CN109583040B

CN109583040B - Optimization method considering continuity of structural parameters of composite material

Info

Publication number: CN109583040B
Application number: CN201811319356.6A
Authority: CN
Inventors: 吴斌; 段婷婷; 杨晔楠; 刘凤楠
Original assignee: AVIC First Aircraft Institute
Current assignee: AVIC First Aircraft Institute
Priority date: 2018-11-07
Filing date: 2018-11-07
Publication date: 2022-11-18
Anticipated expiration: 2038-11-07
Also published as: CN109583040A

Abstract

The invention belongs to the field of airplane structure design, and particularly relates to an optimization method considering continuity of composite material structure parameters. The method comprises the following steps: the method comprises the steps of initial structure analysis, parameter partition, base area selection, establishment of ratio relation between other parameter partitions and the base area, establishment of ratio constraint conditions, optimization design and derivation of optimization results. The optimization of the structural parameters of the composite material laying layer is realized, meanwhile, the continuity of the laying layer design is considered, and the optimization design result only needs a small amount of correction and can be directly applied to the detailed design of the engineering structure. The method is strong in operability, suitable for various optimization analysis programs, high in calculation efficiency and low in resource consumption.

Description

Optimization method considering continuity of structural parameters of composite material

Technical Field

The invention belongs to the field of airplane structure design, and particularly relates to an optimization method considering continuity of composite material structure parameters.

Background

The optimized design of the metal structure only needs to obtain the parameter distribution of each optimized design subarea, but for the composite material structure, in order to take account of the manufacturability of the layering, the parameters among each optimized design subarea have continuity.

When a classical optimization design algorithm (such as a planning algorithm) is used for optimization design, the thickness of a layer laid by each partition of a composite material can only be used as an optimization design parameter, layers laid among the partitions are difficult to continue, the optimization design result needs to be corrected, and in many cases, the correction of the optimization design can bring resilience of weight, so that the optimization weight loss benefit is weakened. As shown in fig. 1, the optimized design results of the regions a and B are shown, where the layer in the region a is subjected to thickness transition from the thick region to the region B, if the thickness transition is performed in both directions, the profile of the transition region is distorted, and both manufacturability and force transfer characteristics are poor, and in order to improve this situation, the result modification (i.e. the-45 ° layer in the region a is supplemented) needs to be performed as shown in fig. 2, and this modification increases the weight of the region a, thereby canceling out the effect obtained by the optimized design.

Although evolutionary optimization algorithms such as genetic algorithm and the like can take account of layering continuity during genome coding, for the structure of large and medium-sized airplanes, a large number of optimization design parameters are needed, if an optimization design result is to be obtained, a large number of computing resources are consumed, and the optimization design result can be obtained only after several days of computing iteration by a plurality of parallel computers. The evolutionary optimization algorithm can be used as a technical reserve for research, but the calculation efficiency needs to be improved from the practical application of engineering.

Disclosure of Invention

By combining engineering design experience and utilizing a traditional planning optimization algorithm, the optimization design of the structural parameters of the composite material considering the continuity of the laying layers is realized, the optimization efficiency is improved, and the optimization analysis result is corrected as little as possible, so that the method is suitable for the detailed design of the engineering structure.

Technical scheme

The engineering structure parameter optimization design is carried out after the paving force transmission path is determined, the optimization design subarea of the part is determined according to the initial load distribution and the structure stress/strain distribution level, and the part mainly comprises a two-dimensional unit for skin or beam web.

And extracting the thickness of the ply of each ply angle in each ply subarea. Taking a thick area or a thin area on the part as a basic subarea, taking the thickness of the layer of each lay-on angle as a basic parameter, and constructing the ratio relation between the thickness of the layer of each lay-on angle of the basic subarea and the thickness of the layer of the same lay-on angle of the adjacent subarea: r1, R2, \ 8230 \ 8230;, rn.

And according to the stress characteristics of the structure and the limitation requirement on the thickness change of the adjacent thickness areas in the design requirement of the composite material structure, giving a value interval for each ratio, introducing the value interval into an optimization design model as a part of an optimization constraint condition, and submitting optimization calculation.

And according to the calculation result, properly adjusting the value interval of the thickness ratio to finally obtain the optimal value of the thickness of the paving layer of each paving angle of the composite material structure, and simultaneously ensuring that the thickness of the paving layer of a certain paving angle in the thin area can be covered in the thick area so that the paving layer is continuous between the adjacent sub-areas. The optimization design flow is shown in fig. 3.

The technical method does not depend on software and algorithm of optimization design, and can ensure the continuity of each layer of the composite material between adjacent subareas in the optimization result. The thickness variation of the adjacent layer partitions of the composite material is converted into the thickness ratio of the layer partitions, the thickness ratio is used as one of optimization constraint conditions and is substituted into an optimization model, the thickness of a certain layer angle in a thick area is larger than or equal to the thickness of the same layer angle in a thin area, and the shape optimization of the composite material layer is converted into numerical optimization.

