Characterization modeling method for surface topography characteristics of two-dimensional woven ceramic matrix composite material

Abstract

The invention discloses a characterization modeling method for surface topography features of a two-dimensional braided ceramic matrix composite, which combines X-ray computed tomography and laser confocal microscopic scanning means to extract geometric feature parameters of a real CMC surface braided structure, and introduces dimensionless scale parameters to carry out unified characterization on surface braided units. Through two-dimensional equivalent contour construction, three-dimensional stretching and Boolean operation, an equivalent geometric model capable of truly reflecting CMC surface weaving morphology features is established. Compared with a traditional smooth or simplified roughness model, the method can accurately describe the main characteristics of the weaving texture of the CMC surface, and has remarkable consistency in the aspects of geometric dimension, weaving angle, boundary transition and the like; therefore, a reliable modeling basis is provided for heat transfer analysis, cooling design and engineering optimization of the CMC turbine blade under different pneumatic and thermal load conditions, and heat transfer prediction precision and structural design rationality in a high-temperature service environment are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of surface feature modeling and heat transfer design technology for high-temperature components of aero-engines, and particularly to a characterization and modeling method for the surface morphology features of two-dimensional braided ceramic matrix composites. Background Technology

[0002] With the continuous development of advanced aero-engines and hypersonic vehicles, the service temperature of engine hot-end components (especially turbine blades) is constantly increasing, and traditional metal high-temperature alloy blades are gradually approaching their performance limits in terms of heat transfer and cooling design. In recent years, ceramic matrix composites (CMCs) have become the most promising material system for replacing metal materials and achieving lightweight and high-temperature resistant turbine blades due to their ability to maintain strength at high temperatures, low density, and oxidation resistance.

[0003] However, unlike traditional metallic materials, the manufacturing processes of CMC (such as braiding, chemical vapor infiltration, and polymer infiltration ablation) inevitably create regular braided morphology features on the blade surface. These features are not smooth or simplified surface roughness, but rather periodic textures caused by factors such as interwoven fiber bundles, uneven matrix filling, and localized spalling. They manifest as a unique morphology with both depressions and protrusions below the smooth profile baseline. This unique surface structure significantly alters boundary layer development, turbulence characteristics, and convective heat transfer distribution, thereby directly affecting the heat load distribution and cooling design of turbine blades.

[0004] Existing studies typically simplify the CMC blade surface to a smooth surface or use only idealized roughness models for heat transfer analysis. This approach fails to accurately reflect the true geometric characteristics of the braided structure, leading to significant biases in heat transfer predictions. Furthermore, the surface morphology of CMCs prepared using different processes exhibits a degree of designability and controllability; for example, the height, width, and braiding angle of the braided units can be controlled through fiber bundle parameters and processing techniques. Therefore, without a unified and accurate characterization model, it is impossible to effectively capture the regularity of true surface characteristics or provide fundamental support for the control and optimization of surface morphology in engineering design.

[0005] In recent years, some scholars have attempted to provide a preliminary description of the surface morphology of CMC (Chemical Motion Compactor) using microscopic measurements and numerical modeling methods. However, most of these efforts remain at the level of two-dimensional cross-sections or idealized geometry, lacking modeling methods driven by actual scanning data. In particular, the mechanism by which surface morphology affects flow and heat transfer under the complex pressure gradient environment of turbine blades remains unclear.

[0006] Therefore, there is an urgent need to establish a method that can extract parameters based on real scanning results, introduce a unified dimensionless characterization factor, and construct a two-dimensional to three-dimensional equivalent geometric model. Summary of the Invention

[0007] This invention provides a characterization and modeling method for the surface morphology of two-dimensional braided ceramic matrix composites (CMCs), addressing the limitations of existing research in lacking unified characterization and accurate modeling of complex braided textures on CMC surfaces. Through an equivalent modeling process based on real scan data, it achieves unified, parameterized, and high-precision characterization of complex braided textures on CMC surfaces, significantly improving the fit between the geometric model and the actual surface. This provides a reliable modeling foundation for aerodynamic heat transfer analysis, cooling design, and life assessment of high-temperature components such as turbine blades for aero-engines.

