Modeling of Aviation Fuel Pipe Welds in Different Regions and Its Effect on Mechanics Properties of Pipes

doi:10.3969/j.issn.1004-132X.2025.09.002

Abstract

Abstract:

Aircraft fuel lines contained various structures such as bends， branches and welded seams， which exhibiedted complex fluid-solid coupling mechanics behaviors under external loads and internal fluid coupling. The microstructural parameters of the welded areas were obtained through metallographic testing and microtensile testing， and a high-precision finite element model of the welded fuel lines with different local structures was constructed. The modal test results show that the errors between tests and simulations are less than 10%， which verify the accuracy of modelling and simulation. The effects of different branch pipe bending radii and pipe diameter ratios on the mechanics properties of the pipelines were investigated. It is found that increasing the bending radii and pipe diameter ratios may help to make the distribution of the flow velocity and pressure fields in the pipelines more uniform， and the intrinsic frequency decreases with the increase of the bending radius； and when the bending radius decreases but the pipe diameter ratio increases， the peak of the random vibratory stresses decreases. The applications of a fuel line model that accurately models welded seams to analyze the effect of local structures on the mechanics properties of the line may provide a basis for line design and optimization.

Key words: coherently welded fuel line, refined modeling, local structure, fluid-solid coupling vibration, mechanics property, modal test

摘要：

飞机燃油管路包含弯管、分支管和焊缝等多种结构，在外部载荷及内部流体耦合作用下表现出复杂的流固耦合力学行为。通过金相检测和微拉伸试验获取了焊接区域的微观结构参数，构建出具有不同局部结构的高精度燃油焊接管路有限元模型。模态试验结果表明，试验与仿真误差小于10%，验证了建模和仿真的准确性。针对不同分支管弯曲半径及不同管径比开展其对管路力学特性影响研究，发现增大弯曲半径和管径比有助于使管路内流速场和压力场分布更加均匀，固有频率会随弯曲半径的增大而降低；当弯曲半径减小但管径比增大时，随机振动应力峰值下降。采用对焊缝精确建模的燃油管路模型，剖析局部结构对管路力学特性的影响，可为管路设计和优化提供依据。

关键词: 相贯焊接燃油管路, 精细化建模, 局部结构, 流固耦合振动, 力学特性, 模态试验

CLC Number:

V228

Changhong GUO, Mengran DI, Hanwen GONG, Lingxiao QUAN, Bin LI. Modeling of Aviation Fuel Pipe Welds in Different Regions and Its Effect on Mechanics Properties of Pipes[J]. China Mechanical Engineering, 2025, 36(9): 1916-1924.

郭长虹, 狄梦然, 宫瀚文, 权凌霄, 李斌. 航空燃油管路焊缝分区域建模及其对管路力学特性影响研究[J]. 中国机械工程, 2025, 36(9): 1916-1924.

Figures/Tables 30

Fig.1 Test piece and welded area metallograph

Fig.2 Schematic diagram of weld area dimensions for coherence welding test piece

Tab.1 Welding area size parameters

参数	尺寸/mm
焊缝厚度l₄	2.60
直角焊缝支管热影响区宽度l₅	7.81
直角焊缝主管热影响区宽度l₆	8.02
外侧余高h_C	0.72
外侧宽度l₃	6.61
A点高度h_A	0.20
A点距中线距离L_A	1.76
B点高度h_A	0.31
B点距中线距离l_B	3.15
平角焊缝支管热影响区高度l₁	4.74
平角焊缝主管热影响区高度l₂	6.06

Tab.2 Material performance parameters by region

区域名称	弹性模量/MPa	泊松比
母材区	75 000	0.35
焊缝区	81 800	0.32
热影响区	74 000	0.29

Fig.3 Pipe welding area model

Tab.3 Pipe structure parameters

参数	设计数据/mm
主管路与分支管路外径D_w	31.75
主管路与分支管路内径D_n	29.97
主管路长度L_u	550
主管路端面距支管路轴线垂直距离L_z	350
支管路直管长度L_i	150
支管路弯曲半径R_z	116
卡箍与管路接触部分宽度B_j	15
支管卡箍端面距主管路端面距离L_k	30
直管卡箍端面距支管路弯头端面距离L_d	20

Fig.4 Physical model of fuel weld line solid domain

Fig.5 Piping with clamps and brackets assembly diagram

Fig.6 Fluid domain model of fuel weld line

Tab.4 Grid quality of pipeline regions and components

名称	单元质量	纵横比	正交质量	偏斜度	网格质量
固体域	0.648	2.438	0.876	0.438	优
流体域	0.793	1.977	0.915	0.151	优
卡箍	0.876	1.646	0.953	0.003	优
螺栓螺母	0.928	1.379	0.702	0.219	优
支架	0.825	1.883	0.991	0.244	优

