A health management algorithm for composite train carbody based on FEM/FBG hybrid method

In this study, a health management program for a composite train carbody was developed using the acquired strain distributions from fiber Bragg grating (FBG) sensor arrays. To determine appropriate locations for the FBG sensors, a finite element analysis (FEA) was executed. In this FEA, a FE model of the Korean tilting train (TTX) was used as a representative composite carbody train. The FEA results of various derailment situations and high speed operation on curved track were used as the database of each deformation case. In the last step, the health management program was produced using LabVIEW software. In this post-processing algorithm, the method of least squares was used to determine the difference between the FEA results and the acquired strains. This program shows the estimated deformations and plots of the acquired strains, as well as displaying an emergency indicator when necessary, all through post-processing of the strains. Finally, this FEM/FBG hybrid method was verified by several simulations using the reproductive sensor data.     

Numerical and experimental studies on the deformational behavior a composite train carbody of the Korean tilting train

In this study, the vertical deflection and sectional deformation of the composite carbody were investigated by finite element analyses and experiments. The vertical and sectional deformations were measured using displacement gauges under the full weight load condition. The maximum deflection measured on the bottom of sidesill was 9.25 mm. The maximum deflection calculated from the finite element analysis was 8.28 mm. The analysis result was in agreement with the measured one within an error of 10.5%. In the cross-sectional deformation, the side wall was deformed inside of the carbody and the roof and under frame outside. The cross-sectional deformation of the composite carbody was compared with the E653 train of Japan Rail east. The deformational patterns were similar to each other.     

A multilevel approach to the optimisation of a composite light rail vehicle bodyshell

The optimisation of design parameters associated with composite sandwich bodyshell walls of light rail vehicles (LRV) is investigated. The main objective is to evaluate a multi-level computational procedure that leads to optimum wall ply thickness and geometric shapes for areas such as door and window openings. The optimisation procedures are extensively automated whereby iterative finite element solutions are executed under the control of a software suite containing information on the optimisation parameters, objective functions and constraints. The steps in the process include a global finite element analysis of the complete LRV bodyshell subjected to an industry standard loading, identification of a critically loaded panel and its division into domains, and optimisation of a window panel fillet radius within these domains. Numerical results are obtained in order to demonstrate the viability of the method as a design tool.     

Adhesively bonded lap-joints for the composite-steel shell structure of high-speed vehicles

Recently the design and manufacture of lightweight train structures have become important in order to increase speed. Composite train structures have many advantages over conventional steel or aluminum train structures because of their high specific strength, modulus and high damping capacity, which is beneficial for NVH (noise, vibration and harshness).

From the structures of high-speed trains, the upper car-body is a good candidate for composite structures which increase the stability of trains due to the low gravity center of vehicles.

If the side body of the train is made of steel plates, then joining of composite structures to the steel structures is required.

In this work, the adhesive joining method between the composite upper car-body structure and the steel side plates was investigated. A 1/10-size model of a real train subjected to internal pressure was developed and tested statically and dynamically.     

Experimental and numerical study of fastener pull-through failure in GFRP laminates

A methodology to design and analyze multi-material bolted joints in hybrid train structures is presented. This methodology enables the prediction of the response of a multi-material bolted joint in a short amount of time and it is suitable to be used for large structures, where the number of bolts can be very high. The method developed is applied to a real industrial case which consists on the connection between the roof and the side of a carbody shell train structure. Experimental tests are performed on a full-size sub-component. The comparison between the experimental data and the numerical results confirms the accuracy of the method.     

An efficient design method for multi-material bolted joints used in the railway industry

A methodology to design and analyze multi-material bolted joints in hybrid train structures is presented. This methodology enables the prediction of the response of a multi-material bolted joint in a short amount of time and it is suitable to be used for large structures, where the number of bolts can be very high. The method developed is applied to a real industrial case which consists on the connection between the roof and the side of a carbody shell train structure. Experimental tests are performed on a full-size sub-component. The comparison between the experimental data and the numerical results confirms the accuracy of the method.     

