped with a tri-axial non-woven fabric  13 . 
     In one variant, the part  10  made of composite material includes several tri-axial non-woven fabrics  13 . 
     As illustrated in  FIG. 2 , the tri-axial non-woven fabric  13  used for the manufacture of the part  10 , includes a first layer  14 A, a second layer  14 B and a third layer  14 C. 
     The first, second and third layers  14 A,  14 B and  14 C are superimposed, the first layer  14 A being the upper layer, the second layer  14 B being the middle layer and the third layer  14 C being the lower layer. 
     Said layers can be called sheets or unidirectional sheets. 
     Each layer consists of fibers disposed parallel to each other. 
     The first layer  14 A comprises circumferential fibers  15  oriented in a first direction, while the second layer  14 B comprises fibers  16  oriented in a second direction and the third layer  14 C comprises fibers  17  oriented in a third direction. 
     The circumferential fibers  15  and the fibers  16  and  17  of the second and third layers are disposed superimposed in planes parallel to each other. 
     The fibers  16  of the second layer  14 B form an angle α ( FIG. 1 ) with the circumferential fibers  15  and the fibers  17  of the third layer  14 C form an angle β ( FIG. 1 ) with the circumferential fibers  15 . 
     The angle β is generally equal to 180−α, and in one form α=60°, so as to obtain a quasi-isotropic behavior in the plane of the fabric  13 . 
     The first layer  14 A including the circumferential fibers is, in one form, an upper layer of the fabric  13 . 
     The fibers  15 ,  16  and  17  of said layers  14 A,  14 B and  14 C are grouped together in strands which are connected together by seams  18  ( FIG. 3 ). 
     As shown in  FIG. 3 , the seams  18  are knit-shape on a first side of the tri-axial non-woven fabric  13 , while they are chain-shaped (not shown) on a second side (not shown) of the tri-axial non-woven fabric  13 , the second face being opposite to the first face. 
     The chain shape corresponds to parallel lines of so-called chain stitches, while the knit shape corresponds to transverse segments  180  connecting two adjacent chain stitches. 
     In a variant represented in  FIG. 4 , the knit shape corresponds to an alternation of transverse segments  180  and longitudinal segments  181 . 
     The seams  18  extend parallel to each other and parallel to the circumferential fibers  15  of the first layer  14 A. 
     The first layer  14 A including the circumferential fibers  15  is positioned in contact with the knit pattern, that is to say in contact with the transverse segments, of the seams  18 . 
     Thus, the first layer  14 A including the circumferential fibers  15  is positioned between the transverse segments of the seams  18  and the second layer  14 B, which is disposed between the first layer  14 A and the third layer  14 C, which is itself disposed between the second layer  14 B and the chain stitches of the seams  18 . 
     The transverse segments  180  of the seams  18  and the fibers  16 ,  17  of the second and third layers  14 B,  14 C, then form sheaths for strands of circumferential fibers  15 . 
     Said strands of circumferential fibers  15  are encased by the sheaths thus formed. 
     In a variant not shown, the first layer  14 A including the circumferential fibers  15  is positioned between the second and third layers  14 B and  14 C. 
     According to this variant, the seams  18  can be in independent parallel lines on the two faces of the fabric  13 , that is to say formed, for example, of straight chains comprising on one face only segments  181  parallel to the circumferential fibers  15  and chain loops on the other face. 
     The fibers  16 ,  17  of the second and third layers  14 B,  14 C then form sheaths between two seam lines  18  for strands of circumferential fibers  15 . 
     Referring to  FIG. 1 , the circumferential fibers  15  are parallel to the circumferential direction  11  of the part  10 . 
       FIGS. 5 a  and 5 b    illustrate a first step of a first variant of the method for obtaining the part  10 , in which the tri-axial non-woven fabric  13  is placed, in the shape of a strip having two opposite ends  20 A and  20 B ( FIG. 6 ), on a roller  21  of non-developable shape having a revolution surface of reduced dimensions compared to the desired final non-developable shape and having a circumferential direction  22 , by placing the circumferential fibers  15  parallel to the circumferential direction  22  of the roller  21 . 
     This first step corresponds to step b) as presented above in relation to obtain a preform. 
     The roller  21  of non-developable shape then has a dome shape or male shape. 
     This first variant is called dome forming. 
     The roller has a tonnoid shape. 
     The tri-axial non-woven fabric  13  is blocked against the roller  21  by a clamped bar  23  ( FIG. 5 b   ), along a generatrix  24  of the roller  21  ( FIG. 5 a   ). 
     In the example of  FIG. 6 , the clamped bar  23  blocks the tri-axial non-woven fabric  13  at a central zone Z of said tri-axial non-woven fabric  13 . 
     Thus, the ends  20 A and  20 B are free. 
       FIG. 6  illustrates a second step of the first variant of the method for obtaining the part  10 , in which a tension is applied in the direction of the arrow F on the end  20 B of the circumferential fibers  15 , by causing the roller  21  to pivot along the arrow R. 
     This second step corresponds to step c) as presented above in relation to obtain a preform. 