Fig.7 Mesh modeling of pipes， clamps and brackets

Fig.8 Verification of mesh-independence under multi-parameter and multi-node

Fig.9 Solid boundary condition setting

Fig.10 Modelling of pipelines with different bending radii for branch pipes

Fig.11 Velocity field distribution in the cross-section of the bend region under different bending radii

Fig.12 Pressure field distribution in the cross-section of the bend region under different bending radii

Fig.13 Stress curves and stress diagrams of the inner wall surface of the pipe under different bending radii

Fig.14 Comparison of the first 20 orders of intrinsic frequency of the pipeline under different bending radii

Fig.15 Stress-frequency response curves at monitoring points under different bending radii

Fig.16 Modeling of different pipe size ratios for branch and mains

Fig.17 Cross-sectional velocity field distribution in fluid domain under different pipe diameter ratios

Fig.18 Cross-sectional pressure field distribution in fluid domain under different pipe diameter ratios

Fig.19 Vertical sectional velocity field distribution in fluid domain under different pipe diameter ratios

Fig.20 Cross-sectional pressure field distribution in pipeline fluid domain under different pipe diameter ratios

Fig.21 Stress distribution of pipe bending region under different pipe diameter ratios

Fig.22 Comparison of the first 20 orders of intrinsic frequency of pipelines under different pipe diameter ratios

Fig.23 Stress-frequency response curves at monitoring points under different pipe diameter ratios

Fig.24 Modal test piece and piping installation

Fig.25 Comparison of intrinsic frequencies between free mode test and simulation

Fig.26 Comparison of intrinsic frequencies between constrained modal test and simulation

