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Equivalent Load Identification and Verification in Frequency Domain for Liquid Rocket Engine

AIAA JOURNAL 2025年第1期63卷 208-218页

作者： Yang, Fengfan Luo, Yajun Wang, Jun Du, Longfei Zhang, Yahong Xie, Shilin Xi An Jiao Tong Univ Sch Aerosp Engn State Key Lab Strength & Vibrat Mech Struct Xian 710049 Peoples R China Xian Aerosp Prop Inst Sci & Technol Liquid Rocket Engine Lab Xian 710100 Peoples R China

Accurately characterizing the dynamic load environment is vital for the structural optimization and fatigue life assessment of liquid rocket engines, but the difficulty in precisely measuring or identifying such distributed loads is substantial. This paper proposed a method to determine the equivalent concentrated loads of liquid rocket engines at main vibration sources using the direct inverse method in the frequency domain. Response verification is performed to confirm the effectiveness of the equivalent loads by assessing the consistency between responses due to them and actual distributed loads. A pumped liquid rocket engine is investigated for specific research. Responses from the hot-fire test are used to identify equivalent loads at three main vibration sources, which are the gas generator, turbine shell, and combustion chamber. The results indicate that the errors in responses induced by the equivalent loads and the actual distributed loads are generally within +/- 4 dB. To further validate the equivalent loads, an experiment is conducted, scaling and applying the equivalent loads to the rocket engine. The resulting responses, after amplification, align well with those obtained from the hot-fire test, confirming the validity of the proposed method. However, response verification errors escalate significantly when nonprimary sources are included in the equivalent locations.

关键词： Liquid-Propellant Rocket Frequency Response Functions Combustion Chambers Rocket Engine Fatigue (Materials) structural design and development Extended Kalman Filter Linear Time Invariant System Convolutional Neural Network Dynamic Modelling

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Smart Space Deployable Truss Based on Shape-Memory Releasing Mechanisms and Actuation Laminates

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JOURNAL OF SPACECRAFT AND ROCKETS 2023年第4期60卷 1085-1099页

作者： Lan, Xin Liu, Liwu Pan, Chengtong Hou, Guanghua Li, Fengfeng Liu, Zhengxian Dai, Wenxu Wang, Linlin Zhang, Fenghua Sun, Jian Yue, Honghao Liu, Yanju Leng, Jinsong Zhong, Xiaoqing Tang, Yong Harbin Inst Technol Ctr Composite Mat & Struct Harbin 150080 Peoples R China Harbin Inst Technol Dept Astronaut Sci & Mech POB 30192 West Dazhi St Harbin 150080 Peoples R China Harbin Inst Technol Sch Mechatron Engn Harbin 150080 Peoples R China Chinese Acad Space Technol Inst Telecommun Satellite POB 5142104 Youyi St Beijing 100094 Peoples R China

A structure-level smart deployable truss (SDT) was further studied for on-orbit verification on the SJ18 Geostationary Satellite in this work on the basis of a material-level validation of a shape-memory polymer composite (SMPC) sheet on the SJ17 Geostationary Satellite in 2016. In the SDT, a shape-memory alloy (SMA) mechanism was used to replace traditional pyrotechnic devices for locking and releasing, and SMPC actuation laminates were employed to replace traditional motor or spring driving mechanisms. With a strict parameter constrain of mass, size, and stiffness, the current form of the SDT flight hardware was finally obtained through several cycles of optimization design. Its systematical ground-based experiments were conducted, and the overall structural and functional performance met the demands of the aerospace standards of China. The locking force and expansion breaking force of the SMA releasing mechanism were similar to 2000 and similar to 10;000 N, ensuring the locking and unlocking reliability for the movable parts with mass 5 kg. The actuation force of all SMPC laminates decreased from similar to 30 N (0 degrees) to similar to 12 N (165 degrees) with a recovery duration of similar to 150 s, which was strong enough for SDT deployment in space. The shape-memory materials show great prospects for smart deployable structures in space.