     This tension allows the circumferential fibers  15  to slide in their sheaths formed by the seams  18 , so that the tri-axial non-woven fabric  13  is pressed against the roller  21 . 
     The tri-axial non-woven fabric  13  is then in continuous contact with the roller  21 . 
     During the sliding of the circumferential fibers  15 , the fibers  16  and  17  of the second and third layers of the tri-axial non-woven fabric  13  are unraveled as a function of the local perimeters of the roller  21 . 
     Indeed, the fibers  16  and  17  of the second and third layers are retained by the seams  18 . 
     Thus, the angles α and β formed between the fibers  16  and  17  respectively of the second and third layers, and the circumferential fibers  15 , vary within the tri-axial non-woven fabric  13  ( FIG. 10 ). 
     During this second step, it is also possible to use a bar  25  to apply pressure on the tri-axial non-woven fabric  13  in the direction of the roller. 
     Holding means such as clamps or adhesives (not shown) make it possible to hold the ends of the fibers  16  and  17  of the second and third layers  14 B and  14 C. 
     These holding means also make it possible to apply tensions on the ends of fibers  16  and  17  of the second and third layers  14 B and  14 C to promote the plating on the shape of the roller  21 . 
       FIG. 7  illustrates the tri-axial non-woven fabric  13  thus rolled up about the roller  21 . 
     The portion of tri-axial non-woven fabric  13  between the central zone Z and the end  20 B of the tri-axial non-woven fabric  13  having been shaped about the roller is blocked against the roller  21  by applying an adhesive or a clamped bar (not shown), among others, that can be removed, so as to keep the tri-axial non-woven fabric  13  rolled up around the roller  21 . The end  20 B is then reversibly blocked. 
     During this second step, the part of tri-axial non-woven fabric  13  is then rolled up between the central zone Z and the opposite end  20 A of the tri-axial non-woven fabric  13  around the roller  21  by pivoting said roller  21  in the direction reverse of the arrow R ( FIG. 6 ), although this is not shown, so as to shape the rest of the tri-axial non-woven fabric  13  around the roller  21 . 
     At the end of this second step, the tri-axial non-woven fabric  13  is shaped, as illustrated in  FIG. 8 . 
       FIG. 8  shows that the circumferential fibers  15  have slipped in the sheaths relative to the fibers  16 ,  17  of the second and third layers  14 B,  14 C after shaping about the roller  21  of a non-developable shape. 
     Before shaping, the ends of the circumferential fibers  15  would have been aligned. 
     In a variant not shown, the first layer  14 A is locally unbound from the second and third layers  14 B,  14 C, in the vicinity of the ends of the fibers  15 , so as to facilitate the gripping of the fibers of these different layers, for the application of the tension or their holding. 
     In another variant not shown, the lateral edges of the fabric  13 , only include fibers  16 ,  17  of the second and third layers  14 B and  14 C, without circumferential fibers  15 , so as to facilitate the gripping of the fibers of the second and third layers  14 B and  14 C independently of the circumferential fibers  15 . 
     A preform  26  ( FIG. 9 a   ) of tri-axial non-woven fabric  13  is obtained, whose angles α and β are variable within the tri-axial non-woven fabric  13 . 
       FIGS. 9 a  and 9 b    illustrate a third step of the first variant of the method for obtaining part  10 , in which the preform  26  is applied to a module  27  identical to the part  10  of the desired final non-developable shape. 
     This third step corresponds to the additional step as presented above in relation to obtain a part made of a composite material of the revolution or quasi-revolution non-developable final shape type. 
     The preform  26  is applied by disposing the seams  18  parallel to the circumferential direction  28  of the module  27 . 
     The module  27  then has a dome shape or male shape. 
     During this third step, the application of the preform  26  on the module  27  is called dome draping. 
     As a variant, the preform  26  can be applied in a module identical to the part  10  of the desired non-developable final shape. 
     The module then has a cradle shape or female shape. 
     The preform  26  matches the shape of the module. It is in continuous contact with the module. 
     This third step is followed by a resin impregnation step and then by a polymerization step, so as to obtain the part  10  according to the present disclosure, as illustrated in  FIG. 1 . 
       FIG. 10  illustrates the variations of angles α and β between circumferential fibers  15  and fibers  16  and  17  of the second and third layers. 
     The angles α between the circumferential fibers  15  and the fibers  16  of the second layer vary between −15° and +15° with respect to the initial orientations of the tri-axial non-woven fabric before shaping. The angle change is desired to achieve the double curvature. 
     The angles β between the circumferential fibers  15  and the fibers  17  of the third layer vary in the same way as the angles between the circumferential fibers  15  and the fibers  16  of the second layer. 
       FIG. 11  illustrates a variant of part  10  including a tri-axial non-woven fabric  13  including a strip of additional fibers  29  whose orientation is perpendicular to the circumferential fibers  15 . 
     According to this variant, the clamped bar  23  ( FIG. 6 ) of the tri-axial non-woven fabric  13  on the roller  21  is disposed on this strip of additional fibers  29 , or close to it. 
     The strip of additional fibers  29  is, in one variant, disposed in a zone with little unraveling. 
