Carbon Fibre Axle (CaFiAx)

CaFiAx项目的目的是尽量减少使用碳纤维增强塑料的铁路轴的质量，以减少轨道损坏和列车二氧化碳排放。重载列车造成高二氧化碳排放和轨道损坏。然而，趋势是增加轨道车辆的重量，需要更大的能量来推进和轨道上更大的负载。轨道车辆的2个转向架占列车总质量的41%（~40吨）。两个轮对（1轴/2轮）安装在每个转向架框架。重要的是，轮对（~1000公斤）与轨道直接接触。当车轮在轨道表面滚动时，轨道上的间隙和不规则（或车轮上的平坦）会像锤击一样产生冲击损伤。在欧洲，每年超过250亿欧元用于维护和更新22万公里的轨道基础设施。在英国，网络铁路（GB铁路）维护着20000英里的轨道，并要求火车运营公司支付轨道使用费。火车越重，收费越高。网络铁路认识到轻型轮对可能节省的维护费用，并为该项目提供技术支持（网络铁路支持函（LoS））。此外，基础设施维修导致轨道关闭、乘客延误和更严重的道路拥堵。很少有人尝试减轻轮对的重量。钢轴轻量化的最佳做法是在中心钻孔。Lucchini RS，一家国际轮对制造商，报告了一个钻孔铁路轴的质量为200公斤。只有使用密度较低的材料才能进一步降低质量。CaFiAx项目引入了CFRP铁路轴，其重量至少比钢轻65%。将220级Voyager列车（34节车厢，4节车厢配置）的车轴从钢制改为碳纤维复合材料（CFRP）将为列车运营商每年节省超过560万英镑的轨道通行费。CFRP管是由围绕圆柱形芯轴滚动的cf -环氧“预浸料”织物制成的。每一层（铁路轴为60层以上）厚度在0.25到0.50毫米之间。该层由碳纤维组成，通常取向为0度（平行），+/-45度或90度（垂直）的管轴。一旦固化，层不能再分开，成为复合层压板。纤维方向控制着轴的刚度和动力性能。值得注意的是，cf -环氧复合材料的比疲劳强度是钢和钛的3.5倍，而密度分别比钢和钛低75%和60%。CaFiAx项目的成功取决于四个目标的实现：-目标1：创建TALON，一个用于优化管状复合材料轴和轴的计算工具。-目标2：生成CFRP管在四点反向弯曲条件下的疲劳强度特性数据集。-目标3：生成连接金属环与CFRP管的粘结强度特性数据集。-目标4：使用TALON与商业有限元分析软件包（Abaqus）协同作用，制作质量优化的CFRP铁路轴的全尺寸有限元模型。CaFiAx解决了旋转轴的基本需求：通过设计满足强度要求（目标1、2和4），并实现了动力传输的元件连接（目标3）。必须先满足这些基本要求，然后才能解决更高层次的需求，如冲击、粗暴处理、动态性能、成本、制造、替代材料等。欧盟认识到需要一种轻型轮对。他们提出并资助了NEXTGEAR: wp3 -未来轮对（NEXTGEAR: 881803）。预计Horizon Europe将继续提供资金。重要的是，CaFiAx项目团队向NEXTGEAR提供了所有概念和结构复合材料设计，并为英国的进一步开发做好了准备。NEXTGEAR的合作伙伴Lucchini意识到了这一点，并支持CaFiAx (Lucchini LoS)，劳斯莱斯也看到了航空发动机变速箱（Rolls-Royce LoS）的应用机会。

The aim of the CaFiAx project is to minimise the mass of railway axles using CFRP to reduce track damage and train CO2 emissions.Heavy weight trains cause high CO2 emissions and track damage. The trend, however, is towards increasing rail vehicle weight, requiring greater energy for propulsion and more intense loading on the rails. The 2 bogies of a rail vehicle account for 41% of the total train mass (~40 tonnes). Two wheelsets (1 axle/2 wheels) are mounted in each bogie frame. Importantly, the wheelset (~1000 kg) is in direct contact with the rail. Gaps and irregularities in the rail (or flats on the wheel) initiate impact damage, like hammering, as the wheels roll across the track surface.In Europe, more than EUR25 B/yr is spent maintaining and renewing the 220,000 km of track infrastructure. Within the UK, Network Rail (GB Railways) maintains 20,000 miles of track and requires the Train Operating Companies to pay track access charges. The heavier the train, the higher the charge. Network Rail recognise the maintenance savings possible from a lightweight wheelset and offer their technical support to the project (Network Rail Letter of Support (LoS)). Additionally, infrastructure repairs cause track closures, passenger delays and greater road congestion.Few attempts have been made to lightweight the wheelset. Best practice for steel axle lightweighting is to bore the centre. Lucchini RS, an international wheelset manufacturer, report a mass of 200 kg for a bored railway axle. Further mass reductions are possible only by using a lower density material. The CaFiAx project introduces a CFRP railway axle that is at least 65% lighter than steel. Changing the axles on the Class 220 Voyager fleet (34 off, 4 car configuration) from steel to CFRP would save the Train Operator over £5.6 M/yr in track access charges alone.A CFRP tube is made by rolling CF-epoxy "prepreg" fabric around a cylindrical mandrel. Each layer (60+ for a railway axle) is a ply of between 0.25 to 0.50 mm thick. The ply comprises carbon fibres typically oriented at 0 deg (parallel), +/-45 or 90 deg (perpendicular) to the axis of the tube. Once cured, the plies can no longer be separated and become a composite laminate. The fibre directions control the axle stiffness and dynamic properties. Notably, a CF-epoxy laminate has ~3.5 times the specific fatigue strength of steel and titanium while being 75% and 60% less dense than steel and titanium, respectively.Success of the CaFiAx project relies on fulfilment of 4 objectives:- Objective 1: Create TALON, a computational tool for the design optimisation of tubular composite axles and shafts.- Objective 2: Produce a dataset of fatigue strength properties for CFRP tubes under 4-point reverse bending conditions. - Objective 3: Produce a dataset of bond strength properties for joining metallic collars to CFRP tubes. - Objective 4: Produce a full-scale finite element model of a mass optimised, CFRP railway axle using TALON synergistically with a commercial finite element analysis software package (Abaqus).CaFiAx addresses the fundamental needs of a rotating shaft: strength requirements are met through design (Objectives 1, 2 and 4) and elements attachment is achieved for power transmission (Objective 3). These essential requirements must be met before addressing higher order needs such as impact, rough handling, dynamic behaviour, cost, manufacture, alternate materials and others. The EU recognise the need for a lightweight wheelset. They proposed and funded, NEXTGEAR: WP3-Wheelset of the Future (NEXTGEAR: 881803). Continued Horizon Europe funding is expected. Importantly, the CaFiAx project team provided all concepts and the structural composite design to NEXTGEAR and are well placed for further, UK exploitation. Lucchini, a NEXTGEAR partner, realise this and support CaFiAx (Lucchini LoS), as do Rolls-Royce who see application opportunities for aeroengine gearboxes (Rolls-Royce LoS).