References 25

[1]	LI Jiajin， KING S， JENNIONS I. Intelligent Fault Diagnosis of an Aircraft Fuel System Using Machine Learning—a Literature Review［J］. Machines， 2023， 11（4）：481.
[2]	刘德刚，王澍，朱德轩. 民用飞机燃油系统管路设计研究［J］. 装备制造技术， 2014（8）：223-225.
	LIU Degang， WANG Shu， ZHU Dexuan. Civil Aircraft Fuel System Conveyance Design Research［J］. Equipment Manufacturing Technology， 2014（8）：223-225.
[3]	温锐杰. 民机燃油焊接管路单元可靠性研究［D］. 秦皇岛：燕山大学， 2022.
	WEN Ruijie. Study on Reliability of Ruel Welding Pipeline Unit of Civil Aircraft［D］. Qinhuangdao：Yanshan University， 2022.
[4]	彭远卓. 飞机供油系统汇流三通管入口流量均衡性研究及优化［D］. 南昌：南昌航空大学， 2021.
	PENG Yuanzhuo. Research and Optimization of Inlet Flow Equilibrium of Confluence Tee in Aircraft Fuel Supply System［D］. Nanchang：Nanchang Hangkong University， 2021.
[5]	周瑞祥，李娜，苏新兵. 飞机复杂燃油管路压力动态研究［J］. 液压与气动， 2006， 30（10）：23-25.
	ZHOU Ruixiang， LI Na， SU Xinbing. Research on Pressure Dynamic Characterstic of Airplane Complex Fueling Pipelines［J］. Chinese Hydraulics & Pneumatics， 2006， 30（10）：23-25.
[6]	车世超. 民用飞机燃油管路流固耦合振动频域特性分析［D］. 秦皇岛：燕山大学， 2021.
	CHE Shichao. Frequency Domain Characteristic Analysis of Fluid-structure Interaction Vibration of Civil Aircraft Fuel Pipeline［D］. Qinhuangdao：Yanshan University， 2021.
[7]	丁亚红，顾伟，李洪林，等. LF2铝合金燃油导管接头焊缝开裂原因及改进［J］. 理化检验-物理分册， 2021， 57（10）：68-71.
	DING Yahong， GU Wei， LI Honglin， et al. Cracking Causes and Improvement of Joint Weld of LF2 Aluminum Alloy Fuel Pipe［J］. Physical Testing and Chemical Analysis Part A：Physical Testing， 2021， 57（10）：68-71.
[8]	徐育烺，李超然，李敬勇，等. 工艺参数对6061-T6铝合金激光焊接接头组织及性能的影响［J］. 热加工工艺， 2023， 52（21）：26-31.
	XU Yulang， LI Chaoran， LI Jingyong， et al. Influence of Process Parameters on Microstructure and Properties of 6061-T6 Aluminum Alloy Laser Welded Joint［J］. Hot Working Technology， 2023， 52（21）：26-31.
[9]	OZTURK F， SISMAN A， TOROS S， et al. Influence of Aging Treatment on Mechanical Properties of 6061 Aluminum Alloy［J］. Materials & Design， 2010， 31（2）：972-975.
[10]	CHOUDHARY S， CHOUDHARY S， VAISH S， et al. Effect of Welding Parameters on Microstructure and Mechanical Properties of Friction Stir Welded Al6061 Aluminum Alloy Joints［J］. Materials Today：Proceedings， 2020， 25：563-569.
[11]	初冠南，王小松，刘钢，等. 激光焊管内高压成形焊缝有限元建模方式［J］. 机械工程学报， 2012， 48（22）：34-39.
	CHU Guannan， WANG Xiaosong， LIU Gang， et al. Laser Weld-seam Modeling for Finite Element Analysis during Tailor-welded Tube Hydroforming［J］. Journal of Mechanical Engineering， 2012， 48（22）：34-39.
[12]	CHIOCCA A， FRENDO F， AIELLO F， et al. Influence of Residual Stresses on the Fatigue Life of Welded Joints. Numerical Simulation and Experimental Tests［J］. International Journal of Fatigue， 2022， 162：106901.
[13]	GHAFOURI M， AHOLA A， AHN J， et al. Welding-induced Stresses and Distortion in High-strength Steel T-joints：Numerical and Experimental Study［J］. Journal of Constructional Steel Research， 2022， 189：107088.
[14]	张林. 航空发动机燃油管路振动分析［D］. 太原：中北大学， 2023.
	ZHANG Lin. Vibration Analysis of Aero-engine Fuel Pipeline［D］. Taiyuan：North University of China， 2023.
[15]	廖桔，赵紫豪，朱林峰，等. 飞机燃油管道随机振动分析与设计优化［J］. 管道技术与设备， 2021（5）：1-6.
	LIAO Ju， ZHAO Zihao， ZHU Linfeng， et al. Random Vibration Analysis and Design Optimization of Aircraft Fuel Pipeline［J］. Pipeline Technique and Equipment， 2021（5）：1-6.
[16]	齐晓燕，陆清. 基于ANSYS的飞机液压管路系统流固耦合分析［J］. 液压与气动， 2015， 39（10）：71-74.
	QI Xiaoyan， LU Qing. Fluid-structure Interaction Analysis Based on ANSYS for Airplane Hydraulic Tube System［J］. Chinese Hydraulics & Pneumatics， 2015， 39（10）：71-74.
[17]	彭刚，于乃江，贾文强. 航空发动机外部管路的结构与动力学特征参数分析［J］. 航空发动机， 2017， 43（5）：1-6.
	PENG Gang， YU Naijiang， JIA Wenqiang. Analysis of Structural and Dynamical Characteristic Parameters of External Pipes for Aeroengine［J］. Aeroengine， 2017， 43（5）：1-6.
[18]	ZHU Hongjun， ZHANG Wenli， FENG Guang， et al. Fluid-Structure Interaction Computational Analysis of Flow Field， Shear Stress Distribution and Deformation of Three-limb Pipe［J］. Engineering Failure Analysis， 2014， 42：252-262.
[19]	PAI¨DOUSSIS M P， LI G X. Pipes Conveying Fluid：a Model Dynamical Problem［J］. Journal of Fluids and Structures， 1993， 7（2）：137-204.
[20]	BATHE K J， ZHANG Hou. Finite Element Developments for General Fluid Flows with Structural Interactions［J］. International Journal for Numerical Methods in Engineering， 2004， 60（1）：213-232.
[21]	张忠义. 航空发动机管路流固耦合振动特性分析及主动控制技术研究［D］. 烟台：烟台大学， 2023.
	ZHANG Zhongyi. Vibration Analysis of Aeroengine Pipeline Considering Fluid-Structure Interaction and Active Vibration Control Technology［D］. Yantai：Yantai University， 2023.
[22]	秦政，滕云楠. 航空发动机外部管路的振动特性分析［J］. 机械设计， 2022， 39（）：1-5.
	QIN Zheng， TENG Yunnan. Analysis of Vibration Characteristics on Aeroengine External Pipelines［J］. Journal of Machine Design， 2022， 39（S1）：1-5.
[23]	YU Tao， ZHANG Zhongyi， ZHANG Decong， et al. Vibration Analysis of Multi-branch Hydraulic Pipeline System Considering Fluid-Structure Interaction［J］. Applied Sciences， 2022， 12（24）：12902.
[24]	邓记松. 单元与网格密度对有限元分析结果的影响［J］. 石油化工设备技术， 2017， 38（1）：12-15.
	DENG Jisong. Effect of Element and Mesh Density on the Results of Finite Element Analysis［J］. Petro-Chemical Equipment Technology， 2017， 38（1）：12-15.
[25]	张安龙. 脉动参数对波壁管内流体流动与传热特性的影响研究［D］. 秦皇岛：燕山大学， 2022.
	ZHANG Anlong. Study on the Influence of Pulsation Parameters on Fluid Flow and Heat Transfer Characteristics in Wave Wall Tube［D］. Qinhuangdao：Yanshan University， 2022.