车下设备悬挂参数与车体结构之间的匹配关系研究

本文通过建立等效欧拉梁车体与设备垂向耦合振动模型,研究了车下设备刚性悬挂与弹性悬挂对车体振动的影响。研究结果表明,车下设备采用弹性悬挂的设计方式能够有效抑制车体的弹性振动。为了研究车下设备弹性悬挂参数与车体结构之间的匹配关系,本文基于模态叠加法原理法建立了考虑车体弹性振动和车下设备的高速动车组刚柔耦合动力学模型。通过该三维模型分析了车下设备质量偏心和弹性悬挂参数对车体振动响应的影响规律。仿真结果表明,车下设备横向偏心主要影响车体的横向振动特性,而车下设备纵向偏心主要影响车体的垂向振动特性;当车下设备的悬挂频率接近车体的垂向弯曲频率时能够降低车体的整体振动水平,而当车下设备的悬挂频率低于车体的垂向弯曲频率时,提高车下设备弹性悬挂系统的阻尼能够一定程度上抑制车体的弹性振动。     

侧风环境下列车高速交会流固耦合振动安全性分析

为了防止侧风环境下列车高速交会压力波对车体结构造成破坏,以及气动载荷冲击对运行安全性的影响,综合计算流体动力学的有限体积法和列车多体系统动力学仿真方法,从流固耦合关系出发,同时对侧风环境下列车高速交会的外流场和列车系统动力响应进行分析,从而考察会车压力波、气动冲击、车体响应和列车运行安全性。计算结果表明：背风侧列车会车压力波头波大于迎风侧列车,而尾波则小于迎风侧列车,最大压力波动出现在背风侧列车。侧风环境下列车高速交会时,彼此具有挡风作用,安全性指标出现波动,列车运行安全性短时间内有所改善。     

基于等效刚度法的车体结构碰撞建模与参数优化

针对轨道车辆碰撞动态行为数值模拟效率低、耐撞性分析手段缺乏的问题,提出了基于等效刚度法的车体结构碰撞建模和参数优化方法.基于等效刚度法和简支梁弯曲应变能相等的原理,提出了中空型材截面梁等效为实芯截面梁后抗弯刚度相等的条件,推导了二者结构等效参数的求解公式,利用多岛遗传优化算法对等效参数进行了优化;详细对比了车体结构等效...     

高速列车车体轻量化层状复合结构隔声设计

随着高速列车车体结构轻量化的发展,层状复合结构车体在高速列车上得到广泛应用,提高层状复合结构的隔声性能,是高速列车减振降噪的关键技术。基于传递矩阵法,建立"铝板+多孔材料层+空气层+碳纤维增强板"的典型高速列车层状复合结构车体隔声计算分析模型,并分析多孔材料和空气层对层状复合结构车体隔声性能的影响。结果显示,混响声场激励下,在铝板和碳纤维增强版之间仅增加空气层只能提高车体结构高频隔声量,低频部分会由于"板-空气-板"的系统耦合共振,形成显著吻合谷,导致其隔声性能在吻合谷频率处大幅下降。对此,利用多孔材料吸声原理,提出在空气层中增加吸声材料层,抑制隔声吻合低谷,通过优化设计,得出"铝板+空气层+吸声材料+空气层+碳纤维增强板"的优化结构形式,在实现车体轻量化目标同时,可有效提高其隔声性能。     

A study on the low-velocity impact response of laminates for composite railway bodyshells

This paper presents a study on the low-velocity impact response of woven fabric laminates for the composite bodyshell of a tilting railway vehicle. In this study, low-velocity impact tests for the three laminates with size of 100 mm × 100 mm were conducted at three impact energy levels of 2.4 J, 2.7 J and 4.2 J. Based on these tests, the impact force, the absorbed energy and the damaged area were investigated according to different energy levels and stacking sequences. The damage area was evaluated by visual inspection and C-scan measurement. The test results showed that the absorbed energy of [fill]₈ laminate was highest whereas [fill₂/warp₂]_s laminate was lowest. The [fill]₈ laminate had the largest delamination area because of the highest impact energy absorption.     