关键词： Trusses Shape Memory Alloys Smart Structures and Materials Geostationary Satellites Mechanical and structural Vibrations structural design and development Fiber Reinforced Composites Shape Memory Polymer

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Theory of Machine Learning Assisted structural Optimization Algorithm and Its Application

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AIAA JOURNAL 2023年第10期61卷 4664-4680页

作者： Xing, Yi Tong, Liyong Univ Sydney Sch Aerosp Mech & Mechatron Engn Sydney NSW 2006 Australia

The machine learning assisted structural optimization (MLASO) algorithm has recently been proposed to expedite topology optimization. In the MLASO algorithm, the machine learning model learns and predicts the update of the chosen optimization quantity in routine and prediction iterations. The routine and prediction iterations are activated with a predefined learning and predicting scheme;and in the prediction iterations, the design variable can be updated using the predicted quantity without running a finite element analysis and sensitivity analysis, and thus the computational time can be saved. Based on the MLASO algorithm, this work first proposes a novel generic criterion-driven learning and predicting (CDLP) scheme that allows the algorithm to autonomously activate prediction iterations in the solution procedure. Second, this work presents the convergence analysis and the computational efficiency analysis of the MLASO algorithm with the CDLP scheme. The MLASO algorithm is then embedded within the solid isotropic material with penalization topology optimization method to solve two-dimensional and three-dimensional problems. Numerical examples and results demonstrate the prediction accuracy and the computational efficiency of the MLASO algorithm, and that the CDLP scheme can remarkably improve the computational efficiency of the MLASO algorithm.

关键词： Mathematical Optimization Optimization Algorithm Machine Learning structural design and development Generative Adversarial Network Lagrange Multipliers Topology Optimization Aircraft Structures structural Optimization Aircraft Engine Mounts

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Dynamic Modal Reanalysis Using Flexibility Disassembly Perturbation Method

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AIAA JOURNAL 2024年第9期62卷 3474-3490页

作者： Yang, Qiuwei Peng, Xi Ningbo Univ Technol Engn Res Ctr Ind Construct Civil Engn Zhejiang Sch Civil & Transportat Engn Ningbo 315211 Peoples R China

In structural optimization design and reliability analysis, it is necessary to repeatedly modify the structure and calculate the corresponding vibration modal parameters. It will require significant computational costs if a complete analysis is used to calculate the vibration modes of each modified structure. In order to improve computational efficiency, this work develops a dynamic modal reanalysis method based on flexibility disassembly perturbation, which utilizes the modal data of the original structure to quickly calculate the modal parameters of the modified structure. The core idea of the proposed method is to use the flexibility matrix decomposition formula to quickly calculate the flexibility matrix after each modification of the structure and then obtain a high-precision reduced eigenvalue problem for solving the vibration modes of the modified structure. Three numerical examples are used to validate the proposed modal reanalysis method. It has been shown that the proposed method has higher computational accuracy and efficiency than the existing modal reanalysis method, especially for high-rank and large modification scenarios.

关键词： Mathematical Analysis Finite Element Modeling structural design and development Reduced Order Modelling Statistical Analysis Mechanical Properties Computing and Informatics Nonlinear Dynamic Analysis structural System

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Subregional Differentiated Safety Factors design Based on Nonprobabilistic structural Reliability

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AIAA JOURNAL 2024年第7期62卷 2424-2432页

作者： Xu, Yusheng Wang, Xiaojun Wang, Lei Shi, Qinghe Gong, Jinglei Yu, Yongbo Beihang Univ Natl Key Lab Strength & Struct Integr Inst Solid Mech Sch Aeronaut Sci & Engn Beijing 100191 Peoples R China Jiangsu Univ Technol Sch Mat & Engn Changzhou 213001 Jiangsu Peoples R China

The structural safety factor is an essential parameter in aircraft design, representing the ratio of the design load to the operating load. Traditional design methods rely on subjective determination of safety factor values based on experience, lacking objectivity in quantifying uncertainty. However, with advancements in aircraft design technology and increasing competition in the commercial space market, new-generation hypersonic aircraft with complex load environments require a more optimal approach. Applying a uniform safety factor to each component within subregions of the aircraft leads to overly conservative results and impacts flight performance. To address this limitation, a design scheme that incorporates subregional, differentiated safety factors is necessary. This approach allows for better material utilization and ensures compliance with safety requirements. This paper utilizes reliability-based design optimization theory to consider uncertainty in structural systems. It establishes a mapping relationship between structural reliability and differentiated safety factors, providing safety under uncertainty while guaranteeing weight reduction. Additionally, this paper develops a subregional, differentiated safety factors distribution program to determine the safety factors of different subregions of the structure. Consequently, a refined subregional differentiated safety factors scheme that balances safety and economy is derived.