[0008] This invention provides a method for characterizing and modeling the surface morphology of two-dimensional braided ceramic matrix composites, comprising the following steps: Step 1: The surface of the two-dimensional braided ceramic matrix composite blade is scanned and measured by a combination of X-ray computed tomography and laser confocal microscopy to obtain the geometric characteristic parameters of the braided morphology on the surface of the two-dimensional braided ceramic matrix composite blade. Step 2: Extract the feature contour of the protruding unit on the surface of the two-dimensional braided ceramic matrix composite blade based on the obtained geometric feature parameters. The protruding unit of the braided morphology on the surface of the two-dimensional braided ceramic matrix composite blade is lower than the reference surface of the smooth blade profile, and presents the geometric feature of low concave boss. Construct a two-dimensional equivalent contour and use smooth transition fitting on the contour boundary. Introduce dimensionless parameters to uniformly characterize the geometric scale of the surface braided unit. Step 3: Based on the two-dimensional equivalent contour, an equivalent surface model containing periodic distribution units is generated through three-dimensional stretching and sweeping operations. Boolean operations are then combined to form a complete three-dimensional equivalent fabric surface model. The boundary transition between texture feature areas and smooth surface areas in the three-dimensional equivalent fabric surface model is corrected using rounded corner radii.

[0009] Optionally, in one embodiment of the present invention, in step 1, the geometric feature parameters of the weaving morphology on the surface of the two-dimensional braided ceramic matrix composite blade include: the height, width, weaving angle, boundary transition fillet, and thickness of the matrix peeling layer of the protruding unit.

[0010] Optionally, in one embodiment of the present invention, in step 1, X-ray computed tomography is used to identify the recessed areas and fiber protrusions formed on the surface of the woven ceramic matrix composite blade due to matrix peeling, and laser confocal microscopy is used to obtain the actual height difference of the protrusion units, the details of the corner recesses, and the transition rounded corner features.

[0011] Optionally, in one embodiment of the present invention, in step 2, the geometric features of the protruding unit are periodic bosses that are lower than the smooth surface, with an approximately rectangular cross-section and local concavities in the four corner areas, which is different from the protruding features of the traditional metal blade roughness model.

[0012] Optionally, in one embodiment of the present invention, in step 2, the dimensionless parameter is defined as the ratio of the unit line width to the overall width, which is used to characterize the geometric morphology changes of the surface protrusion unit under different processes.

[0013] Optionally, in one embodiment of the present invention, in step 3, the two-dimensional equivalent contour is smoothly fitted using piecewise curves, the three-dimensional surface is generated by sweeping, and Boolean operations are used to connect the unit cycles, so that the overall surface maintains continuity and periodicity.

[0014] Optionally, in one embodiment of the present invention, the method further includes: comparing and verifying the established three-dimensional equivalent fabric surface model with the actual scanned two-dimensional woven ceramic matrix composite blade surface; measuring the geometric features of the two-dimensional woven ceramic matrix composite blade surface using a laser confocal microscope; and comparing the geometric features with the design values ​​to obtain the maximum error of the width, height, and weaving angle not exceeding the threshold.

[0015] The surface morphology characterization and modeling method for two-dimensional braided ceramic matrix composites (CMC) according to embodiments of the present invention achieves high-fidelity, parametric characterization of complex braided surfaces by starting from real scan data and combining dimensionless parameter definitions with a three-dimensional equivalent modeling process. The core innovation of this method lies in overcoming the limitations of traditional roughness models and establishing a unified geometric modeling framework applicable to heat transfer analysis and design optimization. Furthermore, its geometric accuracy is experimentally verified, enabling its direct application to predict aerodynamic heat transfer in CMC turbine blades. This approach not only improves the model's fidelity to actual surfaces but also provides a new technical path for the future cooling design and life assessment of CMC materials under extreme thermal environments.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A flowchart illustrating a method for characterizing and modeling the surface morphology of a two-dimensional braided ceramic matrix composite material according to an embodiment of the present invention; Figure 2This is a schematic diagram of the cross-sectional scan of a 2D CMC braided blade and an XCT scan, representing an embodiment of the present invention. Figure 3 This is a partial scanning diagram of the surface morphology of a 2D CMC braided blade according to an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the process of establishing the feature lines and surfaces of the 2D CMC surface equivalent model according to an embodiment of the present invention; Figure 5 This is an equivalent model and dimension annotation of the 2D CMC surface morphology features in an embodiment of the present invention; Figure 6 The surface morphology scan of the actual object of the 2D CMC equivalent model in the embodiment of the present invention; Figure 7 This is a comparison chart of the Nusselt numbers of the test results of blades with 2D CMC morphology features and blades with roughness, according to an embodiment of the present invention. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] Figure 1 This is a flowchart illustrating a method for characterizing and modeling the surface morphology of a two-dimensional braided ceramic matrix composite material according to an embodiment of the present invention.