The parts are mainly skins or beam webs and mainly comprise two-dimensional units

Technical effects

1. The optimization of the structural parameters of the composite material laying layer is realized, meanwhile, the continuity of the laying layer design is considered, and the optimization design result only needs a small amount of correction and can be directly applied to the detailed design of the engineering structure.

2. The method has strong operability, is suitable for various optimization analysis programs, and has high calculation efficiency and less resource consumption.

Drawings

FIG. 1 is a diagram of ply optimization design results

FIG. 2 is a revised graph of the optimization design results

FIG. 3 is a flow chart of composite material structural parameter optimization taking into account ply continuity

FIG. 4 is a schematic representation of typical composite ply thickness variation

FIG. 5 is a plot of exemplary airfoil optimization design parameter partitions

FIG. 6 is a diagram of exemplary optimal design parameter continuity definitions

Detailed Description

Case one:

a part has three thickness partitions t1, t2 and t3, as shown in FIG. 4, wherein the direction indicated by the arrow is the thickness variation direction. The thickest t1 zone is taken as a basic zone, and the thickness ratio relation of the same paving angle layer between the t1 zone and the adjacent t2 and t3 zones is respectively established (taking the thickness of the paving angle layer of 0 degree as an example, the same ratio relation can be established for other paving angle layers): r1= t1 _0° /t2 _0° 、R2＝t2 _0° /t3 _0° . Proper constraints on the ratio range are required in connection with composite structural design: r1 is more than or equal to 1 and less than or equal to 1.2 (the more clear thickness changes from a thick area to a thin area), R2 is more than or equal to 0.85 and less than or equal to 1.15 (the relatively unclear thickness changes), if the base thickness is thinner, the upper and lower constraint limits can be widened, for example, for a 90-degree layer, the upper and lower constraint limits can be set to 0.5-2.0, and if the base thickness is thicker, the upper and lower constraint limits can be tightened. The constraints are taken as part of optimization constraint conditions and brought into an optimization model, the optimization design result can enable the 0-degree layer in the t3 area to be completely covered by the t2 area, and the 0-degree layer in the t2 area can also be covered by the t1 area, and finally the 0-degree layer is continuous in the whole part while the part obtains the optimal design parameters.

Case two:

fig. 5 shows a parameter partition of an optimized design part of a MA700 aircraft vertical stabilizer skin, according to the structural arrangement, a 10000x1 region is a connection region of the skin and a beam, which is a main force transmission path of an airfoil, a 1000011 region is a root butt-joint region, a 1000081 region is an end butt-joint region, which are main bearing regions, and load transition bearing regions and common bearing regions are arranged between the rest regions, and the thickness of the skin is always transited from a high-load region to a common bearing region, and is stably and uniformly distributed at a certain thickness partition. A parameter optimization analysis file is compiled by using a SOL200 solver of Nastran, and fig. 6 shows 0 ° ply thickness design variables corresponding to each region and a ratio relationship thereof, wherein the 0 ° thicknesses of the thin regions are 0.8-1.0 of the thick regions from 1000011 to 1000041, the 0 ° thicknesses of the thin regions are 0.8-1.0 of the thick regions from 1000051 to 1000081, the thickness change is not clear from 1000041 to 1000051, and the ratio change range is 0.8-1.1.

Other ply sections and ply angles are defined in this manner. The model is optimized and designed to obtain the overall weight of 129.7Kg of the box section structure, and the weight is reduced by more than 8% compared with the vertical stabilizer structure of the same type of airplane, wherein the optimized weight of the wallboard is 31.8Kg, skin parameters only need to adjust the paving sequence, paving is not needed to be added after strength professional checking, the strength margin is 0.1-0.2, the detailed design weight of the final wallboard structure is 32.5Kg (including paint and fasteners), and the optimized design and the detailed design weight are consistent.

Claims

1. An optimization method considering the continuity of the structural parameters of the composite material is characterized in that,

the engineering structure parameter optimization design is developed after the ply-spreading path is determined, and the optimization design subarea of the part is determined according to the initial load distribution and the structure stress/strain distribution level;

extracting the thickness of the ply of each ply angle in each ply partition; taking a thick area or a thin area on the part as a basic subarea, taking the thickness of the layer of each paving angle as a basic parameter, and constructing the ratio relation between the thickness of the layer of each paving angle of the basic subarea and the thickness of the layer of the same paving angle of the adjacent subarea: r1, R2, \\8230 \ 8230;, rn;

according to the stress characteristics of the structure and the limitation requirement on the thickness change of the adjacent thickness areas in the design requirement of the composite material structure, a value interval is given to each ratio and is introduced into an optimization design model as a part of optimization constraint conditions to submit optimization calculation;

and according to the calculation result, properly adjusting the value interval of the thickness ratio to finally obtain the optimal value of the thickness of the paving layer of each paving angle of the composite material structure, and simultaneously ensuring that the thickness of the paving layer of a certain paving angle in the thin area can be covered in the thick area so that the paving layer is continuous between the adjacent sub-areas.

2. An optimization method taking into account the continuity of structural parameters of the composite material according to claim 1, characterized in that said elements are two-dimensional elements of the skin or beam web type.