关键词： structural Reliability Analysis structural design and development Multidisciplinary design Optimization Aircraft design structural System Hypersonic Aircraft Aircraft Performance Space Commercialization Trusses Sequential Quadratic Programming

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Patch Antenna Dielectrics Reduction by Topology Optimization and Radio Wave Characteristics

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JOURNAL OF SPACECRAFT AND ROCKETS 2024年第2期61卷 448-457页

作者： Torisaka, Ayako Tokyo Metropolitan Univ Dept Aerosp & Astronaut Tokyo Japan

This research is aimed at exploring the potential for reducing the overall mass of large space structures on which space systems are supported. A key component of these systems comprises microwave arrayed antennas, which are distributed across the surface of the structure. Given that dielectric materials constitute a significant portion of the antenna mass, this study is primarily concerned with minimizing the mass of these antenna dielectrics. It is crucial to note that while reducing mass is a priority, the stiffness of the antenna system must be preserved, as it needs to adhere securely to the structure's surface. To achieve this objective, we embark on a process of optimizing the topological distribution of the dielectric material. We investigate how this optimized configuration impacts the microwave characteristics of a patch antenna. Our approach involves conducting topological optimization while concurrently ensuring structural stiffness. Subsequently, we assess the influence of this optimized distribution on the antenna's patterns and gains using different materials.

关键词： Space Inflatable Structures Electrical Properties structural design and development Topology Optimization Antenna Gain Dielectric Constant Lightweigth patech antennas Micro-wave characteristics Strucural stiffness

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Novel Skin-Reinforcement design by Cross-Longitudinal Layout Inspired by Dragonfly Wing

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AIAA JOURNAL 2024年第4期62卷 1311-1317页

作者： Kawabe, Hiroki Aoki, Yuichiro Nakamura, Toshiya Univ Tokyo Grad Sch Frontier Sci Kashiwa 5-1-5 Chiba Japan Japan Aerosp Explorat Agcy Aviat Technol Directorate Tokyo Japan

The objective of this study is to develop a novel aircraft design approach using biomimetics as an alternative to traditional airframes. This approach is primarily inspired by the dragonfly wing, which possesses reinforcement structures composed of cross veins and longitudinal veins. These structures are assumed to regulate deformation and enhance stiffness, respectively. The cross veins were replicated using weighted centroidal Voronoi tessellation (WCVT) based on the out-of-plane displacement of the skin. In contrast, the longitudinal veins were replicated by extracting a centerline from the topology optimization (TO) results on the skin, achieved through image analysis techniques such as binarization and skeletonization. The longitudinal layout effectively reduces compliance by distributing internal loads, utilizing only essential reinforcements on the skin without increasing its mass. The WCVT layout significantly enhances the buckling resistance of the reinforced skin. As a result, the skin reinforced using both cross-longitudinal layouts from TO and WCVT exhibited a buckling load 2.7 times greater while maintaining a lower mass compared to conventional layouts.

关键词： Aircraft Components and Structure Mathematical Optimization Aircraft design structural Analysis Aircraft Wing design structural design and development Mechanical Properties Aircraft Wing Components Topology Optimization Biomimetic design

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design and development of Composite Plywood that Integrates Fire Resistance,Water Resistance and Wear Resistance

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Journal of Renewable Materials 2023年第5期11卷 2333-2344页

作者： Xingyu Liang Xiaoyu Gu Myint Myint Paing Hsu Yuhang He Rongzhuo Zhang Conghui Cai Zheng Wang College of Materials Science and Engineering Nanjing Forestry UniversityNanjing210037China College of Civil Engineering Nanjing Forestry UniversityNanjing210037China Jiangsu Shancong Wood Co. Ltd.Lianyungang222505China

In order to improve the fire resistance,water resistance and wear resistance of ordinary plywood products in the wood processing industry,three composite structures of plywood products S1,S2 and S3 were designed in this paper,and a reasonable production process was *** the physical and mechanical properties and fire resistance testing and technical and economic analysis,the applicability of composite plywood was *** results of the study showed that the physical mechanics of the three kinds of composite structure plywood met the standard requirements,and their fire resistance was far better than that of ordinary *** them,the S1 structural board had the best overall physical and mechanical *** S3 structural board showed the best fire resistance,which was about 1.9 times more than that of ordinary plywood,and the added cost was the *** thin cork board added to the S2 structural board had poor fire performance since the air in the cork board cavities had a certain combustion-supporting effect,which inhibited the fire resistance of high-pressure laminate(HPL)***,the additional cost of the S2 board was the highest,and its comprehensive performance was the *** S3 structural plywood product composed of HPL fireproof board with a thickness of about 1 mm in the surface layer and ordinary plywood with a thickness of about 12 mm in the core layer was the most cost-effective product,which could meet the needs of various fields such as construction,home furnishing,decoration and transportation.