[0020] like Figure 1 As shown, the characterization and modeling method for the surface morphology features of this two-dimensional braided ceramic matrix composite (2D CMC) includes the following steps: Step 1: The surface of the two-dimensional braided ceramic matrix composite blade is scanned and measured using a combination of X-ray computed tomography (XCT) and laser confocal microscopy to obtain the geometric characteristic parameters of the braided morphology of the two-dimensional braided ceramic matrix composite blade surface, including the height, width, braiding angle, boundary transition radius, and thickness of the matrix peeling layer of the raised unit.

[0021] In embodiments of the present invention, X-ray computed tomography is used to identify the recessed areas and fiber protrusions formed on the surface of the woven ceramic matrix composite blade due to matrix peeling, and laser confocal microscopy is used to obtain the actual height difference of the protrusion units, details of the corner recesses, and transition rounded corner features.

[0022] Step 2: Extract the feature contours of the protruding units on the surface of the two-dimensional braided ceramic matrix composite blade based on the obtained geometric feature parameters. The protruding units of the braided morphology on the surface of the two-dimensional braided ceramic matrix composite blade are lower than the reference surface of the smooth blade profile, exhibiting the geometric features of low-concave bosses. Construct a two-dimensional equivalent contour and apply a smooth transition fitting to the contour boundary. Introduce dimensionless parameters to uniformly characterize the geometric scale of the surface braided units.

[0023] In an embodiment of the present invention, the geometric features of the protruding unit are periodic bosses that are lower than the smooth surface, with an approximately rectangular cross-section and local concavities in the four corner areas, which is different from the protruding features of the traditional metal blade roughness model.

[0024] In embodiments of the present invention, a dimensionless parameter ω is introduced to uniformly characterize the geometric dimensions of the surface weave unit, where ω is defined as the unit line width. W s With overall width W t The ratio of [value] can be used to characterize the geometric morphology changes of surface protrusion units under different processes. It is derived from actual scanning data and also considers the designability of the 2D CMC process, making the unit height [value] [value]. H 0 ,width D 0 Weaving angle S 0 The parameters can be adjusted according to the weaving and densification processes to achieve parametric generation of different morphological models. Because the surface morphology of CMC is designable, the height of the unit... H 0 ,width D 0 and weaving angle S 0 All parameters can be adjusted, thus achieving scalability of the equivalent model.

[0025] Step 3: Based on the two-dimensional equivalent contour, an equivalent surface model containing periodically distributed units is generated through three-dimensional stretching and sweeping operations. Boolean operations are then combined to form a complete three-dimensional equivalent fabric surface model. The boundary transition between textured regions and smooth surface regions in the three-dimensional equivalent fabric surface model uses a rounded corner radius. R 0 Make corrections.

[0026] In embodiments of the present invention, the two-dimensional equivalent contour is smoothly fitted using piecewise curves, the three-dimensional surface is generated by sweeping, and Boolean operations are used to connect the unit cycles, so that the overall surface maintains continuity and periodicity.

[0027] In embodiments of the present invention, the established equivalent geometric model is compared and verified with the actual scanned surface. The geometric features of a typical test piece are measured using a laser confocal microscope and compared with the design values ​​to obtain the width. D 0 ,high H 0 With the weaving angle S 0 The maximum error does not exceed 0.031 mm, which meets the accuracy requirements for heat transfer analysis.

[0028] The equivalent geometric model was used to fabricate test pieces via SLA 3D printing. Scanning measurements showed that the geometric accuracy of the characterization model was within ±0.05 mm, effectively reproducing the surface texture features of real CMC. This characterization modeling method can accurately depict the main weave morphology of 2D CMC blade surfaces, providing a unified geometric model basis for aerodynamic heat transfer analysis, cooling design, and thermal protection performance prediction, thereby improving the accuracy and reliability of heat transfer prediction under high-temperature component service conditions.