     It has the effect of further blocking the deformation of the tri-axial non-woven fabric due to the fourth fiber direction. This strip is, in one variant, narrow with respect to the dimensions of the fabric and to the circumference of the roller  21 . 
     In a second variant, not shown, of the method for obtaining the part  10 , the first step consists in placing the tri-axial non-woven fabric  13 , in the form of a strip having two opposite ends  20 A and  20 B ( FIG. 6 ), directly on the module  27  ( FIGS. 9 a   ,  9   b ) identical to the part  10  of the desired final non-developable shape, by placing the circumferential fibers  15  parallel to the circumferential direction  28  of the module  27 . 
     In this first step, the tri-axial non-woven fabric  13  is held pressed against the module  27  by a clamped bar (not shown), along a generatrix  30  of the module  27 . 
     The clamped bar blocks the tri-axial non-woven fabric  13  at one end  20 A of said tri-axial non-woven fabric  13 . 
     The second step then comprises of applying a tension in the opposite direction to the blocked end  20 A, on the free end  20 B of the circumferential fibers  15 . 
     As a variant, during the first step, the clamped bar blocks the tri-axial non-woven fabric  13  at a central zone of the tri-axial non-woven fabric  13 . 
     According to this variant, the second step consists in applying a tension at the level of the two ends  20 A,  20 B of the circumferential fibers  15 . 
     This tension allows the circumferential fibers  15  to slide in their sheaths formed by the seams  18 , so that the tri-axial non-woven fabric  13  is pressed against the module  27 . 
     The tri-axial non-woven fabric  13  is then in continuous contact with the module  27 . 
     The tension is gradually applied to the ends of the circumferential fibers  15 , along the longitudinal axis (not shown) of the module. 
     During the sliding of the circumferential fibers  15 , the fibers  16  and  17  of the second and third layers of the tri-axial non-woven fabric  13  are unraveled according to the local perimeters on the module  27 . 
     Thus, the angles α and β formed between the fibers  16  and  17  respectively of the second and third layers, and the circumferential fibers  15 , vary within the tri-axial non-woven fabric  13  ( FIG. 10 ). 
     During this second step, a bar (not shown) exerts pressure on the tri-axial non-woven fabric  13  in the direction of the module  27 . 
     Holding means such as clamps or adhesives (not shown) make it possible to hold the ends of the fibers  16  and  17  of the second and third layers  14 B and  14 C. 
     At the end of this second step, the tri-axial non-woven fabric  13  is shaped. 
     This step is followed by a resin impregnation step then by a polymerization step, so as to obtain the part  10  according to the present disclosure, as illustrated in  FIG. 1 . 
     In a third variant not shown, the first step consists in disposing the tri-axial non-woven fabric  13 , in the form of a strip having two opposite ends  20 A and  20 B ( FIG. 6 ), in an element of non-developable female or cradle shape, which may be identical to the desired final non-developable shape. 
     As a variant, the female shape has a revolution surface of reduced dimensions compared to the desired non-developable final shape. 
     According to this variant, the tri-axial non-woven fabric  13  is clamped against the element by a clamped bar, along a generatrix of the element. 
     A tension is then applied on the circumferential fibers  15  by clamping the tri-axial non-woven fabric  13  against the cradle element, while applying the tri-axial non-woven fabric  13  along the surface of the female shape by pressing rollers or pushing elements, or by displacing the clamping bar along the circumferential direction of the element. 
     In this way, the tri-axial non-woven fabric  13  is gradually pressed into continuous contact with the surface of the female shape. 
     The parts  10  according to the present disclosure do not only include tri-axial non-woven fabric  13 . They can also include other layers of fibers of other materials, and/or biaxial woven or non-woven fabrics. 
     In variants not shown, the non-woven fabric could be one or more quadri-axial non-woven fabric. 
     Further, in other variations, the non-woven fabric could be a tri-axial multilayer fabric, that is to say including three directions of fibers, but more than three layers of fibers. For example the non-woven fabric may be a tri-axial penta-layer including one layer  14 A comprising circumferential fibers  15  oriented in a first direction, two layers  14 B comprising fibers  16  oriented in a second direction, and two layers  14 C comprising fibers  17  oriented in a third direction. 
     According to this example, the layer  14 A comprising the circumferential fibers  15  oriented in a first direction is disposed between the layers  14 B and  14 C comprising the fibers  16  and  17  oriented in the other directions, said layers  14 B and  14 C being alternated. Thus, resulting in the following stack: 
     layer  14 B including the fibers  16  oriented in the second direction, 
     layer  14 C including the fibers  17  oriented in the third direction, 
     layer  14 A including the circumferential fibers  15  oriented in the first direction, 
     layer  14 C including the fibers  17  oriented in the third direction, 
     layer  14 B including the fibers  16  oriented in the second direction. 
     This sequence offers a so-called “mirror” stack balanced in the direction of thickness. 
     The method presented above on a double curvature shape including a so-called tonnoid convex face, also applies to shapes having curved generatrixes such as diabolo shapes, or shapes with corrugated generatrixes then including parts which can be compared to tonnoid shapes and parts comparable to diabolo shapes. 
     Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability. 
     As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” 
     The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.