关键词： Wear resistance plywood structural design and development physical and mechanical properties fire resistance

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Establishing Standards for Lunar In Situ Resource Utilization structural Materials

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AIAA JOURNAL 2024年第7期62卷 2414-2423页

作者： Dyke, Shirley J. Sharma, Akanshu Mount, Eliza M. Bobet, Antonio Ramirez, Julio A. Purdue Univ Sch Mech Engn W Lafayette IN 47907 USA Purdue Univ Lyles Sch Civil Engn W Lafayette IN 47907 USA Purdue Univ Lyles Sch Civil Engn Civil Engn W Lafayette IN 47907 USA

Lunar structures will be exposed to one of the most extreme environments that have ever been considered for human settlements. In situ, regolith-based materials are being proposed for construction on the moon, offering the benefit of reducing the cost of transporting large amounts of materials or prefabricated elements, and relying on the ability to transport mainly the equipment needed to construct landing pads, shelters, blast shields, habitats, roadways, etc. However, the properties of materials that are made, all or in part, from indigenous lunar resources are likely to change based on the make-up of the material, the location where it was taken from, the production processes, and time. No standards or building codes exist for the design and construction of infrastructure on the moon. Engineers will need dependable information about these materials before any design can be completed. Hard-won lessons from centuries of using similar resources on Earth need to be leveraged to develop the best procedures that will be critical for testing such materials for structural applications. Here we discuss the technical challenges of establishing such standards. Using the timely example of a landing pad on the moon, we identify the gaps in both knowledge and testing capabilities that exist today.

关键词： Space Exploration and Technology Mechanical Properties Mechanical Testing Stress-Strain Analysis structural design and development Lunar Environment Strength of Materials ISRU (Resource Utilization) Launch Pad Standards and Recommended Practices

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High-Fidelity Gradient-Based Wing structural Optimization Including Geometrically Nonlinear Flutter Constraint

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AIAA JOURNAL 2023年第7期61卷 3045-3061页

作者： Jonsson, Eirikur Riso, Cristina Monteiro, Bernardo Bahia Gray, Alasdair C. Martins, Joaquim R. R. A. Cesnik, Carlos E. S. Univ Michigan Dept Aerosp Engn 1320 Beal Ave Ann Arbor MI 48109 USA Univ Michigan Ann Arbor MI 48109 USA Georgia Inst Technol Daniel Guggenheim Sch Aerosp Engn 275 Ferst Dr Northwest Atlanta GA USA

Lightweight high-aspect-ratio wings make aircraft more energy efficient thanks to their lower induced drag. Because such wings exhibit large deflections, design optimization based on linear flutter analysis of the wing undeformed shape is inadequate. To address this issue, we develop a framework for integrating a geometrically nonlinear flutter constraint, which considers in-flight deflections, into a high-fidelity gradient-based structural optimization. The wing mass and stress constraints are evaluated on a linear built-up (detailed) finite element model to capture realistic structural features. The geometrically nonlinear flutter constraint is based on a condensed low-order beam representation of the built-up finite element model, which captures the impact of in-flight deflections with tractable computational effort for optimization. The flutter constraint is differentiated with respect to the detailed structural model sizing variables using the adjoint method to enable large-scale optimizations. The framework is demonstrated by minimizing the mass of a wingbox model subject to the geometrically nonlinear flutter constraint along with stress and adjacency constraints. The geometrically nonlinear flutter constraint adds a penalty of up to 60% of the baseline mass due to the impact of in-flight deflections on the flutter onset speed and its mechanism. In contrast, a linear flutter constraint evaluated on the undeformed wing adds a mass penalty of only 10%. This methodology can help design energy-efficient aircraft with high-aspect-ratio wings, which require geometrically nonlinear flutter analyses early in the design cycle.

关键词： structural design and development Finite Element Modeling structural Dynamics and Characterization Aircraft Components and Structure Nonlinear Aeroelastic Systems Aircraft Wing design structural Optimization Flutter Analysis Nonlinear structural Dynamics Dynamic Aeroelasticity

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