[0029] This method can not only accurately reproduce the woven morphology features of the 2D CMC surface, but also ensure high geometric consistency with the actual blade surface, thus providing a reliable basis for the aerodynamic thermal analysis, cooling structure design and service life prediction of CMC turbine blades.

[0030] This invention proposes a characterization and modeling method for the surface morphology of two-dimensional braided ceramic matrix composites. Its core lies in obtaining geometric feature parameters through real surface scanning and establishing an equivalent model with unified parameter definitions and high geometric accuracy, which can then be used for turbine blade heat transfer analysis.

[0031] like Figure 2 As shown, a two-dimensional braided ceramic matrix composite (CMC) blade and its XCT cross-sectional scan diagram are presented. The XCT results reveal a distinct braided morphology on the 2D CMC blade surface. This morphology is formed by surface undulations caused by interlacing fiber bundles and uneven matrix filling. Its surface morphology differs from the smooth surface of traditional metal blades and does not exhibit the random distribution characteristics of conventional roughness. Instead, it displays a periodic boss structure with a braided pattern, and its formation mechanism is closely related to localized spalling defects in the matrix.

[0032] like Figure 3 The image shows a high-resolution scan of a local area on the surface of a 2D CMC braided blade. By using a laser confocal microscope to scan a typical area, the geometric characteristic parameters of the surface units, including the height of the raised units, can be accurately obtained. H 0 ,width D 0 Weaving angle S0 and the radius of the boundary fillet R 0 The scanning results revealed that individual geometric features are approximately rectangular in cross-section, with concave regions at the four corners. Statistical analysis of the platform width and total width in the surface morphology allows for the further acquisition of a dimensionless parametric description.

[0033] like Figure 4 As shown, the process of establishing the feature lines and surfaces of the 2D CMC surface equivalent model is presented. First, the two-dimensional geometric feature contours of the surface units are extracted based on the scan data. Second, the boundaries are made continuous using piecewise smooth curves, and local concave regions are reconstructed using rounded corner transitions to ensure the smoothness and realism of the geometric features. To unify the surface features under different fabrication conditions, a dimensionless parameter ω = is introduced. W s / W t (in W s The width of the unit line. W t (This refers to the overall width), used to standardize geometric proportions. This paper statistically yields ω=0.6. This parameter not only originates from actual scanning results but also possesses design flexibility, allowing for variations in geometric parameters. H 0 , D 0 , S 0 These variables can all be used as adjustable variables, facilitating the application of the model under different weaving process conditions. Finally, complete surface geometric units are obtained through three-dimensional stretching and sweeping operations, and periodically distributed fabric surface structures are generated using Boolean operations.

[0034] like Figure 5 As shown, the final 2D CMC surface morphology equivalent model and its geometric dimensions are presented. This equivalent model fully preserves the protrusion height, width, and rounded corner features within the unit scale, and forms a continuous surface through periodic splicing.

[0035] like Figure 6 As shown, the surface morphology scan of the equivalent model sample is presented. A typical equivalent surface sample was prepared by 3D printing, and its surface was scanned using a laser confocal microscope. Comparison with the surface morphology of a real 2D CMC braided blade reveals that the sample is highly consistent with the real structure in terms of the "central boss and four corner recesses" features, verifying the rationality and accuracy of the equivalent model construction method.

[0036] like Figure 7As shown, the Nusselt number distribution of blades with 2D CMC surface morphology features and blades with conventional roughness was compared in heat transfer experiments. The results show that the conventional roughness model cannot reflect the fluctuating description of heat transfer behavior by CMC surface morphology, while the 2D CMC equivalent characterization model established in this invention can clearly reveal the periodic fluctuation characteristics of heat transfer distribution, making heat transfer and flow prediction closer to the real laws, demonstrating the necessity and superiority of this modeling method in heat transfer research.

[0037] In summary, the two-dimensional CMC surface morphology feature characterization and modeling method proposed in this invention can accurately capture the real weave morphology features, and achieve the unification and designability of geometric features by introducing the dimensionless parameter ω. Compared with traditional roughness models, this method shows significant advantages in both geometric modeling accuracy and heat transfer prediction accuracy, and can provide a reliable geometric modeling foundation for aerodynamic heat transfer analysis, cooling structure design, and service life prediction of CMC turbine blades.

