CN-122020909-A - Curved surface blade structure topology optimization feature geometric reconstruction method based on coordinate space mapping

CN122020909ACN 122020909 ACN122020909 ACN 122020909ACN-122020909-A

Abstract

The invention belongs to the field of structural optimization design, and discloses a geometric reconstruction method of topological optimization features of a curved blade structure based on coordinate space mapping. Based on the topological optimization result of the three-dimensional curved surface blade structure of the engine, carrying out topological optimization geometric reconstruction on the internal ribs, firstly realizing deformation from a three-dimensional grid to a two-dimensional grid, and mapping the three-dimensional node grid onto a rectangular flat plate according to a certain proportion by the three-dimensional density optimization result through grid deformation. And then processing the density result of the surface of the flat plate to obtain a plane density image, capturing key geometric features according to image morphology processing and skeleton extraction technology, and obtaining skeleton point coordinates of corresponding parts. And mapping the extracted pixel skeleton points back to grid nodes in the actual two-dimensional model, re-mapping the extracted pixel skeleton points back to grid nodes of the original three-dimensional blade according to the two-dimensional grid nodes, reconstructing the model in CAD software according to the three-dimensional grid nodes, and combining the original cavity structure to complete geometric reconstruction of the topological optimization of the three-dimensional curved surface structure.

Inventors

MU LIZHONG
XU SHENGLI
WANG XIAOYANG
ZHOU CAIHUA
WANG YUETONG
BU FANZI
YANG CHENGLI
Zhou Baizhuo
LUAN XU

Assignees

大连理工大学
中国航发燃气轮机有限公司

Dates

Publication Date: 20260512
Application Date: 20260211

Claims (9)

1. The curved surface structure topology optimization feature geometric reconstruction method based on coordinate space mapping is characterized by comprising the following steps of: Firstly, establishing a rectangular flat model, carrying out grid deformation on a curved grid expressing density distribution information on a topological optimization density distribution result of a three-dimensional curved blade structure, mapping the deformed grid on the rectangular flat model, simultaneously mapping the topological optimization density distribution result on the rectangular flat model, and processing the topological optimization density distribution result on the rectangular flat model to obtain a two-dimensional density field RGB image; Step 2, inputting a two-dimensional density field RGB image into pycharm software, setting a pixel value threshold of the image through a global fixed threshold binarization method to obtain a binarized image with clear density field characteristics, and performing color inversion on the binarized image to obtain a color-inverted binarized image; Step 3, filtering the binarized image with the color reversed obtained in the previous step by using morphological opening and closing operation, filling small holes mapped to the topological result on the image space and removing discontinuous areas; Step 4, determining the sizes of the removed small color blocks and the filled holes by adjusting the opening and closing and the operation core size and the operation times, repeating the step 4, comparing the images obtained by each treatment, taking the least left holes and discontinuous small color blocks as targets, and finally obtaining the binarized image with the least noise; step 5, aiming at the binarized image processed in the previous step, using a nonlinear filtering technology, and adopting a median filtering function suitable for bandwidth to remove pits and burrs on the boundary to obtain a binarized image with a smooth boundary; Step 6, searching all contours of the binarized image after median filtering processing by using a Suzuki boundary tracking algorithm, extracting to obtain a hierarchical contour and storing all points on the contour; Step 7, respectively carrying out morphological refinement on the contour extracted by each boundary tracking by using a morphological refinement algorithm to obtain a skeleton, and extracting and storing all skeleton points by using a Suzuki boundary tracking algorithm; step 8, mapping the extracted skeleton points to grid nodes on the flat plate obtained by grid deformation in the step 1, and mapping and processing the grid nodes on the curved surface on the original three-dimensional curved surface blade structure to obtain point coordinates of the residual effective material area of the blade after corresponding topological optimization in the three-dimensional real space; Step 9, based on NURBS curve fitting method, selecting the part of the point set obtained in the last step, which belongs to the internal connecting ribs in the blade topology optimization result, and performing integral B spline curve fitting in CAD software to obtain the two-dimensional profile of the internal ribs; And 10, modeling based on a two-dimensional contour, processing an original hollow blade model through a shell extraction function of CAD software to obtain an inner cavity model, stretching and surface processing the rib contour by means of the surface of the inner cavity model to obtain a three-dimensional rib model, and finally carrying out Boolean operation on the three-dimensional rib model and the external entity of the blade left by shell extraction to obtain a complete hollow blade reconstruction model.
2. The geometrical reconstruction method of topological optimization features of a curved surface structure based on coordinate space mapping according to claim 1, wherein in the step 1, the mapping is to change the positions of nodes of the curved surface grid to carry out grid deformation, the connection mode of the nodes is not changed, the number of nodes on the boundary is not changed, and the mapping is carried out on a rectangular flat model.
3. The geometrical reconstruction method of topological optimization features of a curved surface structure based on coordinate space mapping according to claim 1, wherein in step 1, the topological optimization density distribution result on the rectangular flat model is processed by intercepting a two-dimensional density field RGB image in data visualization and analysis software.
4. The method for reconstructing the topological optimization feature geometry of the curved surface structure based on the coordinate space mapping according to claim 1, wherein in the step 2, the existence or non-existence of the density distribution on the rectangular flat model is mapped to be the value of 0 or 255 of the image pixel, the pixel value of the material area before the color inversion is 0, and the pixel value of the material removal area is 255.
5. The method for reconstructing the topological optimization feature geometry of the curved surface structure based on the coordinate space mapping according to claim 1, wherein in the step 2, morphological opening and closing operation is realized in pycharm software through a function in OpenCV.
6. The geometrical reconstruction method of the topological optimization feature of the curved surface structure based on the coordinate space mapping according to claim 1, wherein in the step 4, the repeated operation is carried out for the step 4, and the pixel value window selected by removing the island and removing the cavity is 1.5 times of the island and the cavity.
7. The method for reconstructing the topological optimization feature geometry of the curved surface structure based on the coordinate space mapping according to claim 1, wherein in the step 6, the boundary search screens the effective contour by the number of contour points contained in each contour or the pixel area occupied by the contour in the pixel space, and further removes the small contour which is difficult to reconstruct.
8. The method for reconstructing the topological optimization feature geometry of the curved surface structure based on the coordinate space mapping according to claim 1, wherein in the step 7, the morphological refinement algorithm gradually removes pixels of the white retention structure through iterative corrosion and expansion until no white pixels meet the corrosion condition, and the iteration is stopped to obtain a skeleton image.
9. The geometrical reconstruction method of topological optimization features of a curved surface structure based on coordinate space mapping according to claim 1, wherein in step 10, the shell is UG, and the thickness of the shell is selected for each surface of the blade according to practical conditions.