Germanischer Lloyd规范Goodman曲线对某型动车组CFRP复合材料设备舱骨架疲劳校核的应用

为了解决国内对适用于复合材料Goodman曲线实验研究较少的问题,基于ABAQUS有限元,利用Python语言编程和计算,按照德国劳氏船级社（GL）规范Goodman曲线对某新型动车组碳纤维增强树脂（CFRP）复合材料设备舱骨架进行疲劳强度校核。通过不同平均应力下疲劳强度实验,绘制Goodman曲线及考虑一定安全系数下的Goodman曲线,并与GL规范的Goodman曲线进行对比研究。结果表明,在EN12663-1∶2010[13]和文献[14]规定的疲劳工况下,GL规范的Goodman曲线对新型动车组CFRP复合材料设备舱骨架疲劳强度校核具有可行性,CFRP复合材料设备舱骨架可满足设计要求,但考虑安全系数n=1.5和n=2时评价有一定的风险性。      

嵌入式共固化复合材料阻尼结构低速冲击性能的数值模拟

Abstract：Embedded and co-cured composite damping structure is a new damping processing structure, which can be widely used in high-tech fields such as aviation, aerospace, high-speed train, etc. Explicit dynamic analysis software LS-DYNA was used to simulate low velocity impact on embedded and co-cured composite damping structure panels. The simulation results are compared with the experimental data to illustrate the validity of modeling and calculation method. The result of simulation shows that the impact resistance of embedded and co-cured composite damping structure is much higher than composite structure without viscoelastic damping material.     

车下有源悬吊设备与车体耦合振动研究

通过对我国高速动车组进行线路试验,发现车下有源旋转设备的不平衡质量所引发设备颤振会与车体地板发生耦合振动,影响车辆动力学性能。为研究有源车下设备与车体耦合振动特性,考虑车体的弹性振动,建立车体与车下悬吊设备的刚柔耦合动力学模型,分析有源旋转设备不平衡量对设备和车体振动的影响。结果表明,有源设备在特定频率范围内容易激发车体的低阶模态,随着不平衡量增加,导致车体振动逐渐增大。为减小车下有源设备振动对车辆动力学性能影响,进行有源设备悬挂参数匹配研究,得出最佳悬挂刚度和阻尼;同时提出有源旋转设备的两级隔振方案,研究发现两级隔振方案能够有效降低车体垂向振动,最大可减小约26%。     

A Study of Strength Transfer from tow to Textile Composite Using Different Reinforcement Architectures

The paper proposes an experimental and analytical approach of designing composites with the predetermined ultimate strength, reinforced with warp interlock fabrics. In order to better understand the phenomena of transfer of tensile properties from a tow to the composite, intermediate phases of composite manufacturing have also been taken into account and tensile properties of tows taken from the loom and the woven reinforcements have also been tested. Process of transfer of mechanical properties of raw materials to the final product (composite) depends on various structural factors. Here the influence of weave structure, which ultimately influences crimp has been studied. A strength transfer coefficient has been proposed which helps in estimating the influence of architectural parameters on 3D woven composites. 3 woven interlock reinforcements were woven to form composites. The coefficients of strength transfer were calculated for these three variants. The structural parameters were kept the same for these three reinforcements except for the weave structure. In was found that the phenomenon of strength transfer from tow to composite is negatively influenced by the crimp. In general the strength transfer coefficients have higher values for dry reinforcements and afterwards due to resin impregnation the values drop.     