[0038] The method for characterizing and modeling the surface morphology of two-dimensional braided ceramic matrix composites (CMCs) proposed in this invention addresses the limitations of existing research in lacking a unified characterization and accurate modeling of complex braided textures on CMC surfaces. It innovatively combines X-ray computed tomography (XCT) and laser confocal microscopy to extract the geometric feature parameters of the actual CMC surface braided structure and introduces dimensionless scale parameters to unify the characterization of the surface braided units. Through two-dimensional equivalent contour construction, three-dimensional stretching, and Boolean operations, an equivalent geometric model that accurately reflects the braided morphology of the CMC surface is established. Compared with traditional smoothing or simplified roughness models, this invention can accurately characterize the main features of the braided texture on the CMC surface, exhibiting significant consistency in geometric dimensions, braiding angles, and boundary transitions. This provides a reliable modeling foundation for heat transfer analysis, cooling design, and engineering optimization of CMC turbine blades under different aerodynamic and thermal load conditions, significantly improving the accuracy of heat transfer prediction and the rationality of structural design in high-temperature service environments.

[0039] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

Claims

1. A method for characterizing and modeling the surface morphology of a two-dimensional braided ceramic matrix composite material, characterized in that, Includes the following steps: Step 1: The surface of the two-dimensional braided ceramic matrix composite blade is scanned and measured by a combination of X-ray computed tomography and laser confocal microscopy to obtain the geometric characteristic parameters of the braided morphology on the surface of the two-dimensional braided ceramic matrix composite blade. Step 2: Extract the feature contour of the protruding unit on the surface of the two-dimensional braided ceramic matrix composite blade based on the obtained geometric feature parameters. The protruding unit of the braided morphology on the surface of the two-dimensional braided ceramic matrix composite blade is lower than the reference surface of the smooth blade profile, and presents the geometric feature of low concave boss. Construct a two-dimensional equivalent contour and use smooth transition fitting on the contour boundary. Introduce dimensionless parameters to uniformly characterize the geometric scale of the surface braided unit. Step 3: Based on the two-dimensional equivalent contour, an equivalent surface model containing periodic distribution units is generated through three-dimensional stretching and sweeping operations. Boolean operations are then combined to form a complete three-dimensional equivalent fabric surface model. The boundary transition between texture feature areas and smooth surface areas in the three-dimensional equivalent fabric surface model is corrected using rounded corner radii.

2. The method according to claim 1, characterized in that, In step 1, the geometric characteristic parameters of the woven morphology on the surface of the two-dimensional woven ceramic matrix composite blade include: the height and width of the raised unit, the weaving angle, the boundary transition fillet, and the thickness of the matrix peeling layer.

3. The method according to claim 1, characterized in that, In step 1, X-ray computed tomography is used to identify the recessed areas and fiber protrusions on the surface of the woven ceramic matrix composite blades caused by matrix peeling, and laser confocal microscopy is used to obtain the actual height difference of the protrusion units, the details of the corner recesses, and the transition rounded corner features.

4. The method according to claim 1, characterized in that, In step 2, the geometric features of the protruding unit are periodic bosses that are lower than the smooth surface. Their cross-section is approximately rectangular, and they exhibit local concavities in the four corner areas, which is different from the protruding features of the traditional metal blade roughness model.

5. The method according to claim 1, characterized in that, In step 2, the dimensionless parameter is defined as the ratio of the unit line width to the overall width, which is used to characterize the geometric morphology changes of the surface protrusion unit under different processes.

6. The method according to claim 1, characterized in that, In step 3, the two-dimensional equivalent contour is smoothly fitted using piecewise curves, the three-dimensional surface is generated by sweeping, and Boolean operations are used to connect the unit cycles, so that the overall surface maintains continuity and periodicity.

7. The method according to claim 1, characterized in that, Also includes: The established three-dimensional equivalent fabric surface model was compared and verified with the actual scanned two-dimensional woven ceramic matrix composite blade surface. The geometric features of the two-dimensional woven ceramic matrix composite blade surface were measured by laser confocal microscopy and compared with the design values. The maximum error of width, height and weaving angle did not exceed the threshold.

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