Description

Curved surface blade structure topology optimization feature geometric reconstruction method based on coordinate space mapping Technical Field The invention belongs to the field of structural optimization design, and relates to a geometric reconstruction method of topological optimization features of a curved blade structure based on coordinate space mapping. Background The research and development of aeroengines serving as 'bright beads' on industrial cassia crowns represent the industrial overall level of a country, and have important significance in the fields of national defense, transportation and the like, and the research and development of aeroengines with higher levels has become a necessary trend under the increasing trend of international technological competition. On the premise of ensuring the structural reliability and safety, the topology optimization design of the key parts of the aeroengine not only realizes the light weight by assisting, but also promotes the improvement of performance parameters such as thrust-weight ratio and the like, and simultaneously reduces the material consumption, thereby effectively reducing the cost of producing the engine, and finally generating remarkable economic benefit. Topology optimization belongs to structural optimization, and optimizes material distribution in a set design area based on given load conditions, constraint conditions and performance indexes. Through technical iterative development, the topology optimization method is widely applied to the aerospace, automobile and even building fields at present, and along with the light-weight design, the topology optimization technology plays an important role in material weight reduction in the aerospace field to occupy more and more important positions. Topology optimization has a high degree of freedom in design, which obtains a structural style satisfying the best performance by directly optimizing the distribution of the design domain flow, solid materials, and in terms of the optimization design, most of the time, the product design needs to balance various factors and determine the best design solution. Topology optimization can avoid the possibility of design failure to a great extent because it can take various factors into consideration in advance. The most attractive point of the topology optimization is that the topology optimization can reduce unnecessary weight, which is very critical in the field of aviation, and a great deal of design cost is required to be increased when one gram of counterweight is added, and the weight reduction and the size reduction mean lower energy consumption. Meanwhile, the topology optimization not only can furthest reduce the use and cost of materials, but also can improve the performance of products, reduce the cost and improve the efficiency by optimizing the material distribution and structure, and promote the improvement of the innovative design level. It has wide application in many fields including aerospace, automotive, manufacturing, construction engineering, etc. The method is an important way for obtaining an innovative structure of the engine and realizing light weight. The blade is used as a key part of the engine, and plays an important role in safe and reliable operation of the whole engine. The early-stage blades mostly adopt solid structures, but the solid blades are heavy and high in fuel consumption, and cannot meet the increasingly higher pushing ratio and lower fuel consumption design requirements of aeroengines, and along with the progress of science and technology and the improvement of engine design requirements, the lightweight design of the blades is rapidly developed. Under the support of advanced technology, the curved surface blade which is more in accordance with the three-dimensional lightweight design of pneumatic design is the development direction of a period of time in the future, the topology optimization is an effective way for realizing the lightweight of the blade, and the optimal distribution of materials can be realized on the premise of meeting the pneumatic performance and the structural reliability through the topology optimization blade. The reconstruction of the result model after topology optimization is always a great difficulty, and the structure generated by the topology optimization method always presents complex porous or net-shaped distribution characteristics, and the highly abnormal structure is difficult to realize directly by the existing processing technology. The method has the advantages that the result characteristic extraction is difficult, an effective parameterized description method is lacked, the model reconstruction work is complicated, the reconstruction result is greatly influenced by human factors, and the subsequent fine design is challenged. Many complex geometries generated by topology optimization are generally difficult to manufacture by traditional industrial manufacturing means, but ad