嵌入式共固化复合材料阻尼结构低速冲击性能数值模拟

嵌入式共固化复合材料阻尼结构是一种新型阻尼处理结构,在航空、航天、高速列车等高科技领域有广阔的应用前景。采用LS-DYNA显式动力学软件建立了该结构的有限元分析模型,对这种新型阻尼结构的低速冲击性能进行数值模拟,并将数值模拟结果与实验数据进行比较以说明模拟方法的有效性。结果表明这种新型复合材料阻尼结构的抗冲击性能大大优于相同材质的复合材料结构。     

填充物、胶膜和Z-pin对复合材料T型接头强度影响对比

为提高复合材料T型接头结构的拉伸强度,对接头中胶膜属性、圆弧区填充物属性和Z-pin增强三种结构参数对T型接头强度的影响进行了研究。设计了两种不同胶膜属性、两种不同填充材料和有无Z-pin的同尺寸试验件,完成拉伸试验,测得极限位移和极限拉伸强度,并进行了对比分析,同时研究了不同T型接头的损伤演化过程。结果表明：J299胶膜复合材料T型接头的极限位移和极限载荷相比于J116B胶膜分别提高了57.8%和64.7%;ZXC195增强芯复合材料T型接头的极限位移和极限载荷相比于单向带材料分别提高了51.7%和30.3%;Z-pin钉对复合材料T型接头的极限位移和极限载荷分别提高了190.8%和31.9%。三种结构参数均只影响接头的极限载荷和极限位移的大小,接头的整体刚度没有改变。胶膜属性对接头极限载荷的提高影响最大,而Z-pin对接头的极限位移提高影响最大。     

Hybrid laser-Metal Inert Gas welding of Al–Mg–Si alloy joints: Microstructure and mechanical properties

Hybrid fiber laser-Metal Inert Gas (MIG) welding is an advanced joining technology that is increasingly employed in the modern industry. In this paper, hybrid fiber laser-MIG welding was applied to join 5 mm thick AA6005-T5 alloy used in the carbody of high-speed railway vehicles. The mechanical properties of the hybrid welded joints were investigated. The results showed that the hybrid welded joints have more excellent mechanical properties than that of the MIG joints. However, there is still strength loss in the hybrid welded joins comparing with the base metal. The reason for the loss of the strength was studied from the aspects of microstructure and vaporization of strengthening elements.     

Investigating the mechanical properties of sisal/coconut palm hybrid fiber reinforced epoxy composite

In this study, a facile hybridization of sisal/coconut palm reinforced epoxy composite, is presented. The fabrication method involved the use of hand lay-up techniques. The results of the fabricated composites were investigated by using the universal testing machine, hardness testing machine, scanning electron microscope, and an impact testing machine. In order to obtain optimize results for the tensile, flexural, and impact strengths of the fabricated samples, the fabrication procedures involved varying the volume fractions of sisal and coconut palm hybrid with different compositions. The maximum tensile, flexural, and impact strengths measured for the fabricated fiber/polymer composite, are: 45 MPa, 90 MPa, and 38.9 kJ/m². The scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS) of the composites showed that the composites with equal volume fractions of sisal and coconut palm fiber exhibited better performance and better mechanical properties. Furthermore, the improved mechanical properties such as hardness, tensile strength, flexural strength and impact strength were obtained with fibers of longer length. By considering the excellent mechanical properties of the fabricated composite, it is envisaged that the composite be suitable for the manufacturing of helmet, automobile and train coach interiors.     

基于响应面法的复合材料疏散平台轻量化设计

在城市轨道交通中,疏散平台是在列车故障或其他异常情况下能够确保迅速、有序地从隧道内组织乘客尽快疏散至安全区域必备的安全通道。复合材料具备轻质、高强、可设计性强和防火等优异性能,因此被逐步应用于疏散平台上。鉴于工程应用中对复合材料轻量化要求的不断提高,在满足材料强度和结构变形的基础上,达到减轻结构质量的目的,本研究根据现有的复合材料疏散平台,对其变形和强度进行了分析,据此定义优化变量,以其质量、强度和整体变形为目标函数,基于响应面法多目标寻优思想,探讨了目标函数和优化指标的函数关系,经比较选出合适的方案,并对选取的方案做了进一步的验证。结果表明,结构优化后复合材料疏散平台在保证强度和整体变形的情况下,质量显著减少。